Random*Source Serge CV-PRO User manual

RANDOM*SOURCE
RANDOMSOURCE.NET 1
Serge Audio Mixer
SERGE Audio Mixer
The Serge CV-PRO / MIXER pcb set by Random*Source can be built as either a (single or dual) Voltage Proces-
sor or as an active Audio Mixer with 3 input chanels, where the phase of the rst input can be inverted for
phase cancellation effects. This document describes only the Audio Mixer setup.
As the Audio Mixer uses only one half of the main pcb, the areas grayed out in the following picture should
be ignored (left empty):
Please note:
• Orientationofthemainpcb:power header is at the bottom(whenlookingatthemoduleup-
right,e.g.inarack).
• Circuitcontainsaninterestingdiode-based limiter sectiontopreventtheaddedsignalsfrom
uglyclipping.ThiswaspresumablyintendedforuseofthemoduleasaCVprocessor.However,
itcanalsobeusedwithaudiosignals-thisleadssoafairlystrongsoftening/roundingofthe
resultingwaveformthataffectsthesoundsimilartoaslightwavefolding.:
Fora“clean“audiomixerleavethejumpersJP1opentoignorethelimitersection.
Toexperiencetheeffectofthelimitersection,install2jumpersatJP1(paralleltotheboard,i.e.
connectingleftandrightpinsinthephotoabove).
• Useanice(dual)op-ampforhighdelity,e.g.aBurr-BrownOPA2134orBurr-BrownOPA2604.

RANDOM*SOURCE
RANDOMSOURCE.NET 2
Serge Audio Mixer
Bill of Materials (Audio-Mixer)
Resistors
2 10R F1, F2 alt: 22R, FERRIT BEAD
1 220R R10
1 820R R9
1 10K R8
7 100K R1, R2, R3, R4, R6, R7, R21
1 220K R5
Capacitors
1 47pF C9 Mica or TDK C0G
4 100nF C3, C4, C5, C6 Decoupling (5mm MLCC) or TDK C0G
4 470nF C11 Film (Polyester)
2 10uF C1, C2 Electrolytic
ICs
1 OPA2134 IC1 Alt: OPA2604
2 1N4148 D1, D2
Misc
2 SIL header 2pol JP1 Jumper to activate Limiter
1 MTA-156 PWR1 MTA-156 power connector
2 SIL header 16pol X1, X2 16-pin connector, links main pcb to
component pcb
1 DIP-8 socket for IC1
4 Banana Jacks (bipolar) for AUDIO inputs / outputs Emerson-Johnson
Mouser: 530-108-0903-1 (black)
1 SPDT switch (ON - NONE - ON) NKK M2012SS1W01 (no cap) or
NKK M2012SS1W01-BB (white cap)
3 Potentionmeter
100K
linear (B100K) or log (A100K) Alpha 9mm vertical pcb mount
available from Thonk, Tayda
Building
This is simply a suggestion - you might nd a different workow more practical:
1. MounttheBananajacksandtheswitchontothefrontpanel.
2. Mountthe3potsontothecomponentpcb.Potsshouldsitontheprintedside-thissidefacesthe
frontpanel.Don‘tsoldertheminyet.
3. Carefullymountcomponentpcb(withthepotsinserted)ontothefrontpanel-youmayhaveto
wiggleabittogetthepotsthrough.Makesurethethreadsofthepotsgothrough.
4. Onceeverythingisnicelyinplace,solderthepotsontothecomponentpcb(whilethefrontpanel
isattached).DONOTSOLDERTHEBANANAJACKSYET!

RANDOM*SOURCE
RANDOMSOURCE.NET 3
Serge Audio Mixer
5. Removethecomponentpcbagain.Soldershortpiecesof(stiff)wire-about10mmlong-intothe
padsfortheswitch.Theseshouldstickupintheairontheprintedside(samedirectionasthe
pots)andshouldonlygothroughthepcbasmuchasrequiredtosolderthemin(i.e.shouldnot
stickoutmuchontheotherside).
6. Stuffthemainboard,beginningwiththeresistors,thencapsetc.
7. MainpcbandcomponentpcbaretobeconnectedthroughprecisionDIPsocketandpins.Itis
recommendedtousethepinsonthemainpcb(facingdown,solderedfromabove)andthepin
socketsonthecomponentpcb(standingup,solderedfromthefrontpanelside).Breakorcutoff
thepiecesyouneedandstickthemtogethersothatmainpcbandcomponentpcbformanice
sandwich(don‘tsolderyet).Checkthatyoudidn‘tleaveoutanypins/holesandthatthesockets
areallonthesameside(componentpcb).Solderallthepinsinwhilekeepingthesandwichto-
gether-thisavoidsanymisalignments.
8. Carefullyseparatethesandwich-ifyouusedprecisionsockets,thismaynottotooeasy-they
sticktogethernicely(givingagoodconnection).
9. Mountthecomponentpcbontothefrontpanelagainandscrewonthepotsfromthefrontside.
10. Makesureeverythingisinplace.
11. Soldertheswitchinbysolderingtheair-wiresontothecorrecpondingcontacts.
12. Solderthebananajacksin.
13. Attachanyscrews/spacersifdesiredandmountthemainpcbontothecomponentpcb.
14. Connectapowercordsupplying+12V,GND,GND,-12VtotheMTA-headeronthemainboardand
youshouldbereadytogo:-)
Calibration
Module does not require any calibration.
(Version 16 Feb 2015)
SERGE Modular by Random*Source. Module and circuit under license from Serge Tcherepnin. All rights reserved.