Silicon Fuzz Face Hfes

[chromesphere]

Hey guys, I have yet to build a silicon fuzz face and was wondering if hfe's are as critical as they are in germanium fuzz faces?  Silicon transistors obviously have a higher hfe and I'm assuming its not as important.
Bonus question (lol): what's your favourite model?  This interest was sparked by fuzz Labradors recent silicon transistor sound test video and in it I liked the bc108 the best:

Cheers
Paul

[culturejam]

If you want to keep the transistor beta at the same general levels as the vintage parts, check out the SS9013.

It's a very un-fancy looking TO-92 plastic package transistor. But, the gains are between about 90 - 120. And they are still readily available. And they are CHEAP.

I've built several Fuzz Face and Tonebender MKII with them, and I think they sound as good as any other silicon tranny.

However, they are now marked for "end of life", so I would suggest stocking up soon. I've been buying them in quantity every time I make a Mouser order, and now I've got certainly more than I can ever reasonably use in my lifetime.    Mouser has about 6500 left as of just now. BYOC also has a large stock of them, but the pricing is much higher than Mouser (as one would expect). The other bigger suppliers don't seem to have them still in stock.

[chromesphere]

Thanks Culturejam!  Ordered 1000.  $20 for 1000, 2c each!  I figure having a low gain NPN silicon around would be handy anyway.  the 100ish hfe transistor I used in my lavache sounded superb!
Paul

[culturejam]

Score! I just ordered another 250 myself, even though it is total overkill for my stockpile.

You other guys better get on it in a hurry!

(Mouser owes me a referral fee)

[chromesphere]

I got mine on ebay culturejam here (and anyone else follow along).  Untested as yet so im not vouching for them:
http://www.ebay.com.au/itm/121139400277?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
Paul

[midwayfair]

Low hfe transistors are really going the way of the dodo ... 2222s are above 100hfe now, BC10_"A" are getting tough to find, and all the really low-gain stuff like smallbear carries are either dead or significantly higher gain in their modern form. (I like these in particular, but then I have an irrational fondness of low-gain transistors.)

In my experience with fuzz faces, it's not so much the gains that are important as the ratio between Q1 and Q2. You want Q1 to be perhaps 66-75% of the gain of Q2, though it can be half or even less and still work right. For some reason the closer you get to the same hfe, the worse it is at things like cleaning up with the volume pot. I built a fuzz face once with two germanium transistors with hfe of only 60 each and it was just a wall of mush, even with the guitar volume at half way and an input trimpot! It's almost like it starts seeing the guitar as a voltage source. I swapped out the first for hfe 40 and it sounded really excellent. I've also gotten excellent behavior from a silicon with BC107A in Q1 and BC109B in Q2. The gain ratio was maybe half. It did have the 10pF bypass cap as designated in the Hipster -- silicon transistors aren't "lossy" like germanium ones, so you just have to simulate the leakage in some way. Forrest's Si tonebender (Grindy's "Bendover") uses those caps, too.

[chromesphere]

Thanks Jon, ill have to try that out (same hfe, versus ratio).

[Rockhorst]

Just bought one of those 1000 packs myself. Let's see what turns up.

[Haberdasher]

i've found that bd139 sounds awesome as q2 but it's in a to-220 package
gain of around 140 or so iirc

[croquet hoop]

Low hfe transistors are really going the way of the dodo ... 2222s are above 100hfe now, BC10_"A" are getting tough to find, and all the really low-gain stuff like smallbear carries are either dead or significantly higher gain in their modern form. (I like these in particular, but then I have an irrational fondness of low-gain transistors.)

I have not auditioned them yet, but I have a bunch of 2N2369A's around 60 hfe. I just checked and mouser has ~17000 of them, so I guess they'll still be available for a while.

[slimtriggers]

Hmmm...  I've never built a Si Fuzz that I actually liked.  This thread gives me hope that it can be done