Which of these transistors for BOG/Fulltone '70 Fuzz?

[Burstbucker]

I'm planning on building a Band-of-Gypsys era Silicon Fuzzface, which is basically what the Fulltone '70 Fuzz pedal is, if I'm not mistaken. 

I'm wondering which transistors to use in this pedal though.  If you had to chose between a pair of BC108, BC108B, BC108C, or BC109C, which would you pick? 

[petemoore]

  I'd start with the lower gain of whatever pair in Q1 position.
  Literally I'd decide by which one sounds good, but I tend to like ~100+ or so Hfe in Q1, a little higher or higher Hfe in Q2.
  If your DMM has an Hfe Tester, it should give usable information for Hfe's of Si transistors.

[Fret Wire]

First up, you could build the RM Axis Fuzz, which is the BOG ckt, or you could go with a silicon Dallas type fuzz, which Jimi also allegedly used during that period. The low gain si transistors are good at mimic-ing the softer ge fuzz sound, which isn't what your looking for here. You're looking for the sharper bite of the "si fuzz sound".

I've always had good luck with anywhere from 175 -300 hfe on the Dallas si ckt. I usually go with the lower gain BC108's, but others work fine. Run a smoothing cap across the Q1/Q2 collectors to take out any oscillations. Depending on the gain, anywhere from 10pf to 100pf. use enough to take out any fizziness, but stop before you kill the trebly bite. Since si trannys have no leakage, Joe Davisson's fuzz bias calculator should be very accurate for biasing values, if you don't want to do it yourself.

[RedHouse]

Definately, if you want BOG ...build an RM Axis Fuzz

[Burstbucker]

Thanks for your suggestions guys.

Actually, I just finished building a Roger Mayer Axis Fuzz a few days ago and it's a REALLY cool little pedal, a really grungy sounding little bugger!  I know that Hendrix supposedly used that fuzz on the album "Axis bold as love" and this pedal does indeed nail that sound, so I guess the pedal turned out great.
8^)

I've already built a couple Germanium Fuzzface pedals(one with NKT275 transistors) and a Silicon/Germanium FF as well.  They're all great in their own way and now with this totally different sounding Axis Fuzz, I've got a lot of basses covered.  The only thing that I'd like to try next is an all Silicon Fuzzface, I wasn't sure if this is what Hendrix used on the BOG's album, maybe it was an Axis Fuzz afterall?

Anyhow, I want to build a hot Silicon FF clone and I'll have to try out a bunch transistors for myself but I was just curious what transistors you'd chose for this type of pedal, thanks.   

[petemoore]

  Q1...2n2369 . [there are other part#'s ]   
  Q2...2n3503 and 2n2222 [lower-ish hfe] or...2n3904 [med] or 2n5088 [High Gain]
  but you might like the taste of a BCxxx [108, 109 etc.], IIRC the BC's suffix letters relate to the gain range, 'a' being low, 'b' being median, 'c' being higher. Q2 postition isn't as sensative as Q1 to Hfe, more grind is had with a higher-ish  gain Q2...
  Lotsa kinds and a DMM w/hfe checker helps to get an idea of what sounds good to you in a FF, tonal differences are mostly just gain related, I think most of the Si's sound at least close to similar if the gain is the same, the BCxxx's being the most exceptional in the 'different voice' for Si Dept.
  OT? Jfet's and Mosfets reportedly have been used...ample schemata and some related texts about their use has been documented.