[sdiy] modding a Plan B Model 9 mixer

[Stewart Pye]

Hi Danjel,

If you turn the volume controls down can you still hear audio on the 
output? If not then maybe this could be the issue...
I had a look on the plan B website and the way they do the routing 
leaves the signal disconnected, not shunted to ground, when in the mute 
position.  Maybe the switch is bleeding the audio through. You could try 
switching it to output B and see if there is any audio on output A...

Perhaps a lower impedance path around the routing switch would help (if 
that is the cause of the problem).


Another solution would be to use a double pole switch for the channel 
muting and use the other pole to control FET's or analog switches to 
shunt the signal to ground when in the mute position.

I hope that made some sense,
Stew.


Danjel van Tijn wrote:
> I have a Plan B Model 9 mixer and it suffers from really bad channel
> bleed. With all inputs muted you can still clearly hear audio on the
> output. This is not an issue with my individual unit, it is a problem
> with the design. Peter G dismissed it as simply an issue with the the
> Doepfer power bus system yet no other mixers suffer from the same
> problems.
>
> The circuit is pretty simple and I was wondering if anyone here (who
> has this module) has taken a look at it and recognized anyways to
> reduce or eliminate the bleed?
>
>
> cheers,
> Danjel
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