RM Axis Fuzz Build Report

[STOMPmole]

Thanks for the info!  I might build one of these for a friend and possibly one for myself since it would be much easier to carry around than the rocketship (and I won't feel bad about adding an LED and modifying it).

[brian wenz]

Hello Hello--
    A friend of mine loaned his Rocketship to me while I was building my copy and the voltages came out REALLY close to his [ this was  without any tranny matching or anything like that...].  I think this circuit is just really "foolproof" and was designed around the 2N3906 and 2N3904 trannys.  After I did the "47K to 22K mod"  he liked the sound of the copy better then his original, though!
Brian.

[Doug_H]

a;lkhd

[brian wenz]

Hello Hello Doug--
     Thanks for the tip on the 2N2222.
 Yeah, I agree, every fuzz should be different!
Brian.

[RedHouse]

Hey Ricky,

If you wanna "take it up a notch" (pardon the Emeril'ism) use 2N5087/88's in the hFe 350-400 range. I built one last year with those transistors and it really perked-up the unit compared to the 2N3904/6 config. Also at the base of Q2 there is a .001uF and 220R resistor in series to ground, many prefer the sound when those are removed from the circuit.

Somebody earlier mentioned the "Humbucker" issue which reminded me of something I realised some time ago. I looked at the schematic of Jimi's olympic-white strat and was quite shocked at the .1uF tone cap.
(yep, that's no typo it's a .1 uF cap in that guitar as verified by Fender and the Experience Music Project which owns the guitar)

Seems that as Roger was making the pedals more treble-laden he was also making the guitars more bass-laden, on another side-note, Jimi used to use those old "coily" cords which were known to be high capacitance treble killers. Could it be he/they were just balancing out the shrill'ness of the Marshalls, after all he was renowned for using blond Fender Twin's in the studio.
(according to Eddie Kramer)

Food for thought.

[RDV]

Also at the base of Q2 there is a .001uF and 220R resistor in series to ground, many prefer the sound when those are removed from the circuit.

I didn't put it in.

RDV

[b_rogers]

my unit is kinda bassy so i left those off too. also im not getting the "swell" effect as strong as some folks?

Brent

[RDV]

It's subtle with mine, the harder you hit the front of it with signal, the more pronounced the swell will be.

RDV

[brian wenz]

Hello Hello--
    I wonder if the swell is more pronounced when the 47K is in the circuit??
Brian.

[b_rogers]

i think my voltages are a little low so maybe thats why..

[brian wenz]

Hello Brent--
   Can you post yer voltages??
I won't be able to check mine until tomorrow [Wed.]  but maybe It'll help...
Brian.

[johnabraham]

Im reading here about resistor changes, one being 47K down to 22K; substitution with a pot there; putting a 1M resistor there in the same place; and talk about different kinds of transistors.

With the 47K resistor, has anyone here ever spoke to Roger Mayer about if he actually did this or not?

How about transistors?

What im wondering is if anyone here has gotten the chance to speak with RM about some of these things. I don't know how open he is with all of this stuff because i have read and heard he doesn't speak much at all. But on the flip-side; he may have at least let some people know what was going on with some of his older stuff, or newer stuff.  John.

[b_rogers]

ill post them tomorrow brian. gotta go to bed



brent

[STOMPmole]

"What im wondering is if anyone here has gotten the chance to speak with RM about some of these things. I don't know how open he is with all of this stuff because i have read and heard he doesn't speak much at all. "

I think getting RM to speak about any of his designs in more than general terms (like disclosing component values for instance) would be near-impossible.

There's a forum over at the Rogermayerusa.com website where people have asked various general questions about RM pedals (like what KIND of transistors are used, Ge or Si, etc. in a given pedal) that have been unanswered because "Roger doesn't disclose his secret proprietary information".  It's apparent that his designs are very closely guarded...probably because if they were common knowledge anyone could build one of his pedals for $15.

I wrote to Northstar audio to try and get some info about my RM wah (I wanted to mod it for more output or variable gain like the current version has) and was told I'd need to send the wah to them for modification.  I ended up diving into it myself and figuring out what I needed to do to increase the gain (change one resistor).  

From what I've seen RM is pretty-much a ripoff artist (steals other people's pedal designs) that has a talent for 'improving' upon a basic design by the use of higher grade parts and/or slight circuit modifications.  I'm not saying this is a bad thing...most of us do it ourselves...it's just my personal observation.  FWIW, I'm actually a big fan of his products.  I think his classic and axis fuzz, as well as his wah pedals are the best you can buy.

I've got the RM Axis fuzz and could open it up to take a look...just let me know what specific values you want me to check in reference to the schematic or in relation to the other components.

[brian wenz]

Hello Hello--
    All the stock Axis Fuzz  [spaceship] circuits that I've looked at [or heard about] have the values that are in the Fuzz Central schematic. Mayer is using some  European trannys, though!
Brian.

[johnabraham]

Stompmole, do you have any idea as into what designs RM "ripped off" so to speak. I can't think of any current schematics of other stuff in which even come close to what his schems look like. Thanks, John.

[b_rogers]

well the classic is a modded fuzz face, and the mongoose is a modded rat.
i believe the axis is original though. nothing wrong with tweaking existing designs as long as you dont claim its an all original circuit.

brian and anyone else who cares  

voltages are: supply= 8.62v on the only 9v  i have!
                   q1 2n3906  
                                     c  2.80
                                     b  3.73
                                     e  4.48

                   q2 2n3904
                                     c  5.89
                                     b  2.80
                                     e  2.20
it works and sounds good but i know those voltages are a little out, so im thinking it will sound even better when i get er biased right.


Brent

[b_rogers]

these voltages are with the 47k pot full up. it changes the b,e voltages when you turn it down.  i should have breadboarded it first..sorry to jack the thread Ricky...i can post it seperately if you want.


Brent

[STOMPmole]

...and the Wah Wah is a modified Vox wah.  He's coming out with some 'new' pedal that I think is a modified Tone Bender.

Is the schematic for the Mongoose availlable anywhere?

[brian wenz]

Hello Hello--
     Here's the voltages from a stock Mayer Axis:
       2N3906            2N3904
       C- 3.20            C- 5.86
       B- 3.64            B-  3.25
       E- 4.34             E- 2.68

      Here's the voltages from my DIY Axis:
         2N3906           2N3904
        C- 3.04             C- 5.68
        B- 3.52             B- 3.04      
        E- 4.21              E- 2.47

Brian.