Intermittent static in TWO EP-3 PRE style pedals.(just a discussion, not troubleshooting!)(now it’s a troubleshooting thread!😅)

[Drayve85]

DISCLAIMER: this is not a troubleshooting thread, I’m just trying to get a discussion on this subject, because I can’t find too much on what could be the cause of issues like this. Any help helps!!!

EDIT: now this is a troubleshooting thread, since moving it.lol (8/4/25)

Alright, just a general question, hypothetically, if you had two EP-3 preamp style pedals on vero board, namely the Chase Tone Secret Pre, and the Catalinbread Epoch Bias, and they’ve run great for quite a while with daily play with no problems at all. Then all of a sudden the Secret Pre develops an intermittent static noise, then a few days later the Epoch Bias catches the SAME disease! What would be your thoughts on WHY?????!!!! and WHAT?! Would cause this? Any help at all, please??!?! On the Secret Pre, I’ve replaced all caps, the charge pump, the pot, the switch, took out the trim pot and soldered in a resistor, and even soldered in the tranny. Idk wtf is going on. They even do it with a battery, so it’s not the power source. It’s not the power jack, I swapped that out too. Also, the jacks and the stomp switch! I know there’s no pics or anything, but I’m just asking for the first thing that comes to your minds.

 

[Drayve85]

C

Does the noise sound a little like Rice Krispies in milk? Like a random seeming crackle and pop?

If it does it could be the bias trimmer or the potentiometer. I’ve had problems with JFETs in the past that just made a bunch of noise. It was hard to diagnose. Some builds would be fine and other would have the problem. I narrowed it down to the trim pot. I think it has something to do with DC and possibly layout, but I don’t know enough to say why. I just know how I have fixed it. I just stoped using trimmers for bias and always use a fixed resistor.

yeah, pretty much. It gets worse tho, almost like an old tv on static. I’ve went thru the trim-pot route. Unfortunately, adding fixed resistors didn’t fix it. I’ve even soldered the trannies straight to the board and not used sockets, but that didn’t fix it. I’m almost done rebuilding both of them, so hopefully the Gremlins are gone.lol

 

[andrewsrea]

I’m just asking for the first thing that comes to your minds.

Lots of good ideas prior to my post, but I am going to share left field similar things which happened to one of my moderate gain drive designs, which uses a charge pump and was on a board with other pedals which did not have a charge pump and did not exhibit the noise:
faulty GFI outlets.

A friend had about 12 amperes of music stuff going at once in his garage, all though one 20-year-old 15A GFI outlet (120VAC US). We were practicing and it drove all kinds of spitting and occasional hissing in my OD, which I could not replicate that fault anyplace else. My analysis is that GFIs have a sensing frequency which, is close to the charge pump frequency (40KHz?) uses the AC 60 cycles as a carrier frequency, which interferes with the charge pump frequency. Like a parasitic signal. GFI and AFIC circuit breakers may also be a culprit and are currently code for bedrooms.

Try the pedals in different locations to see if that is the problem.

Additionally, do not keep your mobile phone in your pocket near your guitar. I figured that one out on a recording session.