I was thinking why my Big Muff Pi is much, much noisier than my Sola Tone Bender MKII pro clone. They have 3 stages, but the transistors of the BMP have a gain of 500, and the ones of the TB a gain of 100. I have some BD139 I bought to build the Axis Fuzz. As I posted earlier, I really like this transistors because they have a gain of about 120 which is fine for the AF's Q2. So I used them to build a BMP clone. I had to use a 390K resistor instead of the std 470K because of the lower gain. Maybe the 10K resistor in series with the 0.1uF coupling capacitor should be modified. I did not do it. The result: same shockwave with less noise. Now, I am not an expert in electronics but I think that less current gain is less thermal noise. What really matters is the voltage gain given by the quotient 15k/0.1k. True or false? Let me know.
When I have some time I'll try Si & Ge transistors with a gain less than 100.