Schematics 101: How To Determine Which Resistors Bias Each Transistor?
- Thread starter Ginsly
- Start date
@giovanni Well, tried a bunch of permutations, and it's just not doing the "under-biased" thing in the way I figured it would...
Like I said, it does reduce noise and kind of thin it out as I turn the pot, but doesn't produce the gated, pinched sound I'm used to. Kind of just sounds more like an overdrive when I adjust it fully. Tried many resistors and a few pots as well. Maybe it's a different transistor I should be playing with?
I did however replace the 10k resistor with a 5k1. I guess it paid off to socket EVERY component on this stripboard! Ha.. Hey, it was my first vero build... It still has plenty of girth at max Fuzz and 8-Bit settings, but I cut noise down a good amount. It's a good compromise for now, but I'd still love to crack this nut!
Like I said, it does reduce noise and kind of thin it out as I turn the pot, but doesn't produce the gated, pinched sound I'm used to. Kind of just sounds more like an overdrive when I adjust it fully. Tried many resistors and a few pots as well. Maybe it's a different transistor I should be playing with?
I did however replace the 10k resistor with a 5k1. I guess it paid off to socket EVERY component on this stripboard! Ha.. Hey, it was my first vero build... It still has plenty of girth at max Fuzz and 8-Bit settings, but I cut noise down a good amount. It's a good compromise for now, but I'd still love to crack this nut!
bean
Well-known member
You can ask one of the designer's of this effect...which is me! This is a Function F(x) Clusterfuzz (Jr version). Actually, this design was mostly Forrest but I'm not above taking undeserved credit.
Anyway, If you want to eliminate some noise at the max settings, increase the 10pF to 47pF and put a small value resistor b/w the 22uF cap and the Fuzz pot (22R - 47R). You can also increase the value of the 4n7 cap a little b/w the base of the MPSA13 and emitter of the 2n5089.
Lastly, if you get any noise when rolling the guitar pot volume down, put a series resistor before the 680pF cap at the input. A 1k or 2k2 is probably enough.
Anyway, If you want to eliminate some noise at the max settings, increase the 10pF to 47pF and put a small value resistor b/w the 22uF cap and the Fuzz pot (22R - 47R). You can also increase the value of the 4n7 cap a little b/w the base of the MPSA13 and emitter of the 2n5089.
Lastly, if you get any noise when rolling the guitar pot volume down, put a series resistor before the 680pF cap at the input. A 1k or 2k2 is probably enough.
Incredible!! Thanks @bean! I actually did indeed buy a Clusterfuzz Micro, but I wanted to build this primarily to get the LED setting! I love love love any kind of Clusterfuzz, thanks to you and Forrest for making such a rich, textured fuzz.
I'll absolutely try those two things - full disclosure, I'm TWO months into all of this, so some of the details are hazy! Ha... In putting a small value resistor between 22uf and the Fuzz pot, it looks like it would go between the - side of the cap and Lug 3 (based on the Vero diagram). Is that totally wrong?? I bet it is. I have a lot to learn. EDIT: Think I was looking at the wrong 22uf cap anyways
Secondly - I really did want to try a "Fuzz Factory" style transistor Bias control to even further choke/squeeze/gate it... I cannot for the life of me figure out what to do! Tried a pot on 10k, didn't work out. I figure between the 8Bit control and a Bias knob, it'll get pretty synthy and weird. Is this a dumb idea?
I really, really appreciate the input. I'll be buying more Function f(x) pedals for sure, this was just top of my list for my little building adventure...
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bean
Well-known member
Incredible!! Thanks @bean! I actually did indeed buy a Clusterfuzz Micro, but I wanted to build this primarily to get the LED setting! I love love love any kind of Clusterfuzz, thanks to you and Forrest for making such a rich, textured fuzz.
I'll absolutely try those two things - full disclosure, I'm TWO months into all of this, so some of the details are hazy! Ha... In putting a small value resistor between 22uf and the Fuzz pot, it looks like it would go between the - side of the cap and Lug 3 (based on the Vero diagram). Is that totally wrong?? I bet it is. I have a lot to learn. EDIT: Think I was looking at the wrong 22uf cap anyways
Secondly - I really did want to try a "Fuzz Factory" style transistor Bias control to even further choke/squeeze/gate it... I cannot for the life of me figure out what to do! Tried a pot on 10k, didn't work out. I figure between the 8Bit control and a Bias knob, it'll get pretty synthy and weird. Is this a dumb idea?
I really, really appreciate the input. I'll be buying more Function f(x) pedals for sure, this was just top of my list for my little building adventure...
Yes, you can put the resistor either b/w the neg side of the 22uF and lug 3 of the Fuzz pot or between lug2 of that pot and ground. This dials back the max fuzz setting just a bit in case noise gets to be too much.
The controls from the Fuzz Factory don't port well to this design since is quite a bit different than a traditional fuzz. But, if you want to try a gate control, here's a suggestion: put a 500kB or 1MB pot either in parallel or in series with that 4n7 cap. Adding a lot of resistance in the feedback path may gate it up some more. I'm not exactly sure off the bat if it's better in series or parallel (or if will work that well at all) but it is an easy thing to try. Use lugs 1 and 2 of the pot so it's set up as a variable resistor where the resistance increases as you turn the pot up. You can leave lug3 unconnected.
Thanks @bean , I actually gave it a shot!
I used a 500k pot and tried the 4n7 in series and parallel- holy cow, quite the squeal! Ha… I think it was series, parallel didn’t seem to do a whole lot- just kind of mellowed things out. The intensity of the siren changed as I turned the pot up or down, and aside from the theremin sounds it did seem to kinda squish things even more. Maybe there’s a way!
More importantly, you’ve given me several ways I can try to shave some noise off without needing a gate. It’s not the circuit’s fault, I just have a noisy environment and high-gain anything amplifies it. So far the resistor between 22uf and the Fuzz pot worked the best.
Again, thanks for the tips! Great stuff!
