[sdiy] Prophet 10 op-amp swaps?

[rburnett at richieburnett.co.uk]

> Part of the problem, I think, is the long length of tracking from the
> inverting pin of the op-amp around the PCB...

I agee with Tony.  Excessive capacitance from the virtual-earth point 
to ground is apt to drive high-performance op-amps unstable.  A long 
trace here on the PCB is particularly bad if it runs over a ground-plane 
too!

Does anyone know how they get around this problem in large analogue 
mixing desks where presumably they route the summing nodes of the mixing 
amps along the full length of the desk!?

-Richie,