A new twist on an old friend.

Dragonfly · July 27, 2007, 09:57:43 PM

Yep. The Fuzz Face. Most of us have built at least a few of them. Still, they're fun to revisit occasionally, and since I had a bit of time, I did just that.

I wanted to find a good use for some of the lower gain oddball PNP germaniums that I have, but I also like my circuits to be negative ground. What I came up with was a Fuzz Face that uses a PNP for Q1 and a NPN for Q2. I was looking at how the Bosstone is set up, and figured "why not give it a go?" In the past, lots of people have wired PNP Fuzz Faces using negative ground, and many have run into problems with oscillations and motorboating. Well, I found that by only having Q1 be a neg ground PNP, i had neither of those issues. I tried this circuit with about 20 different PNP germaniums (AC128, AC188, OC44, 2N1526, 2n652, etc, etc) for Q1, and 10 different NPN silicons (2N3903, 2N3904, 2N5088, BC108, BC109, etc) for Q2, and by using a larger trim pot than normal, I was able to bias 99% of them in easily. One of them required a 27K setting to get Q2 at 4.5v (which set up Q1 just fine...IIRC, about 1.1 or 1.2v at the emitter), and several required over 10K, so a 50K is appropriate....a 20K will work in most cases however. Take note that Q1's "collector" goes to ground and the "emitter" connects to the 33k and Q2's "base". The 220pF cap across Q2's collector-base was purely a personal thing to calm the silicon down a bit, but if you like your Fuzz Faces with more "spit", feel free to omit it. The lower gain PNP's tended to give a more "overdrive-like" sound, but be using a higher HFE transistor for Q2 I was able to get them "fuzzier". Oh, I also tried silicon PNP's for Q1, and they worked fine as well.

If you don't have a 50K trim pot handy, you can use a 10K-20K trimmer and swap the 100K resistor for a 150K resistor. Everything should bias up ok.

Oh...I used RG's drawing and modified it. Hopefully he won't mind, but if he does, I can redraw it.

Enjoy.

momiel · July 27, 2007, 11:59:08 PM

Good work!
In the last month i've freaked with fuzz face and only real fuzz (vintage) progects. They are THE pedals.
Good work.

PS: im'gonna try it on new week. tomorrow out for a gig!!!

Marcos - Munky · July 28, 2007, 01:51:35 AM

Hey Andrew, could you please give us some time to build your effects before you post your new works??? Just kidding, keep posting your works and we will building them until we build all of them

. Another one added to the list. Oh, if things keep going this way, I will have a pedalboard with only Dragonfly effects

. I just need you to work on a few non-fuzz/distortion/overdrive effects to make an entire Dragonfly pedalboard

.

Dragonfly · July 28, 2007, 02:04:18 AM

Quote from: Marcos - Munky on July 28, 2007, 01:51:35 AM
Hey Andrew, could you please give us some time to build your effects before you post your new works??? Just kidding, keep posting your works and we will building them until we build all of them . Another one added to the list. Oh, if things keep going this way, I will have a pedalboard with only Dragonfly effects . I just need you to work on a few non-fuzz/distortion/overdrive effects to make an entire Dragonfly pedalboard .

I've got a few other things I'm working on, but some of them I cant post as theyre possible licensed circuits. If the licensing doesnt happen then they will probably get posted....

I hope things are going well for you.

jaytee · July 28, 2007, 06:14:53 AM

Funny that you just posted that because I was just looking at this circuit in an electronics book and was thinking about messing with it.

It has the second stage flipped upside down. I was wondering if it would sound any different. You could probably do the same with the first stage, the emitter to positive and collector resistor to ground. So any combination.

slacker · July 28, 2007, 06:31:39 AM

I've messed around with something similar to that, it sounded good but not much like a fuzzface. You might have to play around with R1 to get it to bias up properly.

markm · July 28, 2007, 06:34:30 AM

Quote from: jaytee on July 28, 2007, 06:14:53 AM
Funny that you just posted that because I was just looking at this circuit in an electronics book and was thinking about messing with it.

Same here!

jaytee · July 28, 2007, 11:57:33 AM

Quote from: markm on July 28, 2007, 06:34:30 AM

Same here!

[/quote]

No you wasnt. Hold on..I know that face. Second thoughts...you don't have a face.

News:

A new twist on an old friend.