* Note:

All Boss pedals have a sticker near the adapter jack, which indicates which adapter is needed. PSA pedals wants to see a regulated 9vDC adapter, while ACA pedals (made before august 1997) wants unregulated 12vDC. Since august 1997, all Boss pedals (including surviving ACA designs) use 9 volts DC and are labeled ”PSA”.

Therefore, adapter listings that read ”ACA/PSA” means that if the pedal is older than mid 1997, it wants the old-style ACA adapter. If it is newer, or if it has been modified to PSA specs, it works fine with the 9vDC PSA adapter. To find out (if the sticker isn’t there), plug your regular 9v supply into the pedal in question (alone, without daisy chain) – if the LED barely lights up, the pedal is definitely older than 1997.

Also, old (pre august 1997) ACA pedals will work fine from 9vDC, if they are daisy-chained with regular PSA pedals, and have signal cables connected between them. There’s a more indepth article about it here, if you’re so inclined. But whatever you do, don’t confuse ACA with ”AC” – the pedal still expects a DC input voltage, and feeding it 9vAC will fry it.