Discussion about the Korg PolySix synthesizer

And thanks for having me J

 

I recently acquired a Polysix in very nice cosmetic condition but it has an
issue with it's sound.

I bought it knowing this but maybe someone here can help me finding out what
to look for as it is quite an annoying problem.

 

Take a listen here:

http://12bit.com/Audio/Polysix/Polysix.mp3

 

It is a clean saw wave playing the first sound and it does not matter if I
turn any MG/LFO knobs. It just sounds like there is always this very fast
LFO running on the VCO.

 

Anyone ever heard of this and know what to look for ? 

 

Best;

 

Kenneth

12bit.com



[Non-text portions of this message have been removed]

First place to look is the VCO Mod output from the CPU board to the 
voice board (CN05 -12).
This should be a smooth voltage;  distortion here will be reflected in 
the VCO sound.
Possible causes are faulty 4051 CV demux, faulty 4558 opamp buffer, 
faulty filtering cap, etc.
It should be easy to track down, following the control signal path with 
a scope.
~G
Kenneth Abildgaard wrote:
>  
>
> And thanks for having me J
>
> I recently acquired a Polysix in very nice cosmetic condition but it 
> has an
> issue with it's sound.
>
> I bought it knowing this but maybe someone here can help me finding 
> out what
> to look for as it is quite an annoying problem.
>
> Take a listen here:
>
> http://12bit.com/Audio/Polysix/Polysix.mp3
>
> It is a clean saw wave playing the first sound and it does not matter if I
> turn any MG/LFO knobs. It just sounds like there is always this very fast
> LFO running on the VCO.
>
> Anyone ever heard of this and know what to look for ?
>
> Best;
>
> Kenneth
>
> 12bit.com
>
> [Non-text portions of this message have been removed]
>
> 



[Non-text portions of this message have been removed]

Should also mention:
something else to try is cutting the trace between CN06-2 and R9;  this 
is the CV from the mod box to the VCO, and it runs very close to a 
digital buss that can inject unwanted noise.  If cutting this trace (at 
BOTH ends) solves the distortion problem, you can solder a wire jumper 
between CN06-2 and R9 to restore the mod control without the unwanted noise.

 >First place to look is the VCO Mod output from the CPU board to the 
voice board (CN05 -12).
 >This should be a smooth voltage;  distortion here will be reflected in 
the VCO sound.
 >Possible causes are faulty 4051 CV demux, faulty 4558 opamp buffer, 
faulty filtering cap, etc.
 >It should be easy to track down, following the control signal path 
with a scope.
 >~G
Kenneth Abildgaard wrote:
>  
>
> And thanks for having me J
>
> I recently acquired a Polysix in very nice cosmetic condition but it 
> has an
> issue with it's sound.
>
> I bought it knowing this but maybe someone here can help me finding 
> out what
> to look for as it is quite an annoying problem.
>
> Take a listen here:
>
> http://12bit.com/Audio/Polysix/Polysix.mp3
>
> It is a clean saw wave playing the first sound and it does not matter if I
> turn any MG/LFO knobs. It just sounds like there is always this very fast
> LFO running on the VCO.
>
> Anyone ever heard of this and know what to look for ?
>
> Best;
>
> Kenneth
>
> 12bit.com
>
> [Non-text portions of this message have been removed]
>
> 




[Non-text portions of this message have been removed]

Thanks for everything.

 

Well .. I kept it on for 10 hours and now the sound is perfect for some
reason.

I have turned it off again and will test it again tomorrow.

 

There seems to be some tune errors now. Not between the six voices which all
tune the same, but between the octave there seems to be a little variation.

 

I will look in the service manual and see if something can be useful.

 

Thanks again for taking the time to answer my post so fast.

 

Best;

 

Kenneth.

 

Fra: PolySix@yahoogroups.com [mailto:PolySix@yahoogroups.com] På vegne af
klosmon
Sendt: 22. august 2011 02:57
Til: PolySix@yahoogroups.com
Emne: Re: [PolySix] Hi Polysix group.

 

  

Should also mention:
something else to try is cutting the trace between CN06-2 and R9; this 
is the CV from the mod box to the VCO, and it runs very close to a 
digital buss that can inject unwanted noise. If cutting this trace (at 
BOTH ends) solves the distortion problem, you can solder a wire jumper 
between CN06-2 and R9 to restore the mod control without the unwanted noise.

>First place to look is the VCO Mod output from the CPU board to the 
voice board (CN05 -12).
>This should be a smooth voltage; distortion here will be reflected in 
the VCO sound.
>Possible causes are faulty 4051 CV demux, faulty 4558 opamp buffer, 
faulty filtering cap, etc.
>It should be easy to track down, following the control signal path 
with a scope.
>~G
Kenneth Abildgaard wrote:
> 
>
> And thanks for having me J
>
> I recently acquired a Polysix in very nice cosmetic condition but it 
> has an
> issue with it's sound.
>
> I bought it knowing this but maybe someone here can help me finding 
> out what
> to look for as it is quite an annoying problem.
>
> Take a listen here:
>
> http://12bit.com/Audio/Polysix/Polysix.mp3
>
> It is a clean saw wave playing the first sound and it does not matter if I
> turn any MG/LFO knobs. It just sounds like there is always this very fast
> LFO running on the VCO.
>
> Anyone ever heard of this and know what to look for ?
>
> Best;
>
> Kenneth
>
> 12bit.com
>
> [Non-text portions of this message have been removed]
>
> 

[Non-text portions of this message have been removed]





[Non-text portions of this message have been removed]

Hi Kenneth,

On 21 aug. 2011, at 14:32, Kenneth Abildgaard wrote:

> And thanks for having me J

Welcome to the group!

> I recently acquired a Polysix in very nice cosmetic condition but it has an
> issue with it's sound.
> 
> I bought it knowing this but maybe someone here can help me finding out what
> to look for as it is quite an annoying problem.
> 
> Take a listen here:
> 
> http://12bit.com/Audio/Polysix/Polysix.mp3
> 
> It is a clean saw wave playing the first sound and it does not matter if I
> turn any MG/LFO knobs. It just sounds like there is always this very fast
> LFO running on the VCO.
> 
> Anyone ever heard of this and know what to look for ? 

First thing to check (and replace!) is the battery, even if it might not be related to the problem at hand. If you haven't read up on this, please visit Old Crow's site:
http://www.oldcrows.net/~oldcrow/synth/korg/polysix/index.html

> Best;
> 
> Kenneth
> 
> 12bit.com

Kind regards,
Ben