[sdiy] A hacked phasor, with vactrols

[Michael Bacich]

On May 1, 2006, at 3:46 PM, René Schmitz wrote:

>
>> They put in a switch to give the user the option of using a knob  
>> or using a control voltage to control the mix. The CV input on the  
>> mix doesn't seem to give the same dramatic change as the pot does,  
>> but you do hear a change as the CV mix input is swept.

I don't know why your CV-controlled mix isn't as dramatic as the  
pot.  However, in my opinion, voltage controlled wet/dry mix will not  
be a very musically useful parameter.  At least on a phaser -- it  
simply will not yield very dramatic sonic results.  It won't be very  
dramatic, regardless of how you control it.  That's one of the  
reasons most phasers don't have any means  for the user to control  
the wet/dry mix -- they just internally set it at 50/50, because  
that's what usually works best to most people's ears.   In my  
opinion, a much more satisfying parameter would be voltage-controlled  
resonance (or feedback).  It appears, though, that your initial  
design doesn't include any feedback/resonance circuitry.  It would  
certainly be easy to add, and would make a *huge* difference in the  
sound of the phaser.  You should try it -- it won't take much more  
than another pot and a couple of resistors to hear how it sounds.   
Voltage control of resonance could probably be done either with  
vactrols or with an OTA.

I will admit, though, that as a technical exercise, voltage  
controlled mix is probably a worthwhile challenge.
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