[sdiy] 1-pole LPF using a differential integrator?

[mark verbos]

Nah, Aaron's right. Although the circuit in a 258 is not as much a  
crossfader as just a VCA mixing in the harmonics on top of the sine  
wave.

mark




On May 1, 2008, at 4:49 AM, Magnus Danielson wrote:

> From: Aaron Lanterman <lanterma at ece.gatech.edu>
> Subject: Re: [sdiy] 1-pole LPF using a differential integrator?
> Date: Thu, 1 May 2008 00:20:42 -0400
> Message-ID: <7F46D30B-9738-4C3E-B582-E325344DD84F at ece.gatech.edu>
>
>>
>> On Apr 30, 2008, at 4:00 PM, rdrake wrote:
>>
>>> how about that center-tapped pot on the output?  would love to  
>>> see an alternative way of implementing that...
>>
>> What did you have in mind?
>>
>> Indeed that is an interesting feature - I don't think I've seen  
>> another synth with something like that.
>>
>> I recall the Buchla 258 - I think - has some FET based circuitry  
>> that lets you crossfade between a sine and a whatever-other- 
>> waveform - maybe something like that could be used here to make it  
>> voltage controllable.
>
> I think you are after the Buchla 259 here Aaron. Please check the  
> schematics.
>
> The wavefolder to some degree simulates a sweeping lowpass-filter.
>
> The even/odd harmonic balance pot is interesting.
>
> Cheers,
> Magnus
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