SRPP/Germanium Push-Pull Fuzz revisited

[Steben]

hey! with 47k's it looks really nice suddenly....
Have you tried omitting the emitter-1k's you put in there and making 4k7's at the collectors? It really looks much better.

[johngreene]

Actually I get the same result if it's in the emitter or collector.

Silly me did all that simulation at first with no load. Add even a 1 Meg load and things change dramatically.



--john

[Phorhas]

So it's back on the menu?

I'll give it a shot after I'll get some good night's sleep (it's 00.10 here)

[Steben]

The push-pull is good as a fuzzy fuzz fuzzer.
I was referring to the second circuit in the middle as not workable.

[MartyMart]

Steben, I quickly made the above "John Greene" version using an OC71 and OC140, with
fairly "even" hfe of around 140.
First off, just a very quiet "splatty" fuzz
I change the 1k's to a pair of 10k trim pots so i could "tune in" the transistors a bit and used
a 1M output "pot" in stead of the 1M "load" resistor
Also a 10uf cap from the NPN's emitter to ground, I now had some more "range" when
turning down the gtr vol pot ....

RESULT  !!  very nice fat "fuzzy fuzz"
Then added a pair of 1N4148's and a 542pf cap to ground before output.....   
We're in "Jordan Boss Tone" land now  ... Fabulous  !
Thanks for sharing this, I recommend those 10k trimmers for a "perfect" tuned fuzz tone, which due
to its "strange" parentage has a tone all of its own, with a "hint" of octave to it 

Marty.

[Steben]

RESULT  !!  very nice fat "fuzzy fuzz"
Then added a pair of 1N4148's and a 542pf cap to ground before output.....   
We're in "Jordan Boss Tone" land now  ... Fabulous  !
Thanks for sharing this, I recommend those 10k trimmers for a "perfect" tuned fuzz tone, which due
to its "strange" parentage has a tone all of its own, with a "hint" of octave to it 

Marty.

Hey, a beta tester!  Thankx, lad.
So you cap-decoupled the emitter, aye? Hmmm, nice idea. At what point of the trimmers you like it best?
Glad you enjoy it! Seems like you did something like Tim did on the harmonic jerkulator (testing with and without diodes).

(now try to put a "low set level" treble booster in front of it...)

[MartyMart]

Hey, a beta tester!  Thankx, lad.
So you cap-decoupled the emitter, aye? Hmmm, nice idea. At what point of the trimmers you like it best?
Glad you enjoy it! Seems like you did something like Tim did on the harmonic jerkulator (testing with and without diodes).

No problem
Without the NPN emitter cap, gtr vol "had" to be full up ?  but with it, you now
have some "gain" control from the gtr vol pot ( always useful )
My only issue is my 1M volume pot, which seems to have a huge "lump" at the far
end, so I guess this is reacting with the circuit when it reaches that value... just before
that its all "smooth" and provides plenty of volume boost anyway !
Both trim values are different ( due to the trannies ) but are about 2k2 ( PNP ) and 3k1 (NPN)
They are in the 4v - 5v area, but I tuned "by ear" before taking a reading
Input cap is a 470n poly and I have a 1M to ground at input also.

Marty.

[Steben]

I've put your actions into SPICE.
Look what It brought us:

-Input is 200mV AC 500Hz.
-I changed the lower 10k trimpot to a real 10k pot with the centerlug to the cap (fuzz face) and let it sweep.The upper trimpot is at 3K.
-Output load is a 50K pot, not 1Meg, so prapably less gain here.
-Note that these are silicon high-gain trannies and propably produce a sharper sound. I haven't got Ge models.

Looks like crossover distortion at "full open" and quite mild at half.