Polysix Filter Problem

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pdub
Common Wiggler
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Joined: Sun Jul 21, 2013 11:40 pm

Polysix Filter Problem

Post by pdub » Tue Nov 13, 2018 5:03 pm

Hi

I have been having a problem with my Modypoly setup.

When I bring the filter cutoff down I hear what sounds like fast triangle modulation even with no modulation active.

I have set all CC controllers to zero and the Modypoly Triangle speed and depth has no control of the modulation. It also isn't related to the speed of the arp or internal MG.

I have reset the unit, re-flashed the firmware but nothing has helped.

Any help would be greatly appreciated.

Thanks!

pdub
Common Wiggler
Posts: 80
Joined: Sun Jul 21, 2013 11:40 pm

Post by pdub » Thu Nov 15, 2018 8:26 pm

So when I disconnect the orange CV option cable from R51 the problem goes away.

Any ideas why this would be happening?

Thanks

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tubbutec
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Post by tubbutec » Thu Nov 22, 2018 6:15 am

Hi there,

some Polysix seem to have this issue, most do not. It comes from improper filtering of the filter CV signal in the Polysix circuitry, maybe there are differences between various Polysix versions.

There is a simple fix to this though:

add a 1k resistor in series to the orange filter wire. And a 100nF cap to ground like so:

Image

pdub
Common Wiggler
Posts: 80
Joined: Sun Jul 21, 2013 11:40 pm

Post by pdub » Thu Nov 22, 2018 12:43 pm

Thank you!

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