VCA DIY projects, what are the options?

[LektroiD]

I'm looking to build some VCA's (possibly 4 at the moment). I'm just wondering what the options are? I'm on a tight budget, but at the same time I'm looking for the best quality, so I guess I'm looking to reach a happy balance somewhere between cost and quality. I thought I'd ask here first.

[bubzy]

Ive just finished the thomas henry vca, you will need to buy the book "A synthesizer for the 21st century" from magic smoke which is the only downside to this if you are on a tight budget. however the book is awesome, and fonik has done a layout for the board too, if you etch your own.

the other problem with this circuit is that it uses a "rare"(ish) chip the SSM2164(quad vca chip), also available from magic smoke, and mammoth electronics sell a clone chip called the V2164D for a reasonable price.

the thomas henry vca (as expected) is very good and likely wont leave you wanting anything more. and its a really easy build.

hope this helps.
-bubzy

[mark_olson]

Another TH VCA on Scott Stites' site:

http://www.birthofasynth.com/Thomas_Henry/Pages/VCA-1.html

A Yusynth VCA:

http://yusynth.net/Modular/index_en.html

MFOS VCA:

http://www.musicfromouterspace.com/

(Sorry, can't do a better URL.)

I have build the last one and like it a lot.

These are all good choices if you want something affordable. PCB artwork is free for the downloading. None of these is too big to do on perfboard for that matter.

Good luck.

Mark

[inlifeindeath]

quick link:
http://www.musicfromouterspace.com/analogsynth_new/DUALVCA/DLLVCA001.html

Alternatively, if you're looking for something pretty simple:
http://www.elby-designs.com/wasp/vca.pdf

Just use a LM13600 or 13700 to build a dual per chip to replace the 3080 if you need to.

[brother303]

Hi,

maybe CGS?

http://www.cgs.synth.net/modules/cgs64_vca.html

[LektroiD]

Are any better or worse than others in terms of audio quality?

[Terrafractyl]

I've built the CGS and the MFOS and recently the TH 21st century (but I haven't actually plugged this one in yet). I don't know if its either my imagination or incorrect trimming, but the 2 CGS VCA's I built function perfectly but seem to somehow lose a little low end... I havnt experienced this before with other VCA's but yeah a big subby bass sound when put through those VCA's just seems to lose a certain something.
The MFO's Linear/Log VCA's are great but when running on 15v the difference in gain between the Linear and Log modes is fairly large, although this could maybe be fixed with some resistor changes...?

These are my experiences anyway

[wmonk]

Due to the requirement of matched transistor pairs (and a triple) in the CGS VCA, I wouldn't call em easy to build. My favourite VCA right now is my Quad VCA / VC Mixer from Oakley Sounds. You can get PCBs on their website: http://www.oakleysound.com/vca-d.htm
Potentiometers can be pcb mount, and are on a good spacing for 5U modules.

[dingebre]

I'm clearly biased, but the Steiner Synthasystem VCA is very interesting.

http://www.xmission.com/~dingebre/VCA.html

David

[Clack]

Iv'e been looking at this one

http://www.sdiy.org/philgallo/mgbvca.html

no PCB , but I really want to try something based on a SSM2164 or a THAT2162 problem is both are exponential response so you have to waste a VCA section if you want to make it linear.


There is also this, but it is quite simple so it suffers from some CV bleeding to the output, I have read

http://www.uni-bonn.de/~uzs159/vca3plus.png

[Clack]

[sduck]

There's also the motm 190 dual vca -
http://www.synthtech.com/motm190.html

pcb and such are available from the Bridechamber -
http://www.bridechamber.com/MOTM_190.html

[Tim Servo]

[prgdeltablues]

Or you could try this one from Nicolas3141:

http://electro-music.com/forum/topic-41277.html

I've just built a quad version of the VCA section - really useful and a simple build. As far as I can tell, no CV bleedthrough.

Peter

[prgdeltablues]

Forgot to add, i used LM13700 instead of LM13600, and used the standard configuration from the datasheet for the input biasing and linearising diodes. You can sub any PNP for the BC559 - I tried 2N3906 and BC557/8 and they all worked fine. Not as flexible as the MFOS VCA - no Log/Lin switch, and no CV offset, but a very useful addition.

Peter

[Mooger5]

There´s a VCA shootout here http://hem.bredband.net/bersyn/VCA/vca_shootout.htm with schematics.
There´s also the CA3280 which someone says it´s the best OTA chip ever.
The old Korg VCA I think has the fewest parts but I don´t find it very dynamic.

[LektroiD]