Something new(ish)? (Re: 1970's again? (was Re: [sdiy] pro EQs))

[Bill Felton]

That's the one all right.
Again, highly recommended -- simple, no expo converters to deal with 
for tracking, very useful addition to the palette.

cheers,
Bill

On Jan 1, 2005, at 2:51 AM, Scott Bernardi wrote:

> This might be the Electronotes circuits you were talking about - 
> Bernie called it a "Timbre Modulator".
> http://home.comcast.net/~sbernardi/elec/og2/og2_timbremod.html
>
>
> Bill Felton wrote:
>
>> There's also a very nice ElectroNotes circuit that, IIRC, had 
>> back-to-back diodes in the feedback path of an op-amp, (output being 
>> then basically center-clipped), then amplifying and adding the normal 
>> (or inverted) center-clipped signal back in to the original.  At full 
>> effect on triangle wave input, this gave frequency tripling.  But the 
>> intermediate stages from tri (or other continuously varying, ie, no 
>> pulse wave inputs allowed) to the 'full effect' setting gave a sound 
>> transform that was rather the inverse of typical synth filtering -- 
>> you went from a low-harmonic to high(er)-harmonic content sound, 
>> under vc of center-clipping amount and mix.  Since this needed no 
>> exp. converters to track, it was significantly cheaper than a filter 
>> circuit, gave an effect similar to, but different from, the 
>> time-variation in timbre from a filter, and thus played a comparable 
>> role in the patching ecology.
>> (I've got two I built and love them; Cynthia is panelling them for 
>> me, along with my EN MultiPhase Waveform animator.  )
>> cheers,
>> Bill
>>
>> On Dec 31, 2004, at 8:35 AM, John Loffink wrote:
>>
>>> Look here:
>>>
>>> http://www.oldcrows.net/~patchell/synthmodules/shaper.html
>>>
>>> and here:
>>>
>>> http://www.wavemakers-synth.com/motm/dws.html
>>>
>>> for examples of diode waveform shapers.
>>>
>>> I find my shaper useful for adding gradual degrees of distortion to
>>> waveforms, or making "composite" tones by modulating with waves from
>>> multiple VCOs or VCFs.
>>>
>>> You are correct that these circuits originated with analog 
>>> computing, yet I
>>> have never seen an implementation in "classic" (i.e., Moog, Buchla, 
>>> Serge,
>>> Emu, etc.) modular synthesizer format.
>>>
>>> John Loffink
>>> The Microtonal Synthesis Web Site
>>> http://www.microtonal-synthesis.com
>>> The Wavemakers Synthesizer Web Site
>>> http://www.wavemakers-synth.com
>>>
>>>
>>>> -----Original Message-----
>>>> From: owner-synth-diy at dropmix.xs4all.nl [mailto:owner-synth-
>>>> diy at dropmix.xs4all.nl] On Behalf Of Anthony Ankrom
>>>> Sent: Friday, December 31, 2004 8:09 AM
>>>> To: Paul Maddox; Synth-Diy
>>>> Subject: Something new(ish)? (Re: 1970's again? (was Re: [sdiy] pro 
>>>> EQs))
>>>>
>>>> I have read about something that I don't think anyone's ever 
>>>> applied to
>>>> synth work, but it might be
>>>> interesting.
>>>>
>>>> Just the other day I stumbled across an old article about 
>>>> "non-linear
>>>> transfer functions". The circuits in the article
>>>> used very large arrays of "forward biased" diodes in the feedback 
>>>> loops of
>>>> op-amps. It said forward biased but
>>>> the diodes were "pointing" the same way as the op-amps so I would 
>>>> think
>>>> this
>>>> would be reversed biased, but hmm
>>>> maybe it was because it was in the inverting input?
>>>>
>>>> And the arrays seemed to be strings of diodes of varying/increasing 
>>>> length
>>>> in parallel. Like the first was one in
>>>> parallel with a string of two in parallel with a string of three 
>>>> and so on
>>>> -
>>>> with variations on this theme.
>>>>
>>>> The aim here was some analog computing application, but isn't that 
>>>> what
>>>> analog synths are in a nutshell?
>>>> They're analog number crunchers with audio user interfaces.
>>>>
>>>>
>>>
>>>
>>>
>>>
>>
>>
>