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Papareil polivoks mods
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Papareil polivoks mods
roman_f
it seems that my polivoks filter has the common issue, but i haven't found the solution

the frequency knob operates in a very narrow range - only 0-2 or so
i it's like almost closed and then it's completely opened

did anyone make this filter and maybe solved that problem?
Blue Lantern
To solve your problem, you want to use a 100k trimmer and 100k resistor attached to the main CV junction. Then you can offset the cutoff range to what ever you like. look at this thread to solve your problem. I solved it a while back.

http://electro-music.com/forum/post-164261.html
jumunius
roman_f wrote:
it seems that my polivoks filter has the common issue, but i haven't found the solution

the frequency knob operates in a very narrow range - only 0-2 or so
i it's like almost closed and then it's completely opened


I did most of what is on this page of Polivoks mods, which Marc Bareille seemed to bless in an email exchange I had. The key one for you is to take the freq pot connection to ground and instead connect it to -15v.

If you follow through Blue Lantern's link, Haxster posts some interesting resonance mods. Towards the end of the thread, I think I tried to translate his mods (made to his own schematic) to the component references on Marc Bareille's board, if that's the one you are using.

One note: if you get around to trying these, I think I actually added a resistor to Haxster's res mod, to tame it just a bit. In fact, I used an on-on-on to give 2 levels of res variation in LPF mode. But I don't know off hand what I did and I neglected to follow up with it on that thread. I can try taking a look at mine if you get inspired to do the mods, or you can just try out some values yourself -- it's really a matter of taste.
Crybaby
I know this is an old question but people could still be looking for a solution. I think the previous answers might be a bit misleading.

There are (at least) two common problems regarding the range of the Polivoks Cutoff knob:
a) The cutoff does not go low enough, so the filter can't be completely closed
b) The cutoff knob does indeed close the filter at 0, but the filter is completely opened at about one fifth of the range, ie at the value of 2. Any setting higher than 2 does not affect the filter.

The replies above seem to concern problem (a) while OP has problem (b)

OP's problem is easily solved like this:

Locate R87, it is a 47K resistor very close to the Cutoff pot
Replace it with 130K (or something reasonably close to that value)
Done

I actually use to leave the 47k and only cut the bottom leg to solder one 82K in series, directly from the Cutoff pot terminal no 2 (the center terminal). This will amount to 129K. Thus I don't have to remove the panel board, knobs, power supply etc, and also the mod can be restored.

Sorry I'm not allowed to upload an image, because I haven't posted 2 messages yet :)
wahee
just goes to show a wee update does wonders. Thanks for the effort. I was able to use your little mod idea, using a 91k resistor in series to sort out the range on my new Polivoks.

Just the LFO to slow down now.

hihi
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