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Gus Smalley: 3 Trans Fuzz Questions

5/2/1999 12:19 AM
Joe Fuzz
Gus Smalley: 3 Trans Fuzz Questions
(I'm assuming that the person who signs his name "Gus" is actually Gus Smalley.)  
Built your 3 transistor fuzz. Really like it. It was one of those effects that as soon as I heard it, I could think of songs where it could be used.  
Plus, with the guitar plugged directly into the effect, the guitar's volume knob doesn't control the volume, it controls the level of distortion. Very nice.  
I increased the High End Rolloff capacitor to 0.05uF to tame some of the high end. When I actually build the box, I'll probably use a switch so I can flip between the 0.01 and the 0.05 there.  
My question is about the low notes; specifically the open E. I've tried increasing the capacitors in the path but the E still comes across as buzzy and sort of flat. Any advice?  
For you lurkers out there, the schematic for the 3 Transistor Fuzz is available at Aron's site.
5/2/1999 6:33 AM

I think I rolled off even more than you did. I used a .1uF cap.  
The version I made, called The Rocket sounds pretty darn good. What is the hFE of your transistors? Mine were ~450.  
5/4/1999 1:14 PM
Joe Fuzz

I think I rolled off even more than you did. I used a .1uF cap.  
I'll try that, too. I think I'm heading towards some sort of rotary switch for my caps on this one.  
What is the hFE of your transistors?  
I didn't measure them but I used MPSA18s for all 3 transistors. I think they have a beta of like 500...  
Thanks for posting the 3TF, Aron. Great circuit!
5/3/1999 6:56 PM
the cap that goes to the 10k resistor is the one to "tune" the one between the input buffer and the gain stage. Buzzy and sort of flat can be to much bass. If you let to much bass though it can make things buzzy the clipped bass is there but there are more high partials. (phycoacoustic effect) sometime limiting the bass makes it sound like more bass. Look at the schematic of a big muff mult high pass filters at >160hz bbut a good BMP sounds bassy. Try a .1uf (.1uf and 10k ~=160hz) Thank you for you input I find I "tune" cap values for the guitar and amp the effect will be used with.  
Gus Smalley
5/4/1999 1:08 PM
Joe Fuzz

Buzzy and sort of flat can be too much bass.  
This occurred to me after I wrote that post. I backed off on the bass coming from the guitar and voila! more definition. I'm wondering what the input impedance of the emitter-follower on the front end is. With the two Rs on the base (470k~p~~p~1Meg), the 0.1uF seems high just glancing at it. What I'm getting at is: I wonder what fc is for that first stage?  
I'll try reducing the value of the caps.  
Thank you for you input  
The circuit's absolutely brilliant. Thanks, Gus!
5/4/1999 2:58 PM
The fc of the first stage is ~=5hz 1/6.26x.1ufx320k. try .01uf ~=50hz. That was done so it was just a clean buffer the offset in the bias is a trade off for more current flow in the transistor. The circuit was set up so only the first transistor needs high gain. The 2nd transistor has it gain controlled as well as temp sensetivy by the 100 ohm emitter resistor and the 10k collector (I like the "sound" of transistor circuits with static current >.5ma). I like to tune the rolloffs in a controlled manner the .022uf and 10k is a brit sound (thanks GFR). If a amp has neg feedback I find I use larger caps.  
5/5/1999 12:56 AM
Ed Rembold

Thankyou, Gus.  
Your tuning tips really helped me, I find  
myself constantly going the opposite way, from  
the direction I should be. You would think I'd  
learn! thanks, Ed R.
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