Spin Semiconductor

Hi,
here's a question for you:
I've built a microphone preamp for my singer that incorporates the FV-1.
The chain is : that 1510 preamp - fet buffer for signal splitting - FV1 with left and right inputs separates - 1/2 ne5532 ic used as a mixer to mix left,right output from FV1 and direct signal from the above buffer - 1/2 ne5532 used as a 2nd order low pass filter - that 1646 to convert unbalanced signal in balanced. There is a 7660s IC used to convert +9V DC in bipolar +- 9vDC. Now, the problem is that in the mixer there is a costant output and when I increase the highs on the mixer I can hear a stange noise and the speakers engage their internal limiter to protect themselves.
The first version of this preamp didn't have the FV-1 and was used with several stompboxes (like boss) in place of the FV-1 without problem.
Is there someone that can help me ?
I can send a schematic.

Without a schematic and board layout I can only make some guesses...

I wasn't familiar with the 7660 but it appears to operate in the audio range (nom 10KHz rate), better to always use a switching regulator that operates outside the audio range. That switching will effect current in the circuit and may effect it to the point the FV-1 is effected in either the internal PLL or by yanking on the mid point used as an internal reference. Try removing the 7660 and running the circuit on battery and see if you still have the problem.