Woolly Mammoth with germanium transistors?

[mordechai]

I saw on the ZVex site that they've produced a version of the WM that uses germanium devices, and I think it sounds great.  I have a veroboard ready to build up the normal version of the circuit, but I'd like to try doing the germanium version.  I imagine there must be some notable changes in the resistor and cap values with that version though.  Can anybody offer some tips about the changes I should make to the original schematic in order for it to better interact with the germanium transistors?

[Elijah-Baley]

I'm gonna build the Wooly Mammoth in these days, too. (I have just guitars.)
The Germanium version has, I assume, germanium transistors instead silicon transistors.
Try to take a look here. https://www.youtube.com/watch?v=TZMMksSb-YU

Replacing the transistors with a pair of germanium I don't say that is necessary change values of some other parts. Maybe a pair or resistors to set the amount of gain. Germanium transistors bring, generically, less gain, a warm and clear and more dynamic sound. And that should what the germanium of the Wooly Mammoth version does.

But, maybe someone know something more than me about this pedal. I'm just assuming all this.

[Mark Hammer]

Given that the WM is basically a tweaked silicon Fuzz Face, I guess it was just a matter of time (and sourcing enough usable transistors).  As Mark/Mordechai notes, the biasing-resistor values will likely change.  I think the best feature on the WM is the "Pinch" control, which adds resistance to the Q2->Q1 feedback path.  This can actually be implemented on pretty much any 2-transistor fuzz conforming to the basic FF architecture, and can introduce some nice sputtering and "zipper" effects.

[mordechai]

Hi Mark, thanks for outing me!  Now how am I supposed to be a vigilante crime fighter??

On my project so far, I've decided to go with a hybrid approach -- silicon Q1 and germanium Q2.  I bough a few CV7351 pieces with really low leakage and excellent gain ranges (many are around 135-150Hfe) so they work really well in a Fuzz Face type setup like this.  I actually used all CV7351's in a custom Fuzz Face I made for a Canadian player for his touring rig and those transistors really sound fabulous.  I highly recommend them if you can nab a few, and they're NPN to boot.

I am finding that the pinch control you discussed above really makes a difference in terms of **not** having to futz too much with the other biasing resistors.  I brought down the level of the Q1C resistor just a bit (47K), brought up the Q2C collector a touch (22K), and also added series resistance with the power coming into the circuit (390R) with had a pleasing effect on the overall sound -- not as violently "scritchy" at some settings.  I also changed the bypass cap off of Lug 3 of the fuzz control to 47uF...it had less aggression but with the germanium transistor in the Q2 position there was additional looseness and a touch of flab with the stock 100uF.  It really does sound nice on bass. 

[Mark Hammer]

Well how do you know I'm not talking about myself in the 3rd person?  When Mark wants to be authoritative, he always talks about Mark like that!

Mark thinks your adjustment to the circuit are interesting, and thoughtful.  One additional thing Mark might suggest doing is trying a bidirectional Gain control.  As posted around, the 100uf cap comes directly off the emitter to a 2k variable resistor to ground.  Consider tying the wiper of a10k linear pot to the emitter, with a different electro value from each outside lug to ground.  In the mid position, gain is more or less set by the 2k2 emitter resistor to ground.  Rotate in either direction and it's like changing the value of that 100uf cap for something else.

At the risk of overthinking and overcomplicating, consider adding a fixed resistor to one outside lug.  The outside lug goes to a smaller value cap to ground, and the fixed resistor goes to a larger value.  So, for instance, the outside lug is connected to ground through a 1uf cap, plus an additional 33uf cap through a 1k resistor.  You now have two AC paths to ground on that side: a potentially zero-ohm path through the 1uf, and a low-ish resistance path through the 33uf.  In principle, this should yield modest gain for lower frequencies, but higher gain for upper mids and highs.

The specific values are not important.  But the idea is that two different gain "shapes" can be on tap.  And of course, if that 1k added resistance were an internal trimmer....well, you know. 

[mordechai]

That's a great idea...sort of a variant on Joe Gagan's input cap blend pot.  I will definitely give that a shot on the next build of this circuit (when I'll have a bigger enclosure). 

In the meantime, your comment reminds me of my favorite moment from South Park, which (lovingly) ridiculed the filmmaker and oceanographer James Cameron, who says "James Cameron doesn't do what James Cameron does for James Cameron.  James Cameron does what James Cameron does because James Cameron is James Cameron."

[Mark Hammer]

And....he's Canadian, which is also why Mark speaks for Mark, because that's what Mark does. 

Now that you mention Joe's input blend, given that the WM is basically a Fuzz Face, you can implement that control as well.  Boy, those knobs are sure starting to add up, aren't they?

[mordechai]

Yeah -- it's a lot of possible tweaking, but I'm making this to be for gigging so I don't want to add TOO many options!  If I build up a second one for at-home shoe-gazing, I might go gonzo on all of the options.  :-)

[Kennt82]

  I just built this germanium fuzz inspired by the Mammoth/Mastotron (has the Mastotron's pre gain control):
http://apocalypseaudio.blogspot.com/2011/01/h-fuzz.html

  using this layout:
https://dirtboxlayouts.blogspot.com/2019/06/apocalypse-audio-h-fuzz.html

Some values, like the collecter resistors, are different. The basic architecture, pinch control &  EQ, is the same.