MOTM

>Has there been any interest in a collective "gathering" of funds to
finance
the re-tooling costs, it would be interesting to see if enough people
would
be up for it.

Hi Andy and all,

I really do not think that this is a cost effective solution at all. A
VCO does not cost a huge amount to build from op-amps and discretes. The
cost of any module is primarily determined by the amount of knobs and
other hardware. Temp co resistors are easily obtainable from Paul and
others and these give good enough performance.

The CEM3340 although good in its day, has some disadvantages too.
The -5V supply is a pain, although Doug Curtis had good reasons to do
this all those years ago. The sync function is terrible, and the
triangle output always needs to be buffered. I reckon it takes about
twenty minutes to settle in pitch as well, but that could be my PSUs or
the synth housing.

The CEM3310 is again very good, but the attack phase could have been
more linear for a more punchy sound. The reliablilty of the 3310 chip
seems to be worse than the VCO. I must admit to having a small stockpile
of both the 3340 and the 3310 to keep my other DIY synths in order. Even
if Doug has got 5000 3310s in his garage, it does seem a little
problematic in using them in any new design.

Juergen Haible has designed a very nice VCADSR, its on the Synthfool
website, that could easily form part of a more complex VC EG design. Its
performance is excellent and uses only bog standard parts. I built one
of these up, and was very impressed how little board area the design
took up. With a few extra op-amps to sum in CVs you could make up quite
a staggering module.

Regards,

Tony Allgood

http://www.techrepairs.freeserve.co.uk/