NAJDA UNDER CONTROL (NUC) - WAF
Contents
1. ns 4 Connecting ou an aaa na auqa a a r a a a E 5 L Creating a new setup sau E a E a A A E TEA Sas 6 TILL S t p types E EA EA EER E TEE E S S EEE 6 HI 1 Setup General Structure amas maaa ha Sie ae Runaka susan 6 HI 2 Classic Free Routing alasan asas Mucdinmcavens 10 HI 2 1 Built in EQ types A E EET 11 HI 2 2 EQ sections ordering a 12 HI 2 3 Custom biquads ENE ARE REL Yen ON PEA Yaar RET Sai 13 II 2 4 More Controls Channel Pairing and Channel Enabling 14 HI 2 5 Classic Free Routing specifications 15 HI 2 6 Classic Free Routing default setup 15 MLS FIR Engine faa gaelic muhuta Q oa e Os B y sa 17 HI 3 1 FIR filtering model a 17 HI 3 2 FIR Engine specifications 19 HI 3 3 FIR Engine default setup samatapas a Shakeela hee 19 IV Preset Management cennin ara oaa uiisqa 20 V Graph Utrlity rn ola uama E i a E aaa aia 22 V 1 Input Processing Graph ii ccscthvesdaeatcessiaatoncisnestncsesteswactentendtsactencsanensads 22 V 2 Output Processing Graph kamata Q AAA A E A EES 23 V 2 1 Loading of frequency response PEA EEE 23 V 2 2 Processed vs unprocessed views EERE E 24 V2 3 El ctrica SUM u anun iei a R 25 VI Bass Treble Settings dialogue a 26 VII Hardware co2. 12S Channel 3 DSPchannel3 12S Channel 4 DSP channel4 12S Channel5 DSP channel5 I2S Channel 6 DSP channel 6 Fig 22 Expansion Port 0 Routing dialogue VII 2 Analogue Outputs Configuration This dialogue allows selecting the onboard DACs interpolation filters and adjusting the output nominal level Two sets of interpolation filter coefficients are made available with the DACs in the CS42428 chip they differ in the steepness of the transition band For details on these filters please refer to the Cirrus Logic CS42428 datasheet In the same dialogue you can adjust the nominal output level either globally for all channels or independently channel wise You ll want to adjust the output level globally when you wish to adapt Najda s output to the analogue level expected by your power amps Please check your amps documentation for their nominal input level Global output level can be set anywhere between 1 Vins and 6 Vins WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 27 r b Board Configuration DAC Interpolation Filter Roll Off Slow Roll Off Fast Roll Off Nominal Output Level requires CS3318 Adjust output level globally 1 0 Vrms Le is output gain independently 0 dB is 1 Vrms 2 5 Vrms 3 0 Vrms 3 5 Vrms 4 0 Vrms 4 5 Vrms 5 0 Vrms 6 0 Vrms 9 cca k d Fig 23 Analogue Outputs Co
3. Dr aO rT Cy e SER a mO tm a Cesi Not connected FS 96 kHz C Users Nico Documents Najda Files Setups Free Routing 9 Pairing type switch Fig 11 View of the Output Processing tab with channel 1 highlighted Note that 10 custom biquads are in use and that phase is inverted and that channel 1 is paired to channel 5 Also Channels 9 and 10 have been disabled WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 16 II 3 FIR Engine The FIR Engine mode is identical to the Classic Free Routing mode section I 2 except that all filtering blocks are of FIR type In the screenshot below 200 coefficients have been loaded in the left input processing path The same processing path also carries a 500 sample delay and a 5 dB gain r W Najda Under Control FIR Engine 48 KHz nsf L sess Selected Input Settings 7 Enable Left Pre gain dB 5 0 200 coefs Left Delay samples 500 5 0 dB Filter Load from file Enable Pairing with Right 0 000 m p Sum n 0 000 ms 0 0 dB 0 000 m O Ocoefs coefs Diff 0 000 ms gt dB 0 000 m Right Input aes a Right 0 000 ms gt dB 4 m h Not connected FS 48 kHz C Users Nico Documents Najda Files Setups FIR Engine 48 K Fig 12 Input Processing tab in FIR Engine mode HI 3 1 FIR Filtering Model The FIR Engine mode
4. i e it includes the changes you wouldn t have saved in the setup file The name typed in this dialogue will appear on the LCD display when the preset is active r Preset Manager Store current setup as DSP preset LCD will display Preset Name when Preset is active 1 Type in here the name of your Name My new preset preset max 13 characters Select Preset Slot and press Save button 2 Select the memory slot m eH 3 Press this button to initiate storage Presets currently stored on Najda x Slot 1 lt Pass Thru 48 gt 4 Press this button to erase a preset Slot 2 lt Pass Thru 96 gt you want to discard Slot 3 lt Pass Thru 192 gt Slot 4 lt EMPTY gt Slot 5 lt EMPTY gt Slot 6 lt EMPTY gt Slot 7 lt EMPTY gt Slot 8 lt EMPTY gt Slot 9 lt EMPTY gt i i gt lt x 9 Px Px J Be Fig 15 Preset Manager dialogue in Synced mode WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 20 E Preset Manager Presets currently stored on Najda Slot 1 lt Pass Thru 48 gt x Slot 2 lt Pass Thru 96 gt Slot 3 lt Pass Thru 192 gt Slot 4 lt My new preset gt x Slot 5 lt EMPTY gt x Slot 6 lt EMPTY gt x Slot 7 lt EMPTY gt xX Slot 8 lt EMPTY gt Be Slot 9 lt EMPTY gt ae j Fig 16 Preset Manager dialogue in Online mode The appearance of the Preset Manag
5. 0 dB 7 646 ms ront p Dera O tm 0 0 dB 0 0 dB 0 000 m on OEN p c gt gt uns a 0 000 m CSB p E p 0 0 dB 0 0 dB 0 000 m Left Ea hha 0 000 m Right _ a 0 000 m Left a ral T eel i 0 000 m chi EU 0 0 dB 0 0 dB 0 000 ms Pre gain dB 0 0 Post gain dB 0 0 Delay samples 367 Filter Load from file 4h 41 gt lap Enable Pairing with Channel 7 es Not connected FS 48 kHz C Users Nico Documents Najda Files Setups FIR Engine 48 K Fig 14 View of the Output Processing tab in FIR Engine mode implementing here a 3 way crossover on channels 1 2 and 3 Note the routing section on the left WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 18 1 3 2 FIR Engine specifications Processing block Implementation Gains 24 dB to 12 dB Input Processing delays All up to 8191 samples except DIFF 4095 samples Output Processing delays All up to 4095 samples Max 1023 coefficients on Left Right Sum Ch 1 2 3 5 6 7 PIR eneh Max 511 coefficients on Diff Ch 4 8 9 10 Coefficient bit depth 24 bit Phase invert Tab 2 Summary of the FIR Engine mode processing blocks II 3 3 Default FIR Engine Setup Upon creating a new FIR Engine Setup NUC will create a setup file with default parameters The default FIR Engine file implements a bloc
6. implements a direct convolution in each filtering block defined as N 1 H z gt hln n 0 where H is the Z transform and h is the impulse response of the filter of length N Najda implements the convolution in its direct form depicted in figure 13 Raw FIR coefficients must be supplied in a text file refer to Appendix B for examples of such files All coefficients must be in the interval 1 1 i e 1 is allowed but 1 is not See table 2 for the number of coefficients allowed files containing more coefficients will be rejected We recommend creating a pair of simple FIR files which will be useful in various situations WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 17 The first file is simply an empty file and could be named fir0 txt It implements an open circuit and can be used to unload coefficients you wish to discard The second file contains only 1 and can be named fir txt It implements a pass through See Appendix B for more details 24 bit h 0 R 24 bit 24 bit Fig 13 Najda s implementation of the convolution The accumulator is 56 bit wide 8 48 r Wm Najda Under Control FIR Engine 48 KHz nsf File Settings Help Input Processing Channel Processing Ch1 Ch 2 Ch3 Ch4 Ch5 Ch6 Ch7 Ch8 Ch9 CN p DPI p C O um 0 0 dB 0 0 dB 3125 ms CMD p P p O uer 0 0 dB 0 0 dB 0 000 ms 2 624 m D gt 23 0 0 dB 0
7. up or down left click on the graph and move the mouse up or down By double clicking on the graph you re restoring the initial graph view 24 dB Wg Najda Under Control pt48 nsf Lo e File Settings Help Input Processing Channel Processing Input Graphs Commands Show Phase E Right E Sum E piff Cursor position 1027 Hz gt 5 35 dB Not connected FS 48 kHz C Users Nico Documents Najda Files Setups pt48 nsf k d Fig 17 Input Graph tab showing magnitude response of filters applied to the Left input signal The button in the top right corner allows toggling between magnitude and phase views fig 18 There s no zooming nor dragging feature in the phase view WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 22 Najda Under Control pt48 nsf L s File Settings Help Input Processing Channel Processing Input Graphs Commands Show Magnitude E Right E Sum El Diff Not connected FS 48 kHz C Users Nico Documents Najda Files Setups pt48 nsf Fig 18 Phase view of the above filters Note that while hovering over the graph the mouse coordinates are displayed in the status bar V 2 Output Processing Graph The Output Graph utility is functionally similar to the former Input Graph However it has a few extra features described hereafter To open a new output graph tab select File Add O
8. 8 dB oct Max number of second order 15 sections per EQ block Peaking Low shelf Ee High shelf Custom Coefficient bit width 48 bit Phase invert Tab 1 Summary of the Classic Free Routing processing blocks Bessel filters are phase matched HI 2 6 Default Classic Free Routing Setup Upon creating a new Classic Free Routing Setup NUC will create a setup file with default parameters The default Classic Free Routing setup file implements a pass through routing left input to channels 1 3 5 7 9 and right input to channels 2 4 6 8 10 In particular All delays set to 0 sample All gains pre and post set to unity 0 dB All crossover filters OFF flat unity response All filtering blocks contain no filter they just let the signal pass through unaltered All polarities positive When you create a new Setup in Synced mode NUC will immediately transfer all default parameters and mute outputs as a safety measure Before you unmute you must make sure your setup is not likely to damage your speakers A good policy is to keep the volume low at design time or design the setup in Offline mode WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 15 F mg Najda Under Control Free Routing 96 kHz nsf X C it PI a o 9 p Aa Ea gt gt 0 0 dB Cp ata gt 0 0 dB gt ACn O gt 0 0 dB Dr EL CD 6 0 dB 500 2000
9. AJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 24 V 2 3 Electrical sum The output graph also includes a summing function that allows viewing how all the drivers on that tab will behave jointly In the screenshot below we have set a LR crossover at 700 Hz to the pair of drivers in fig 19 r Nm Najda Under Control pt48 nsf L sess File Settings Help Input Processing Channel Processing Input Graphs Graphs 1 Commands Show Phase Show Unprocessed V Electrical Sum Include Delay in Phase channel 3 Bo X El Chane 4 E gt Channel 5 E gt Channel 6 E gt E Chane 7 gt Chanel 8 gt E Chane 9 E gt x 3 lt 3 lt Se x x x F Channel 10 gt Not connected FS 48 kHz C Users Nico Documents Najda Files Setups pt48 nsf Fig 20 Electrical sum of the 2 drivers in fig 19 with a LR network at 700 Hz Phase reversal will not impact the magnitude responses of individual drivers It will however dramatically impact the magnitude summed response Similarly the delays will not impact the individual drivers responses but it ll have a dramatic effect on the sum We have elected to display optionally the delay effect because in some circumstances it s relevant to crossover network design and sometimes not If your network design is IIR based then you re most probably going to use delays for aligning temporally drivers that are offset
10. NAJDA UNDER CONTROL NUC Software User Manual V 1 1 0 About this manual This is the user reference manual for the Najda Under Control NUC software NUC is the control application that communicates via USB with the Najda board This manual does not contain information on the Najda hardware platform For hardware details and installation notes please refer to the Najda Startup Guide available for download on our website www waf audio com If you can t find in this manual the information you re looking for please contact us via email at support waf audio com Najda is an upgradeable product Make sure you ve installed the latest software and firmware combo and that the instruction manual is relevant to the revision your running WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 2 A few definitions Setup vs Preset A Setup is a collection of DSP parameters saved in a file on the host computer It can be re opened modified and saved again Setup files have the extension nsf Najda Setup File and are XML formatted so they can be viewed in a text editor When a Setup is transferred to the Najda board it becomes locally a Preset A Preset cannot be read from Najda back to the host computer It cannot be modified either In order to alter DSP parameters from a Preset one must first load the corresponding Setup file in NUC apply the changes then overwrite the Preset in Najda Idle Offline Onl
11. Q sections can be reordered Although EQ sections ordering doesn t impact what you see on the frequency response plot it does impact the amount of headroom you need to allocate and hence the sound quality of your filtering strategy Let s see now a simple example of headroom to channel ordering dependency Fig 9 below shows two peaking filters centred about 1 kHz The blue line is 6 dB gain with Q 3 and the orange line is 6 dB gain with Q 1 10 Hz 100 Hz 1 kHz 10 KHz Fig 9 In blue PEQ 1 kHz 6 dB Q 3 In orange PEQ 1 kHz 6 dB Q 1 In green their combination The cascaded combination of the two filters is shown in green It s the same regardless of sections ordering i e regardless of whether the signal is first processed by the blue section then by the orange or the way around WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 12 If you choose to filter through the blue section first then you need to allocate at least 6 dB of headroom It doesn t matter that the boosting filter is followed by a compensating dip in absence of the specified headroom the blue filter will clip in the first place and the ovf segment of that channel will light on in the Monitor Note that by allocating 6 dB of headroom you re shaving off one bit of resolution from the 24 original resolution bits of your signal Consider now the reversed ordering The orange filter doesn t require any headroom other than tra
12. WARE USER MANUAL V 1 1 0 3 List of keyboard shortcuts Alt 0 Expansion Port 0 Routing Set channel routing for PS outputs on Expansion Port 0 Alt A Analogue Outs Configuration Select DAC interpolation filters and set analogue output level Alt C Connect or disconnect Initiate or cease communication between Najda and host computer Alt D Display Options Set the type of display used Customise sources names Alt F1 About Display application and firmware version numbers as well as board serial number connection required Alt G Add Output Graph tab Up to 5 Output Graph tabs may be simultaneously opened Alt I Show Input Graph tab Only 1 Input Graph tab is allowed Preset Manager AIRE Load or delete a Preset Alt R Remove Selected Tab Close topmost tab Closing any of the Input Processing or Channel Processing tabs will result in closing the Setup file Alt T Bass Treble Settings Enable disable Bass Treble unit adjust corner frequencies and headroom Exit a Quit the application New Setup Soy Create a new Setup file Open Setup carg Open an existing Setup file Save Setup CUES Save changes in current Setup file FI Help Open the Help documentation this file sns pa Mute or Unmute p Affects only analogue outputs WAFAUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 I Connecting In order to connect there must be a USB cable running between the host computer a
13. acoustically because they re mounted on the same plane panel In this case you should leave the delay out of the sum On the other hand if your design is based on FIR filters then you will also use delays to compensate for the inherent delay difference exhibited by filters of different lengths In this one case you should at some point include the delay in the sum in order to make sure the network is behaving according to your expectations WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 25 VI Bass Treble Settings Dialogue Najda includes a Bass Treble unit see figure 5 that acts like a tone control independent of the processing parameters These filters are 1 order shelving filters implemented according to the Mitra topology they allow boosting or attenuating bass and treble content in dB steps by up to 6 dB and offer some configuration options via the Bass Treble Settings dialogue First thing first this unit can be disabled This is beneficial if you don t intend to use any tone correction as you save the corresponding DSP computational resources In order to enable or disable the Bass Treble unit tick or untick the checkbox on top of the dialogue fig 16 Additionally the corner frequencies of the shelving filters can also be customized Corner frequencies are defined as the mid excursion point in the transition band see fig 7 Finally as for any filter the Bass Treble unit requires some headroom i
14. ceiver are disabled Most of the commands that are usually available through keypad and IR remote controller are doubled in the Monitor s controller section Additionally to VU meters the Monitor tab displays important information relative to the processing status The load meters show how much DSP resources are being used It s your responsibility to ensure the load of each core is kept below 100 Input processing clipping is displayed in the Clip Warning panel Channel processing clipping is shown on the ovf top segment of each VU meter Disconnecting Select File Disconnect in the menu Keypad and IR receiver are enabled again If a Setup was transferred without being stored as a Preset the LCD displays Setup From PC This set of processing parameters is volatile it will WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 5 remain active until you load another Preset or turn off Najda II Creating a new Setup Select File Create New Setup in the menu r h Create a new Setup Please enter the basic properties for the new Setup File name Location C Users Nico Documents Najda Files Setups h Browse DSP Sampling Frequency 48 kHz 96 kHz 192 kHz Crossover network type FIR Engine k d Fig 3 Create a New Setup dialogue In this dialogue you type the name of the Setup file that will be saved onto your computer in the se
15. er dialogue is slightly different in Online mode as pictured in figured 16 In Online mode you cannot store a preset because you haven t opened a setup file The Preset Manager dialogue still displays the list of presets and lets you erase the ones you d want to discard As a final note there must be at least one preset stored into Najda s memory otherwise the unit wouldn t be able to boot This explains why the Preset Manager dialogue will only allow you erasing all but one preset WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 21 V Graph Utility NUC Includes a flexible graph utility that displays the expected processing outcome One single Graph tab may be opened in relation to the Input Processing block and up to five Graph tabs are allowed for the Channel Processing block Having one separate Output Graph tab per speaker box is a healthy approach V 1 Input Processing Graph To display the Input Graph tab select in the menu File Show Input Graph Tab or press Alt i This menu item is available only if you have opened or created a setup file Select in the right panel what processing paths you wish to view Left Right Sum and or Diff By default this graph shows the magnitude of the processing in the range 24 dB with the 0 dB line in the middle of the window With the mouse wheel or the scrolling feature of the mouse pad you can alter the range of magnitudes You can also drag the 0 dB line
16. g to compensate for driver unequal efficiencies Post gain dB value will usually be negative as well Generally although not always a positive gain in dB is the clue of an improper gain structure Note that if your board includes the analogue volume chip there s a third gain stage doubling with the post gains but taking place in the analogue domain Where possible analogue gains should be preferred to digital ones Refer to section VII 2 I ve set up a system with crossover filters only i e no EQ no gain The frequency response exhibits no boost anywhere however the signal is clipping Why is that The frequency response shows how the filters are handling steady state signals It doesn t show how the system is handling transients A steady state signal is a sine or a collection of sines Music and speech however contain a lot of transients In order to assess how the filters handle transients we would look at other types of plots such as for example the step response Filters usually exhibit on these plots a certain amount of overshoot If your listening material is normalized for 0 dBrs as is most commercial material then it s necessary to provide some headroom for the processing Indeed any amount of overshoot on a 0 dBrs transient will lead to clipping otherwise The required headroom depends on the filters 3 dB pre gain is a good starting value What about DSP load As for the Input Processing block Channel Processing
17. ght Sum and Diff can be routed to any channel followed by a pre gain a filtering block a post gain a phase inverter and finally a delay Again the nature of the filtering block depends on the selected Setup type The Channel Processing section is visualised in the Channel Processing tab WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 7 0L HO 6 H9 8 H9 HO 9 H9 SHO tHo H9 ZHO L HO Burss o5oid uueuo SdNJas JD o uounuoo 4njon Us BUISSIJOAd JDABUALD SI Bui ss oSoiq1ndu e ddla 2409 dSGQ i wns aourjeg LHS 1431 8 WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 Why are there 2 gains on each channel pre gain vs post gain A proper gain structure is essential to preserve as much as possible the information contained in the original audio signal Use the pre gain to set signal amplitude to the limit of clipping in the subsequent filtering block then use the post gain to scale signals fed to your drivers In other words pre gain is solely connected to the nature of the filtering block and must be chosen as large as possible but not too large so as not to clip Pre gain dB values will usually be negative i e attenuating the signal Post gain purpose is two folded on the one hand it s going to compensate for different pre gain settings on different channels that have same routing on the other hand it s goin
18. glance at the right panel reveals that these filters are parametric EQs defined each by a set of data Note that signal paths that are not used can be disabled in order to save processing resources Also input channels can be paired so that the changes made are reflected immediately on the paired channel too HI 2 1 Built in EQ types The first filter in the processing chain is a low pass shelving filter with 200 Hz characteristic frequency 6 dB gain and a slope factor S of 8 The second filter is a high pass shelving filter with 800 Hz characteristic frequency 4 dB gain and a slope factor S of 4 The characteristic frequency is defined as the filter mid excursion point The slope factor is limited to the range 3 to 12 with the latter being the steepest slope achievable The slope of the filter in dB oct is proportional to the S factor 100 Hz Fig 7 Tllustration of the shelving filter parameters This is a low pass at 1 kHz 6 dB gain and a slope factor of 8 The third and last filter in figure 6 is a peaking filter set at 2000 Hz with a negative gain of 3 2 dB and a quality factor Q of 3 55 The higher the Q the narrower the filter See figure 8 WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 1 1 Fig 8 lustration of the peaking filter parameters This one is centred about 1 kHz 6 dB gain and a quality factor Q F AF of 1 II 2 2 EQ sections ordering As illustrated in fig 6 E
19. ine Synced When the user launches Najda Under Control NUC hereafter the application is said to be in Idle state The application displays only a white tab with WAF s logo The Offline state is the situation where a Setup file is open but connection with the board has not been initiated This is typical when the user creates a new Setup file loads his measurements and starts thinking about the processing strategy It s also the normal state in demo mode i e when one wishes to evaluate NUC In Offline state the Monitor tab is not available and neither are any of the hardware configuration dialogues The Online state occurs when the user connects and no Setup file is open NUC displays the Monitor tab and all hardware configuration dialogues are functional Finally the Synced state takes place when connection is established and a Setup file has been opened In this mode any change to the parameters on screen is immediately transferred to the board Open Setup OFFLINE Connect gt Z x Disconnect S y CloseSetup 4 IDLE SYNCED I Y k Open Setup 7 gt Connect A Disconnect ONLINE a Close Setup Fig 1 Transitioning between software states Connected In the whole user manual the term Connected refers not only to the physical link of a USB cable between Najda board and the host computer but also to software communication initiated with the board WAF AUDIO NAJDA UNDER CONTROL NUC SOFT
20. k all and routes left input to channels 1 3 5 7 9 and right input to channels 2 4 6 8 10 In particular All delays set to 0 sample All gains pre and post set to unity 0 dB All filtering blocks contain no coefficient hence they block the signal and act as open circuits All polarities positive In order to create a pass through FIR you must load the unity filter see file fir txt described in section III 3 1 into each filtering block WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 19 IV Preset Management Up to 9 presets can be stored into Najda onboard memory A limitation applies to FIR Engine presets which can potentially involve large amounts of data FIR presets can only be stored into memory slots 1 to 3 Classic Free Routing IIR presets can be stored into any slot In order to store or delete a preset it should be fairly obvious that Najda must be connected As a matter of fact the menu item File Preset Manager is greyed out and the corresponding dialogue is not available until connection is established The Preset Manager dialogue in Synced mode is shown in figure 15 below This dialogue displays the name of the preset stored in each of the 9 memory slots and lets you transfer the current setup into the preset slot of your choice It also allows you erasing a preset you d like to discard Note the transferred setup corresponds to the most current configuration
21. lected folder Prefer explicit file names e g 3 WaylirPlusSub rather than setup47 The two remaining fields set important properties of your Setup These are the sampling frequency and the type of Setup they are set here once for all and cannot be altered at a later time Refer to section III for details on available Setup types As soon as the OK button is pressed a Setup file is created on the hard drive of the host computer This file is initially loaded with default values proper to the selected Setup type Default values are overwritten as the user progresses in setting parameters and saves the changes The Setup file name appears in the window top bar A trailing star means the Setup file has been modified since it was saved last time The full path to the Setup file is displayed in the status bar If Najda Under Control is Online i e if it s connected the default Setup of selected type and sampling frequency is immediately loaded onto the board As a safety measure all outputs are muted Najda is now in Synced mode III Setup Types HI 1 Setup General Structure Figure 5 shows the general processing structure common to all Setup types Left and right inputs go through the balance stage then across the Bass Treble unit Note that the latter can be bypassed see Bass Treble in section VI WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 6 As a next step the signals enter the Input Processing section
22. load is split between the DSP cores Fig 5 shows DSP core 0 is in charge of channels 1 2 3 4 and 9 meanwhile DSP core 1 processes channels 5 6 7 8 and 10 Within a core filtering resources are allocated dynamically so that additional filtering on channels 1 2 3 4 and 9 will increase the load on DSP core 0 meanwhile additional filtering on channels 5 6 7 8 and 10 will increase the load on DSP core 1 If your Setup is not processing intensive then you don t need to care too much about DSP load as long as you make sure it s less than 100 for each core Indeed what a DSP load in excess of 100 actually means is that the DSP is dropping samples expect alias and distortion In the opposite case if you know your Setup is going to require lots of resources because you favour 192 kHz sampling rate or your speakers have many ways or you have designed long FIR filters then you will want to balance the load on each core This requires that you consider carefully how you re going to distribute the speaker channels between cores which on its turn is going to impact the physical connections to Najda board Generally your Setup is going to be quite symmetrical between left and right so a good start is to reserve one core for the left speaker and one core for the right speaker If you have a sub in your WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 9 Setup put it on core 1 Indeed core 1 has usually fewer
23. mportant NUC expects to find the following sequence bo bi b2 ai a2 F 3 biquad_canonical txt Notepad File Edit Format View Help 0 001023217 6384572448 0 00204643527 69144897 0 0010232176384572448 1 9075016260205944 0 9115944965744232 0 9953826895856792 1 9907653791713589 0 9953826895856792 1 990744059502277 0 99078669884044 0 9953826895856792 1 9907653791713589 0 9953826895856792 1 990744059502277 0 99078669884044 The text file above is the stripped down version of the former The 2 files as seen by NUC are functionally equivalent WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 30 Appendix B FIR Coefficients File Examples The simplest FIR file is the open circuit it s just an empty file fir 0 txt i A firO txt Notepad L sss File Edit Format View Help The pass through FIR file contains one single coefficient fir txt e J firL txt Notepad Sox File Edit Format View Help Below is the moving average filter the output is equal to the average of the previous and current inputs fir_avg txt r A J fir_avg txt Notepad Lo jarss File Edit Format View Help WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 31 Appendix C Examples of Compatible Frequency Response Files Below is the start of a compatible frequency response file Note the first line Freq
24. n order to prevent clipping The amount of required headroom depends on the amount of boost you intend to apply so the headroom is also configurable via the Bass Treble Settings dialogue P Bass Treble Settings Enable Bass Treble on DSP Headroom dB Bass Cutoff Hz 500 Treble Cutoff Hz 2000 Fig 21 Bass Treble Settings dialogue Bass Treble settings are independent of the processing parameters They apply to all the presets stored in Najda and must be seen as a global parameter subset WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 26 VII Hardware Configuration Dialogues This last paragraph describes the remaining hardware configuration dialogues As for the Bass Treble unit see section VI these settings act globally and are not tied to any preset VII 1 Expansion Port 0 Routing Expansion Port 0 comprises 3 PS lines that can convey 6 audio channels and are useful if you wish to experiment with external DACs Any of the 10 processing channels can be freely routed to these lines In the example screenshot below channels 9 and 10 are routed to the I2S_EXTO LINE pin of the expansion port One use of such a setting could be an external DAC section with headphone amp Please refer to the Startup Guide for Expansion Port 0 pinnout Expansion Port 0 Routing I2S Channel 1 DSPchannel9 w 12S Channel 2 DSP channel 10 v
25. n the sum and diff channels On the Output Tab the default pairing is as follows 1 e 5 2 6 30 7 4 8 9 lt 10 This is the recommended pairing strategy as it helps maintaining a balanced loading of the DSPs refer to Fig 5 An alternate pairing strategy has however been made available where the paired channels are laid in a successive order i e 1 2 3 4 5 6 7 gt 8 9 10 Switching between pairing strategies is achieved by clicking on the pairing type button see fig 11 Pairing two channels doesn t necessarily result in the channels being identically parametrised Indeed you can first pair the channels and apply the common settings then unpair and apply individual settings to each channel Each processing path also features an Enable switch It s recommended to disable all the channels WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 14 that are not going to be used at all in the final form of the setup By disabling unused channels you lower the load on the DSPs By default when creating a new setup all channels are enabled HI 2 5 Classic Free Routing specifications Processing block Implementation Gains 24 dB to 12 dB Input Processing delays Allup to 8191 samples except DIFF 4095 samples Output Processing delays All up to 4095 samples Butterworth 6 12 18 24 36 48 dB oct Crossover filters Bessel 12 18 24 36 48 dB oct Linkwitz Riley 12 24 36 4
26. nd Najda board and the latter must be switched on i e not in Stand By Select File Connect in the menu In Online mode the DSP keeps running the same Preset that was already running prior to connecting The Monitor tab pops up and displays the Preset s sampling frequency in the status bar r ry i Najda Under Control L sss Clip Warning Status Controller 3 cc SPO Lock Mute J Bass Treble PLL Unlock Source analogue z 48 efn DSP Load Core 0 Volume g 42 x Richtin 1 Balance g La 42 348 sumin DSP Load Core 1 pss a ofin B o T mak oF ovf ovf ovf ovf ovf 4 1 x l y 3 3 2 3 3 3 3 3 3 12 12 34 12 Zyl 15 115 15 15 ah 8 18 18 A 18 j j 1 j 3 2 2 32 2 42 42 42 42 2 48 48 48 48 48 1 2 3 4 5 6 T 8 9 Mute mute Mute Mute mute mute mute mute Connected CIDE open or create a Setup file K A Fig 2 Monitor tab in Online mode Circled in red DSP sampling frequency in the status bar In Synced mode i e when a Setup file was open priory to connecting the Setup file parameters are immediately loaded into the DSP From here on any change to the Input Processing and Channel Processing tabs will be transferred in real time so that you hear what you see In both modes on connecting outputs are muted as a safety measure The LCD displays Host Connected and both keypad and IR re
27. nfiguration dialogue for global nominal output level setting Alternatively you ll want to set output levels independently when you wish to substitute digital post gains with analogue gains and therefore compensate in the analogue domain for drivers efficiency discrepancies Output level can be adjusted between 15 dB and 15 dB 0 dB is 1 Vins uses Outs Configuration DAC Interpolation Filter Roll Off Slow Roll Off Fast Roll Off Nominal Output Level requires CS3318 Adjust output level globally 1 0 Vrms Adjust channel output gain independently 0 dB is 1 Vrms chi ch2 h3 Ch4 h5 Ch6 Ch7 Ch8 1dB 1dB 3dB 6dB 9dB 12dB 15dB 2dB maaan ac Fig 24 Analogue Outputs Configuration dialogue for independent channel output level setting VII 3 Display Options The purpose of this last dialogue is two folded Since the Najda supports 3 types of displays namely LCD HD44780 or compatible OLED WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 28 WS0010 and VFD PT6314 it s required to let the board know what display has been installed Declaring the wrong type will result in display artefacts and inappropriate menu options Setting of the display type should happen only once when you connect for the first time It can also be required after you have installed a new display of after updating the firmware This dialogue allows also customising the names of the sources as they a
28. nfiguration dialogues PE EEE d kau A A E 27 VII 1 Expansion Port 0 Routing dialogue 27 VIL2 Board Configuration dialogue a 27 VII 3 Display Options Gstaad cig NE ce vise aa detainee ada aus 28 Appendix A Custom biquads file examples s 30 Appendix B FIR coefficients file examples 31 Appendix C Example of compatible frequency response file sislos hequhehaedettanatle 32 WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 33
29. nsient overshoot buffer see transients handling on p 7 Also the orange filter attenuates that same band that the blue filter is boosting As a consequence this section ordering doesn t call for specific headroom allocation and should be preferred to the former The case above is synthetic and trivial Real cases are likely to involve more sections and require a more careful look as the number of sections increases the number of possible ordered sequences grows as the factorial of the number of sections The aim of section ordering is always to minimize headroom while prevent clipping EQ section ordering is only available with built in EQs it s not available with custom biquads Indeed with custom biquads sections are ordered as per the supplied file HI 2 3 Custom biquads Each filtering block consists of N cascaded second order IIR sections also known as biquads For those inclined to maths the Z transform of such a complete block is given by N lt 9 N 1 2 bon b Zz d A Hle 10 Pa 1 n 0 I a z a Z where bon Din b2n Ain and az are the coefficients of section n Each biquad is implemented in Direct Form 1 with all coefficients being 48 bit This is illustrated in the figure below 48 bit 48 bit Fig 10 Najda s biquad implementation Note the sign in front of a and a coefficients Incoming audio is 24 bit outgoing audio is rounded back
30. of processing strategy that s made available on marketed DSP cross over units This section will describe the peculiarities of the commands in the control application and will provide an overview of the DSP implementation The figure above shows the Input Processing tab of the IIR aka Classic Free Routing mode where the SUM processing path has been highlighted In order to highlight 1 e select a signal click with the mouse on the block diagram at the appropriate height or select the input in the top right combo box The remaining components in the right panel are immediately filled with the current user settings In the example above there s a 230 sample delay which corresponds to a 2 396 ms delay at 96 kHz sampling frequency FS field in status bar One can change the delay by entering a new value in the right panel An alternate way is to click on the ring in the block diagram and use the up and down keyboard keys to alter the setting Generally clicking on a specific block will give software WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 10 focus to the associated component in the right panel so that you can immediately alter the parameter value The pre gain here is set to 6 dB In order to change the pre gain setting type in a new value in the right panel or click with the mouse on the gain symbol the triangle and use the up and down keys The same processing path shows that 3 biquads are in use A
31. ppear on the display Display Options Display Type LCD HD44780 compatible o J C VFD PT6314 driver Noritake CU1602 series Source Aliases Type below the new names of your sources as they should appear on the display Analogue Tuner CD Player Fig 25 Display Options dialogue WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 29 Appendix A Custom Biquads File Examples m L biquad_test txt Notepad File Edit Format View Help This is a comment line M n 3 The file contains 3 biquads b0 0 0010232176384572448 That s the first biqua b1 0 0020464352769144897 b2 0 0010232176384572448 al 1 9075016260205944 a2 0 9115944965744232 bO 0 9953826895856792 Here s the second biquad b1 1 9907653791713589 b2 0 9953826895856792 al 1 990744059502277 a2 0 99078669884044 b0 0 9953826895856792 b1 1 9907653791713589 b2 0 9953826895856792 a1l 1 990744059502277 a2 0 99078669884044 And that s the third one 4 The example text file above contains definitions for 3 biquads The top line is just a comment ignored by NUC The 2 line is also ignored NUC collects coefficients and deduces the number of biquads There s a break before the 3 biquad definitions line breaks are fine too The coef identifiers b0 b etc and the coma also are optional The coefficients order is i
32. side tasks than core 0 Note that delay and gain settings phase inversion and routing do not impact DSP load In particular a delay of N samples is identical to a delay of 0 sample in terms of DSP computational resources II 2 Classic Free Routing NN Najda Under Control Free Routing 96 kHz nsf l Lo File Settings Help Input Processing Channel Processing Selected Input Settings mee m 0 000 m Gain dB 6 0 Left Input Yz Left Isrum 230 0 000 ms 0 0 dB n Enable Pairing with Diff 0 822 m Bypass _ Fie _ adda QO p Esm sa 2 396 ms 6 0 dB F Hz 200 G dB 6 0 T LoShelf Q s 8 00 0 000 m O gt ES on Section 2 oo 0 000 ms 0 0 dB F Hz 800 dB 4 0 Type HiShelf Qs 400 0 000 m ji Right input 11a gt ED rim Ta ial 0 000 ms 0 0 dB Fi Hz 2000 2 G dB 4 2 2 toe ds fos Not connected FS 96 kHz C Users Nico Documents Najda Files Setups Free Routing 9 4 5 1 2 3 Fig 6 Input Processing tab in Classic Free Routing mode Use the up 1 and down 2 arrows to reorder the parametric filters in the processing chain To suppress a filter click on the cross 3 The whole EQ section can be bypassed 4 Alternatively to parametric EQs filtering can be defined by raw coefficients contained in a file 5 The Classic Free Routing Setup type is in essence the most common kind
33. tions defined by note the signs in the denominator bytby z b z 2 biquad Z izai a In order to allow the loading of files generated by these applications NUC will invert the signs of all a and a coefficients This is important to keep in mind only if you intend to write your own routines for coefficients computation you don t need to care otherwise Parametric EQs and custom biquads are mutually exclusive this means that you can t have both in the same EQ block The bypass switch is effective also with custom biquads so it s safer to reserve these for filters others than crossovers It s often useful to inspect visually the files generated by third party applications Indeed if you spot a section defined by bo 1 bi 0 b 0 a 0 az 0 just delete that section because it s a pass through that uses DSP resources without any effect Similarly if you spot a section with following coefficients by B b 0 b 0 a 0 a2 0 where B is any number then this section is a simple gain of value 20 log o B in dB see if you can suppress that section and report the corresponding gain in one of the pre or post gains II 2 4 More controls Channel Pairing and Channel Enabling Channels may be paired in order to speed up the definition of a setup when there s a certain amount of symmetry between the left and right speakers On the Input Tab the left and right channels can be paired as ca
34. to 24 bit but the whole the internal path is 48 bit Alternatively to defining parametric filters one can load raw biquad coefficients contained in a text file This feature known as custom biquad allows implementing types of filters other than the ones readily available such as Linkwitz transformers for example We ll describe now the required file format WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 13 A maximum of 15 biquads may be loaded in each EQ section When opening a file Najda Under Control expects to find the coefficients in a column in the following sequence bo bi b2 ai a2 Note in particular that ao is implicitly unity and is therefore omitted 5 coefficients fully describe one biquad thus the file can contain up to 75 coefficients A file containing more than 75 coefficients will be rejected as will be a file containing any number of coefficients which is not a multiple of 5 See Appendix A for examples of compatible files Coefficients are checked for stability if the file contains one or several unstable biquads then the whole file is rejected Also the global gain of each biquad cannot exceed 24 dB so the file will also be rejected if any coefficient is greater than 2 10 31 69 After we tested several third party applications generating biquad coefficients we found out that they use a different sign convention Indeed all these applications compute coefficients for second order sec
35. ts by users who don t own a SPL calibration reference the output graph utility embeds a routine for automatically aligning level wise the plots of several drivers This routine works the following way If only one single frequency response is loaded the output graph will offset the curve so that it crosses the 0 dB line at 1 kHz If successive frequency responses are loaded the graph utility will pick as the reference the response that exhibits the largest magnitude at 1 kHz The remaining curves will be offset so that the relative magnitude difference is maintained Here s the recommended approach for measuring all the drivers of one speaker in their enclosure Position your measuring microphone at m in the axis off axis or at listening position Select a suitable level for the test signal It has to be high enough for the measurement purpose but not too high so you won t damage any of the drivers Measure each driver successively without moving the microphone and without altering the test signal level V 2 2 Processed unprocessed views The graph utility displays the global outcome of the processing strategy i e the combined effect of the filters pre and post gains phase reversals and optionally delays see V 2 3 Electrical Sum In order to quickly assess how the setup is actually performing you can toggle between the processed and unprocessed views using the Show Unprocessed checkbox WAF AUDIO N
36. uency Hz Magnitude dB is optional and can be omitted This file contains magnitude information but no phase information NUC will assume phase is null at all frequencies r frs csv Notepad 3 573 594 615 637 659 681 704 727 750 773 797 PRE RRR F 107 235168 107 235245 107 235321 107 235405 107 235489 107 235573 107 235672 107 235779 107 235901 107 236031 107 236214 107 236397 File Edit Format View Help Frequency Hz Magnitude dB The next file is quite similar to the former except that it contains a third column with phase information Again the first line is optional NUC sees it as a comment line r E frs_phase csv Notepad 552 3 573 1 594 1 615 1 637 1 659 1 681 1 704 1 727 1 750 3 273 1 797 File Edit Format View Help Frequency Hz Magnitude dB 107 235168 107 235245 107 235321 107 235405 107 235489 107 235573 107 235672 107 235779 107 235901 107 236031 107 236214 107 236397 173 935516 173 894012 173 852127 173 809845 173 767197 173 724167 173 680740 173 636917 173 592697 173 548080 173 461487 173 373749 Phase deg WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 32 Table of contents Aboutthis manual aaa ananas a Quan ia Tu D uwa 2 A fewidefinitions usasapa asua aaa qaya 3 List of keyboard shortcuts
37. utput Graph tab in the menu or press Alt g V 2 1 Loading of frequency responses In the screenshot below we have set a graph to display the individual responses of the drivers forming a 2 way bookshelf speaker Channel 1 is dedicated to the tweeter orange and channel 2 holds the woofer s signal green To load a frequency response file click on the button near the channel index number To unload a file click on the button with a cross in it The expected file format is CSV like with the first column being the frequency the second column being the measured magnitude in dB at the former frequency and the optional third column being the measured phase in degrees See Appendix C for examples of compatible files WAF AUDIO NAJDA UNDER CONTROL NUC SOFTWARE USER MANUAL V 1 1 0 23 E ms Najda Under Control pt48 nsf L File Settings Help Input Processing Channel Processing Input Graphs Graphs 1 Commands Show Phase V Show Unprocessed E Electrical Sum F Indude Delay in Phase Channel 3 gt X Channel 4 By Channel 5 Be Channel 6 Be Channel 7 B Channel 8 Be Channel 9 BR x x Se x x x x E Channel 10 E gt Not connected FS 48 kHz C Users Nico Documents Najda Files Setups pt48 nsf Fig 19 Output graph loaded with the frequency responses of the drivers for a 2 way project In order to accommodate measuremen
38. which is represented in the control application by the Input Processing tab In the Input Processing section two additional signals namely Sum and Diff are generated as Sum Left Right 2 Diff Left Right 2 Sum signal used alone is mostly useful for feeding subwoofers Jointly Sum and Diff signals can be used to create a 3 speaker Left Center Right stereo configuration Indeed from the 2 expressions above one can see that Left Sum Diff Right Sum Diff This suggests the LCR configuration below L C R Fig 4 3 speaker LCR configuration using the Sum and Diff Signals Note the phase inversion of the signal feeding the right speaker In the Input Processing section all 4 signals Left Right Sum and Diff pass through a delay then a gain and finally a filtering block The nature of the filtering block i e HR or FIR depends on the type of Setup selected One important feature to keep in mind is that Left and Right signals are processed by DSP core 0 meanwhile Sum and Diff signals are processed by DSP core 1 At the core level filtering resources are allocated dynamically hence adding filters to the path of signals Left and Right will increase the load on DSP core 0 Similarly adding filters to the path of signals Sum and Diff will increase the load on DSP core 1 The Channel Processing section consists of a routing block in which any of the 4 pre processed signals Left Ri
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