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Subject: Re: [korg_mono-poly] Video of M/P Unstable Filter - Diagnostic Help??

From: Alan Dicker <alanmdicker@yahoo.co.uk>
Date: 2011-09-27

If you leave a playing in hold an apply pressure to different areas of the case or gently knok it can you create the same effect?
I think Florian may be on to somthing with the mod wheel area.  initially I would have said chck your filter chip is in place correctly as some monopoly's have them in sockets and it may have worked a little loose over time but the way the kayboard effects the sound I think the problem would by on the lower area of the cabinet and not the under side of the front panel where all the voice circuitry is located.  I was thinking along these lines but didn't consider the mod wheels but the PSU but if there were bad solder joint there this is would effect far more than just the filter. Still might be worth checking up stairs to see if the SMM2044 filter IC is socketed and if so if its firmly in place.

Alan


To: korg_mono-poly@yahoogroups.com
Sent: Tuesday, 27 September 2011, 13:12
Subject: Re: [korg_mono-poly] Video of M/P Unstable Filter - Diagnostic Help??

 
Hello Kaleb

I cannot see the complete MP in the video, but I assume, that sometimes
modwheel modulation feeds through to the filter. I'd check for dirt or
loose contact in the modwheel destination switch. It would explain that
the fault is sensitive to mechanical influences from the keybord.

At least the video shows, that your MP is dirty like hell. It doesn't
make me wonder that you have troubles with it.

Florian

Am 27.09.2011 07:38, schrieb Kaleb:
> Hi,
>
> I have made a video of the unstable tone my Mono/Poly has recently contracted, originating somewhere from the low pass filter.
>
> What's curious is the velocity-sensitive aspect -- the harder I hit the keys, the more mangled and unstable that key's tone becomes. (Some part of me has always believed the M/P was sensitive to velocity, or responded to how hard it was played.)
>
> This filter freak-out causes the sound to unexpectedly drop off, or pitch to randomly change when the LP is in self-oscillation.
>
> Please have a look/listen, and maybe we can diagnose the problem.
>
> http://www.youtube.com/watch?v=SttZhs7sKHE
>
> Thanks everyone!
>
> -Kaleb
>
>
>
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