[sdiy] expo accuracy? or integrator accuracy?, or both?

[Magnus Danielson]

From: Grant Richter <grichter at asapnet.net>
Subject: Re: [sdiy] expo accuracy? or integrator accuracy?, or both?
Date: Sun, 09 Feb 2003 09:03:59 -0600

> > I've had an ASM-1 VCO measure in at a 21 octave range, but the last part
> > wasn't
> 
> That would be about 6 decades or 10E-9 to 10E-3 from the current source.
> 
> That should be normal for an exponential pair, but of course a current of
> 10E-9 can easily leak away or be absorbed by bias currents.
> 
> Rather than perfecting the a "good enough" core, wouldn't it be more
> interesting to investigate new dynamic waveshaping designs like the Buchla
> Music Easel?
> 
> It seems to me the frequency stability is acceptable, but new timbral design
> has barely been touched on. Timbre is arguably the next most important
> parameter after pitch is satisfactory.

While I agree with you, I just want you to remember that one of the things we
where discussing was an alternative to TEMPCO resistors and alternative
solutions to that. That is one of the things which I think is fashinating and
the experiments that Tim and Scott have done is encouraging to say the least.
But onces you've got an oscillator which allows itself to be built from not so
rare components and doesn't need constant tuning to be reasnoble, then looking
at means of modulation, timbral aspects, etc. all come in, I agree, but that is
to some degree a different matter. The through zero modulation for instance,
might be an interesting timbral effect, or it might not be as exciting.

As for the Music Easel, you'll find the schematics online on my site if you
need inspiration. One of the things which is really fashinating about it, and
indeed other Buchla designs such as the rest of the 200 series, is the CV
control of virtually everything.

The Buchla wavefolder acts similar to a lowpass VCF sweeping over the
overtones. That it does this by adjusting the gain into the wavefolder is a
curious thing ;O)

The Buchla way of selecting the balance between odd and even overtones is
another interesting concept.

For me the Buchla stuff is inspiring since you are forced to think differently.
After studying them I'm nowdays more leaned over towards triangle oscillator
cores than sawtooth oscillator cores for instance. You see how this stuff
affects me!

Cheers,
Magnus