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Socket PCB 

1.

 

Solder the 12 sockets to the 12 Socket pcbs, 

socket sits on it’s silkscreen footprint

 

 

 
 
 
 
Final Assembly 

1.

 

Present the pcb to the panel, and bolt the two together using the washers and nuts 
for the pots and switch 

2.

 

Cut 12 pieces of male header to be 6 pins wide. Place the long end of each into the 
12 female headers. 

3.

 

Present each socket pcb assembly to the main pcb, bolt into place, making sure that 
the male headers line up with their places on the socket pcbs. Solder the male 
headers to the sockets pcbs. 

   

Calibration 

 

 

Bias: 

Adjust Bias trimmer to sweet spot, ie a nice clean undistorted VCA output with 

no thunk when a snappy ADSR is applied to a CV input.  I do this without any audio at 
the inputs. The chances are that that the sweet spot is around the mid position. 

 

Lin and Exp: 

you can set these up to output matching voltages, however, in reality 

it’s better to set them up to perceived volume.

 

 

RDH 27/07/19 

http://www.frequencycentral.co.uk/ 

 

 

Summary of Contents for MU System X Dual Amplifier

Page 1: ...e the correct pinout as shown by the half circles p This signifies PNP BC557 transistors Note the correct pinout as shown by the half circles f This signifies 2N5485 FETs Note the correct pinout as shown by the half circles The PCB shows the correct orientation for BC547 BC557 Other transistor types can be used eg 2N3904 2N3906 but please observe the correct pinout Please observe the correct polar...

Page 2: ...180K x 4 1M x 2 All resistors watt metal film 47pF x 2 10nF x 2 22uF x 8 47uF x 4 LM13700 x 1 TL072 x 1 BC547 x 4 BC557 x 4 2N5485 x 2 16 pin IC socket 8 pin IC socket x 1 A100K x 2 B100K x 4 20K trimmer x 2 100K trimmer x 4 SPDT toggle x 2 6 3mm socket x 12 Male 40 pin header x 2 6 pin female header x 12 DOTCOM 6 pin header ...

Page 3: ...pots and the two switches Make sure they fit snug to the PCB Main assembly REAR 1 Solder all trimmers 2 Solder all of the 6 pin female headers These will later accept the Socket PCBs 3 Solder the DOTCOM power header Don t for get to make it keyed by removing the second pin in the PCB won t accept it otherwise it s keyed too 4 Solder the electrolytic capacitors ...

Page 4: ...pcb bolt into place making sure that the male headers line up with their places on the socket pcbs Solder the male headers to the sockets pcbs Calibration Bias Adjust Bias trimmer to sweet spot ie a nice clean undistorted VCA output with no thunk when a snappy ADSR is applied to a CV input I do this without any audio at the inputs The chances are that that the sweet spot is around the mid position...

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