Newbie Germanium Fuzzrite concern

[8mileshigh]

I've built a couple fuzzrites now and thought I'd try my hand at the germanium version.  I have some high gain 313B russian transistors with a gains between 500 and 600 that I'd like to try but I don't really know well enough to know if they'll function well in the layout/circuit  Dragonfly has in his folder.  Is there anything obvious I need to swap in the circuit for use of high gain trannies ?  For biasing Q2, would a 50K trim pot do ?

http://aronnelson.com/gallery/album17/GERMANIUM_FUZZRITE

Thanks for any pointers on this,
Chris

[8mileshigh]

Well, despite no responses to my questions, I dove in and perfed the circuit last night and not suprisingly, the circuit didn't work with the high gain Russion transistors.   I then tried some AC176 trannies and I was relieved to hear the circuit fire to life but it sounded like very weak/like crap.  So I went to the basement and brought up some more odd transistors and started with two Raytheon T59247 that I bought on Ebay and my quest ended there.  The circuit breathes fire with 200 hFE in Q1 and 163 in Q2, gives you those classic psychedellic fuzz tones but with the added fur from the germanium transistors.  I was also quite pleased with the sustain compared to the silicon clones that I've made in the past. 

The collector voltage on Q1 is -5.9V and sounds just about perfect to my ears   Call it beginners luck.

I just wish I understood how the circuit works so I can try to adapt it for some of the of other transistors I have in the basement.  Any "Technology of the Fuzzrite " articles out there ?  Has anybody else build the germanium version ?  Any way to run some AC128's or 176's in this circuit ?

Thanks for any help
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[brett]

Hi

The circuit breathes fire with 200 hFE in Q1 and 163 in Q2,

That's similar to my experience, where I used 2 BD139s with hFE of 160 and got ripping tone.  I would think that even hFEs of 100 would produce huge amounts of distortion in this circuit.  MJE3055s would be interesting to try.

The circuit is very simple.  It uses no resistor on the emitter of Q1 to maximise gain and create a distorted, inverted signal at the collector of Q1.  This signal is then fed into Q2, which does the same thing, but is even more distorted because of the size of the signal going in.  The fuzz control blends between the signals out of Q1 (mild) and Q2 (wild).

You might get some advantages in this circuit of using germanium transistors, because like Q1 in the fuzzface, there is no emitter resistor, and the base is held closer to ground (0.3V) than with silicon (0.7V).

cheers

[Dragonfly]

just caught this thread...i'm only online about once a week...

glad to see you got it worked out...the original schematic for this layout came from a japanese website, though i can't remember which one...i'm sure it's filed somewhere in my "mental rolodex"...

germ fuzzes are odd ...takes some trial and error to get em to sound great, as you found out...once you get them dialed in though, watch out !

[8mileshigh]

Thanks for the information guys.  I was comparing all three of my fuzzrites this afternoon and the germanium sounds best but one of the transistors still needs tweaking.  I'll play with it more next weekend when I get some free time.  The silicon version with 2N5089's also sounds good but is more compressed.

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[brett]

Hi
Is this the Fuzzrite with the 10k collector resistors (as in Dragonfly's layout) or the 470k?
I'd expect 2n5089s to go wild with 470k on their collectors.
cheers

[8mileshigh]

Brett,

I perfed a version of Dragonfly's silicon layout, it does sound over the top and a little crazy but I made an error in  the cap values that lead to the fuzz depth pot so it sounds bloody insane.  I think I used .001 instead of .02uf.  I'm going to add a DPDT switch so I can switch between different cap values, should be fun.

What readings are you getting off your collectors ?  The fuzzrite clone I built from the schematic floating around the web sounds pretty flat and has ultra low collector readings but I heard they were built like this on purpose and certainly add to the splat factor.  I think I'll go to Tone Frenzy and listen to the real one to compare.

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