Korg Mono/Poly

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

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
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
>

Hi Florian,

Yes, I should have cleaned her up for her grand youtube debut. I admit, I am not much for dusting, but clean the MP, inside and out, with alcohol every few months.

Very insightful point about the modulation wheel area. Yes, in fact, the problem started years ago around the mod wheel area -- I forget which switch, pitch or mod -- I believe the pitch wheel -- but when you would press the switch all the way down, it would warble. This later spread to the intensity knob for the wheel, when it was turned all the way to 10.

I will take the wheels off and have a look to see if anything is noticeably amiss with the wiring/contacts.

I suspect a destination switch might be difficult to replace. Crossing my fingers its something minor.

-K

--- In korg_mono-poly@yahoogroups.com, Florian Anwander <fanwander@...> wrote:
>
> 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
> >
> >
> >
> > ------------------------------------
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
>

Hello Kaleb

> but clean the MP, inside and out, with alcohol every few months.

Don't do this. The alcohol will remove useful lubricants on
potentiometers and switches; those will become scratchy - even the
effect you are having now might be increased by having potentiometer
without lubricant(*). Also I would not want to test, how too much of
alcohol interacts with older capacitors.


Keep the MP dust free, and avoid any liquid on the synth in any case
(the video shows spots of tea or coke on the keyboard - these are
killers!). That is all.

> I suspect a destination switch might be difficult to replace.

I don't think you have to replace it. It should be easy to clean. First
remove grabable dust with a pair of tweezers; then use compressed air to
blow out the rest of dust (compressed air is even available as spray in
a can). Then apply Caig Deoxit as deoxidant and sealer.
Same with potentiometers, but use Caig FaderLube FL5 for cleaning and
Federlube FL100 for sealing.

Florian