Tonebender MKII crackling/static

[EFK]

Hi people - I got a really good deal on one of those JMI tonebender clones, looks very nice and sounds great ***but*** it's noisy as all hell. I am not a pedal guy - in fact, it is the first and only distortion-type pedal I've ever owned. According to what I've read, I realize these are not dead quiet pedals and I can live with some hiss or white noise, but this is really bad. I build a lot of amps, and it sounds like what you would expect with either a bad plate resistor or a bad ground. Just lots of crackling and static that can overwhelm the actual tone. The pedal seems to be working well otherwise - great fuzz, it easily hits unity gain by about 1 or 2 o'clock on the level knob, but these funky snap, crackle and pops are driving me nuts. The attack knob doesn't seem to make any difference to the noise. I've tested all the grounds, tested all the connections, swapped batteries, checked my voltages compared to what I've found online... everything seems to be ok, so I don't know what could be wrong. I suspect one of the transistors is wiggy but I have no idea how to test them nor which one to suspect. Any tonebender fanatics care to walk me through this? These things look dead simple, which is why I suspect a transistor, because I can't imagine what else it could be.

[The Dude]

Since you don't know how to test them and guessing by reading your post you don't have a scope to trace the problem, the easiest solution for you would be to just buy 3 transistors (they all appear to be identical) and replace them all. It won't cost that much and since you'll have to tear it apart anyway, you might as well just replace all 3.

[The Dude]

......or 2 transistors if you have this version/reissue.

[EFK]

Yep, this is the three transistor version although it's actually a "supa fuzz" so a couple of the resistors are slightly different, but I see now I can get a set of three for around $18. I'll just swap them out and save the original three in case someone wants an extra side helping of vintage noise. Thanks!

[The Dude]

There were resistor changes to accommodate whatever readily available germanium transistors they could get. Not to mention there are several versions of this circuit in different pedals tweaked to taste. Just curious,......what transistors does your particular unit have inside?

[EFK]

This has black mullard OC75. Looking at your sola sound schematic above, mine has 10uf in place of both 5 uf, which I think was standard for the supafuzz. Q1 is using 10K above and below. Q2 is biased with 47K. Those are the only differences. I really do think this is a transistor issue, because sometimes it will work pretty well, some background hiss or white noise but probably normal for a gainy circuit and relatively steady. Other times, I'll get lots of louder static that seems to smoothly fade in and out, like ocean waves. Very loud and distracting, with some occasional crackling. It is definitely not a ground or a jack, have checked all of those, and the resistors are all carbon film and check out perfectly. I have a set of replacement oc75 coming from smallbear, which seem to be a reputable place that tests them, so I'm going to swap them out carefully and see if it makes a difference.

[EFK]

Well so far, I swapped Q1 and it seems to have made a noticeable difference. Still some hiss/white noise, mostly when the amp is up loud, but it seems fairly steady without the snap/crackle/pops I was getting. I don't know if I should continue on with Q2 and/or Q3 or leave well enough alone for now. I think I'm going to try it as-is for a few days and see if any of the nasty noises come back.

Not being familiar with these, I'm not sure how much hiss/white noise is acceptable when the pedal is engaged. When the amp (@ 15-17 W, a 1624T) is on low volume, it's barely noticeable. If I dime the amp volume, when the pedal is engaged it's certainly noticeable when not playing but as I said it's pretty steady without the swooshing ocean waves I was getting.

[The Dude]

One should expect some noise with the amp dimed given the amount of gain produced by the pedal. At least you have some spares.