[sdiy] more pitch shifter thoughts

[Scott Gravenhorst]

Grant Richter <grichter at asapnet.net> wrote:
>You can build one with just a top octave chip and a CD4046. The TOC just
>need a high frequency clock phase locked to a reference VCO square wave. A
>switch can select the high or low C from the TOC and give and octave above
>or an octave below the reference VCO. (IIRC with a 50240)

Being a 4046 PLL kind of guy, I have wondered about stability and tracking
when doing this.  I have a PLL module that uses a divide by 12 counter in
the loop and it works just fine.  But the MK50240 has a range from divide
by 239 to divide by 478.  

What kind of problems, if any, will there be with such large counters?  

I would think that proper VCO capacitor selection is important.

Over/undershoot?  

Does a large counter affect lag very much?  

My own circuit has adjustable damping for the loop filter and allows me to
adjust it so that frequency changes are so immediate that I do not hear any
over/undershoot or lag.  But then, my PLL has only a divide by 12 counter
in the loop.


>> From: Steve Ridley <spr at spridley.freeserve.co.uk>
>> Reply-To: spr at spridley.freeserve.co.uk
>> Date: Mon, 10 Jan 2005 18:32:05 +0100 (CET)
>> To: synth-diy at dropmix.xs4all.nl
>> Subject: Re: Re: [sdiy] more pitch shifter thoughts
>> 
>> 
>>>> EML PolyBox
>> 
>>> Any idea how they did it?
>> 
>> Schematics are available at the yahoo EMLSynth group.
>> 
>> 
>> Steve
>> 
>> 
>> 
>> 
>> -- 
>> 
>> Whatever you Wanadoo:
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>> This email has been checked for most known viruses - find out more at:
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