Si/Ge hybrid fuzz again

[markusw]

Hi all,

I would like to build a Ge/Si fuzz since they are supposed to be less temperature sensitive. So my question is: which version gives you a sound closer to an all Ge fuzz, the version with a Ge Q2 like Joe Gagan´s easy face or the one with a Ge Q1.

Thanks for your comments,

Markus

[Steben]

Hi all,

I would like to build a Ge/Si fuzz since they are supposed to be less temperature sensitive. So my question is: which version gives you a sound closer to an all Ge fuzz, the version with a Ge Q2 like Joe Gagan´s easy face or the one with a Ge Q1.

Thanks for your comments,

Markus

Ge on Q1 gives smooth second harmonic when less gain, Ge on Q2 gives smooth second harmonic when more gain, I guess.

Low gain, blues: Q1
Shred: Q2

Second opinions anyone?

Edit: Choose a low gain Si tranny (hFE<<200).

[markusw]

Thanks. Now it´s a little bit more clear. If got it right, it´s impossible to have an all-Ge-like sound over the whole gain range. But is it possible to say which version considering both have a classical setup with Q1 hfe ~70 and Q2 hfe ~120 sounds closer to an all Ge fuzz with the same gain values?  :?: And: do the two variants feature a similar temperature stability?

[petemoore]

Q2 sets bias for Q1 IIUC.
 so...having a temperature stable Q2 [Si] it would follow that bias will be more stable.
 Inserting a  1 GE into a FF circuit IMO definitely influences it with a Ge tone.
 Sounds like your'e ready for some serious FF testing, for which I recommend the FF test board...
 You can socket or trimpot everything pretty easily [what ...12+ parts]
 I find the 33k can be 100k with very minimal tonal differece, using a 1k then paralleling a 1k to it [where the 470R goes] you can see what you get...just install the 1k [where the 470 goes] and leave enough lead length atop the board to easily parallel a 1k to it...or something like a 820R to get real close to 470R or above.
 Runoff Grooves Multi Face is a good board, I'd trimpot Q2's collector for a test board.
 Wide tonal variations can be had from a little FF circuit.
 Test Jig...just an open top cardboard box on a metal box with jacks in it, jacks grounds connected together and to a wire with an alligator test clip on the end of it, then two more 'clipwires' coming from input jack tip, and output jack clip. place the circuit on the test jig 'platter' and connect the three wires and battery...can be used for testing/tweeking all your circuits.
 Breadboard is certainly an option worth considering, still I like my perfed FF testboard...been using it for years...handy thing to have...
 Socketted all caps and transistors, trimpotted Q2's collector [see multi face for Q2 emitter trimpot implementation] , used sockets or long lead resistors for the rest...
 One other option is a 100R or so on Q1's emitter [see AMZ 'YAFF'].
 I didn't get much mileage tweeking the 33k and 100k...

[Steben]

Q2 sets bias for Q1 IIUC.
 so...having a temperature stable Q2 [Si] it would follow that bias will be more stable.
 Inserting a  1 GE into a FF circuit IMO definitely influences it with a Ge tone.
 Sounds like your'e ready for some serious FF testing, for which I recommend the FF test board...
 You can socket or trimpot everything pretty easily [what ...12+ parts]
 I find the 33k can be 100k with very minimal tonal differece, using a 1k then paralleling a 1k to it [where the 470R goes] you can see what you get...just install the 1k [where the 470 goes] and leave enough lead length atop the board to easily parallel a 1k to it...or something like a 820R to get real close to 470R or above.
 Runoff Grooves Multi Face is a good board, I'd trimpot Q2's collector for a test board.
 Wide tonal variations can be had from a little FF circuit.
 Test Jig...just an open top cardboard box on a metal box with jacks in it, jacks grounds connected together and to a wire with an alligator test clip on the end of it, then two more 'clipwires' coming from input jack tip, and output jack clip. place the circuit on the test jig 'platter' and connect the three wires and battery...can be used for testing/tweeking all your circuits.
 Breadboard is certainly an option worth considering, still I like my perfed FF testboard...been using it for years...handy thing to have...
 Socketted all caps and transistors, trimpotted Q2's collector [see multi face for Q2 emitter trimpot implementation] , used sockets or long lead resistors for the rest...
 One other option is a 100R or so on Q1's emitter [see AMZ 'YAFF'].
 I didn't get much mileage tweeking the 33k and 100k...

I guess that's what I was saying about bluesy on Q1  :wink:

[markusw]

Thanks a lot  for the infos and tips. I´ve etched a board right now and it includes almost all of the mod possibilities I could find, pregain control, fat control, bias pot for Q2, contour pot, a simple low-pass filter for treble reduction. For the Qs I´ve got a matched pair of AC128s from Banzai (gains about 70 and 100) with a quite high leakage current around 350 µA. Alternatively I have some 2N2904As all with a gain around 70-80 and some 2N3906s with gain of about 160. I just have to find a AC128 with a little higher gain and a Si with a little lower gain.

However, has anybody done a comparison like I mentioned above?? Any preinformations before I get stated would be highly welcome.

Markus

[jmusser]

I built Joe's Easy Face when it first came out, and I have been well satisfied with it's tone and lack of noise. I didn't use any fancy componets. I used an old stock AC128 that one of the IT guys up here where I work found for me. Mine is real dark sounding and smooth as silk. I wish I could tell you if it's real "germy" or not, but my ear is not quite that sophistocated. I do know, that you would have to be awful big guy to wrestle it out of my hands!