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DCS ANALOGUE TO DIGITAL CONVERTER dCS 904 User's Manual

1. Single Dual or Quad AES dCS 904 ensiviy Regea Reference Our ain MAINS FUSE 2A T ON OFF R 06 6 e a O Oe z HAL CHZ R CH CH SDIF 2DSD Remote of 75R ut ce m HO I J Je JEG aes Ss EI Analogue source dCS 992 AES 1 a 3 eo 8 3 a E ee 69 amp cel Mam Fuse AT On oe ole E Figure 5 Syncing a dCS 904 to a Master Clock Make sure A SL Autoslave is On and DSD is set to Off dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Storing DSD on an 8 track 16 44 1 PCM Recorder dCS 904 MAINS FUSE2A T ON OFF e gt je Digital VO To 8 channel 44 1kS s 16 bit recorder Analogue source Figure 6 Storing 2 channel DSD on an 8 track 16 bit 44 1 kS s PCM recorder Set DSD to On and DSD 4 to On P3D units only Set DSD to DSD 4 set AES O to On Six Channel PCM Set Up Analogue source CH2 CH1 24 96 Dual AES Channels 1 amp 2 MAINS FUSEZAT ON OFF Sensiiviy Reen e Reference Oui AEST e Zm Scan El US QOIS 2 AO ee MASTER 24 96 Dual AES Channels 3 amp 4 MAINS FUSEZA ON OFF e EE AEE e I
2. Figure 2 Front Panel The dCS 904 uses a combination of front panel buttons for frequently changed functions and a step through menu for features you might set and forget Sample Rate Multiplier The 2 buttons on the left side of the front panel select the sample rate Press the Sample Rate button repeatedly to cycle through the sample rates in the order 192 176 4 96 88 2 48 44 1 32 192 ete To step through more quickly press the Multiplier button repeatedly to cycle through in one of the following sequences depending on the starting sample rate 48 96 192 48 96 192 a etc 44 1 88 2 1764 441 882 176 4y etc To change sample rates quickly use the two buttons together For example to change from 176 4 kS s to 192 kS s press Sample Rate once then Multiplier once Do not press the buttons too fast as a delay is built in to the software The sample rate selected is shown on the LED display in the centre of the panel Mute The Mute button forces a mute in addition to the automatic ones The digital outputs are automatically muted at power up and when the sample rate is changed or the unit is locking to a reference source A forced mute is indicated by the mute LED above the mute switch lighting up In normal use pressing the Mute button mutes the digital outputs and lights the mute LED Pressing the Mute button again unmutes the ADC as long as no automatic mute
3. ees 21 33 Mara y senio setae litri tdem bes 72 Serial Number eene 11 Website sit act cry suits tenia feist teal 77 Signal generator EE 20 60 VE 62 Software issue 20 79 dE 41 Software updating een 71 weighting Fs nb iot a terii es 41 65 Support calling TO is aset deir esu TT Word Clock alignment In tO OUt eee 37 T Word clock daisy chain 11 Word length reducton 64 Temperature ambient 63 Temperature internal 63
4. 21 Generator mHz resolution 21 R Generator lest eee ient 21 Reference daisy e ET BEE 10 dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCS Ltd June 2000 Reference active ini dia ette citi 15 Temperature operating ss 63 Reference Input eot sees 10 Temperature rise in rack 63 Reference termination 10 Termination reference input 10 9 232 dre ett 11 53 71 U RS 232 address sssssseeeeeererrnsrnree 22 27 RS 232 cable format 11 Unlocking front panel essess 23 RS 232 daisy chaining 11 53 Updating manuals scenerne 71 RS 232 example eeneg 55 56 Updating software taki Ee EEN 71 RS 232 remote control suuss 55 RS 232 updating software by 71 V S VCXO frequency adjustment 23 31 VCXO initial accuracy sees 31 SACD E2 Sp6c noii cte dn 32 VCXO Long Term Stability 31 SACD E3 Spee onr e a a 32 VCXO re calibration cen 72 SACD full Scales eects 33 VCXO Temperature Gtabilty 31 sample lU 37 VCXO EE 68 Sample alignment AES3 in to out 39 MD 68 Sample alignment AES3 to Word Clock 37 SDIF 2 EE 33 50 Ww SDIF 2 Message 51 vera jeans 72 SDIF 3 format
5. c Digital VO 24 96 Dual AES Channels 5 amp 6 Reference Out AEST AESZ Hin MAINS FUSE 2A T ON OFF 21 aa aal Ia oe TI e S fo AIO ee Figure 7 Six channel set up without a Master Clock The top dCS 904 needs to have its Ref In option set to Int The middle one should be set to Loop and the bottom one should be set to oop t The units self align quite accurately see Sample Alignment on page 37 onwards Alternatively word clock may be used as the syncing method with no special set ups dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Storing 6 channel DSD on a 24 track 16 44 1 PCM Recorder dCS 904 ga NL Cd ck QE e j Digital VO dCS 904 MAINS FUSE A T ON OFF 8 HE To 24 channel 44 1kS s 16 bit recorder dCS 904 MAINS FUSE2A T ON OFF 3 Analogue source Figure 8 Six channel DSD recording on a 24 track 16 44 1 kS s recorder Make sure DSD 4 is turned on from the menu The top dCS 904 needs to have its Ref In option set to Int The middle one should be set to Loop and
6. Product EE 2 Formats 2 Syncing 2 Functions 2 Test Generator 2 Ease of Use 2 Mel gv 4 About this Manual 5 Using Your dCS 904 For The First Time eren 6 Product Overview 6 What s in the Box 6 Mains Voltages 6 Installing Unit in a Rack 7 Getting Started 8 The Hardware Controls and Connectors eene 10 Rear Panel 10 Balanced Analogue Inputs 3 pin XLR female 2 off 10 Input Level Adjustment trimmers 10 Reference In 3 pin XLR female 10 Reference Out 3 pin XLR male 10 AES1 2 3 amp 4 Digital Outputs 3 pin XLR male 4 off 10 SDIF DSD CH1 CH2 Data BNC 2 off 10 SDIF DSD CIk In BNC 11 SDIF DSD CIk Out BNC 11 Remote In amp Out 9 pin D type male 2 off 11 Mains Supply 3 pin IEC CEE22 11 Additional Information 11 Serial Number 11 Front Panel 12 Sample Rate 12 Multiplier 12 Mute 12 Word Length 12 Noise Shaping Menu 12 Overload Level Menu Sige 13 Overload Indicator Overload LED 13 ADC Data Menu SIS 14 Master Slave Menu BoA 14 Output Format Menu ie 15 Mode Display 15 Sample Rate Display 16 The Software the Menu mmrrnnvnvvnnnnnnnnnnnnnnnvnnnnnnnnnvnnnnnnnnnnnnnnnnnnnnnnnnnennnnnnvnnnnn 18 Overview 18 Entering the Menu 18 Moving through the Menu 18 The Menu Sequence 19 Menu Items 20 Issue 20 Filt 20 DSD 20 DSD 4 or AES O for P3D units 20 DSDO 21 Tone 21 Test 22 7 Seg 22 Heat 22 Phone 22 Part 22 S No 22 RS232 22 BNC O 22 dCS 904 Use
7. The PLL is very robust and will lock to very poor signals if necessary Data is decoded using a much wider band faster PLL so AESS type low frequency jitter on the input clock can be handled and will be cleaned If you need to synchronise several items of digital equipment we recommend using a dCS 992 Master Clock dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 DSD DSD Overview DSD is a single bit very high sample rate 2 822 MS s format where the single bit words are heavily noise shaped to push noise energy above audio The frequency response is very high well above 100 kHz although at these ultrsonic frequencies noise is also present The dCS 904 offers a number of different DSD modulators as Filter options All the modulators in have the same signal frequency response They differ in the way they shape the out of band Q noise and in how far they suppress the in band Q noise Filters 1 to 5 suppress Q noise at least 120 dB below the nominal 0dB DSD signal which is one of the marketing specs for SACD Filter Comments SQNR Stability Description 20 kHz dB 1 High SQNR high stability 126 14 1 710 Two complex Zeros 2 High SQNR 127 23 8 2 10 Two complex zeros 3 High SQNR very high 124 66 1 5 10 Two complex stability zeros 4 Extremely high stability 122 07 3 010 Two complex zeros 5 Reduced 100k noise 122 27 T5407 Two complex zeros 6 Single complex zero 1
8. d xxx Temporary display during locking the unit has detected the base reference sample rate and is attempting to lock to it XXX Temporary display during locking the unit is lining up word clock out to word clock in Important error messages are given below a full list is given in the section Error Codes and Messages on page 74 dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCS Ltd June 2000 BadFs The clock source is not in pull in range or is poorly formatted The unit cannot lock to it Err xy An error has been detected Please refer to Internal Device Error Codes on page 74 for more specific details on error codes Hot The unit is overheating probably due to inadequate ventilation Please check positioning and cooling Ouch The Hot warning has been ignored and the unit is getting so hot damage may follow blank If the display is completely blank for any significant period try switching off for 10 seconds then switching on again If this does not solve the problem contact your distributor or dCs The display is also used for MENM options dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCS Ltd June 2000 THE SOFTWARE THE MENU Overview The dCS 904 has many other functions that either need to be accessed only occasionally or are informative in nature These functions can be accessed either by the Remote software running on a PC and connected
9. they are either passed through where this is sensible or generated and inserted by the unit See section AES3 AES EBU Format on page 47 for more details The enhanced AES EBU interface is fully implemented Each channel has its own parity and data validity bit as well as User and Channel Status messages Cyclic Redundancy Counts CRC s are generated from the Channel Status message The Dual AES interface allows a 96 or 88 2 kS s 24 bit signal to be coded as two standard 48 or 44 1 kS s 24 bit AES data streams recorded as four channels on a recorder with standard capacity replayed and decoded back into a single data stream channel pair SDIF 2 used for PCM data has its message bits internally set to zero with the exception of the block code which is implemented See section SDIF 2 on page 50 for more details DSD has at the time of writing no messaging structure over SDIF 2 or SDIF 3 Messaging for P3D is allowed for but not defined yet Contact dCS for more details dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 AES3 AES EBU Format Message Handling The AES EBU interface transmits a data structure that conforms to the dCs version of AES3 1992 This contains 28 bits of Manchester encoded data and a 4 bit near Manchester encoded preamble in a subframe and subframes are further assembled in a block and frame structure Each subframe contains e preambles to allow the
10. 10 secs then Flash Erased quick then Programming Flash At this stage a progress bar with a count down time is displayed showing how much time is left 30 mins or so After this has counted down the PC says Done and the ADC reboots itself Depending on the nature of the software update it unit may then need to re initialise its internals if it does it will say Hold on its front panel Do not do anything at this stage Then when that message disappears it will be back to normal use dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Hardware Update or Calibration You may wish to have your unit updated occasionally 4CS offer this service we will install any modifications or hardware updates that have occurred since your unit was first shipped and give the unit a full retest to current standards including re calibrating its VCXOs which drift over time The price will depend on the hardware changes necessary so contact your dealer or us In order to ensure speedy turn around please contact us prior to returning the unit Warranty Your dCS 954 is guaranteed for a period of 12 months against faulty workmanship or materials Warranty repairs should only be carried out by dCS or an authorised distributor This warranty will be invalidated if the unit is misused or tampered with in any way Safety and Electrical Safety There are no user serviceable parts inside the dCS 904 and so there is no n
11. 44 1 kS s dCS 904 User Manual dCS Ltd Manual for Software Version 1 5x and 1 36 June 2000 AES3 in and out are related as below where they are at the same sample rate and the AES3 input is used as a sync source The alignment is better than 40 nsecs Input is at the top of the displays output is at the bottom Signals are at the sockets on the dCS 904 and the unit was slaved to AES Ref In Ze running 1 2 00 Vv div BH lim 3 500 V i 2 10 00 1 1M dc i i Nr MX UE i 2 2 00 Widi v HBH lim 4 000 V 10 00 1 1H dc 1 0000 us 0 000 s 1 0000 us 200 ns div repetitive Trigger Mode Edge E f 2 184 V Figure 20 AES3 in to AES3 out 96 kS s Ze running 1 2 00 Vv div BH lim 3 500 W 10 00 1 1M dc 12 200 w div 2 5000 us 0 000 2 5000 us 500 ne div repetitive Trigger Mode Edge E 4 2 184 V Figure 21 AES3 in to AES3 out 44 1 kS s dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 AES3 data out is also related to the phase of word clock in The scope shots below were taken with the unit sync d to Word Clock Ze running 1 2 00 V div BH lim 2 500 W 1 000 1 1M dc 2 00 V div 1 0000 us 0 000 s 1 0000 us 200 ns diw repetitive Trigger Mode Edge 1 f 678 1 mv Figure 22 Word Clock in to AES3 out 96 kS s Ze running 1 2 00 Vv div BH lim 2 500 1 000 1 1M dc 2 00 Vv div 2 500
12. structure of 256 stereo samples rather than the 192 of AES EBU There are 8 bits of message per channel per sample with a further 3 bits being used for an illegal code based sync code Of the 8 bits per sample the 8 in the first sample are reserved for system messaging and the rest are for User messages The 4 wires are Ground return Left Channel Right Channel Word Clock The sync codes can enable data recovery without the word clock if necessary but with the number of data formats in current operation this method of locking is strongly discouraged The waveforms below SDIF 2 waveforms data and word clock at 44 1 kS s and 96 kS s Ze running 1 2 00 Vv div BH lim 3 500 Vv 1 000 1 50 dc 2 2 00 V div os 1 000 V 10 000 us 0 000 10 000 us pl on 2 00 us div repetitive Trigger Mode Edge 1 1 500 V Figure 31 SDIF 2 PCM format at 96 kS s dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Ze running 1 2 00 Vv div BH lim 3 500 V 1 000 1 50 dc 2 2 00 Vv div pos 1 500 V d 1 000 1 50 dc 25 000 us 0 000 s 25 000 us pl on 5 00 us div repetitive Trigger Mode Edge 1 2 500 V Figure 32 SDIF 2 PCM format at 44 1 kS s SDIF 2 Messaging The SDIF 2 message is given in the table following The dCS 904 implementation sets all bits of the User message to 0 DESCRIPTION Definition Default Message Undefined 0000 Oxxx
13. 0000 Oxxx Emphasis No emphasis XXXX XOOx XXXX XOOx Emphasis 15usec 50usec XXXX XOTX Dubbing Prohibit Dubbing allowed XXXX XXXO XXXX XXXO Dubbing inhibited XXXX XXX 1 Block Code Start of block XXXX XXXX 1 as required Not start of block XXXX XXxx 0 as required Table 10 SDIF 2 Message Table dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 DSD on SDIF 2 SDIF 2 can be used for DSD The waveforms appear quite different to PCM format However they do produce transitions where the illegal code transitions were and for this reason we advise against locking to the illegal transitions in SDIF 2 Ze running 1 2 00 V div BH lim 3 500 V 1 000 1 50 dc uu pi 4 2 2 00 v div pos 5 000 V 000 1 50g dc HL Ve FR HAI 25 000 us 0 000 os 25 000 us pl on 5 00 us div repetitive Trigger Mode Edge 1 1 500 V Figure 33 DSD using SDIF 2 electrical format DSD on SDIF 3 SDIF 3 embeds a clock in the SDIF 2 data stream and so does not need word clock It is used only for DSD it is not used for PCM Contact SONY for more details dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 RS 232 Remote Control Interface Overall Description dCS 9xx units can be controlled using a simple serial protocol via the RS 232 ports using the control format described below All commands available from the front panel and a few o
14. DSP 04 Error initialising DSP for coefficients 05 Error initialising DSP for coefficients 06 Error loading DSP coefficients 07 Error loading DSP coefficients 08 Error sending command 09 Error sending command 10 Error sending command 11 Error sending command 12 Error with LSB MSB configuration 13 Error with LSB MSB configuration 14 Error with LSB MSB configuration 15 Error configuring FPGA 99 DSP error Table 13 Internal Error Codes If you get any of these please contact dCS with as much information as possible to help us re create the problem Some of these may have hardware problems as their cause some may have software dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 System Messages and Error Codes Some other messages may be displayed that give indications of errors from other sources outside the unit Display Description n Aud The data has been flagged by an AES3 message as non audio perhaps a CD ROM This message may also be displayed briefly when the sample rate is changed Hot The unit is overheating and performance may suffer Ouch The unit is seriously overheating and should be turned off before damage occurs Bad Fs The sample rate coming in is not one the unit can lock to or there is an input signal quality problem Table 14 System Error Codes Trouble Shooting Your System If you experience difficulties when using your dCS 904 the fo
15. Figure 36 Truncation Only Spectra dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 OPTIONS Mains Voltage We ship with the mains wired according to the destination The voltage option should be specified when the unit is ordered by specifying the country of use It can be updated later by your dealer if necessary Video Frequency VCXOs We can fit additional video frequency VCXOs enabling frequencies such as 44 056 kS s and 47 952 kS s These are best fitted at dCS to allow full checking P3D DSD Pro and Other Formats We can fit larger FPGAs to allow P3D DSD Pro and other formats This has to be done at dCS Ordering Options For A New Unit To order any option just tell us dCS 904 for use in lt country gt with options IMPORTANT Always specify the intended country of operation otherwise we will assume that country of delivery is the same as country of operation Having Your Options Changed dCS support modifications updates and option changes to supplied dCS 904 units If you are in any doubt please contact your Distributor or dCS In general these will be carried out at dCS because we have extensive test facilities and can verify the changes IMPORTANT Please do not attempt the changes yourself The unit s performance and reliability may be impaired and the warranty will be invalidated dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs
16. Ltd June 2000 Manual part no DOC 135904 iss 2B2 Page 69 135904ma2b2 pdf file available from website Contact dcs on 44 1799 531 999 email to more Qdcsltd co uk inside the UK replace 44 with 0 web site www dcsltd co uk dCS 904 User Manual dCS Ltd Manual for Software Version 1 5x and 1 36 June 2000 MAINTENANCE AND SUPPORT Hardware Service amp Maintenance dCS audio products are designed not to need regular maintenance and contain no user serviceable parts there are no moving parts there are no short life or wear out parts used the units have no holes through which liquids or contamination can normally enter no dust deposits build up to degrade performance All parts are replaceable or upgradeable by dCs for a period of at least five years from the date you purchased your unit If your unit is damaged in some way please contact your Distributor or dCs User Changeable Parts IMPORTANT There are no user serviceable parts inside the case Routine maintenance is not necessary and repairs are generally carried out by dCS since this allows us to thoroughly verify the results before shipment There is a mains fuse in the mains socket accessible from the outside of the unit This may be changed by the user The current consumption of the unit is very low 150 mA at 110 V so it only blows if there is a fault usually if the unit is set to its low voltage setting 100 120V but has been plugged into a hig
17. MODE Response gt ACK immediate 4 actual mode Transmit gt 5 REQUEST DSD MODE Response gt ACK immediate 5 actual mode The system should now be set up with the Master Clock configured for 44 1k operation and the ADCs and DACs locked in P3D mode dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Command name Command Number of Parameters Parameters in Command RS_AUTO_SLAVE 0 do not automatically slave 1 automatically slave to a reference input First parameter 1 Master 0 Slave If slave second parameter 0 AES 2 SDIF Global Command Select Output Fs Select Filter 0 3 Select De emphasis filter to use 0 Auto 1250 15 2 CCITT 3 None 0 Output SDIF wordclock on w cik out 1 Output AES on w clk out No of output bits 16 24 3 7 MEC NES SI NE NUN Noise shaper 0 Auto 1 Off 2 1st Order 3 3rd order 4 9nth order RS_MASTERSLAVE 0 Normal mode e g D in A out for DAC A in D out for ADC 1 D in D out 0 Low speed output e g Dual 88 2 Quad 192 EE High speed option HO vre Mute 1 Turn off automatic input selection ER DAC 1 Turn off 7 segment display 0 Set CR format for DACs 0 Auto 1 Single wire 2 Dual Wire 4 Quad 0 Enable 4 wire DSD outputs ae 1 SE 4 wire DSD outputs 1 Flip channels SAT i a giai E RS FINE LOCK MODE Es
18. Size and Weight 62 Operating Conditions 63 General Technical Information rrnnnnnvnnrennnnnnnnnnnnvnvnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnenn 64 Word Length Reduction 64 What does it look like 66 Eea E 68 Mains Voltage 68 Video Frequency VCXOs 68 P3D DSD Pro and Other Formats 68 Ordering Options For A New Unit 68 Having Your Options Changed 68 Maintenance and Support scene REELLE ELLLER 70 dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Hardware 70 Service amp Maintenance 70 User Changeable Parts 70 Software 71 Installing New Software 71 During An Update 71 Hardware Update or Calibration 72 Warranty 72 Safety and Electrical Safety 72 TFOUDIOSNOOTIING BE 74 Error Codes and Messages 74 Internal Device Error Codes 74 System Messages and Error Codes 75 Trouble Shooting Your System 75 The unit fails to power up 75 The audio output is low or absent 75 The level trimmers on the rear panel do not change the input level 75 The Left and Right channels are swapped 75 One output channel is low or absent 76 Clicks or crackles occur on the outputs 76 The unit fails to slave to a Master Clock 76 The unit slaves to Word Clock but not AES EBU 76 The Overload indicator will not go out 76 External meter does not show overload dCS 904 does 76 AGS SUP POM E 77 wish 77 If You Need More Help 77 Other Information 77 Indexes and Software Version N
19. a linear supply so these changes are kept to a minimum Power consumption is independent of mains voltage selector switch setting Power Consumption with Mains Voltage measured as AC power into mains socket Nominal mains 25 W Mains 10 22 W Mains 10 27 W The actual intended supply voltage is shown on the rear panel 50 Hz or 60 Hz operation is not important the unit can use either In general users will not need to change the mains input configuration If you do need this to be done please see the section Having Your Options Changed page 68 in this manual and contact your distributor or dCS Size and Weight The dCS 904 dimensions correspond to a standard 2U 19 rack mount case Four heavy duty feet fitted to the base extend the overall height to slightly greater than 2U Dimensions Width 430mm see note i Height without feet 44 mm 2U Height with feet 52 mm Depth 390 mm see note ii Weight 6 8 kg see note iii note i Removable 19 rack mount ears are supplied taking total width to 483 mm 19 note ii Measured from front panel to rear panel connectors Additional depth should be allowed to accommodate cable connectors note iii The high quality case is necessarily heavy consideration should be paid to appropriate support shelving when installing the units in a rack dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Operating Conditions The dCS 90
20. dCS 904 The noise shaper plots above are all on the same vertical scales for easy comparison and the vertical grid is approximately 1 bit per grid line Note that for the audio band 9 order noise shaping at 176 4 kS s or 192 kS s gives huge gains 8 bits or more This means that recording these formats on 8 channel 44 1 kS s or 48 kS s recording machines that store only 16 bits is quite practical and there is in practice very little quality loss dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Digital Interface Specifications AES EBU AES3 Input Output Type Balanced differential Impedance 110 110 Q Sensitivity unloaded 1 10 gt 5 V pk pk Maximum Wordlength 24 24 bits Damage level gt 20 V pk pk Connector XLR3 female XLR3 male Connections Pin 1 Ground or shield Pin 2 Signal Pin 3 Signal Table 6 AES EBU i o specifications SDIF 2 SDIF 3 and Input Output DSD Type Single ended ground referred Impedance 100 25 Q Sensitivity unloaded TTL TTL Maximum Wordlength 24 24 bits Damage level gt 10 V pk pk Time skew Wordclock in out lt 50 ns Connector BNC x 1 BNC x 3 Connections CH1 left CH2 right Wordclock In amp Out Table 7 SDIF 2 SDIF 3 and DSD i o specifications Remote control interface Input Output Type RS 232 Level RS 232 Baud Rates 1200 2400 4800 Data Format See page 53 Connector 9 way D type male Table 8 Remote C
21. e o CHYL CH2 R e _Wlerence out MAINS FUSE2AT ON OFF e Digital 1 0 P3D out CH3 amp 4 PCM Meter feed for Ch 1 amp 2 dCS 904 sensitivity CH1 L CH2 R MAINS FUSE2A T ON OFF e 1 PCM Meter feed for Ch 3 amp 4 dCS 992 AES 1 AES 2 AES 3 AES 4 e Mains Fuse 2AT On Off Ki External syne UE Remote letz Gt ls AES EBU Outputs ja P3D out CH5 amp 6 Analogue source dCS 904 sensitivity MAINS FUSE2AT ON OFF e CH1 L CH2 R dCS 904 ensi seen gg Reference Out MAINS FUSE2AT ON OFF e CH1 L CH2 R Ol e Figure 10 8 Channel P3D DSD Set Up PCM Meter feed for Ch 7 amp 8 Four P3D capable 4CS 904 units and a Master Clock can be used as above to give 8 channel DSD with additional simultaneous AES3 PCM outputs to give level monitoring on PCM equipment dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Manual part no DOC 135904 iss 2B2 Page 29 135904ma2b2 pdf file available from web
22. for double speed AES at 88 2 kS s or 96 kS s Use AES1 AES2 or AES3 AES4 for dual AES 88 2 kS s or 96 kS s or 176 4 kS s or 192 kS s Use all of AES1 AES2 AES3 AES4 for quad AES 176 4 kS s or 192 kS s For DSD see the DSD section Note that all the outputs are active simultaneously on the dCS 904 If the mode the unit is in needs them to be different they will be otherwise they will be the same and may all be connected to external equipment simultaneously if required Now you will need to familiarise yourself with how the front panel controls and the menu system work Read the short section on The Software the Menu on page 18 so you know how the buttons and menu work You may also find it convenient to refer to the Quick Start Guide while you are getting to know the unit dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Manual part no DOC 135904 iss 2B2 Page 9 135904ma2b2 pdf file available from website Contact dcs on 44 1799 531 999 email to more Qdcsltd co uk inside the UK replace 44 with 0 web site www dcsltd co uk dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 THE HARDWARE CONTROLS AND CONNECTORS Rear Panel Sensitivity CH1 CH2 R Reference In GNR eu o ou CHi L CH2 R ce e S Digital VO Reference Out AES1 AES2 AES3 AES4 Quot C
23. in DSD can re pack it Test Generator High quality 160 dB signal generator with mHz resolution Can be noise shaped truncated Ease of Use e Remembers last settings e Lockouts e Software upgrade able without opening the box e Can be remote controlled from PC dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Manual part no DOC 135904 iss 2B2 Page 3 135904ma2b2 pdf file available from website Contact dcs on 44 1799 531 999 email to more Qdcsltd co uk inside the UK replace 44 with 0 web site www dcsltd co uk dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCS Ltd June 2000 CONTENTS Product Features eec nui aa eaae tur reas dete h a taceo viue Sad Ce Bo RA TO TNR ERE EAT 2 pella apte EE dl 4 About this Manual 5 Using Your dCS 904 For The First Time rrnnrnrnnnnnvnnnnnnnnvnnnnnnnvnnnnnnnennnnnnnnvensnnnner 6 Product Overview 6 What s in the Box 6 Mains Voltages 6 Installing Unit in a Rack 7 Getting Started 8 The Hardware Controls and ConnectOrS rrurrssvvnnnnnnnvnnnnnnnvnnnnnnnnvnnnnnnnnnnnr 10 Rear Panel 10 Front Panel 12 The Software the Menu mmrrnnnnvvnnnnnnnnnnnnnnnvnnnnnnnnnvnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnvnnnnn 18 Overview 18 The Menu Sequence 19 Menu Items 20 Typical ApplicationS ernnnnnnnnnnnnvnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnvnnnnn 24 Using a dCS 904 to output DS
24. in parallel beware is internally driven with the same signal as AES 1 A SL Turns Auto slaving On or Off When set to On connecting an AES EBU reference or a word clock in causes the unit to slave and lights the Slave LED If both are present the unit picks the highest priority one AES EBU unless the Master Slave button is used to move down the priority list When set to Off the unit does not react when a reference is connected Offst Trims the appropriate VCXO frequency in master mode by up to 9 9ppm in 0 1ppm steps Use the JJ and SRY buttons to change this setting hold a button down to accelerate the change The trim is remembered Loc Panel Lock normally Off Set to On to prevent unauthorised changes using buttons The menu has to be accessed to turn the lock off again End Exits the menu dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 TYPICAL APPLICATIONS Using a dCS 904 to output DSD Analogue source DSD Out MAINS FUSE 2A T ON OFF e a i Qi CE Digital 1 Figure 4 DSD output configuration Set DSD in the menu to On Most likely check your other equipment you will need word clock Make sure BNC O is set to CL64 Select your filter P3D units only Set DSD to P3D or DSD4 instead of On as required Using a Master Clock to Sync a dCS 904
25. is being applied Word Length Noise Shaping Menu ERA The AES EBU format accommodates data up to 24 bits If a shorter word is needed and the extra bits are just ignored the result is typical digital sound due to the abrupt chopping off of the low level signal information To avoid this the dCS 904 allows proper truncation of the data and uses Noise Shaping to maintain low level performance See the section on Word Length Reduction on page 64 for some background on this If you do use word length truncation make sure that Noise Shaping is not set to OFF without realising it dCS 904 User Manual dCs Ltd Manual for Software Version 1 5x and 1 36 June 2000 Pressing the Word Length button repeatedly cycles the word length through the sequence 24 23 22 21 20 19 18 17 16 24 etc The Word Length is briefly shown on the main display and if a setting other than the maximum is set the word length LED above the button lights Noise Shaping is a technique which improves the noise performance of the ADC in the audio band by moving the quantisation noise energy introduced by reducing the word length from one part of the spectrum to another It keeps it out of the middle of the band where the ear is most sensitive and places it at the top end or ultrasonic region where the ear is less sensitive or insensitive See section Word Length Reduction on page 64 for more background Pressing the Noise Shaping butto
26. is the Isb of the output word for CDs it is at the 16 bit level which equates to about 90 dBO The level is high enough to be quite audible and the effect must be tackled to make reasonable quality end product There is really only one way of tackling the problem another signal has to be added to the wanted one to smooth the staircase transfer function that truncation causes Mathematically with two signals present the transfer function that the wanted signal sees is the convolution of the PDF of the second signal and the staircase function The converse is also true the transfer function the additional signal sees is the convolution of the PDF of the wanted signal and the staircase function This aspect is not a problem with the dither types considered below but it can be with some highly frequency shaped dithers The trick is to make the second signal as inaudible as possible It is usually referred to as dither and it is usually noise like because then its statistics can be controlled and the converse effect of the signal modulating the dither can be made insignificant or zero However there are a number of ways that this dither signal can be generated and treated The major options are e generate it from the signal or generate it independently and add it Dither It seems implausible that the dither signal can be generated from the signal but it can and this gives the lowest added noise power option It is nois
27. set press the ETT button again if you wish to continue cycling through the Menu There is a knack in doing this easily once it has been gained it becomes very easy to use the functions it accesses dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 The Menu Sequence To access the Function Menu hold down the Menu Step button and press the Menu Set button To step through the Menu items press the Menu Step button repeatedly To step back press the Noise Shaping button To select an item or one of its options press the Menu Set button To exit the Function Menu either select the End item or wait five seconds Displays the Selects an Selects DSD Enables DSD Function Menu fitted software alternative ne on AES 1 4 issue number filter XLR outputs Opens the Filt 2 Displays the Disables the 7 Runs a display internal segment display and DSP self temperature when idle test routine Turns on and Selects DSD sets a test tone SDIF format Fahrenheit Celsius Freq kHz On Off Up sSDIF2 SDIF3 Displays dCS Displays the Displays the Displays and Sets the mode telephone control PCB control PCB sets the unit s of the 75R Out number part number serial number RS232 address connector dCS002540 0002 540 Trims the Locks out the Automatically Sets the mode Exits the mastermode front panel slaves when ref of the AES Ref Function Menu VCXO contr
28. the Y subframe preamble The scope shots below were taken in Master mode Ze running 1 2 00 Vv div BH lim 2 500 V 1 000 1 50 dc i i i 2 2 00 w div BH lim 4 000 V EEES NE EE ROSEN EEE Sage Joe eRe ee 1 0000 us 1 0000 us repetitive Trigger Mode Edge 1 f 678 1 mv Figure 16 Word Clock and AES3 outputs 96 kS s Ze running 1 2 00 V div BH lim 2 500 W 1 000 1 50 dc 2 2 00 V div BH lim 4 000 10 00 1 1M de 2 5000 us 0 000 8 2 5000 us 500 ne div repetitive Trigger Mode Edge 1 f 678 1 mv Figure 17 Word Clock and AES3 outputs 44 1 kS s When word clock in is used as a sync source in and out are related as below The lower waveform is the output the upper one is the input The misalignment is less than about 40 nsecs The scope shots below were taken with the unit sync d to Word clock in dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Ze running 1 2 00 Vv div BH lim 2 000 V 1 000 1 1M dc 2 2 00 Vwv div BH lim 5 500 V 1 000 1 50 dc 1 0000 us 0 000 s 1 0000 us 200 ns div repetitive Trigger Mode Edge 1 1 500 V Figure 18 Word Clock in to Word Clock out 96 kS s Ze running v div 000 V Le Leg Gras ga reg Ar A BRC Fa e Vd ee Me de idiv S00 V 50 dc 2 5000 us 2 5000 us 500 ns div repetitive Trigger Mode Edge 1 1 500 V Figure 19 Word Clock in to Word Clock out
29. the input on the destination equipment for the Left channel data probably labelled AES 1 AES A or Left and AES 2 or AES 4 output is connected to the input on the destination equipment for the Right channel data probably labelled AES 2 AES B or Right See the manual of the destination equipment for information dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 e In Quad AES mode ensure that AES 1 2 3 amp 4 outputs are correctly connected to the corresponding inputs on the destination equipment See the manual of the destination equipment for information One output channel is low or absent e Check that all cables are connected correctly and not damaged Damaged cables are a VERY common source of malfunctions e Check that the balance is not offset elsewhere in the system e If the level trimmers on the rear panel have been adjusted check that one has not been set much lower than the other Clicks or crackles occur on the outputs e Check that all cables are connected correctly and not damaged e Check that the overload LED does not light The unit fails to slave to a Master Clock e Press the Master Slave button to select Slave mode If a suitable reference is connected the LED should light and the unit should lock after a few seconds e Check that the Reference In or 75R In cable is connected correctly and not damaged e Check that the Master Clock is switched on set to the right s
30. the other menu buttons MIKE type on the front panel it is the D I button Pressing the Output Format button repeatedly causes the output format to cycle through the allowed options from the sequence Single AES Dual AES Quad AES Single AES etc If any format is not available at that sample rate it is skipped from the sequence Mode Display The single digit LED mode display to the right of the Format button shows the output format Display Output Format 0 DSD mode AES outputs turned off 1 Single AES 2 Dual AES 3 P3D mode 4 Quad AES or 4 wire DSD Table 2 Output Data format indication higher sample rates When the Output Format is selected the main display briefly shows the format code dCS 904 User Manual dCs Ltd Manual for Software Version 1 5x and 1 36 June 2000 IMPORTANT Al for Single AES Standard speed encoding bl for Single AES Double speed encoding b2 for Dual AES Standard speed encoding C2 for Dual AES Double speed encoding C4 for Quad AES Standard speed encoding If an invalid combination is selected e g Single AES at 192kS s the invalid combination will flash e g C1 then be replaced by the nearest available combination In Single AES mode the same data stream is available on all four AES outputs In Dual AES mode two sets of identical data streams are available on AES1 amp 2 and AES3 amp 4 outputs In Quad AES mode the data stream uses all fo
31. 0 us 0 000 s 2 5000 us 500 ne div repetitive Trigger Mode Edge 1 f 678 1 m Figure 23 Word Clock in to AES3 out 44 1 kS s dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Noise Shaping The dCS 904 uses noise shaping that is optimised to the E weighting curve It does not affect signal frequency or transient response but shapes the frequency response of errors Q noise or truncation errors so that they fall as much as possible in the less sensitive part of the spectrum The architecture used also shapes dither where this is added For all the major sample rates 32 kS s 44 1 kS s 48 kS s 88 2 kS s 96 kS s the noise shapers have been individually optimised and the first 10 orders are offered The 1 3 and 9 shapes for 44 1 kS s agree well with Wannamaker s published results Noise Shaping adds more noise power but because of the shaping it is perceived as lower noise There is a compromise to be drawn as more aggressive shaping is used more noise is added and less perceived improvement occurs In practice things stop improving much above the 9 order The increased real noise power can cause small clicks in editing if this is carried out after the shaping For this reason noise shaping should be used as late as possible in the mastering process we recommend recording at the very highest possible sample rate and resolution and only reducing either at the latest poss
32. 00 e g E 100 00 D g E 120 00 140 00 160 00 180 00 10 100 1000 Q Noise rel Full Scale DSD dB 100 120 140 160 180 200 220 240 260 280 0 1 Frequency kHz Figure 13 DSD output Filter responses Integrated Q Noise Spot Q Noise for DSD Filters F Weighted in 400 Hz bandwidth 20 1 ae wW EEE x F2 0 Ka F3 20 i F F5 M F6 60 FT 80 SEER F weighting curve right hand scale 100 120 140 160 180 1 10 100 1000 Frequency kHz Figure 14 DSD output Filter responses F weighted Spot Q Noise F weighting dB dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Power Spectrum v1 50 ADC DSD filters 0 10 Filt1 20 Filt2 i 32k FFT H6 window effective noise Filt3 bandwith per bin 200 Hz 30 Fit4 Filt5 40 Filt6 50 Filt7 Amplitude dB 4 e 100 110 120 130 140 1000 10000 100000 Frequency Hz Figure 15 DSD output with analogue and Q spot noise dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Sample Alignment The dCS 904 aligns samples such that word clock out aligns with AES3 samples out the rising edge of word clock aligning with the start of the first illegal code in the X Z subframe preamble and the falling edge aligning with the start of
33. 1 999 email to more Qdcsltd co uk inside the UK replace 44 with 0 web site www dcsltd co uk dCS 904 User Manual dCs Ltd Manual for Software Version 1 5x and 1 36 June 2000 INDEXES AND SOFTWARE VERSION NUMBERS This manual is for standard software version 1 5x and P3D unit software v1 36 v1 5x differs from v1 3x in having substantially improved DSD modulators and in having a more friendly menu structure with readback on current settings without having to change the settings Definitions of Units dBo dBu dBV kS s ADC DAC DDC Level in decibels referred to a full scale sine wave in a sampled system So 0 dBO is full scale Level in decibels referred to a 0 775V rms sine wave with no external loading u unloaded The level of 0 775V is derived from the older dBm for which the reference level is 1mW of signal power into a 6002 termination from an output with 6002 source impedance Level in decibels referred to a 1 0V rms sine wave with no external loading Sample rate in kilo samples per second This replaces kHz which is technically incorrect when referring to sample rates Analogue to Digital converter also known as an AD Digital to Analogue converter also known as a D A DSP operations that change the data Digital to Digital converter used for format conversion and some dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Full Contents
34. 10 78 3 7 10 Single complex zero 7 Real zeros 101 5 2 0 10 Real zeros only Table 3 DSD Filter Summary Signal to Q Noise and SACD Specs Although 120dB SNR over the 0 20 kHz band is a good target it does not match the ears response that well The F weighted curve is currently accepted as a good model for the ear and we can use this to weight the noise produced by the various filter choices Such a weighting is shown in Figure 14 on page 35 DSD gives very good performance using such a weighting better than 23 bit pcm The figure shows that filter 6 and 7 give more F weighted Q noise suppression in the audio band than filters 1 to 5 Filter 6 gives around 20 dB more suppression than filters 1 to 5 under all circumstances and filter 7 gives 20 dB more suppression below 10 kHz SACD specifies ultrasonic noise in two bands These are specs informative specs E2 and E3 and filter performance for a number of specs including these are given below The measurements given have been made using a Fourier Transform based method 3 Super Audio CD System Specifications Part 2 Audio Specifications available from Philips System Standards and Licensing Licensing Support Building SFF 8 PO Box 80002 5600 JB Eindhoven The Netherlands dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Filter Comments SQNR SQNR E2 spec E3 spec 20 kHz F weighted dB dB dB dB 1 High SQNR 126
35. 14 136 56 25 98 28 96 high stability 2 High SQNR 127 23 138 76 25 85 28 95 3 High SQNR 124 66 134 38 27 32 30 49 very high stability 4 Extremely high 122 07 129 91 25 54 29 53 stability 5 Reduced 100k 122 27 130 14 27 13 31 99 noise 6 Single 110 78 151 02 25 19 23 55 complex zero 7 Real zeros 101 5 132 41 25 29 27 04 SACD Spec 20 00 28 00 Table 4 DSD Filter Performance DSD Full Scale The SACD standard sets 0 dBO for programme material 6 dB below the peak to peak level one might expect a full scale sinewave to occupy This ensures that artefacts that begin to occur at the limits of the DSD frequency range stay well away from the audio band and is shown in Figure 11 on page 34 The dCS 904 complies with this standard If the unit is set up for full scale PCM and then switched to a DSD format the levels will be correctly set to meet SACD standards DSD Mute A DSD mute is unlike a PCM mute which is 00000 because with only two levels there is not a single value that sets the output in the middle of the range In all DSD formats except P3D the dCS 904 outputs 010101010101 as a DSD mute For P3D it outputs 01101001 as a P3D DSD mute DSD Overload Behaviour DSD is more benign than PCM under overload conditions In the overload region the performance gradually and gracefully degrades The size of this region depends on the modulator used but in general a modulator with a high
36. 16 bit truncation with 4 8 dB 4 8 dB All noise Triangular dither modulation and unpleasant effects removed but noise floor is high 16 bit truncation with 4 8 dB 1 2 dB All noise Noise Shaped modulation and Triangular dither unpleasant effects removed Not much perceived noise penalty 16 bit truncation with 3 6 9 dB 10 5 dB Okay with input order noise shaping and noise floors down to no dither 102 dB 16 bit truncation with 3 11 0 dB 9 2 dB Unconditionally free order noise shaping and from truncation Noise Shaped effects with all Triangular dither inputs 16 bit truncation with 9 23 4 dB 17 9 dB Okay with input order noise shaping and noise floors down to no dither 120 dB 16 bit truncation with 9 28 2 dB 16 7 dB Unconditionally free order noise shaping and from truncation Noise Shaped effects with all Triangular dither inputs Table 12 Dither and Noise Shaping Noise Powers Straight forward dither always adds noise it can only produce signals with a noise floor higher than Q noise on its own However the noise power added is a few dBs for simple types Noise shaping adds rather more noise but it can be made to add it in parts of the spectrum that the ear is less sensitive to so the perceived noise F weighted noise is lower up to three bits lower It results in a signal that the ear hears as having a far lower noise floor than a 16 bit truncated signal rather than the not much
37. 3 out 96 kS s sssssssssseeeeenee 39 Figure 21 AES3 in to AES3 out 44 1 KS S ssssssssseeeeeenee 39 Figure 22 Word Clock in to AES3 out 96 kS s u u ssseeneeeeeeernn nerne 40 Figure 23 Word Clock in to AES3 out A41k is renerne 40 Figure 24 1 Order Noise Shapers implemented on dCS 904 42 Figure 25 3 Order Noise Shapers implemented on dCS 004 42 Figure 26 9 Order Noise Shapers implemented on dCS 904 43 Figure 27 AES3 format at 48 kS s over 16 metres eens 48 Figure 28 AES3 format at 48 kS s over 94 metres eee eee 48 Figure 29 AES3 format at 96 kS s over 16 metres eects 49 Figure 30 AES3 format at 96 kS s over 94 metres 0 eee eee ete 49 Figure 31 SDIF 2 PCM format at 96 kS s Gu u u usssseeeeernereer ennen ken en nn nerne en nen 50 Figure 32 SDIF 2 PCM format at A4 1k is kernerne renerne nere renee 51 Figure 33 DSD using SDIF 2 electrical format esesessssse 52 Figure 34 Temperature rise above ambient for a unit in a stack of 3 with poor ventilation i diete utet edt detulit uie 63 Figure 35 Noise Shaping and Dither Spectra sss 66 Figure 36 Truncation Only Spectra W W u u ssseeeeeererren ternene renterne rn kr renerne 67 Figure 37 Changing Mains Fuse keen sense ne ense nens sn ennen eks sn nnee 70 dCS 904 User Manual Manual
38. 4 has no ventilation slots or fan cooling It dissipates relatively low power so that usually allowing natural convection provides enough cooling in most circumstances It is sensible however to not install the unit near heat sources such as radiators hot air ducts or in direct strong sunlight Operating conditions should be such that internal temperature does not exceed 70 C substantially as read out from the internal temperature sensor see the menu function Heat on page 22 This will tend to be met if the ambient temperature is below 50 C although it will depend a bit on how the unit is positioned Internal temperature should not fall below 0 C and should be a non condensing The unit monitors its internal temperature and displays one of two error messages as the temperature rises At and above an internal temperature of 78 C the unit displays Hot on its front panel as a warning Performance and reliability will be degraded if operated in this range for long periods At and above 88 C the unit displays Ouch and should be turned off See section System Messages and Error Codes on page 75 Figure 34 below shows the rise of internal temperature for the middle unit of three stacked as in a rack with support plates between Allowing 3 cms between units gives reasonable cooling If in doubt the easy test is the dCS 904 is happy to work anywhere a human is dCS 9xx EXCESS TEMPERATURE Measured as dCs 954 Middle unit of 3 in b
39. CK 15 seconds 7 requested mode Transmit gt 8 DSD_MODE to change mode to PCM of unit 8 Responds gt ACK 15 seconds 8 requested mode Transmit gt 9 DSD_MODE to change mode to PCM of unit 9 Responds gt ACK 15 seconds 9 requested mode Command ADCs 2 3 4 and 5 to change mode the units may take up to 15 seconds to complete this command if the previous mode had been DSD the FPGAs need to be re loaded which takes time There is no need to wait prior to moving on to step 3 Transmit gt 2 DSD_MODE to change mode to PCM of unit 2 Responds gt ACK 15 seconds 2 requested mode Transmit gt 3 DSD_MODE to change mode to PCM of unit 3 Responds gt ACK 15 seconds 3 requested mode Transmit gt 4 DSD_MODE to change mode to PCM of unit 4 Responds gt ACK 15 seconds 4 requested mode Transmit gt 5 DSD_MODE to change mode to PCM of unit 5 Responds gt ACK 15 seconds 5 requested mode Check DACs for mode change This command allows the Transmitter to check the mode of the DACs If a unit has not changed the transmitter should go back to step 1 and repeat the command Transmit gt G REQUEST DSD MODE Response gt ACK immediate 6 actual mode Transmit gt 7 REQUEST DSD MODE Response ACK immediate 7 actual mode Transmit gt S REQUEST DSD MODE Response gt ACK immediate 8 actual mode Transmit gt S REQUEST DSD MODE Response gt ACK immediate 9 ac
40. D 24 Using a Master Clock to Sync a dCS 904 24 Storing DSD on an 8 track 16 44 1 PCM Recorder 25 Six Channel PCM Set Up 25 Storing 6 channel DSD on a 24 track 16 44 1 PCM Recorder 26 Operating Several Units on One Remote Chain 27 8 Channel P3D DSD Set Up with Monitoring 28 dCS 904 Technical Information rrrnnnnnnnnvvnnonnnnnnnnnnnnvnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnenn 30 Anti Alias Filtering 30 Clocking 31 DSD 32 Sample Alignment 37 Noise Shaping 41 Digital Interface Specifications 44 Analogue Input Specifications 45 Digital Data Formats Supported 46 AES3 AES EBU Format 47 SDIF 2 50 RS 232 Remote Control Interface 53 Power Consumption 62 Size and Weight 62 Operating Conditions 63 General Technical Information rrnnnnnvnnvennnnnnnnnnnnvnnnnnnnnnnnnnnnnnnvnnnnnnnnnnnnnnnenn 64 Word Length Reduction 64 Options aus sos ts a mudring i et Sis 68 Maintenance and Support rarnnnnnnnnnnnnvvnnnnnnnnnnnnnnnvnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn 70 Hardware 70 Software 71 Hardware Update or Calibration 72 Warranty 72 Safety and Electrical Safety 72 TroubleShooting rrt nra 74 Error Codes and Messages 74 dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Internal Device Error Codes 74 System Messages and Error Codes 75 Trouble Shooting Your System 75 ACS SUP POM EE NN EE Rg 77 wish TT If You Need More Help 77 Other Information 77 Indexes and Softwa
41. ENEE ce d edad 10 Figure 2 Front Panel 21 2 cce io reti ze Oo odde ce dera degkeet 12 Figure 3 Menu Sequence reiri REEE a EER EI EEE EE I 19 Figure 4 DSD output configuration sesseeeen enn 24 Figure 5 Syncing a dCS 904 to a Master Clock W u u u dvdsseeeeeeerereen kerne rren kernen 24 Figure 6 Storing 2 channel DSD on an 8 track 16 bit 44 1 kS s PCM rECOrden musea tetto t M e SE LER aka eere 25 Figure 7 Six channel set up without a Master Clock 25 Figure 8 Six channel DSD recording on a 24 track 16 44 1 kS s recorder 26 Figure 9 Multi unit Remote Daisy Cham 27 Figure 10 8 Channel P3D DSD Set Un 28 Figure 11 DSD showing DSD full scale rarannrrnnnonnrrnnnrnnrrnnnnnnrrnnnenrrnnrnnnnne 34 Figure 12 DSD Output Filter Responses Spot Q Noise 34 Figure 13 DSD output Filter responses Integrated ONoise 35 Figure 14 DSD output Filter responses F weighted Spot Q Noise 35 Figure 15 DSD output with analogue and Q spot nolse esserne 36 Figure 16 Word Clock and AES3 outputs O6Gkls rn nenene 37 Figure 17 Word Clock and AES3 outputs A4 1k is nenene 37 Figure 18 Word Clock in to Word Clock out 96 kS s sssssssssss 38 Figure 19 Word Clock in to Word Clock out 44 1 kS s sssssssss 38 Figure 20 AES3 in to AES
42. ES1 2 3 amp 4 Digital Outputs 3 pin XLR male 4 off Four AES EBU outputs which may be used independently or in groups of two or four They are used for the various PCM formats including normal and double speed and two and four wire and also for some DSD formats SDIF DSD CH1 CH2 Data BNC 2 off These BNC connectors can be both outputs and inputs In normal operation they are outputs for SDIF 2 encoded PCM or for SDIF 2 and SDIF 3 encoded DSD They are both TTL level signals for a 75 ohm line They can be set to TTL level AES3 coded signals using the menu see the BNC O command page 22 In addition they can be used for data input for re formatting DSD data under the control of the ADC Data button see page 14 dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 SDIF DSD Clk In BNC SDIF DSD Clk Out BNC This pair take in and give out Word Clock and can be set to Bit Clock for DSD The functions are set by the menu Clock In is terminated and Clock Out is regenerated internally so these lines can be used for daisy chaining many units together without loading problems See Figure 18 and Figure 19 for the time alignment of these signals Remote In amp Out 9 pin D type male 2 off If the Windows Remote software is in use connecting Remote In to a com port RS 232 port on a PC running the Remote Control program allows the unit to be controlled by the PC Remote Out may be connected t
43. O Figure 1 Rear Panel MAINS FUSE 2A T ON OFF Ki Analogue All input and output connectors are mounted on the rear panel Individual connectors are clearly identified by the panel legend Viewed from the rear from left to right the connectors are as follows Balanced Analogue Inputs 3 pin XLR female 2 off Input Level Adjustment trimmers Two multi turn potentiometers set the full scale input levels These are factory preset for full scale with input levels of 20dBu If necessary adjust with a suitable trim tool or a small screwdriver Turn clockwise for increased gain Take care to ensure the stereo inputs remain in balance The trim range is 6dB Reference In 3 pin XLR female Reference Out 3 pin XLR male Reference In is an AES EBU reference input for synchronising the unit to a Master Clock Reference Out is an unbuffered loop through directly coupled to it for use in a reference daisy chain A terminating resistor may be turned on or off using the menu see Ref In command page 23 if several units are to be daisy chained with the same word clock In addition under the control of the ADC Data button the Reference In connector can be used as a data input In this mode it takes data from the input instead of from the internal ADC and allows all the formatting and DSP functions such as noise shaping and word length control to be applied to input data See page 14 A
44. Use coarse lock RS_WAVETYPE E Signal Generator Off IRS AMP LE ee Amplitude format X RS FREQ Generator Frequency Specified as db 32 bit number Expressed as a fraction of Sample Frequency dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Command Number of Parameters Parameters Byte Parameters in in Command Response ka parameter is terminator AES unterminated i terminated second is reference mode 1 ref out is internal 0 pass through RS_OVLD_LEV 1 Overload threshold formatX RS_VOL Joa ae ent e Digital volume control formatX Phase 0 None inverted 1 Both inverted left inverted right inverted 2 SDIF 2 Clock word clock am SPDIF1 or AES3 Echos X X xX 1 DSD SDIF message 2 4 wire DSD IRS BAUD RATE 141 1 Globalcommand Noe XIX X X REQUEST DSD MODE 142 0 rspone DSDmode Yes REQUEST FREQUENCY 143 o response gt Frequency tunt ves Table 11 RS 232 Command Set Format X the level set number is 0 1dB times the 16 bit positive integer used So for example 260 would set 26dB below full scale for generator amplitude dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Power Consumption The dCS 904 has a linear power supply and so power consumption changes as the mains voltage changes The internal regulation is comparatively efficient for
45. ample rate and does not require re calibration e Connect a different piece of digital equipment to test the locking capability of the unit If the condition persists contact your Distributor or dCs The unit slaves to Word Clock but not AES EBU e This can be caused by erroneous system messages Contact your dealer or dCS for advice The Overload indicator will not go out e Remove any input and reference input If the condition persists contact your dealer or dCS the unit may be faulty External meter does not show overload dCS 904 does e The dCS 904 monitors a number of internal points and data word values in its calculation of overload This may cause it to indicate an overload while the final external data word may not show it for example with a very narrow but large spike that the low pass decimation filter may broaden out sufficiently that the output data does not saturate It is likely that if the dCs 904 says it is in overload it is You can choose to ignore it e Some digital meters are quite insensitive to overloads Such equipment may include a sensitivity setting where an overload is only flagged when a number of consecutive digital words saturate typically 1 2 4 or 8 consecutive samples There is some justification for this single saturation events are not always audible The dCS 904 flags their presence it is up to the recording engineer to decide what to do about it dCS 904 User Manual Manual for Soft
46. anual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Ze running 1 2 00 Vv div BH lim 3 500 V 10 00 1 1M dc 2 2 00 Vv div pos 4 000 V 10 00 1 ns dc 2 5000 us 0 000 s 2 9000 us 500 ns div repetitive Trigger Mode Edge E 15 35 V Figure 27 AES3 format at 48 kS s over 16 metres Ze running 1 1 00 diy BH lim 2 000 V i 10 00 1 1M dc I2 190 wvidiv pos 2 000 V 10 00 1 1M2 de 2 5000 us 0 000 s 2 5000 us 500 ne div repetitive Trigger Mode Edge E 15 35 V Figure 28 AES3 format at 48 kS s over 94 metres dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Ze running 1 2 00 Vv div BH lim 3 500 V 10 00 1 1M dc 2 2 00 Vv div pos 4 000 V 10 00 1 ns dc 7 CC IC 1 0000 us repetitive Trigger Mode Edge 1 0000 us E 15 35 V Figure 29 AES3 format at 96 kS s over 16 metres Ze running 1 1 00 Vidiv BH lim 2 000 Ul 10 00 1 1M dc 2 1 00 Vv div pos 2 000 10 00 1 IMs dc 1 0000 us 0 000 s 1 0000 us 200 ns div repetitive Trigger Mode Edge E f 15 35 V Figure 30 AES3 format at 96 kS s over 94 metres dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 SDIF 2 PCM Format The SDIF 2 interface is a 4 wire NRZ interface so the DC level on each signal line may not be constant It contains 20 bits of audio data and has a block
47. brightly and the Master LED will turn off To return to Master mode press the Master Slave button again If both AES Reference and Word Clock are connected pressing the Master Slave button cycles through the sequence Master AES Reference Word Clock Master etc dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 If the active reference source is lost the unit will select the next option in the sequence If the Auto Slave option in the Function Menu is turned On the unit will automatically slave when a suitable reference is connected If both AES Reference and Word Clock are connected AES Reference takes priority Word Clock may be selected by pressing the Master Slave button it moves down the priority list Once slaved the unit can internally multiply the reference input sample rate by 2 or 4 if required by pressing the Multiplier button The Master Clock must be set to a suitable sample rate Master Clock Sample dCS 904 Sample Rate kS s Rate kS s 32 32 44 1 44 1 or 88 2 or 176 4 48 48 or 96 or 192 88 2 88 2 or 176 4 96 96 or 192 Table 1 Reference Clock and Sample Rates For Menu operation as the Menu NG button see the section The Software the Menu on page 18 Output Format Menu DS The Output Format button is dual function on its own blue type on the front panel it sets the output format single dual quad AES etc With
48. ction and some reformatting available to it For normal operation this is set to ADC LED off In Data mode the ADC Data LED lights and the data stream on the AES Reference Input is output on the AES1 4 outputs If the Reference Input sample rate is 88 2 or 96kS s and the Output Format is Dual AES the input will be converted to Dual AES on AES1 amp 2 and AES3 amp 4 Data mode also affects the SDIF connectors BNCs in any DSD mode The data lines two of the four connectors become inputs and DSD fed into these is packed and re formatted into the output format selected No DSP is carried out For Menu operation as the S button see the section The Software the Menu on page 18 Menu pr The Master Slave button is dual function on its own blue type on the front panel it sets the clocking mode master or slave With the other menu buttons MIS type on the front panel it is the menu PN button In Master mode the calibrated voltage controlled crystal oscillators VCXOs inside the unit generate an accurate sample rate The LED labelled Master will be lit to indicate this If a Master Clock is available this may be connected to the Reference In connector for AES EBU reference or the 75R In connector for SDIF 2 Word Clock To slave the unit to the Master Clock press the Master Slave button The unit will attempt to lock to the Reference this will take a few seconds If lock is achieved the Slave LED will light up
49. d processed by a dCS 972 The equivalent simply truncated spectrum is shown in Figure 36 separately because it is so revolting In it we can see that at the signal level shown 90 dB error power from the quantising truncation is beginning to pile into the fundamental which is showing an amplitude error of 1 3 dB as well as all the unwanted harmonics This would show up on a conventional linearity plot although the sign of the error could be either way We see that the noise shaping approach maintains low noise in the critical audio mid band Noise Shaper and Dither Only Comparison dCS 972 SW v1 54 16 bit truncation Noise Shaped Triangular dither 16 bit truncation Top Hat dither eie 16 bit truncation high order noise shaping only 4 6 8 10 12 14 16 18 20 22 Frequency kHz Figure 35 Noise Shaping and Dither Spectra B for comparison with the table 10 and 9 order noise shaping are very similar dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Spectra of 90dB 24 bit sinewave truncated to 16 bits with dither options dCS 972 SW v1 54 60 24 bit source data 80 Josias 16 bit truncation no dither i 89 70 dB 16 bit truncated 91 00 dB source signal 100 a i Ki 1 2 T 3 Hei S A E 3 420 140 lt h H I f I A ape d Acl ae Aa I A la A nh M a Dal D MI LU AMA 0 2 4 6 8 10 12 14 16 18 20 22 Frequency kHz
50. dCS 904 Analogue to Digital Converter User Manual Standard Software version 1 5x P3D Software version 1 36 June 2000 1997 1999 2000 dCs Ltd All rights reserved Reproduction of this manual in any manner whatsoever without the written permission of dCS is strictly forbidden Additional copies of this manual may be obtained from dCs Information contained in this manual is subject to change without notice and whilst it is checked for accuracy no liabilities can be accepted for errors 1 dCS Ltd is Data Conversion Systems Ltd Company registered in the England no 2072115 dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 PRODUCT FEATURES Formats e DSD and PCM from 192 kS s down to 32 kS s Data formats supported are AES EBU XLR and BNC Dual AES XLR Quad AES XLR AES data at TTL levels and SDIF 2 PCM and DSD SDIF 3 DSD DSD packed into 4 AES links P3D option DSD packed into 3 AES links Syncing Operates in Master mode or can sync to Word Clock or AES reference or signal and sync to video option available Functions Very high performance ADC free from gain ranging High quality VCXO internal clocking in Master mode Multichannel Sync capability Noise shaping truncation 1 37 9 order High speed or dual AES 88 2 kS s 96 kS s Dual or Quad AES 176 4 kS s and 192 kS s Data mode can take in digital data in both PCM and noise shape truncate it and
51. dible Noise Shaping S P Lipshitz and R A Wannamaker J AES vol 39 no 11 p836 852 8 Psychacoustically Optimal Noise Shaping R A Wannamaker J AES vol 40 no 7 8 p611 620 dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Noise Amplitude dB Noise Amplitude dB 1st Order Noise Shape Plots 36 1 32 kS s 42 44 1 kS s 25 48 kS s ences 88 2 kS s 54 4 TT 96 kS s d 176 4 kS s 66 192 kS s 72 4 78 4 84 1 10 100 Frequency kHz Figure 24 1 Order Noise Shapers implemented on 4CS 904 3rd Order Noise Shape Plots 32 kS s 2 pr 44 1 kS s 48 g id SS ze A TTT TT ues 88 2 kS s 54 SS SE p eg UA ik 2 Hs obo esed 96 kS s A 176 4 kS s 66 4 192 kS s 72 4 784 84 J 1 10 100 Frequency kHz Figure 25 3 Order Noise Shapers implemented on dCS 904 dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Noise Amplitude dB 9th Order Noise Shape Plots 32 kS s ical 44 1 kS s Vossii 48 kS s i z EE RE 7 SE NE 88 2 kS s TTS x bete pop ST d TT esses 96 kS s sge A SES EIL p V 176 4 kS s Ee ele EEE EE TAS m uw 192 kS s N 4 4 Nad NZ 10 100 Frequency kHz Figure 26 9 Order Noise Shapers implemented on
52. e Shaping 12 18 41 66 Dither PDF gees edet 64 Noise audio band esses 33 DSD 11 14 16 20 22 32 33 65 68 Nolen imde taies tecla 32 65 RTR E HE 20 25 Noise ultrasonic rrrrnrnnrrarnnnrarevnrnnrrnnnnnnnnere 32 DSD Input 2 5 0 Rei etie 21 o DSD modulators seseseeeeess 32 DSD MULES uae 33 Operating conditions seeren 63 DSD overload capability 33 Overload indication 13 76 DSD P3D da estie ear eds 20 Overload LED 13 D9D 9DIE 2 intet titan 52 Overload level settng 13 DSD SDIE 3 nne eter 52 Overloads DD 33 F P Filter EIR usine ete eet 30 BCEE 5 68 Filte IR iiit ace er 30 P3D mut r eet beoe ive boots iiec 33 Filter selection Rane 20 Pants MOVING DEEN 70 Filter transient response 30 41 Parts short lte 70 Filters anti aliasing esses 30 Parts user serviceable 70 72 Format X rcs Age each d Zeg ees 61 PDCMmute eren 33 Front panel locking ssessss 23 PLL lock in me 31 Front panel unlocking sssss 23 PLL pull in range scenerne 31 Fuse maner 70 72 75 Power consumption nentes 62 EEE EE ere s 70 Q G Q noise DSD at eee bt eritis da 32 Generator frequency sssssseseeerkrrnnnnee 21 Qinolse POM nee ere 65 Generator level
53. e new frequency before any further RS 232 activity 6 Command Master Clock to change frequency Allow the system time to settle after this command with no RS 232 activity three seconds should be sufficient Transmit gt 1 SEL_FS change to 44 1k Responds gt ACK 3 seconds 1 requested frequency Wait for 3 seconds Check Master Clock has changed frequency If it has not go back to step 6 Transmit gt 1 REQUEST_FS request actual frequency Responds gt ACK immediate 1 actual frequency Command DACs 6 7 8 and 9 to change mode the units may take up to 15 seconds to complete this command if the previous mode had been PCM the FPGAs need to be re loaded which takes time There is also no need to wait prior to moving on to step 9 Transmit gt 6 DSD_MODE to change mode to P3D of unit 6 Responds gt ACK 15 seconds 6 requested mode Transmit gt 7 DSD MODE to change mode to P3D of unit 7 Responds gt ACK 15 seconds 7 requested mode Transmit gt 8 DSD_MODE to change mode to P3D of unit 8 Responds gt ACK 15 seconds 8 requested mode Transmit gt 9 DSD MODE to change mode to P3D of unit 9 Responds gt ACK 15 seconds 9 requested mode Command ADCs 2 3 4 and 5 to change mode the units may take up to 15 seconds to complete this command if the previous mode had been DSD the FPGAs need to be re loaded which takes time There is also no need to wait prior to moving on to ste
54. e shaping on its own but there are some circumstances where it needs help from additional dither e add inside or outside an error shaping loop e frequency shape to match the ears response or not One can use techniques that suppress error energy in the areas where the ear is sensitive and put it in areas where the ear is not sensitive Usually this shuffling around process costs something we remove a little from the sensitive areas and add back rather more in the less sensitive parts but that s life We still gain some improvements The table below gives the actual noise levels for 16 bit truncated signals with no dither various types of dither noise shaping on its own and noise shaping with dither The 0 dB reference level is taken as the minimum noise we could 10 PDF Probability Distribution Function References to Rectangular Dither or Triangular Dither refer the shape of the PDF of the dither Manual for Software Version 1 5x and 1 36 June 2000 dCS 904 User Manual dCS Ltd possibly get away with the amount that simple 16 bit truncation 16 bit Q noise would give if it were well behaved which it is not xTruncation Type Noise Noise Comments with 44 1 KS s data unweighted F weighted rate rel 16 bit Q rel 16 bit Q noise noise 16 bit truncation 0 dB 0 dB Unpleasant low level effects 16 bit truncation with 3 dB 3 dB Okay can show Top Hat dither noise modulation at low signal levels
55. e turned into inputs so that DSD data can be fed in and formatted Sample Rate Multiplier Mute Word Length Noise Shaping Overload Level and Output Format buttons do not work the Tone Generator does not work The Master Slave button works and the Auto Slave function see later in Menu Items works Filt works there are 7 filter options in DSD mode See the section on DSD starting on page 32 for more details they trade off in band and out of band noise DSD 4 or AES O for P3D units This function controls the use of the XLR connectors on DSD mode There are two options whose behaviour depends on whether the unit is a P3D unit or not Standard non P3D units Off The XLRs carry AES clock only On The XLRs carry DSD data packed into 4 AES3 links for storage on 16 bit 8 channel 44 1 kS s PCM machines non P3D units P3D units Off XLRs carry AES clock only dCS 904 User Manual dCs Ltd Manual for Software Version 1 5x and 1 36 June 2000 IMPORTANT DSD O Tone On XLRs carry either DSD 4 format or P3D format as set by he DSD menu item In P3D format where DSD to be packed into 3 AES3 links the 4 XLR output carries a PCM encoded signal for metering purposes to allow DSD to be recorded on existing 8 track 24 bit PCM recording machines at a lower than normal level This XLR control function is separate from DSD mode for safety reasons Because DSD into a PCM device can cause full scale noi
56. eed to remove the covers apart from front panel software updates If for some reason you do IMPORTANT Disconnect from the mains before removing any covers or changing the fuse There are no substances hazardous to health inside the dCS 904 dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Manual part no DOC 135904 iss 2B2 Page 73 135904ma2b2 pdf file available from website Contact dcs on 44 1799 531 999 email to more Qdcsltd co uk inside the UK replace 44 with 0 web site www dcsltd co uk dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 TROUBLESHOOTING Error Codes and Messages The error codes reported by dCS 904 provide an effective means to diagnose the majority of problems that may be encountered in use including problems with the overall system the unit operates in internal device warnings and internal device failures Please note that through damage or component failure the unit self check may fail to operate If this happens please contact your distributor or dCS for assistance Internal Device Error Codes Sometimes the unit may misbehave If there is an internal reason an internal device error code may be displayed as follows Err xy an error xy see table below has been detected where xy values have the following meanings Code Description 01 E memory EEPROM not present 02 Error initialising DSP 03 Error loading
57. eping the last settings At power up the generator is set to Off I kHz and 18dB0 as a safety measure When in use if the generator is turned Off the unit remembers the last frequency and level setting The generator frequency can be set to much finer 32 bit resolution using the RS 232 control See section RS 232 Remote Control Interface on page 53 for more details dCS 904 User Manual dCs Ltd Manual for Software Version 1 5x and 1 36 June 2000 Test 7 Seg Heat Phone Part S No RS232 IMPORTANT BNC O Runs a display and DSP self test routine When successfully completed the unit displays Pass and returns to normal operation Otherwise an error message Err xy is displayed please refer to Error Codes and Messages on page 74 for more specific information Disables the 7 segment LED display When set to Off the display turns off 4 seconds after the last button press A dot in the lower right hand corner of the display remains lit to indicate that the display has been deliberately blanked The display springs back into life temporarily if the menu is used subsequently Error or warning messages are displayed regardless of this setting Displays the internal temperature of the unit measured near the internal VCXOs Press Sl to toggle between Fahrenheit and Celsius See section Operating Conditions on page 63 dCS telephone number scrolls across the display The control board part
58. er stability will allow a larger overload region see Table 3 DSD Filter Summary The overload region may be several dB In the dCS 904 the signal level is digitally clamped about 1 5 dB above SACD OGB level dCS modulators recover from overload rapidly DSD Electrical and Data Structures Electrically for the SDIF 2 and SDIF 3 outputs TTL levels are used There is no framing or block structure and each channel uses one BNC connector The clock word or bit clock uses the third connector See Figure 33 on page 52 dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 DSD Format showing Full Scale Signal dCS 972 SW v1 54 1 5 4 0 5 0 0 5 1 1 5 0 50 100 150 200 250 300 350 400 450 500 Time usecs Figure 11 DSD showing DSD full scale DSD has only two levels printer artefacts make it look like more Spot Q Noise for DSD Filters in 400 Hz bandwidth 0 SET 20 F2 F3 E F4 40 F5 F6 m 60 F7 ZS 2 120dB in 20 kHz a A 80 2 3 2 100 Ej LL 9 o 120 2 o z 440 160 180 200 1000 Frequency kHz Figure 12 DSD Output Filter Responses Spot Q Noise dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Integrated Q Noise for DSD Filters normalised for Full Scale DSD at 0dB 20 00 F1 Lg 0 00 F2 F3 20 00 F4 ER F6 c 40 00 2 Er S 3 60 00 be o 2 9 80
59. eral DSD formats are all supported Multiple units may be slaved together for stable multi channel operation The unit is mains powered and is housed in a 1U 1 75 high 19 rack mounting case It may be controlled either from its front panel or from a software based remote control running on a PC via a com port The unit s last setting is automatically stored on power down so that fixed installations may be set up at leisure installed and then left alone Unauthorised alterations to settings may be prevented by a panel lock out feature The unit is highly software based and more functions and features are added from time to time Software updates from dCS are free Whats in the Box The contents of the box are at least dCS 904 User Manual Quick Start Guide Mains Lead 2 Spare Fuses Remote cable Remote software Mains Voltages The dCS 904 is shipped with its mains voltage preset for operation in the destination country The voltage is not intended to be changed by the user If it needs to be changed contact your dealer or dCs IMPORTANT The dCS 904 must be used with a mains earth free if we email them and you download from a PC com port Low cost if you ask us for EPROMs or other media we charge for media and handling dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Installing Unit in a Rack The unit is supplied with 19 rack mount ears fitted If it is to be mou
60. for Software Version 1 5x and 1 36 dCs Ltd June 2000 Keywords and Phrases A L ADC mode rann 14 21 LED ADG Data sakene 14 D RTE 16 46 75 LED Master una AEA 14 AES3 quad ii eii etes 16 76 LED mute oc etie bisce ier 12 anti alias filtering sees 30 LEID overload ci metis 13 76 RRE 14 B LED word eng 13 Button ADC Data a om ale rense nere bed 14 Locking front panel sss 23 Button master slave 14 23 76 M Button multiplier 12 15 B tton mule ae ten nti ab natt 12 Maintenance regular 1 70 Button noise Shaping ssssssss 13 Menu Back button 13 Button output Tomat 15 Menu Down button 14 15 18 Button overload level 13 Menu Set button 14 18 Button sample raie aeneae 12 Menu Step button 13 18 Button word engt 13 Menu Up button 15 16 D Mode ADG mun lege 14 21 Mode data 14 Daisy chain reference 1 seere 10 Mode master 14 31 Daisy Chain RS 232 11 53 Mode Slave zur daner bedre darat 76 Daisy chain word clock sssss 11 Mute Dee Raeren nee 33 Paa modo ee n a 14 Mute CR 33 dCS contacting WEE 77 Mute PCM 5e tede te ce 33 De emphasis ccccceceeeeeeeeeeeeeeeeeeeeeeeees 60 N Display mode ccceceeeeeeeeeeeeeeeeeeeeteees 15 BIEN 64 66 Nois
61. h voltage mains 220 240V Usually no other damage is caused but if the fuse blows repeatedly on replacement some other damage will have been done and the unit must be returned to dCS for repair Fuse Type 20 x 5mm 2 amp HRC fuse If the fuse should fail it is essential that it be replaced with one of the same type Failure to do so could result in damage to the unit and may invalidate the guarantee To gain access to the fuse remove the IEC mains connector use a small flat bladed screwdriver to pry up the tab on the fuse carrier and pull it out Push the fuse out of the clip in the carrier and replace it with a new one Push the carrier back into the unit so that it clicks home Remove Fit old fuse new fuse A MAINS FUSE 2A T ON OFF o N gt I o O no o Co Ses D gt o mit ee c o i aa Figure 37 Changing Mains Fuse Disconnect from the mains before changing the fuse dCS 904 User Manual dCs Ltd Manual for Software Version 1 5x and 1 36 June 2000 Software Installing New Software IMPORTANT During An Update Updated operating software can be downloaded via the RS 232 link from a PC comm port using the Windows Remote software running on the PC or can be copied from an EPROM installed internally Using the RS 232 download is hands free but takes about 40 mins per unit With special software contact dCS multiple units can be daisy chained together so that one PC can
62. hat there is no RS 232 activity for 3 seconds after the Master Clock frequency is switched to ensure all units have time to settle When operating in DSD mode units assume their reference clocks are operating at 44 1kHz f a different frequency reference is used they will continuously monitor the reference clock frequency preventing RS 232 accesses t is therefore important to ensure the reference clock is set to 44 1kHz prior to entering DSD mode and that DSD mode is left prior to changing the reference clock to another frequency Example Switching to 96k PCM The following example covers the system of nine units in two complex format changes Change the ADC and DAC operating mode to PCM prior to changing the Master Clock frequency Change the DAC operating mode prior to the ADC When changing the Master Clock frequency the system should be allowed to settle to the new frequency before any further RS 232 activity 1 Command DACs 6 7 8 and 9 to change mode the units may take up to 15 seconds to complete this command if the previous mode had been DSD the FPGAs need to be re loaded which takes time There is no need to wait prior to moving on to step 2 Transmit gt 6 DSD MODE to change mode to PCM of unit 6 Responds ACK 15 seconds 6 requested mode dCS 904 User Manual dCS Ltd Manual for Software Version 1 5x and 1 36 June 2000 Transmit gt 7 DSD MODE to change mode to PCM of unit 7 Responds gt A
63. ible minute If however you have to reduce word length the perceived noise gain taking into account the ear s response and the actual increase in noise mainly out of band in given in the table below Sample Perceived Actual Perceived Actual Perceived Actual Rate Gain F Increase Gain F Increase Gain F Increase kS s weighted in Noise Weighted in Noise Weighted in Noise 1 Order 4 Order 3 Order 3 Order 9 Order gt Order dB dB dB dB dB dB 32 3 3 1 9 7 5 4 2 8 1 6 1 44 1 5 5 2 4 10 5 6 9 17 9 23 4 48 6 2 2 5 11 7 7 6 21 0 23 8 88 2 11 1 2 8 23 8 11 3 42 2 24 0 96 11 8 2 9 25 7 11 3 45 3 22 5 176 4 17 0 3 0 40 6 12 6 63 0 21 8 192 17 7 3 0 42 8 12 6 65 9 21 8 Table 5 Noise Shaper Gain by Order and Sample Rate The 3 order shaping tends to follow the E weighting curve by chance The 9 order is very aggressive and can give very large gains at the higher sample rates For example 176 4 kS s or 192 kS s material truncated to 16 bits so it can be stored on a DA 88 or ADAT loses nothing in the audio band in terms of perceived noise with either 3 or 9 order shaping For more information on this topic either see section Word Length Reduction on page 64 or read the references below 6 it actually uses an Error Shaping architecture but the name is now being used for entirely other things and is less well known so we call it erroneously Noise Shaping Minimally Au
64. llowing suggestions may help to resolve the problem The unit fails to power up e Ensure there is power available on the mains cable and the units mains Switch is On e Check the rated supply voltage shown on the rear of the unit matches the local supply voltage e Check that the fuse has not blown if so correct any obvious cause then replace the fuse as described in the section User Changeable Parts e Check that the mains cable is pushed fully home into the mains inlet in the rear of the unit The audio output is low or absent e Check that all cables are connected correctly and not damaged Damaged cables are a VERY common source of malfunctions e Check that the source and destination equipments are switched on and correctly set up e Check that an audio signal is present on one or both of the inputs e Ensure Mute is not enabled LED off The level trimmers on the rear panel do not change the input level e Ensure the trim tool or screwdriver you are using is narrow enough to reach the adjuster about 2 5mm or 0 1 diameter and long enough at least 12mm or 0 5 e The trimmer may be at the end of its travel try turning it several times the other way It is a 20 turn device The Left and Right channels are swapped e Check that the audio input cables are not reversed e Check that the channels are not swapped elsewhere in the system e n Dual AES mode ensure that the AES 1 or AES 3 output is connected to
65. lters always have some ripple For zero ripple filters this is in the udB to pdB region dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Clocking The sample clock quality significantly determines the output performance of an ADC The highest quality clocks that are available are crystals so we use these In Master mode the dCS 904 uses one of two on board voltage controlled crystal oscillators VCXOs as clock sources one for 48 kS s related outputs and one for 44 1 kS s related outputs When an external clock is applied for Slave operation the internal VCXO is synchronised to this by a phase locked loop PLL The PLL is of a special narrow bandwidth type that provides a high degree of clock cleaning but even so signal quality may degrade if particularly poor slave clocks are used A consequence of the narrow bandwidth is that it takes quite a long time for the PLL to lock to a new clock frequency of the order of 2 seconds The PLL uses DSP assistance to keep this time acceptable Internal clock Accuracy when shipped 10 ppm Long Term Stability 10 ppm year at room temp Temperature Stability 15 ppm over operating temperature range The VCXO frequency can be trimmed by using the Offst function in the menu see page 23 each VCXO is independently adjustable Synchronising to source Pull in range 300 ppm about nominal frequency Lock in time 2 seconds for most situations
66. m of 9 units with ID s set up as noted 1 Master Clock ID 1 4 P3D compatible ADCs ID 2 3 4 and 5 4 P3D compatible DACs ID 6 7 8 and 9 RS232 operating at 1200 baud It is assumed that the transmitter operates on a round robin polling scheme and that each step completes before the next allowing for time outs Except in the case of a time out a unit should not be accessed within the response time of its previous command Within each step there is no need to wait for the command response time prior to moving on to the next unit once an acknowledge has been received the controller can safely assume that the unit is getting on with the command it has received and can move on to the next unit At the end of a step there is no need to wait before moving on to the next step Command strings are not given fully the parameter string and the checksum are not explicitly given A typical command is shown as ID Command Type information about command A typical response is ACK Type ID information when requested When changing the operating frequency of a unit the internal crystals are Switched lt is recommended that after a crystal switch units are allowed to settle for a short time 1 second to ensure optimum performance In this case the units are being controlled by a Master Clock so time should be allowed for this to switch and for the other units connected to it to also switch and begin to settle It is recommended t
67. n repeatedly cycles the unit through 5 noise Shaping characteristics The characteristic is shown briefly on the main display Auto Unit sets noise shaping automatically depending on word length 24 bits no noise shaping 20 to 23 bits 1 order noise shaping 16 to 19 bits 3 order noise shaping Off No noise shaping Ist 1 order noise shaping 3rd 3 order noise shaping 9th 9 order noise shaping The noise shaping LED above the button lights when the setting is other than Auto For Menu operation as the IIS button see the section The Software the Menu on page 18 Overload Level Menu JE The Overload Level button is dual function on its own blue type on the front panel it sets the level at which overloads are detected by the unit With the other menu buttons MAKA type on the front panel it is the menu BE button Overload detection is normally set to full scale The detection level may be reduced in 0 1dB steps down to 3dBO by pressing the Overload Level button repeatedly or holding it down The set level is shown on the display for a few seconds The overload level LED above the button lights when the setting is other than full scale 0 0dBO For Menu operation as the BE button see the section The Software the Menu on page 18 Overload Indicator Overload LED This overload LED lights for a few seconds when the set overload level is exceeded by a signal peak The detection circuitry mo
68. nitors both input and digital filtering circuitry for overload conditions The analogue input sensitivity trims mounted on the rear panel should be set so that the overload indicator does not light on signal peaks dCS 904 User Manual dCs Ltd Manual for Software Version 1 5x and 1 36 June 2000 ADC Data Master Slave The overload indication given by the dCS 904 is comprehensive The detection circuitry monitoring the digital filter does not simply check the final output word but all the data from which the output word is formed If any of these overload this may not be apparent from the output data an overload is flagged The filter itself has sufficient numerical accuracy that if the input data is not overloaded the filter computations cannot generate an overload only a raw data overload can cause an error The overload indication is thus much more accurate than any external meter based indication for this reason it is stored in the AES EBU validity bit for later reference Menu The ADC Data button is dual function on its own blue type on the front panel it sets the input mode analogue or digital With the other menu buttons type on the front panel it is the menu S button As an input mode switch it switches between the analogue inputs ADC mode or a digital input on the AES Reference input Data mode Data mode routes the digital input through to the outputs and makes noise shaping word length redu
69. nted in a 19 rack the ears supplied may be used to locate it in the rack and stop the unit sliding forward but they are not strong enough to support the unit IMPORTANT The ears should not be used as the only mechanical support The unit should rest on a Shelf or be supported in some other way The ears will just locate it in the rack and stop it sliding forwards If the unit is not to be rack mounted the ears may be removed dCS 904 User Manual dCs Ltd Manual for Software Version 1 5x and 1 36 June 2000 Getting Started Here s what to do If the unit does not behave the first time you power up contact your dealer or dCs Check the appropriate mains supply for your local mains is marked on the rear panel If it is using the lead supplied connect the unit to the mains connect no other leads at this stage and switch on The seven segment display will briefly show and then the sample rate for example Connect a signal source to the analogue inputs Connect an output eg from AES1 to your system or a DAC Press the Sample Rate button left hand end button to get the sample rate you want Press the Output Format button right hand end to get the format you want Set up like this the dCS 904 will operate in Master mode and the system it is connected to will have to lock to it You should have audio Use any of AES1 AES2 AES3 or AES4 as an output at 32 kS s or 44 1 kS s or 48 kS s or
70. number version scrolls along the display The control board serial number scrolls along the display You will need something to write this on if you call us for help Displays and allows access to the unit s RS 232 identity code an address between 0 and 99 This is used by the remote control software to send specific messages to specific units Use fj and BENA to change this address if you are operating several units in a multichannel set up Each unit in the daisy chain MUST be set to a different RS 232 address Sets the format of the 75 ohm BNC outputs and changes depending on whether the unit is in PCM or DSD modes In PCM mode the options are AES Sends out AES3 coded data but at TTL levels at up to 96 kS s on the Clk Out connector SDIF Sends out SDIF 2 encoded data with a word clock on the Clk Out connector In DSD mode the options are changed to CLI Sends out DSD data along with a bit clock on the Clk Out connector CL64 Sends out DSD data along with a word clock on the Clk Out connector dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Ref In Sets the mode of the AES Reference In Out connectors The options are Loop Loops the input through to the output with no termination resistor termination is then about 1kohm so several units can be daisy chained Loop t As above but terminates the input Use at the end of a daisy chain Int The output and input
71. o another suitably equipped dCs unit allowing several units to controlled by the same PC with one RS 232 daisy chain In addition the unit may be software upgraded without removing the lid by downloading new software via the Remote In port see Installing New Software on page 71 Connect up Remote ports using a 9 way screened cable fitted with 9 way D type connectors at each end wired pin 1 to pin 1 pin 2 to pin 2 etc The same type of cable can be used unit to units as com port to first unit Suitable cables are available from dCs Mains Supply 3 pin IEC CEE22 Switched fused and filtered IEC mains connector Additional Information As well as connectors the rear panel displays the following information about the unit near the mains supply connector Mains Voltage The actual voltage setting supplied Model Number dCS 904 Manufacturers Name and Country of origin dCS Ltd UK Serial Number The underside of the unit will have a label on that contains a number such as 904 4B1 6B2 2A1 3A2 12345 This is the serial number but it also contains vital configuration information We will need this number all of it to give you support over the phone or to ship you software updates dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Front Panel Sample Rate Multiplier Mute D dCS 904 Ato D Converter Data Conversion Systems
72. ols input available I O connectors frequency 9 9 9 9ppm Standard software v1 5x Some features are not available in DSD mode P3D software v1 36 P3D mode is only available on some hardware configurations Figure 3 Menu Sequence dCS 904 User Manual dCs Ltd Manual for Software Version 1 5x and 1 36 June 2000 Menu Items Issue Filt DSD Displays the software issue when F is pressed Selects one of several anti alias filter responses The filters should be evaluated by ear Filtl gives the sharpest cut off just below half the sampling frequency This is the normal setting Filt2 Filt3 Filt4 give progressively more relaxed responses degrading the alias performance but sharpening the impulse response This affects the stereo or multi channel image Different filters may be appropriate for different material Turns on DSD mode and in P3D units cycles through the DSD format options available Off On P3D DSD 4 When on the unit displays dSd The mode takes about 15 seconds to load during which time the menu cannot be used This mode is so different from PCM that most of the PCM related front panel buttons are no longer appropriate DSD is output on the BNC connectors and the following other changes occur XLR outputs are clock only unless DSD 4 or AES on P3D units is on see below the BNC O options change to CL 1 bit clock or CL 64 word clock ADC Data allows the SDIF connectors to b
73. ontrol Interface Details dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Analogue Input Specifications Balanced Inputs Type Balanced Format AES14 1992 Impedance 5 kQ 5 kO CMRR gt 100 dB spec gt 120 dB typ gt 108 dB typ gt 80 dB typ gt 74 dB typ Level for Full Scale 20 dBu as shipped Trim range 6 dB Connector type XLR3 female Connections Ground or shield Signal Signal Table 9 Analogue XLR Interface Details The analogue inputs are balanced not floating with a stable high common mode rejection ratio Either input may be used on its own with the other floating if single ended operation is wanted dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Digital Data Formats Supported The unit supports the following digital data i o formats AES EBU often referred to as AES3 PCM format Dual AES part of the AES3 spec PCM format for 88 2 kS s 96 kS s Quad AES for 176 4 kS s and 192 kS s High Speed AES part of the AES3 spec PCM format for 88 2 kS s 96 kS s Dual High Speed AES For 176 4 kS s and 192 kS s TTL AES AES3 on single ended TTL levels SDIF 2 DSD or PCM High Speed SDIF 2 for 88 2 kS s and 96 kS s SDIF 3 DSD only DSD using the SDIF 2 or SDIF 3 connector format For all AES3 type formats the incoming Channel Status and User messages are handled according to a priority system
74. ox with shelf plates Excess temperature deg C 0 1 2 3 4 5 6 7 8 9 Unit spacing cms Figure 34 Temperature rise above ambient for a unit in a stack of 3 with poor ventilation dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 GENERAL TECHNICAL INFORMATION Word Length Reduction Word length reduction truncation causes an error signal to be added to the wanted signal The error signal is usually referred to as Q noise or Quantisation noise the approximation is usually made that the errors are noise like This is reasonably true for large signals where the errors are very complex if they are not exactly noise like Importantly though for smaller ones it is not so As the wanted signal gets smaller the complexity of the error signal decreases The errors first of all pile into ever fewer lower order harmonics or intermods and then as the level of the signal sinks below the Q level the majority of the error power piles into the signal fundamental This causes its amplitude to become unpredictable it may drop abruptly to zero and disappear or it may cease to go down any more and just stay at a constant level From the audio viewpoint this sounds very unpleasant As a signal tail decays away the tonal quality changes and then it decays into distorted mush and then either abruptly stops or else keeps fuzzing away until a new signal starts The level at which all this happens
75. p 10 Transmit gt 2 DSD_MODE to change mode to P3D of unit 2 Responds gt ACK 15 seconds 2 requested mode Transmit gt 3 DSD_MODE to change mode to P3D of unit 3 Responds gt ACK 15 seconds 3 requested mode Transmit gt 4 DSD MODE to change mode to P3D of unit 4 Responds gt ACK 15 seconds 4 requested mode Transmit gt 5S DSD MODE to change mode to P3D of unit 5 Responds gt ACK 15 seconds 5 requested mode dCS 904 User Manual dCS Ltd Manual for Software Version 1 5x and 1 36 June 2000 10 Check DACs for mode change This command allows the Transmitter to check the mode of the DACs If a unit has not changed the transmitter should go back to step 8 and repeat the command Transmit gt G REQUEST DSD MODE Response gt ACK immediate 6 actual mode Transmit gt REQUEST DSD MODE Response gt ACK immediate 7 actual mode Transmit gt SJ JREQUEST DSD MODE Response gt ACK immediate 8 actual mode Transmit gt S REQUEST DSD MODE Response gt ACK immediate 9 actual mode 11 Check ADCs for mode change This command allows the Transmitter to check the mode of the ADCs If a unit has not changed the transmitter should go back to step 9 and repeat the command Transmit gt 2 REQUEST DSD MODE Response gt ACK immediate 2 actual mode Transmit gt 3 REQUEST DSD MODE Response gt ACK immediate 3 actual mode Transmit gt A REQUEST DSD
76. put data Once a signal has aliased it cannot be corrected However as far as the ear is concerned this may not matter The ear can tell the frequency of a signal up to a point As the frequency rises the accuracy with which the ear can tell what the frequency is decreases and above a limit all the ear can tell is that there is a signal and it is above KHz It can tell no more So it may be that some degree of aliasing is acceptable to the ear The filters that we have included give increasingly good energy smear performance and consequently have increasingly relaxed roll off FiLT1 gives the sharpest roll off with no aliasing but the worst energy smear Then as the number increases the smear decreases but the aliasing increases Try them to see which you prefer You may find that for different material different filters are appropriate and you may find that for different stages in the recording and mastering process different filters are appropriate The dCS 904 uses linear phase FIR filters to avoid the limit cycle problems that come with many IIR filters Linear phase gives filters a symmetrical transient response before and after a transient pre ringing The passband may or may not have a ripple depending on the filter being used The stop band is typically below 110 dB and can be as low as 130 dB See for example Principles of Digital Audio 3rd Edition by Ken C Pohlmann McGraw Hill Inc 1995 Fi
77. r Manual Manual for Software Version 1 5x and 1 36 June 2000 Ref In 23 A SL 23 Offst 23 Loc 23 End 23 Typical Applications EEN EEN ao ed 24 Using a dCS 904 to output DSD 24 Using a Master Clock to Sync a dCS 904 24 Storing DSD on an 8 track 16 44 1 PCM Recorder 25 Six Channel PCM Set Up 25 Storing 6 channel DSD on a 24 track 16 44 1 PCM Recorder 26 Operating Several Units on One Remote Chain 27 8 Channel P3D DSD Set Up with Monitoring 28 dCS 904 Technical Information rrrrnnnnnnnnvvnnonnnnnnnnnnnnvnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnenn 30 Anti Alias Filtering 30 Clocking 31 Internal clock 31 Synchronising to source 31 DSD 32 DSD Overview 32 Signal to Q Noise and SACD Specs 32 DSD Full Scale 33 DSD Mute 33 DSD Overload Behaviour 33 DSD Electrical and Data Structures 33 Sample Alignment 37 Noise Shaping 41 Digital Interface Specifications 44 Analogue Input Specifications 45 Digital Data Formats Supported 46 AES3 AES EBU Format 47 Message Handling 47 How Far will it Go 47 SDIF 2 50 PCM Format 50 SDIF 2 Messaging 51 DSD on SDIF 2 52 DSD on SDIF 3 52 RS 232 Remote Control Interface 53 Overall Description 53 Physical Interface 53 Timing Accuracy and Warnings 53 Transmit Message 54 Acknowledge Message 54 Example 55 Special Commands and Protocols 55 Command Streams 56 Example Switching to 96k PCM 56 Example Switching to P3D 58 Power Consumption 62
78. re Version Numbers rnrnnnnnnnnnnnnnnnnnnnnnnnnnnnnnsnnennnnnnnnner 79 Definitions of Units 79 Full Contents 80 Tables 83 Figures 84 Keywords and Phrases 85 About this Manual Note that there is a fuller Contents at the end of the manual page 80 along with an index and lists of figures and tables References to other sections in the text have the Section Name page in quotation marks and bolded IMPORTANT Important information is presented like this ignoring this may cause you to damage the unit or invalidate the warranty The manual covers standard units and units with P3D option P3D is a DSD data format and these units have changed internal hardware to accommodate it Information that is specific to P3D units is greyed The manual is designed to be helpful If there are points you feel we could cover better or that we have missed out please tell us dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 USING YOUR dCS 904 FOR THE FIRST TIME Product Overview The dCS 904 ADC Analogue to Digital Converter is a high performance converter designed for studio and live recording applications It is designed to produce very high standard digital output for example 192 kS s or DSD that may be used directly or archived If these formats are used lower resolution formats for example Red Book CD may produced by subsequent downsampling AES3 SPDIF SDIF 2 PCM formats and sev
79. re switched off and on they do not remember what they were last set to 9600 baud is currently not fully tested over all temperatures It can be used for single units operating in a benign environment Timing Accuracy and Warnings The units use clock dividers derived from their crystals to produce the RS 232 signals The frequency of operation is measured to be better than 2 for all baud rates with both crystals Some of the commands however switch clock frequencies and these may be controlled by phase locked loops with long time constants While this is happening correct RS 232 timing cannot be guaranteed and the units should not be addressed a period of 30 secs should be allowed after switching clock frequencies for timings to stabilise Units acknowledge and repeat back their actions on receipt of a command The acknowledge should be waited for and checked before proceeding to the next command see Acknowledge Message below dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Transmit Message The system employs the following protocol all transactions are initiated by the PC The PC is the transmitter and units on the daisy chain are receivers Byte 1 ID of unit to process command Byte 2 Command single byte Byte 3 Length of parameter string Byte 4 List of parameters Last byte Checksum of parameter list The minimum length of a transmit message is 4 bytes maximum 64 byte
80. receiver to sync up e up to 24 bits of audio data transmitted Isb first e V a validity bit e U auser bit for the User Message e C a Channel Status bit for the System Message e P a parity bit The default AES EBU message attached to the output data by the unit before being changed by the user is as follows Professional On Non Audio Off Mode Stereophonic Source DCS1 Destination null For more information on the way dCS implement the AES3 system message to handle higher sample rates see the Appendix to this manual For the formal definition of the AES3 interface see footnote from the AES How Far will it Go The AES EBU format was designed to go reasonable distances at 44 1 kS s and 48 kS s Figure 27 and Figure 28 below show it over 16 m and 94 m using average cables The waveform at 94 m can still be decoded although it is quite degraded Cable delay is about 5 6 nsecs metre At 96 kS s twice the data rate the format was designed for the allowed cable length is less Figure 29 and Figure 30 below show this over 16 m and 94 m At 16m the waveforms are still very good but at 94m they are really quite unreliable We recommend restricting 96 kS s cable runs to 20 m or less and using good cable near this length AES3 1992 ANSI S4 40 1992 AES Recommended practice for digital audio engineering Serial transmission format for two channel linearly represented digital audio data dCS 904 User M
81. rm commands simultaneously the transmitter coming back to busy units periodically It is also recommended that units are not accessed for the first of their response time nothing untoward will happen but the unit will be ignoring the RS 232 and will not respond so the transmitter would just time out anyway To set unit 2 Emphasis to AUTO using the RS 232 control format transmit the string 2 34 11 0 0 and the receiving unit will respond 169 Special Commands and Protocols BREAK Continuous high on transmit line for more than 100 msec Resets ALL units on daisy chain to 1200 baud GLOBAL ADDRESSES Address FO hex 240 decimal ALL units on daisy chain react to command Nothing acknowledges This should only be used for setting baud rates to 2400 4800 or 9600 baud Never change baud rate from a higher rate to a lower rate as this could result in unexpected behaviour always reset the daisy chain to 1200 baud and then issue the appropriate command Never change the baud rate of a single unit in a multi unit daisy chain as this could result in the chain locking up Address F1 hex 241 decimal Command RS ENABLE DEBUG 19 decimal ALL units on daisy chain react to command Nothing acknowledges This enables dCS debugging commands This may result in unstable behaviour of the unit dCS 904 User Manual dCS Ltd Manual for Software Version 1 5x and 1 36 June 2000 Command Streams Example a syste
82. s limited by a buffer within the receiving unit There are two cases for parameter length mismatch a Receiver expects n parameters transmitter sends more This condition may arise when a later version remote tries to communicate with an earlier version of receiver The receiver acts on first n parameters in list ignores rest The full parameter list is check summed b Receiver expects n parameters transmitter sends less This condition may arise when a earlier version remote tries to communicate with an later version of receiver The receiver acts on all parameters in list and uses sensible defaults for the rest ideally no action except where this is silly Do not truncate a command sequence expecting the receiver to do something sensible The full parameter list is check summed The checksum is the sum of the bytes in the parameter list bytes 4 to last 1 byte modulo 256 The receiving unit checks the checksum and will only act upon a command if the command is complete and the checksum is correct Acknowledge Message The addressed receiving unit ADC DAC DDC Master Clock etc acknowledges within 50 msecs of the last transmitted byte in the transmit message For some special cases dCS use only see Special Commands and Protocols below commands do not acknowledge If the checksum is incorrect the receiving unit will ignore the command clear its buffer and will not acknowledge Only valid command bytes will genera
83. se with a very high high frequency content that can damage speakers this feature has to be explicitly turned on If it is turned on and DSD mode is turned on the unit outputs DSD packed into AES3 data streams in the appropriate manner Contact dCS for further details If DSD is packed into AES3 links DSD 4 or P3D the dCS 904 sets the Non Audio flag in the AES3 message so that a DAC further downstream will mute if it cannot accept the format but beware if the Non Audio flag is stripped by the recorder a DAC could accept DSD data as AES3 PCM and will output potentially damaging full scale noise This page selects the output format of the SDIF connectors SDIF 2 or SDIF 3 SDIF 3 is only valid for DSD SDIF2 The BNCs output SDIF 2 formatted DSD in ADC mode On The BNCs output SDIF 3 embedded clock in ADC mode Definitions of these formats are available from the SONY Corporation This accesses a test generator whose level and frequency can be adjusted Pressing Set enters a submenu which accesses the following functions Level The output level in dBO It can be changed in 0 1dB steps using the Iff and BR buttons Freq The output frequency in kHz It can be changed below 1kHz in 10 Hz steps or above 1kHz in 100 Hz steps by using the J and BENN buttons On Off Toggles whether the generator is on or off Up Allows the menu to be re entered to set other functions Alternatively if left the menu will just time out ke
84. site Contact dcs on 44 1799 531 999 email to more Qdcsltd co uk inside the UK replace 44 with 0 web site www dcsltd co uk dCS 904 User Manual dCS Ltd Manual for Software Version 1 5x and 1 36 June 2000 dCS 904 TECHNICAL INFORMATION Anti Alias Filtering 3 The dCS 904 offers a choice of 4 anti alias filters on most sample rates These filters affect the ultrasonic part of the spectrum 20 kHz upwards The unit is an ADC with an output data rate set by the interface standard used The bandwidth of the input stages and oversampling converter used is high and so any signals that that are in the input signal up to a MHz or so will be aliased back into the output signal if they are not removed by filtering The demands on this anti alias filter can be quite severe at the lower normal sample rates it must pass signals in the audio band 0 20 kHz unimpaired but it must prevent aliasing about Fs 2 This can result in a very sharp filter and it is an unavoidable mathematical result that sharp filters have a poor ringing transient response One effect of the ringing is to spread the energy in a transient over a significant period of time it can be up to 1 ms This seems to affect the stereo image that the ear would otherwise form One can trade off filter roll off and energy smear more relaxed roll off gives less energy smear but it may allow some of the signals in the input to alias irrevocably into the out
85. te an acknowledge other command bytes will be ignored clearing the receiver buffer The acknowledge response starts with Byte 1 101010xx indicates successful transmission to physical address with xx indicating the time the unit may take to respond to the command and then with a command dependant part Byte 2 ID of unit that processed command Byte 3 Command single byte Byte 4 Length of response string Byte 5 List of response bytes Last byte Checksum of response list dCS 904 User Manual dCS Ltd Manual for Software Version 1 5x and 1 36 June 2000 Example The checksum is the sum of the bytes in the parameter list bytes 5 to last 1 byte modulo 256 The minimum length of an acknowledge message is 1 byte maximum 64 If the checksum is incorrect the transmitter should re issue the command For the first byte the response times are XX 00 immediate less than 50 msecs 01 up to 3 seconds 10 up to 15 seconds 11 up to 25 seconds The receiving unit will ignore any transactions on the RS 232 while it is busy If the transmitter sends commands to a unit when the unit is busy the unit will not send an acknowledge back The transmitter must be designed to time out after 50 msec and repeat the command if necessary In a multi unit environment it would be sensible to organise the transmitter to access units with a round robin polling scheme in this way several units can be instructed to perfo
86. the bottom one should be set to Loop t The units self align quite accurately see Sample Alignment on page 37 onwards Alternatively word clock may be used as the syncing method with no special set ups P3D option only Set DSD to DSD 4 set AES O to On dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCS Ltd June 2000 Operating Several Units on One Remote Chain B XO 2 2 ER Get eode ect Ge MAINS FUSE 2A T ON OFF e 5 GE aat Ole Ge MAINS FUSE 2A T ON OFF e e Or The hue Correct Computer Co ol 6 COM PORT CH Sie Reference Out ett 090098 TR Jer CHAIR MAINS FUSE2A T ON OFF E SDIF 20SD SET Figure 9 Multi unit Remote Daisy Chain The PC can control several units up to about 5 on each daisy chain To make them individually addressable each unit needs its RS 232 address to be different They can then be identified and grouped in the remote window See Remote In amp Out on page 11 for cable details dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCS Ltd June 2000 8 Channel P3D DSD Set Up with Monitoring Analogue source P3D out CH1 amp 2 dCS 904 AEST Sensitivity
87. thers dCS use only of a unit can be remotely controlled using this approach Each unit must have a unique ID in the range 0 to 99 which must be set up by hand using the menu system on the front panel The units remember their ID when powered down so this setting up only has to be done once Physical Interface Units are all connected in a RS 232 daisy chain up to a maximum of 11 units with a serial cable DB9 pin female straight cable connected between the Serial Out and Serial In ports of the units The same type of cable is used to connect the Serial In port of the first unit on the chain to the COM port of a PC By default all units are configured to operate at 1200 baud Standard RS 232 signal levels are used Bytes are transmitted with 1 start bit 8 message bits 1 stop bit and no parity Units can be switched to 1200 2400 4800 or 9600 baud An RS 232 break will reset all units on the daisy chain to 1200 baud A special command and ID is used to configure the units to other baud rates see Special Commands and Protocols below The following rates are recommended 3 or less units 4800 baud 4 to 7 units 2400 baud 8 to 11 units 1200 baud Operation of the daisy chain at higher than the recommended rates may result in incorrect behaviour of the system either because the units misinterpret commands or more likely because the controlling computer misinterprets their replies Units will revert back to 1200 baud if they a
88. to the unit by an RS 232 link or in most cases by the Menu If a function is set by the menu or the Remote the unit remembers it and it will be set this way for ever or until you set it to something different You can customise your unit in this way Information only items are displayed for a time then the display reverts to normal Menu buttons are indicated by white text on the front panel There are for otherwise Overload Level otherwise ADC Data otherwise Master Slave otherwise Output Format otherwise Noise Shaping Entering the Menu The Menu is entered by holding down the BZ and then pressing the EAR button once The display will show Fune You are now in the menu and the menu buttons now have their alternate meanings Moving through the Menu Press the Step button again to step through the Menu items listed below When you reach the required item press the Set button once to display the current setting and press again to change its setting This either toggles the previous state or causes an information function to read out or enters a lower level as in the Tone generator for example If you have entered a lower level pressin S R steps through its options When you reach the one you want press Set and then use the Jy or PEN buttons to increase or decrease a value such as Level or Frequency on the Tone generator If no changes are made in 4 seconds the unit exits the Menu When one item has been
89. tual mode Check ADCs for mode change This command allows the Transmitter to check the mode of the ADCs If a unit has not changed the transmitter should go back to step 2 and repeat the command Transmit gt 2 REQUEST DSD MODE Response gt ACK immediate 2 actual mode Transmit gt S REQUEST DSD MODE Response gt ACK immediate 3 actual mode Transmit gt A REQUEST DSD MODE Response gt ACK immediate 4 actual mode Transmit gt 5 REQUEST DSD MODE Response gt ACK immediate 5 actual mode Command Master Clock to change frequency Allow the system time to settle after this command with no RS232 activity three seconds should be sufficient Transmit gt SEL FS change to 96k Responds gt ACK 3 seconds requested frequency Wait for 3 seconds dCS 904 User Manual dCS Ltd Manual for Software Version 1 5x and 1 36 June 2000 Check Master Clock has changed frequency If it has not go back to step 5 Transmit gt 1 REQUEST FS request actual frequency Responds gt ACK immediate 1 actual frequency The system is now set up with the Master Clock configured for 96k operation and the ADCs and DACs locked in PCM mode to 96k Example Switching to P3D Change the Master Clock frequency to 44 1k prior to changing the ADC and DAC operating mode to DSD Change the DAC operating mode prior to the ADC When changing the Master Clock frequency the system should be allowed to settle to th
90. umbers eese 79 Definitions of Units 79 Full Contents 80 Tables 83 Figures 84 Keywords and Phrases 85 dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCS Ltd June 2000 Tables Table 1 Reference Clock and Sample Rates sssssssssssssss 15 Table 2 Output Data format indication higher sample rates 15 Table 3 DSD Filter Summary esee enm PE RR Ae aE 32 Table 4 DSD Filter Performance sss 33 Table 5 Noise Shaper Gain by Order and Sample Rate 41 Table 6 AES EBU i o specifications ccecccecceceeeeeeeeeeceeeeeeeeeeeenieeeeeeeeneees 44 Table 7 SDIF 2 SDIF 3 and DSD i o specifications sssssssse 44 Table 8 Remote Control Interface Details 0 ceccesecceceeeeeeeeeeeeeeeeeeeeteees 44 Table 9 Analogue XLR Interface Details sss 45 Table 10 SDIF 2 Message Table sessee eme 51 Table 11 RS 232 Command Get 61 Table 12 Dither and Noise Shaping Noise Powers seeeeene 65 Table 13 Internal Error Codes rrorrnnnenornnrnnrnrrnnrnnarrnnnnnnnnnnrensrrnrnnnnnnnnrenerrnnnn 74 Table 14 System Error Codes n 75 Table 15 dCS Phone Number TT dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Figures Figure 1 Rear Paniel incidente
91. update them all serially overnight To update the software by the RS 232 link load the new software into a convenient directory on the PC then run the Windows Remote programme with whatever units you want connected The software will scan the RS 232 chain for units this takes a while to see what it thinks is connected and then reports back For each unit there is an Info button Select the Info button for the unit you wish to update and then select Download Flash The programme will prompt you for the file to use and then will start the download If you want to programme many units automatically say overnight contact dCS for special software to enable this function Do not turn the unit off until the download is complete The unit has to erase its current programme before it can store the new one so if the power is turned off its internal programme store will have been erased but no new programme installed Contact dCS if this happens inadvertently the situation can be recovered if it does happen but it involves taking the lid off the unit To find out if there are any software updates available for your equipment call us or email us with your units serial number or check our web site www dcsltd co uk In general software updates are free Manuals for updated software can be downloaded from our web site or just call us As soon as the download starts the ADC will display Prog The Windows programme will say Erasing Flash
92. ur AES outputs In DSD mode data in the AES outputs can be turned off leaving the unit just outputting an AES clock This is controlled by the menu item DSD 4 or AES O for P3D optioned units See page 20 dCS equipment encodes messaging into the various data streams to enable receiving equipment to tell what is going on and to decide which wire is which in the unlikely event of user wiring errors Not all equipment from other manufacturers does this so Take extra care when connecting Quad AES as it is very easy to connect the wires in the wrong order If this is not detected it may result in badly aliased mono signals being recorded Numbering each connector is a sensible precaution For Menu operation as the J button see the section The Software the Menu on page 18 Sample Rate Display The main LED display generally shows the sample rate in kS s or the mode DSD When other parameters are set it briefly shows the new setting word length noise shaping etc then reverts to its normal display In the case of an error condition it will display an error message If the unit is being slaved the display also indicates which input connector it is slaved to XXX The sample rate in kS s 32 44 1 48 88 2 86 176 4 or 192 XXX Slaved to the BNC input typically word clock XXX Slaved to AES Reference in There are also some temporary displays that show what the unit is doing during its locking phase
93. ware Version 1 5x and 1 36 dCS Ltd June 2000 dCS SUPPORT I wish If you wish your unit did something it does not or that this manual told you something it does not or that we made something we currently do not tell us If we can fix it with software or a manual reprint and we do so we will update your unit free of charge If we do decide to make the thing we will discuss with you how you would like it to operate We value our customers and we want to make products that do what you want If You Need More Help The please contact dCS Our office hours are 8 00 am to about 7 00 pm Monday to Friday UK time UTC in summer or UTC 1hr in winter Contact us by phone or fax on Inside the UK Outside the UK Telephone 01799 531 999 44 1799 531 999 Fax 01799 531 681 44 1799 531 681 Table 15 dCS Phone Numbers You can write to us at dCs Ltd Mull House Great Chesterford Court Great Chesterford Saffron Walden CB10 1PF UK Our E Mail address more dcsltd co uk Our web site is http www dcsltd co uk Other Information dCS produce technical notes from time to time on issues related to ADCs If you are interested in these please do not hesitate to contact us or check our web site dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Manual part no DOC 135904 iss 2B2 Page 78 135904ma2b2 pdf file available from website Contact dcs on 44 1799 53
94. worse of dither alone even though there is really more noise present 11 12 16 bit Q noise is 98 1 dB relative to a full scale sine wave DSD carries this further The principle is the same but with DSD there is more noise than there is signal even at full scale It is just that it is in a part of the spectrum the ear cannot hear dCS 904 User Manual Manual for Software Version 1 5x and 1 36 dCs Ltd June 2000 Noise shaping on its own is not perfect It relies on a small amount of noise in the input signal to generate the frequency shaped correction signal and if there is very low noise in the input signal this mechanism can break down With ADCs however this situation does not arise because of the analogue noise in the ADC and the input signal There is another option not supported by the dCS 904 generate the dither independently of the signal and frequency shape it prior to addition but do not add it in an error shaping loop This seems to dCS to combine the worst of all worlds the high noise floor in the 0 6 kHz area of straight dither and the high total noise of noise shaping However some people use it What does it look like 60 80 100 Amplitude Real Data dB 140 120 Figure 35 gives the spectra of 16 bit truncated 44 1 kS s signals with a 90dB sine present for two dither only signals Top Hat Noise Shaped Triangular and with a 10 order noise shaped signal generated an

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