Join Date: Dec 2000
Location: Longmont, Colorado
Did your One Spot "whistle" when you first got it, or is this a new thing?
If it is not a new thing, here is what is going on. The "whistling" is from the One Spot, they use digital switching for their rectification so you don't hear 60 cycle hum, its a much higher pitch, somewhere in the kilohertz range but not quite out of the audible frequencies (unfortunately for us, your dog may disagree). I have a One Spot too, and it does the same thing. A Boss power supply will hum, at 60 cycles (50 if you are in other parts of the world).
The only way to get a clean power supply is to spend the $ on a Voodoo Pedal Power, Fulltone Power Supply, or similar that uses DC regulators. They aren't cheap though. If you have some electronics skills, you can build your own with parts from Radio Shack. Maybe that's a project while I'm unemployed, come up with a cheap, "clean" power supply. Might be able to come up with a box that you plug another power supply into that cleans it up. No promises guys, don't hit me with tons of e-mail yet, I'll post something if I get a chance to work on it.
BTW, if you have a power supply hooked up to your pedals, it doesn't matter if there is a battery in them or not, they are running off the power supply.