I made power supply by soldering cluster of plugs onto wall wart. I've used it with various permutations of several different effects (2 envelope filters, 2 wahs, 3 distortions, 5 compressors, 1 DI) with up to 5 simultaneously and had no problems. Enter poison apple and there is loud hum, but only when other pedals are present on same supply. IOW, if poison apple is by itself or powered by its own separate supply it does not hum. So, is it normal that just *some* pedals cause hum only when used with other pedals on poor, non-isolated power supplies, and getting an isolated supply will likely fix the poisonous hum, or is this more likely an issue with the pedal itself?
Power supply hum: Poison Apple only with other pedals
- Thread starter arficus
- Start date
Robert
Reverse Engineer
Is there anything that sets the Poison Apple build apart from the others?
Different style DC or 1/4" jacks, battery snap, one jack grounded vs both, etc?
Take a close look (or post pics) of the wiring. Nothing jumps out at me as a source of hum in the circuit and since it plays fine on its own it sounds like it could be some sort of grounding issue.
Different style DC or 1/4" jacks, battery snap, one jack grounded vs both, etc?
Take a close look (or post pics) of the wiring. Nothing jumps out at me as a source of hum in the circuit and since it plays fine on its own it sounds like it could be some sort of grounding issue.
All the other effects used were commercially produced except 1 derailer. Both the derailer and poison apple
use 1/4 jacks salvaged from 50s/60s military gear, and they both use cheap external screw DC jacks from Tayda.
The ugly caps at C3 and C11 are 2 x .068uf in series in attempt to lower peak freq of effect (as suggested by someone
on the forum; I didn't have the recommended .033uf). The hum was also present with the original .022uf caps in place.
There's continuity between case, neg terms on all jacks, and pads labelled "GND" or "-" on board and breakout board.
