[sdiy] Continuously variable waveshaping (was Behringer Neutron)

[Tim Parkhurst]

" 'High frequency hash' is a direct quote from Ken Stone's description of
that
circuit, by the way."

- and the band name for my new EDM / free jazz group.


Tim (add in some corned beef and you've got a tasty breakfast) Servo
---
"Imagination is more important than knowledge." - Albert Einstein




On Sun, Apr 8, 2018 at 11:36 AM, Guy McCusker <guy.mccusker at gmail.com>
wrote:

> On Sun, Apr 8, 2018 at 6:54 PM, David G Dixon <dixon at mail.ubc.ca> wrote:
> > My wavefolder (as found in the Intellijel uFold) uses TL072, and doesn't
> > generate "high-frequency hash".  Also, I've achieved what looks a lot
> like a
> > resonant filter output with a sawtooth wave, without a filter.  Given the
> > way that this folder works (with diode "turnaround" circuits) I'm not
> sure
> > that slew rate is a significant factor.  The opamp outputs in the folder
> > chain are confined to relatively small voltages -- the first one to
> about 3V
> > or less, and the subsequent ones much less.  Other folders may have
> > significantly different modes of operation where slew rate is important,
> but
> > not the ones based on diode turnarounds.
>
> There's a bit of talking at cross-purposes here I think. The wave
> folder in the CGS29 and also the Serge wave multiplier (middle
> section) also does not generate "high frequency hash" and works fine
> with a fast op amp. Their design is also similar to your "turnaround"
> idea, as it happens.
>
> The "high frequency hash" business concerns a different part of the
> CGS29, the Grinder section, which exploits op amp overshoot and
> ringing. It makes sense that slew rate is a factor there. ("High
> frequency hash" is a direct quote from Ken Stone's description of that
> circuit, by the way.)
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