hi guys,
I built up a fuzz face recently with some MP38A's and I'm trying to track down some michrophonic behavior when the pedal is on. I first noticed it when I accidentally bumped the pedal with my foot and it made a really loud popping noise. So I started tapping around on it, the jacks, DC jack, stompswitch, enclosure, etc., thinking it might be a bad solder joint or something but wasn't able to isolate where the issue is. I can get the popping sound by tapping pretty much anything on the outside of the pedal. I suppose it could be a cold solder joint somewhere but was wondering if it's possible for transistors to be microphonic? Any ideas?
Possible but rare. Ceramic caps more often.
Reflow your solder joints. Especially if your transistor is in a socket.
I had a similar thing happen to me once. The problem for me was that the ground connections on the jack were loose. Once I reflowed those the problem went away. I was quite confused because no matter where I tapped it would make a popping noise. Crazy it was the jack!
Faulty grounding could indeed cause noisy behavior, at least when it is noise just by touching a supposedly grounded part. If you can hear tapping on the enclosure through the amp, but not a soft touch with the fingers, it would appear to be a microphonic component.
I recently had a faulty ground connection in a guitar; it relied on grounding through the pickguard shielding, but apparently that was not such a good idea. After time, the connection became poorer and the guitar became noisy to my touch (in a different manner than I intended :)).
good call on reflowing the solder joints, that seems to have fixed the issue. I think it was a dodgy solder joint on the DC jack, and a couple lugs on the stomp switch that looked kind of crusty.
thanks for the suggestions!
Any good Hfe on those transistors? I had a good bit of leakiness on a lot of 50 last year. readings all over the place.Mine were pretty noisy? a smallish capacitor across base & collector usually quiets those noisy ones somewhat? But in your case it really does sound like a dodgy ground connection.
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