Pump’d Up Fuzz Face v5 Q1 and Q2

[Vincent]

Are there hfe and leakage recommendations for Q1 & Q2?

[Playsforfun]

Hello Vincent. What I read is this. Hope it helps

“Don’t get too hung up on the exact numbers – they’ll change in a second anyway as the device heats or cools. Look for low leakage, and approximately the right gains.

The right *real* gains are from 70 to about 130. Within that range, people report the best sounds. Some people prefer equal gains, others prefer having a lower gain of 70-100 for the first transistor and 90 to 130 for the second.”

[Barry]

I will add that if you are doing Bonamassa Fuzz face style gains they can be much lower.

So Q1 50-65, and Q2 70-85 (socket and see what you like)

[Big O]

I usually shoot for 70-90 hfe for Q1 and 100-130 hfe for Q2 with low leakage.  Higher transistor leakages are better reserved for Mk1 and Mk2 Tonebenders as the leakage is used to self bias the transistors in these circuits.  Low gain Si transistors also can work well for Si fuzz faces, although higher can do as well.  I have built NPN Ge, NPN Si/Ge, and multiple NPN Si Fuzz Face circuits over the years and done all the variations including PNP Ge variants (Vox Tonebender).

[Vincent]

I bought 50x MP42B Germanium transistors off of Ebay from Ukraine.  I used a DCA55 to sort through them, bagged them, and finally got around to building the PUFF.  Q1 and Q2 were 74 and 94 respectively and the bias was set in the middle.  Sounded great without even metering or adjusting the bias.  Played around with bias and ended up back where I started.

Fun build, thanks for the input!

[Author]

Posts