Q: I just bought a new stompbox and decided that I really didn’t want to feed it batteries. Fortunately, I had an old AC adapter left over from a stompbox that no longer worked. But when I plugged it in, it didn’t power up the new one. Since they both run on 9 volts, why isn’t my old adapter working? Could it be that it died prematurely, as well?
A: Hopefully it’s fine. Check out the power supply and pedal (or its manual) carefully. It could be that the old adapter did not have the correct polarity to run your new pedal. Most stompboxes from big manufacturers of pedals, such as BOSS and Digitech (to name a few), require the tip of the connector (the one that plugs into the pedal) to be negative (ground) rather than positive. It’s also possible that the old adapter is 9V AC, which could have resulted in damage.
Always double-check power adapters before connecting them to your gear!
You’ll have to either purchase the correct adapter or use 9-volt batteries.