LA Audio Electronic SPX20 User's Manual
Contents
1. i T 1 P LEFT RIGHT TRIM LANI 7 a mr 1 2 3 4 5 6 0 X B TRIM TRIM TRIM amp TRIM TRIM 4 1 INPUTS SECTION INPUT 1 Left amp Right sockets These are insert points for Input 1 Plugging into these connectors breaks the signal from Input 1 s rear panel XLRs They are intended to allow a quick and easy way of temporarily connecting an external piece of equipment to the SPX20 TRIM control The TRIM control for Input 1 has a range of 10dB which should provide adequate adjustment for levels provided by pro semi pro and commercial equipment The centre position 12 o clock provides unity gain OdB and has a mechanical detent for easy positioning 1 button Pressing this switch selects Input 1 as the signal source It is fed to the TAPE RECORD output on the rear panel OUTPUT 1 amp 2 and the Headphone amplifier The associated led lights to show Input 1 selected 2 3 4 5 6 button These select Inputs 2 through 6 as the Input source Each select button has an associated led To select more than one input at the same time press and hold the first input and whilst holding this button press another button It will be necessary to hold down all the inputs you want selected as each time a button is pressed it tries to cancel all other selections Release all buttons TRIM control Each input TRIM provides a gain range of 6dB attenuation at counter clockwise CCW to 10dB cloc2. led Switches OUTPUT 1 on and off LEVEL 2 control Similar to LEVEL 1 ON switch led Similar to OUTPUT 1 4 3 HEADPHONES SECTION VOLUME control Controls the headphones signal level Fully CCW is off The headphone amplifier on the SPX20 is designed to drive headphones with an impedance from 8Q to 400Q POWER indicator The green POWER indicator is lit whenever power is applied to the unit Page 10 5 0 APPLICATIONS The majority of mixing consoles even quite expensive models offer only 2 or possibly 3 monitoring inputs So if you want to simultaneously connect a CD player DAT machine stereo cassette deck 2 track analogue tape machine etc you will have to use up input channels These are often already used for tape returns or for FX so some repatching and gain adjustment will necessary in order to replay these sources The SPX20 has been designed to extend the number of monitor inputs and to offer some extra facilities not found on budget priced consoles The SPX20 is intended to be used in one of two ways 5 1 AS THE MAIN MONITOR CONTROLLER In this application the SPX20 is used as the control centre for selecting sources and controlling levels in the monitors Although this requires the SPX20 to mounted in a readily accessible place it does offer a number of advantages The two separate outputs with on off switching and level controls can be used to drive different types of monitor speakers Alternatively one ou
3. arrangement TRS jack inserts on Input 1 Tip Hot Signal Ring Cold Signal Sleeve Screen Signal ground For unbalanced operation join Ring and sleeve and connect to screen signal ground and use Tip as Hot signal Plugging a mono jack into these inserts effectively unbalances the connection Sleeve Tip Screen Hot Fig 2 6 4 Mono jack pin arrangement Tip Hot signal Sleeve Screen signal ground Page 6 Plugging into the inserts jacks on the front panel breaks the signal from the rear panel XLRs INPUT 2 amp 3 These are balanced inputs on TRS jacks see Fig 2 6 3 For ubalanced operation wire as described above for Input 1 inserts or use a mono jack plug INPUT 4 5 amp 6 These are all unbalanced inputs which have RCA phono connectors These are wired with the centre pin as hot signal and the sleeve as screen signal ground TAPE RECORD This is line level output of the selected input or inputs Output level depends on the settings of the input TRIMs and on how many inputs are selected at the same time If the input TRIMs are set up as described in the Description of Controls sections then the level will be approximately OdBu OUTPUTS section No user serviceable parts inside OUTPUTS RECORD OUT C Disconnect from mains before removing cover 2 eS 7 N This equipment must be earthed R E R LS Manufactured in the UK by LA Audio R TEEN SERIAL no OUTPUT 1 amp 2 O
4. Off 2 i l I O Select 2 Select 3 Input Select O Select J VOLUME I i Ie 6 Z l HEADPHONES Select 5 Select 6 TAAT On Off 1 On Off 2 l OUTPUT 1 ON OFF OUTPUT 2 ON OFF Fig 6 1 1 SPX20 block diagram showing main signal paths INPUT 1 The input is routed through a pair of half normalled TRS jacks and into a differential amplifier The TRIM varies the gain of the differential amplifier so ensuring maximum headroom at all gain settings The output of this amplifier is fed via CMOS switches onto the mix buss INPUT 2 amp 3 Inputs 2 and 3 are similar to Input 1 without the insert jacks INPUT 4 5 amp 6 These inputs are similar to Inputs 1 3 but are unbalanced The CMOS switches are controlled by the input select logic block This consists of six set reset latches Pressing a select button sets its latch and sends a reset signal to all the other latches Signals on the mix buss are summed by two virtual earth amplifiers These feed the TAPE RECORD output The mixed signal also feeds the BALANCE pot MONO and DIM switches OUTPUT 1 amp 2 are relay switched These relays are controlled by the OUTPUT on off switches and the power on off circuitry The output amplifiers are configured as ground compensated balanced impedance All inputs and outputs have RFI filtering Page 13 7 0 SPECIFICATIONS INPUTS 1 electronically balanced 20kQ XLR F pin 2 hot 2 amp 3 elec
5. SPX20 STEREO SOURCE SELECTOR PREAMPLIFIER OPERATION MANUAL Version 1 April 2000 2 1 2 2 2 3 2 4 2 5 2 6 Introduction Installation Inspection and un packing Operating environment CE standards Power requirements Signal levels External connections Warranty Description of controls Inputs section Outputs section Headphones section Applications Using the SPX20 Circuit description Specifications Page 2 CONTENTS Page 3 OahAR A oe 9 10 10 10 11 13 14 1 0 INTRODUCTION The SPX20 is a six input stereo source selector designed to extend the number of inputs and range of monitoring facilities available on a typical mixing console However the SPX20 is suitable for a wide range of monitoring applications including tape dubbing audio visual and digital workstations and for installation in background music applications Each of the inputs on the SPX20 has a level trim with sufficient range to cope with 4dBu and 10dBV equipment and for balancing the levels between the different sources Inputs are selected by momentary action buttons which also allow more than one input to be selected at a time Multiple inputs are mixed summed Two separate outputs with level controls and on off switching provide a means of selecting and balancing levels between two types of monitor speakers or alternatively to add a monitor mix to studio facility to your mixer The outputs have relay s
6. e For your information the unit can be internally rewired for use in 230V or 115V and 100V countries contact your dealer for information A special 220V 60Hz version is available for the Republic of Korea The mains lead connections to the appliance are coloured in accordance with the following code Green and Yellow Earth Blue Neutral Brown Live e WARNING THIS APPLIANCE MUST BE EARTHED 2 5 SIGNAL LEVELS For input level ranges see TRIM control in the Description of Controls section The TRIM range allows the SPX20 to work with 4dBu and 10dBu equipment IMPORTANT NOTE To ensure the best performance from the SPX20 it is important to adjust the input TRIM controls to give the correct operating levels within the unit Signals in excess of 20dB will cause the unit to distort 2 6 EXTERNAL CONNECTIONS Jacks INPUTS 3 1 T Hot R Cold S GND L INPUTS section INPUT 1 This input is balanced on XLR connectors and is wired as follows Page 5 Pin 2 Hot Pin 1 Screen Pin 3 Cold Fig 2 6 3 Pin arrangement for XLR inputs on the SPX20 Pin 1 Screen Signal ground Pin 2 Hot Signal Pin 3 Cold Signal For unbalanced operation join pins 1 and 3 and connect to Screen signal ground and use pin 2 as Hot signal Input 1 also has a pair of front panel inserts on TRS jacks which are wired as follows Sleeve Ring Tip Screen Cold Hot Fig 2 6 3 Pin
7. e ambient temperature conforms to these levels 2 3 CE STANDARDS AND THE LOW VOLTAGE DIRECTIVE LVD The SPX20 has been designed to meet the latest Electromagnetic Compatibility EMC regulations However we recommend you do not operate the unit close to strong emitters of electromagnetic radiation such as power transformers motors mobile telephones or radio transmitters The unit should only be connected to a power supply of the type described in 2 4 POWER REQUIREMENTS or as marked on the unit The unit must be earthed for safe operation Disconnect the mains supply before removing any cover 2 4 POWER REQUIREMENTS There is a mains fuse located inside the unit which is accessed by removing the cover This fuse is for protection against unit faults and as such will not normally need replacing If you think you have a power related problem please refer to your dealer The voltage and fuse rating have been factory set for 230V 50mA UK 220V 50mA Republic of Korea 115V 100mANorth America e The correct voltage and fuse rating is indicated on the rear panel Page 4 e Please check that your unit is correctly rated for the voltage in the country of operation If the fuse requires changing at any time please ensure the correct fuse is fitted An incorrect fuse could cause damage to the unit and may constitute a fire hazard If you carry your SPX20 from one country to another it is very important to ensure the voltage is compatibl
8. kwise CW Setting up the SPX20 To ensure maximum headroom noise and crosstalk performance it is important to have the correct signal levels within the SPX20 Please follow the following simple procedure When using equipment with a 4dBu output turn TRIM to almost CW and to fully CCW for 10dBV equipment as a starting point Connect one of the outputs to your monitoring system and set LEVEL 1 or 2 control to give a suitable listening level Then select each input in turn and adjust TRIM to give the same listening levels for each input It should not be necessary to turn TRIM far from these settings Page 9 4 2 OUTPUT SECTION OUTPUTS HEADPHONES BALANCE ai LEVEL 1 LEVEL 2 VOLUME C v dk an wn a A 1 t 1 4 5 y Stereo Source Selector V4 va MS MS MONO ON oe A BALANCE control This control allows adjustment of the stereo centre position The centre detent position gives equal left and right levels Turning BALANCE fully CCW cancels all right output signals and vice versa BALANCE affects OUTPUT 1 amp 2 and Headphones DIM switch Pressing this switch in reduces output levels by 20dB DIM affects OUTPUT 1 amp 2 and Headphones MONO switch Pressing the MONO switch sums left and right signals MONO affects OUTPUT 1 amp 2 and Headphones LEVEL 1 control This control adjusts the level of OUTPUT 1 Fully CCW is off and fully CW is 10dB Unity gain OdB is around 7 ON switch
9. tput can be used for the control room monitors and the other provide a studio room feed The monitoring system benefits from the added protection of the delayed power on and rapid power off switching included in the SPX20 A number of playback sources with different output levels can be balanced to provide a consistent listening level across all the inputs The TAPE RECORD output allows a stereo recorder to be connected to record a rough mix whilst laying down tracks MONITOR OUTPUT Mixing console WELLL LELLL d INPUTS RECORD OUTPUTS o OO O 0 0 0 0 0 0 O 000 00 Oo SPX20 Stereo source selector Page 11 Fig 5 1 1 Connecting the SPX20 as the main monitoring controller 5 2 AS A MONITOR EXTENDER If you prefer to keep control of the control room monitors within the mixing console the SPX20 can be connected as shown in Fig 5 1 2 The SPX20 is now selected by pressing the 2T 2 track return on the monitor section of the mixing console 2T INPUT MONITOR OUTPUT Mixing console LELLI ULUL L Power amp INPUTS OUTPUT o OO O O O 0 0 0 O O 000 00 Oo SPX20 Stereo source selector Fig 5 2 1 Connecting the SPX20 as a monitor extender Page 12 Left Left Right 6 0 CIRCUIT DESCRIPTION MIX L R Tape SendL LR r MONO rm DIM I F e BALANCE a LEVEL 1 l U On Off 1 OUTPUT 1 Tape Send R Right Xx Left gies Li Select H OUTPUT 2 Right l l 1 l LEVEL2 On
10. tronically balanced 20kQ 1 4 TRS Tip hot 4 5 amp 6 unbalanced 20kQ RCA Phono Centre pin hot OUTPUTS TAPE RECORD 100R RCA Phono Centre pin hot OUTPUT 1 amp 2 Type Ground sensing balanced impedance 1 4 TRS jack OdBu nominal wired Tip hot Impedance lt 1000 Max output 20dBu PERFORMANCE THD N lt 0 015 Noise lt 90dBu 20Hz to 20kHz Frequency response 0 0 5dB 20Hz to 20kHz Crosstalk lt 70dBu 10kHz CONTROLS TRIM 1 10dB TRIM 2 6 10dB 6dB DIM 20dB LEVEL 1 amp 2 to 10dB POWER SUPPLY Mains voltages 230Vac 50Hz 6VA Europe 115Vac 60Hz 6VA North America 220Vac 60Hz 6VA ROK Mains connector Standard IEC receptacle MECHANICAL Dimensions 1 75 44mm H x 19 482mm W x 6 5 165mm D Weight Unit 2 2kg Shipping 2 85kg LA Audio reserves the right to alter any feature or specification without prior notice E amp OE Page 14
11. utputs on the SPX20 are via 1 4 TRS jacks see Fig 2 6 3 Tip Hot Signal Ring Cold Signal Sleeve Screen Signal ground Output amplifiers on the SPX20 are ground compensated balanced impedance type Page 7 3 0 WARRANTY Your LA Audio SPX20 has been manufactured to a high standard using quality components If correctly installed and operated the unit should give years of problem free operation However in the event of a defect in material or workmanship causing failure of the unit within one year of the date of original purchase we will agree to repair or at our discretion replace any defective item without charge for labour or parts To receive service under this warranty it is necessary to return the unit to an LA Audio authorised service centre or to the factory with a dated receipt as proof of purchase After repair the unit will be returned to you free of charge Limitations This warranty does not cover damage resulting from accident or misuse The warranty is void unless repairs are carried out by an authorised service centre The warranty is void if the unit has been modified other than at the manufacturers instruction The warranty does not cover components which have a limited life and which are expected to be periodically replaced for optimal performance We do not warrant that the unit shall operate in any way other than as described in this manual Page 8 4 0 DESCRIPTION OF CONTROLS INPUTS Cc
12. witching which is delayed at power on to prevent annoying and potentially dangerous thumps and clicks reaching your monitor speakers The output section also has an overall Balance control Mono and Dim switching The SPX20 also has a built in headphone amplifier with separate level control and front panel accessible connector Main features of the SPX20 include Six stereo inputs with level adjustment Momentary action input select with led indicators Front panel accessible insert and level adjust for Input 1 Mixing of multiple input selects Balanced and unbalanced inputs on XLR 1 4 TRS jack and phono RCA connectors Output Balance Mono and Dim Two separate outputs with level control and on off switching Power on off output relays Tape record output Headphone output with level control Page 3 2 0 INSTALLATION IMPORTANT PLEASE READ THIS SECTION BEFORE USING THE SPX20 2 1 INSPECTION AND UNPACKING The SPX20 has been carefully packed at our factory in a carton designed to withstand handling in transit Should the unit appear to have been damaged in transit notify your dealer immediately and do not discard any of the packing The carton should contain e The SPX20 unit e Power cord e Operator Manual this book 2 2 OPERATING ENVIRONMENT The SPX20 is designed to operate between 0 and 50 C 32 122 F with relative humidity no more than 80 Should the unit be installed in an equipment rack ensure that th
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