Axis Face - successful build

[chuckmoose]

I've been banging my head against a MKII with little success, so I gave a silicon Axis Face fuzz a try and still no luck. 



I got all sorts of weird noise, oscillation, occasionally a little nasty fuzz, but I was convinced I had the layout correct on my breadboard.  After 2 days of trying I finally found my error.  I had switched the pot values on the Attack and Smooth controls!

It's an interesting fuzz.  I need to try it through my gigging amp, I have only been using a practice amp at my work area so far, but it strikes me as not cleaning up as smoothly and being as dynamic with the guitar volume control as some fuzzes I have used.  I'll keep messing with it though, and see what I can do.

Hopefully my MKII issue will turn out to be something equally stupid...

Quick question, do all BD139 transistors have the pins in an order different from the norm?  The ones I have are ECB, so some rerouting is necessary to get them to work.  What might be a good substitution in this circuit?

[chuckmoose]

After playing with this fuzz for several hours I think I like it pretty well.  I am admittedly not a fuzz guy, so my opinion is somewhat meaningless, but I like this almost as much as anything else I have tried.  My SunFace NKT275 was darker and smoother, and had better sustain without fizzing out, but this one seems like it has a better cutting tone without being overly harsh. 

With some experimentation and a few searches I found some values I prefer :
R1 = 47K, drops the bass a bit, but makes it feel more responsive, with more even tone over the sustain of the note
R2 - 12K, biases Q1 to about 1.4v
Q2 = 2N3904, the BD139 sounds about the same, but is much larger and the pins are funky, so I'm going with the one that's easier to deal with
C4 - I may add a switch to select between the standard 10nf cap and a larger .1u cap for added low end

I have not experimented with inputs caps yet, but I plan to.
I may try a few tone controls and see if I can find anything useful to tame the top end just a touch.
I may set one of the controls, Attack or Gain with fixed resistors so it only needs one knob to control the fuzz.  We'll see, depends on whether I add a tone control and don't have room for four knobs. It is nice having the extra control though...

[The French connection]

Sorry for the resurrecting this thread but Is this Axis face layout verified? Have you used it?

Thanks!

Dan

[chuckmoose]

The final version I built of this is modified, but I used the layout as a starting point.  I was barely reading schematics when I did it and built my breadboard version based on the stripboard layout  So I think it's safe to say it is verified.  Try a smaller value for R1, maybe 47K, for a much more touch responsive pedal. 

And I finally got that MKII built but I like my modified Axis much more!

[BoxOfSnoo]

Bringing the thread back to life... purely because I just built one successfully!   

I used a 47K resistor too, and 2222a for both Q1 and Q2, it worked great!

[Philippe]

Congrats on your build. This is definitely one of the better DIY silicon fuzz designs out there. With a Q1 of 80-90 & a Q2 of 116-120 it is capable of producing a Ge-like tone but with a tad more 'bite' & the negative ground design makes powering-up with an AC adaptor a lot easier (although I still use a zinc-carbon battery with this particular effect). I built the Phillip Bryant/Brett Robinson version 3 & am very pleased with the outcome.

[The French connection]

Bringing the thread back to life... purely because I just built one successfully!   

I used a 47K resistor too, and 2222a for both Q1 and Q2, it worked great!

So the layout is verified???

Thanks!

Dan

[BoxOfSnoo]

I used the layout as is, with only a few parts changes

- R1:47k
- Q1 & Q2: 2222a (I'm going to try a 2N3904 in Q2 today)
- C3: .047uF
- D1: 1N4004

For C3 and D1 they were not because of preference, but the only things I had on hand...  I also made some insignificant layout changes due to the geometry of the board I had (just working around a screw hole, mostly).

I'd trust it (well, I did).