Mangler Project

[rlopes]

Hello.
I finished my mangler project: a NPN classic fuzz using BC108C transistors and i tested it before i put it in a box as you recomend and it did work but i can only get a real fuzz at the bottom end of the fuzz knob (like after i turn about 95% of the knob). Before that i get some kind of boost/light drive but no fuzz tones. Is this normal?? I was expecting to get a progressive fuzz tone but that didn't happen.

I ordered the Banzai's Fuzz Face Classic Si Transistor Set (BC 108C) and i test their hFe with my DMM (i don't have a semi-component analyser so that's the best i can do) and i got 2 very distinct values: one of the transistors have hFe=150 (i used it in Q1) and the other hFe=630 (i used it in Q2). I adjust the internal trimmer until i get a 4.5v reading (the instructions said that i had to get a negative (-) 4,5v but my reading was positive). After that i increased the voltage reading to 5v and then to 5.5 v but the result was very similar (fuzz tones just at the very end of the fuzz pot) and i get the feeling that i was starting to get some oscillation.
I also tried another set of BC108C transistors that i have (with hFe +/- 500) and got the same results.
Am i doing something wrong here?
Best regards.

[madbean]

That's how the vast majority of Fuzz Faces behave, I'm afraid, so you have not done anything wrong. One thing you can do is to use a reverse audio taper for the 1k Fuzz control. This will spread out that last 10% of fuzz into a wider range.

Alternatively, you can leave the fuzz pot at max, and then use a 50kB pot wired as a variable resistor at the input of the circuit. This actually gives you more control over the overall fuzz amount than the traditional fuzz control by limiting the amount of signal going into the circuit itself.

[pryde]

Yes as MB says wire in a pre-gain pot. I built a mangler pretty much just like yours with the pre-gain and it has a lot of versatility and works well with many guitars (LP, tele, strat, etc) I still need to get mine boxed up though  .

[rlopes]

Thank you both for your reply.  I was affraid i had done something wrong. I duble and triple check everyting (component values, polarity caps, transistors pin outs, voltage reading) and although i really like the sound i get with the fuzz knob cranked up i thought i have done something else wrong because the real fuzz tones only start at the very end of the fuzz knob as i said before.
It would be cool to have a little more control over the fuzz so can you please explain me a little more the opptions that you gave me (like a schematic or diagram of thar pre-gain option) because i'm still a real nobb.
Best regards

[pryde]

Basically you are putting a pot inline between the 3pdt switch and the input of the mangler pcb. I used a 100kB pot but a 50kB would work fine also.

Note in the drawing the pot is facing down (looking at bottom of pot)
Good luck

[rlopes]

Thank you.
What about my choice of transistors? As i said i got a hFe reading of 150 and 630 in my DMM but i don't know how much is their leakeage so i'm not sure if these are their real hFe's. I bought the Banzai's Fuzz Face Classic Si Transistor Set so i was expecting to get something tested and ideal to get a classic fuzz tone. Do you think my transistors are good?