Help me identify this noise

[Morocotopo]

Hi people, could you help me identify this noise?
http://www.aronnelson.com/gallery/main.php/v/Morocotopo/LHX2++whine.mp3.html
The file is maximized to better hear it.

The build is the LHX2 Fender amp sim and cab sim. All opamp circuit. It has a 3 band EQ added at the end, bright and mid switches, a whole lotta controls (read a whole lotta wiring flying around).  All wiring is shielded, though. It has a small transformer and plus / minus voltage regs/filter mounted inside the same enclosure (it´s a +9 / -9 circuit), but I get no hum at all. All quite tightly packed inside an alu enclosure.
At first i thought oscillation because of the wiring, but the noise is independent of the controls position, AND the noise is intermittent, sometimes it does it, sometimes it doesn´t.
Another alternative I thought is noise coming through the power (220V) line, but I don´t have much experience with it. I believe there are power filters fore that, but never tried them.
Also, the chips don´t have power supply decoupling... could that be? (most are quad opamps) I have it plugged into the same power outlet as my mixer, computer, monitor...

Any help appreciated

Morocotopo

[stm]

Sounds like high frequency oscillation which may be very well due to lack of decoupling capacitors, as you mention.  I'd suggest installing a 100nF (0.1uF) capacitor on each V+ and V- power pin to the nearest GND.

[darron]

Sounds like high frequency oscillation which may be very well due to lack of decoupling capacitors, as you mention.  I'd suggest installing a 100nF (0.1uF) capacitor on each V+ and V- power pin to the nearest GND.

100nF? go nuts and chuck in a 0.0022F... that's how i cure my fuzz face oscillations

edit: and connect it to the +V as close as possible to the load.

[Morocotopo]

Thanks boys, will try.
By the way stm, the 3 band EQ it has after the cab sim is your circuit... hehe. Works like a charm.

Morocotopo

[stm]

Glad to hear that!