Power supply hiss question

[bwanasonic]

I have been using my AMZ Mosfet Boost and DIY Orange Squeezer with a Visual Sound One-Spot into my Rivera Quiana with flawless (and hiss free) performance for some time now. I recently purchased a Traynor YCV20 and have noticed some strange behavior from my DIY pedals when using power supplies vs. batteries (slight hiss and a slight bit of high-pitched whine). Why would one amp work fine with the same setup, and another hiss and whine? I tried a *Big Ass Cap* across the rails to no avail. My commercially made pedals (TS9, Dyna-Comp) don't have this problem. Wadda they got that I ain't got? Any tips appreciated.

Kerry M

[DaveTV]

I had a similar noise problem using a 9V power supply with one of my home-brewed pedals. Connecting a 100uF cap across the rails wasn't enough to solve the problem.

Instead of just connecting a 100uF capacitor between the power supply input and ground (like you already tried), I'd recommend trying it again, but this time putting a small value resistor (100-470 ohms) between the power supply input and the capacitor. Also, connect the wire supplying power to the circuit board to the junction point between the resistor and the cap (not directly to the power supply input).

The schematic for the Mini-Booster (if you have it) shows what I'm talking about.