[sdiy] CEM / V3340 output spikes

[Martin Klang]

Hello list,

I've been prototyping with the Coolaudio V3340, their CEM3340 clone.

I'm seeing a voltage spike on the ramp output at the oscillator reset
point. The output, which is 0-8V positive (with +/-12v supplies), swings
negative as it resets.

This is not so much an issue for a sawtooth waveform, since it just adds
more harmonics (flavour!). My problem is that I'm cross-fading the ramp
and tri outputs to get a variable output waveform, and the spike bleeds
through in an ugly way.

Is this something anyone else has come across, with the V3340 or the
original?

I've tried loading the output in different ways but it doesn't seem to
make much of a difference. A fixed filter can get rid of the spike, but
then I'd loose a lot of lovely high harmonics!

any ideas would be much appreciated!

cheers,

Martin Klang
Rebel Technology