Axis Fuzz Build Report

[phillip]

I just finished building the RM Axis Fuzz, and I have to say, it's a pretty nice fuzz.  I've heard a lot of people say that it's not all that great, but try removing the 220R/0.001uF series from the collector of Q1...makes a world of difference.  I also used a 2N5087 for Q1 and a 2N5088 for Q2.

For those who've built the Axis Fuzz...does this thing actually do some octave doubling in the higher frets?  I'd swear that I'm hearing some octave in there...after all...the Axis Fuzz has pretty much the same front end as the RM Octavia.

Phillip

[Davefx]

Hey Phillip...  What is the sound with that cap and resistor left on? Harsher? Also, how does it clean up with the guitar volume? It's supposed to be good for that.  If it is what Jimi used on BOG, it definitely should clean up well, as he  did a lot of cleaning up with his volme with the fuzz on, on that record.

Thanks....

[phillip]

Oh man it sounds pretty bad with that resistor and cap on there...it was sputtery sounding on the one that I built.  When I took them off it sounded 100% better....like a Fuzz Face x 2.  Those two components were only put in the US-made pedals to help get rid of any radio interference that the pedal might pick up...which the Axis Fuzz seems to be known for.  

It cleans up fairly well with the guitar volume...not quite as well as a regular Fuzz Face though.

Phillip

[Ammscray]

Oh man it sounds pretty bad with that resistor and cap on there...it was sputtery sounding on the one that I built.  When I took them off it sounded 100% better....like a Fuzz Face x 2.  Those two components were only put in the US-made pedals to help get rid of any radio interference that the pedal might pick up...which the Axis Fuzz seems to be known for.  

It cleans up fairly well with the guitar volume...not quite as well as a regular Fuzz Face though.

Phillip

Hi Philip, there may be an error in your layout or perhaps a problem with the lead dress, because those extra parts are not supposed to add or subtract anything from the sound, they just eliminate static when you turn down the volume control of your guitar...and if you're in the US, it works! Without those parts, the pedal will sound the same when the guitar volume is all the way up...

FWIW I have never had any RF problems with axis fuzzes, and I have a US model, a European one, and a couple of clones I did...

IMO the only cool-sounding RM pedal

[Boofhead]

I'm sure those parts are in the original unit.   I thought the 1nF and 220Ohms values are correct for the octavia (but  I've never been totally convinced the values were correct anyway).  Their main pupose is to stabilized the feedback network and they can be finicky to get right.  The fact yours is spattery sounds like it is oscillating and that indicates the values aren't correct.  Layout issues could also be causing oscillation and you are compensating for this by changing these components - in effect solving the wrong problem.

Another uncertainty is the value of the input cap 470pF,  47pF or other?

[phillip]

Actually, it works fine without the 220/0.001uF.  The 2N3906 and 2N3904 are smoother sounding, but I originally went with the 2N5087 and the 2N5088 for more "oomph"...they produce a more raspy sounding fuzz.  I ended up going back to the original components.  I'm giving the Axis Fuzz a thumbs up

No circuit noise to speak of...it's a pretty quiet fuzz.  It only gets noisy when the single coils of my Tele get a little too close to the TV

Phillip

[Ammscray]

I'm sure those parts are in the original unit.   I thought the 1nF and 220Ohms values are correct for the octavia (but  I've never been totally convinced the values were correct anyway).  Their main pupose is to stabilized the feedback network and they can be finicky to get right.  The fact yours is spattery sounds like it is oscillating and that indicates the values aren't correct.  Layout issues could also be causing oscillation and you are compensating for this by changing these components - in effect solving the wrong problem.

Another uncertainty is the value of the input cap 470pF,  47pF or other?

Those 2 extra parts come stock in the US version, but not in the European version because at 240V they don't have all the problems we do with our wimpy 120V...

The input cap should be .1 if you go lower you lose bass which in this circuit is not good...it's a great fuzz, with my V into my 72 Marshall SL it's Isle of Wight all over the place!

Pssst!  Brian Wenz where are you!

[Boofhead]

Those 2 extra parts come stock in the US version, but not in the European version because at 240V they don't have all the problems we do with our wimpy 120V...

I wasn't aware of that.  I analysed the circuit in detail once and it looked like it could be unstable, depending on layout and specifics.  Those components generally would help improve feedback stability.

The input cap should be .1 if you go lower you lose bass

I'm actually refering to the cap to ground at the input as opposed to the one in series with the input.

[brian wenz]

Hello Hello--
Yeah, I'm here!
The Axis is pretty cool...I built one up with a BS170 for Q2 and it sounds good, too.
So, has it been established that removing those two parts would NOT change the sound in any way??   I wonder why Phillips' circuit sounded different with the parts' change?
Hey Phillip---try yer Axis with the BS170 in Q2 and let me know what you think.
How about messing around with some of the other res. values to get rid of the "woofiness" at higher volumes??   Anybody??    [----AMMSCRAY---??]
Brian.

[Ammscray]

Hello Hello--
Yeah, I'm here!
The Axis is pretty cool...I built one up with a BS170 for Q2 and it sounds good, too.
So, has it been established that removing those two parts would NOT change the sound in any way??   I wonder why Phillips' circuit sounded different with the parts' change?
Hey Phillip---try yer Axis with the BS170 in Q2 and let me know what you think.
How about messing around with some of the other res. values to get rid of the "woofiness" at higher volumes??   Anybody??    [----AMMSCRAY---??]
Brian.

B- IMO the circuit sounds great the way it is, with both stock single coils AND humbuckers...what more could you want?

boofhead: right, it's a 470 pF... and the circuit is very stable, I've been playing it for many years now...when I want to get the BOG or IOW there's nothing else...use the stock FF with BC108C's for woodstock though

[Kleber AG]

Where could I find a good schematic for this one?
Wich have you used?

Regards
Kleber AG

[brian wenz]

Hello Hello--
 Fuzz central has a schematic and a layout.
Brian.

[Doug H]

Back when I breadboarded it I didn't notice a tonal difference with/without the filter. I thought it was pretty stable with 2n3904's too. FYI, you can get the schem at Justin Philpot's site, I believe.

Doug