A question about noise

[rockhorst]

I know pedal noise has been covered a lot, but still I'd like to have some advice on the following:

I built a pedal for a friend, basically a hot rodded TS, built on a MadBean board with the usual power filtering (2 caps, resistor). It was dead quiet when I tested it, it was dead quiet in the rehearsal room with the guys normal setup (Gibson -> Morley Classic Wah -> Korg DT-10 -> Hot Rodded TS -> MXR Carbon Copy, daisy chained one spot for power). This weekend he had a serious gig (opening for a big band) and during sound check the pedal hummed. I wasn't there, so I can't really say which kind of hum it was, but it was loud. They tossed it aside and subbed a standard Boss BD-2 Blues Driver, the pedal he usually uses. Hum went away (or became significantly less). As you can see, there's quite a serious light show and other stuff going on at the gig:



Now, rethinking how I made the pedal, it's not entirely 'star grounded' and there is one quite long ground wire that *could* make a loop in combination with others. I also haven't used shielded wire for the in- and output. So those are obviouse things I could change. An isolated power supply would probably solve all problems, but this friend is a rock star on a budget.

I can't check the pedal in 'true gig situations' before the next show, so it's a bit of a shot in the dark. What bugs me is that (as far as I can tell) Boss doesn't do anything special to keep their pedals quiet (except maybe the star ground, not sure), but switching the pedals solved the whole problem. Is there something I'm missing?

[Jdansti]

Have you had a chance to see if it still hums with the same PSU and location in the pedal board chain away from the venue?  There could have been some noise in the power system or from lighting or other electrica at the venuel.  Check for a good ground connection to the enclosure. The enclosure might not provide enough shielding from higher doses of stray RF if you didn't ensure a good connection from board ground to the enclosure.

[rockhorst]

In all other situations, the pedal was quiet, so it's very probable that it's the lighting at the show. It's an aluminum enclosure with unshielded jacks. Now that you mention it, I do recall that there was some powdercoat. My guess is that circuit and enclosure are not electrically connected because of the paint isolating it from the jacks. So that's another thing to add to the list.