[sdiy] Adding offset to vactrol??

[Grant Richter]

BTW, your first impulse may be to say, well, I can imitate a Vactrol  
with a VCA and a slew rate limiter on the control path.

But, patch it up and try it first by ear, I think you will find they  
are not the same.


On Jun 4, 2008, at 1:28 PM, Grant Richter wrote:

>>
>> I'm not sure I follow you there - vactrols just don't respond very  
>> fast; that's part of their charm. Also, for different audio input  
>> frequencies, the response time seems to be different, so as you  
>> close down on the vactrol you can get an interesting ringing  
>> effect. At least that's what it sounds like to me. I think Peter  
>> Grenader has written about that, and if you search for the sound  
>> file examples of his Plan B version of the Buchla LPG you can hear  
>> examples of it.
>>
>
> Vactrols do a very complex math operation called "convolution".  
> They complexly combine their pulse response with the input control  
> signal. The ear seems to like or recognize this.
>
> This link to a DSP site explains deconvolution in regards to a  
> gamma detector response, but the same idea applies to Vactrols (IMHO).
>
> http://www.dspguide.com/ch17/2.htm
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