2333 Hz whine on breadboarded Bluesbreaker—what might cause it?

[Buran1997]

I recently breadboarded a Marshall Bluesbreaker. I've run the circuit off of a 9V battery with no issues, but when I tried running it from a 9V DC wall wart, I noticed a quiet whine. I used a sine wave generator to match the frequency, and I think that the whine is about 2333 Hz. Adjusting the potentiometers (including turning the volume down to zero) doesn't affect the noise at all, so I suspect that it's coming from ground instead of the circuit. I've run other pedals that I've built off of the same wall wart with no issues, so I wonder if it might be an interaction specifically between the wall wart and the breadboard, but I want to make sure that this issue won't persist when I build the circuit on perfboard.

Has anyone else encountered a similar issue? Is this likely to persist once the circuit is built and boxed?

[willienillie]

If it's quiet with a battery, the noise is coming from the wall wart.  SMPS, has a high-pitched whine.  Some pedals filter the noise out better than others.  You can add filtering to your Bluesbreaker to help combat power supply noise.  A small series resistor (47~100 ohms) at 9VDC in, followed by a large-ish electrlolytic cap (47~100µF) to ground with a 100n ceramic in parallel, should do very well.  A quieter wall wart, intended for audio/pedal use, would be a good thing too.

[GGBB]

Is this likely to persist once the circuit is built and boxed?

Possibly, but probably not. You can test with aluminum foil and/or a pie/cake pan - any metal "box" like thing (grounded).