nirgalidietrich asked: My drummer told me you're a gear-genius, especially with BOSS pedals, so I've come to you with a question; I own a BOSS HM-2 Heavy Metal pedal, which as you probably know is supposed to run on the old 12V ACA adaptor. What should I ideally be running this on or what will suffice if I don't have an ACA adaptor? Will it be fine on a 9V power chain?
In most Boss pedals designed for the 12V unregulated supply, you’ll see a diode and resistor in series with the negative power input. In the HM-2, these are D1 and R2 (330 ohms). These are a crude “regulator” to knock down the 12V to a 9V-ish level. If you use a pedal designed for the ACA with a modern regulated supply, the pedal will see a lower-than-normal voltage internally, which lowers headroom. If you want to use a modern supply, just short out the diode and resistor, so that the power supply is connected directly, just like the battery.