Difference in sound w/ same schem

[oldrocker]

A friend heard my Fuzz Face I made and he liked it so much that I gave it to him.  I figured I'll just make another one.  So I made another FF with the same parts, layout etc...  The wierd thing is the new one doesn't sound or act the same.  It sizzled with a fart sounding fuzz with short sustain compared to the first one I made.  To make this FF usable I took a 10k pot and put in place of the 8.2k resistor off the collector of Q2.  I played and adjusted the pot until it sounded good.  Then I removed the pot measured the resistance (which was around 4.7k) and replace the 8.2k with a 4.7k resistor.  It  sounds pretty good now but I was wondering if anyone else ran into something like this.  Why wouldn't both FF's sound the same with the same parts and circuit layout.

[Seljer]

The main difference in the fuzzface  is that different transistors have different amounts of gain and need to be biased differently. With germainum transistors this difference is even bigger.

Read the Fuzz Face article on geofex http://geofex.com/Article_Folders/fuzzface/fffram.htm

[RedHouse]

That resistor ALWAYS has to be tuned to the transistor, yes, we've been there, done that.

But isn't it cool that you were able to get your 2nd one dialed-in?

[oldrocker]

OK.   It all makes more sense now thanks.  Now I want to call my friend (he lives in a different state) and tell him I need to dial in his FF.  LOL.  The new FF sounds a little better than the one I gave him (not by much).  He's not into electronics at all so I don't think I can talk him through it. 
Yes it's great to be able to mess around with the circuit and find a way to make it sound better.  When I build more from now on I'll always dial it in to get the best sound out of it.

[MartyMart]

I've hardly built any "FF" type circuits without trimpots.
For a dollar or so you can fit a couple ( 20k and 50k for FF ) and dial in the "exact" sound
you want , you can also adjust for different trannies, presuming that you used sockets for
those .

"Uber-flexible" and worth doing IMO

MM.

[Grocha]

The main difference in the fuzzface  is that different transistors have different amounts of gain and need to be biased differently. With germainum transistors this difference is even bigger.

This happens with Dr. Boogie too??

[bwanasonic]

To make this FF usable I took a 10k pot and put in place of the 8.2k resistor off the collector of Q2.  I played and adjusted the pot until it sounded good.  Then I removed the pot measured the resistance (which was around 4.7k) and replace the 8.2k with a 4.7k resistor.

This is all I did to dial in my FF,  but keep in mind that *dialing in* Q1 can also help tailor the fuzz to your taste. I *got lucky* with my first FF build, so I haven't experimented beyond tweaking Q2's collector, so I can't offer any practical advice on further tweaking, other than "search".

Kerry M

[oldrocker]

Thanks.  I think on the next FF build I'll add trim pots to both Q1 & Q2 and see what I come up with.  I always socket the trannys so I can try different ones.  I'm thinking of trying some GE's and see how that goes too.

[petemoore]

  With the FF, go for 'lucky Fuzz' ..or tailor it to your preference, the latter is by far the more certain of these two ways to get a FF to 'act right', at least in my experiences.
  For Si FF's, try the Axis Face or it's .047uf/1k treble rolloff wiring.