Hey Fuzzhead. I built this one. It does work but it's very gated. Will try some different transistors and report back. My trim pot doesn't have much effect if any so something isn't quite right on mine
I was doing some research on this one, because it's never seemed quite right, but supposedly this was the same trace they did at Ghost from an actual unit. The biasing/gain is different from the germanium version. Everything I've heard is that it will be gated. The trimpot biases the base, and it is dramatic (it will behave really weirdly until you get right where it should be). If you measure the base voltage, you should see it change with the trim pot. I have no idea what a good voltage would even look like. The Basic Audio version replaces the trimpot, but it has a crazy biasing setup that would appear to change as you adjust the gain (which the germanium did, though differently.) I'd love to hear if you get it working. One day I'll play around with it again.
Do you have the jumper on the trim pot? If you don't, the circuit will have power but the trimpot won't do anything, and the resistance would always be 500k. It's worth looking at.
Yeah, I was looking at that. So the 'pep' pots (gain) are wired differently in the germanium vs. silicon, and the Basic Audio wires it more similarly to the germanium version, which makes me suspicious that the schematic that's circulating for the silicon version is not correct. My reading would be that the germanium and basic audio versions slightly rebias the second transistor as you adjust the gain, whereas the silicon version does not.
Slight correction: The Basic audio actually wires it differently... it has a resistor to the positive going to both the first and third lugs of the pot, which means that it's doing something more complicated with the biasing, presumably making the biasing tapered, which is really interesting. I don't know what to think about it, although I do appreciate that you don't have to deal with the trimpot. I've been reluctant to spend much time on this, just because it's so gated, so you can't really roll back the volume on it.
Apparently there was some awesome drama with a company called "Sharptone" that did a 'reissue' of this pedal, only it wasn't this pedal, it was a mysterious 'prototype' that some how sounded better... if you get bored, look it up, it's hysterical.
Hey Fuzzhead. I built this one. It does work but it's very gated. Will try some different transistors and report back. My trim pot doesn't have much effect if any so something isn't quite right on mine
ReplyDeleteI was doing some research on this one, because it's never seemed quite right, but supposedly this was the same trace they did at Ghost from an actual unit. The biasing/gain is different from the germanium version. Everything I've heard is that it will be gated. The trimpot biases the base, and it is dramatic (it will behave really weirdly until you get right where it should be). If you measure the base voltage, you should see it change with the trim pot. I have no idea what a good voltage would even look like. The Basic Audio version replaces the trimpot, but it has a crazy biasing setup that would appear to change as you adjust the gain (which the germanium did, though differently.) I'd love to hear if you get it working. One day I'll play around with it again.
DeleteI haven't yet. I did play around a little and jumpered a cut and it roared into life. So need to double check my build
ReplyDeleteDo you have the jumper on the trim pot? If you don't, the circuit will have power but the trimpot won't do anything, and the resistance would always be 500k. It's worth looking at.
ReplyDeleteI will have another look and report back
ReplyDeleteHave you guys looked at the basic audio Pep box? I made it and quite like it.
ReplyDelete(It's on here)
ReplyDeleteYeah, I was looking at that. So the 'pep' pots (gain) are wired differently in the germanium vs. silicon, and the Basic Audio wires it more similarly to the germanium version, which makes me suspicious that the schematic that's circulating for the silicon version is not correct. My reading would be that the germanium and basic audio versions slightly rebias the second transistor as you adjust the gain, whereas the silicon version does not.
DeleteSlight correction: The Basic audio actually wires it differently... it has a resistor to the positive going to both the first and third lugs of the pot, which means that it's doing something more complicated with the biasing, presumably making the biasing tapered, which is really interesting. I don't know what to think about it, although I do appreciate that you don't have to deal with the trimpot. I've been reluctant to spend much time on this, just because it's so gated, so you can't really roll back the volume on it.
DeleteApparently there was some awesome drama with a company called "Sharptone" that did a 'reissue' of this pedal, only it wasn't this pedal, it was a mysterious 'prototype' that some how sounded better... if you get bored, look it up, it's hysterical.
ReplyDeleteNoted. I'll check it out
ReplyDelete