synth-diy

[Andrew Schrock]

On Mon, 21 Dec 1998, Johan Gustavsson wrote:
> > im interested in building my own synth equiptment. what is the best way
> to
> > get started? i dont have experience with this sort of thing but am very
> > curious...
> 
> I'd recommend, as I always do, TomGs "Electronics for music" site for
> actual, practical circuits. http://www.mindspring.com/~vco

One thing I'll toss in here as pure opinion from personal experience.. I
had real problems using 3-pad-per-hole rat shack vectorboard. I mean, my
filters had awful hum, my envelope generators had problems, etc. etc...
after I switched to doing circuits off breadboard (w/no solder pads), they
all went away. Perhaps it's because I can focus more on layout on
breadboard, or that I take a little more care with how I construct the
modules. I'm sure capacitance between power rails and parts was reduced
as well. The breadboarded modules are quite sturdy, however, and I use 
them all the time. 

> Work is now finally underway on the Moxie Maxx Modular, and so far (as
> of today) we've built one ordinary boring dual LFO and one simple VCO
> (the LFO-1A and the VCO-5A). Tomorrow we'll do the VCF-8b (the dual
> KLM one) and go looking for a good box to put it all in, as well as
> finish the PSU. Now, the point of this is that both I and my building
> friend are relatively new to this building thing, and have access to a
> good soldering pencil, a couple of multimeters, a scope and nothing
> more. We etch circuit boards one by one, using layouts made in MS Word
> of all amazing programs transfered to plastic film. Can you say
> "budget"? And they both worked first thing when we plugged them
> in. Sure, they are both relatively simple constructs, and I haven't
> yet tried the vco with a proper 1v/oct CV source, but still - We
> turned on the power and got nice squares and triangles on the scope,
> reacting the way they ought when we turned the pots. Amazing enough
> for me :-)
> 
> My initial meterings seems to indicate that the VCO isn't responding
> in quite as linear-ish fashion as I'd like -
> 
> -11  v from the pot	-   90 hz
> - 7.5v			-  180 hz
> - 4  v			-  352 hz

These readings are confusing.. I don't have the schematic for the 1a in
front of me, so I won't embarass myself with trying to diagnose the
problem. 

> much. I'm planning on building the VCO-2s as main voices. and started
> off with the simpler stuff just to get a feel for it. Make it up as
> you go along, y'know. :-)

I've found the 2a's to be quite nice. There are two of them in my main
modular. There are a few mods you can do to make it more user-friendly
(esp. w/PWM) but overall a _very_ nice VCO once it warms up. 

Andrew

| Andrew Schrock							|
| Network Programmer, Synthesizer and electronic music enthusiast	|
| aschrock at cs.brandeis.edu						|