[sdiy] Continuously variable waveshaping (was Behringer Neutron)

[Dave]

I haven't had time to fully read the patent application, but the typical problem with these slope control approaches is to make it hit a specific frequency.  

-Dave



On April 10, 2018 6:33:42 AM PDT, Rutger Vlek <rutgervlek at gmail.com> wrote:
>I recently stumbled on this recent patent by Moog:
>https://patents.google.com/patent/US20160335998A1/un
>
>It concerns continuously variable waveforms, but implements it at the
>core
>of a VCO rather than by crossfading the outputs (waveshapers) of one.
>The
>idea is awesome, but I have my reservations about the real-world
>feasibility of the method (given component tolerances and accuracies).
>
>Rutger
>
>
>
>2018-04-08 21:09 GMT+02:00 Tim Parkhurst <tim.parkhurst at gmail.com>:
>
>> " '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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>>
>>
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