Building an RM Axis Fuzz

[Xplorer]

Hello guys,

well, i'm quite happy with this cool blue Dunlop Hendrix fuzz, very good into my 45/100 clone.
But since i'm allways loving the BOG tones ( Fillmore east Hendrix, band of gypsys, machine gun, who knows etc ) , and that i'm convinced it was a 45/100 that night, ( recorded ) over the superlead used the night before, i'd like to build a proper Axis fuzz, to see how it reacts into a 45/100.

i have a few noodling clips here ( recorded at bedroom level ) :

https://soundcloud.com/xplorer80/little-wing-noodling

https://soundcloud.com/xplorer80/who-knows-noodling

https://soundcloud.com/xplorer80/machine-gun-noodling

https://soundcloud.com/xplorer80/power-to-love-noodling

https://soundcloud.com/xplorer80/them-changes-noodling

https://soundcloud.com/xplorer80/machine-gun-tone-45-100


i think it was my first build a few years ago, but it didn't work properly, and it was too trebly or something.
Now i think that it's a matter of which amp you're using, and how.
for example, my megavibe sounds great with a superlead, while with a 45/100 i'll choose my signed RM Voodoo vibe, much better.

So, i checked for some schematics on the net, but there were several variants.
I took a gut shot from internet and started on toshop.

i'll use some Motorola 3906 and 3904.
170 and 190 or something. according to what i read on an hfe recommendation, here, it should probably work.

But i notice that some résistor and cap ( 220 ohms and 0,001 uf ) simply don't exist on the photo i see, between Q1 and Q2 ... So why are they on schematics all arround ? was there any older version of the Axis fuzz or something ?

i wish i could post some pictures but there's no upload link ( ? )

[Xplorer]

ok nevermind, i put that on flickr :

http://www.flickr.com/photos/28160216@N08/sets/72157639376517323/

i prefer to start from a real RM axis fuzz, and later see what is correct or not in the schematics of the web, even in the fuzz central schem in the link.

[Xplorer]

http://www.flickr.com/photos/28160216@N08/11753561303/

[dwmorrin]

So why are they on schematics all around ? was there any older version of the Axis fuzz or something ?

A survey of google search "roger mayer axis fuzz schematic" reveals at least 3 different possibilities/versions of the Q1 collector to Q2 base node.  Possibly a tracing error, or could be a real design change from Roger.
Two of the schematics are dated 2 years apart.
There are also UK and US versions of the pedals.  He's operated the company on 2 different continents.

Try to find and read interviews with Roger.  I'm pretty sure somewhere he talks about continuously updating his designs throughout the years.  This isn't conclusive evidence for your research, but it may be comforting to know.
The differences appear to be quite minor and can easily be tested on a breadboard.
A small cap to ground will affect HF rolloff.  The resistor fine tunes it.
One schematic shows a 100k to ground.

While I can't give you conclusive evidence, I would assume that different versions exist.  There's definitely a lot to read on the subject of Roger Mayer variations if you start researching the Octavia...

[Xplorer]

thank you.

well, googling the axis fuzz, i found various pcb versions, but all with the same components, no extra components.

i think i'll try what i have in my flickr link, but i wish i could verify the electrolytic caps values from pictures. unfortunately i can't.
( also pots values )

[Xplorer]

http://www.flickr.com/photos/28160216@N08/11762797305/sizes/h/in/set-72157639376517323/

[idy]

There are (were) posted gut shots of a lighter colored PCB (original RM) that had pads and holes (empty) for the resistor and cap to ground between Q1 and Q2. Some folks have said it is better to leave off and most people (including RM) do. It would seem to be a high-cut on this super bright pedal.

A quick google search and I don't see these photos any more. Not mine shouldn't post.

[hellwood]

build this one: http://fuzzcentral.ssguitar.com/schematics/axisfuzzschem.gif

it will tear your face off!

I tried all kinds of gain combos to get the thing to sound good and ended up with Q1/Q2 - 171/255.

Q1-   c.2.84
        b.3.24
        e.3.93

Q2-   c.5.30
        b.2.84
        e.2.30

[GibsonGM]

build this one: http://fuzzcentral.ssguitar.com/schematics/axisfuzzschem.gif

it will tear your face off!

I tried all kinds of gain combos to get the thing to sound good and ended up with Q1/Q2 - 171/255.

Q1-   c.2.84
        b.3.24
        e.3.93

Q2-   c.5.30
        b.2.84
        e.2.30

Got a sound clip?

[LucifersTrip]

build this one: http://fuzzcentral.ssguitar.com/schematics/axisfuzzschem.gif

it will tear your face off!

I tried all kinds of gain combos to get the thing to sound good and ended up with Q1/Q2 - 171/255.

Q1-   c.2.84
        b.3.24
        e.3.93

Q2-   c.5.30
        b.2.84
        e.2.30

Got a sound clip?

he linked to clips in another threat...the axis is there
http://theharshcarpets.com/i-make-guitar-pedals-here-are-some-sound-clips/

[mitchelr]

build this one: http://fuzzcentral.ssguitar.com/schematics/axisfuzzschem.gif

it will tear your face off!

I tried all kinds of gain combos to get the thing to sound good and ended up with Q1/Q2 - 171/255.

Q1-   c.2.84
        b.3.24
        e.3.93

Q2-   c.5.30
        b.2.84
        e.2.30

Got a sound clip?

he linked to clips in another threat...the axis is there
http://theharshcarpets.com/i-make-guitar-pedals-here-are-some-sound-clips/

The first seven clips don't work for me, anyone else have the problem

[hellwood]

The first seven clips don't work for me, anyone else have the problem

I noticed that with Mac/Firefox. Try a different browser or a PC. I will have to change those files from wav to mp3. ...sorry about that

[mitchelr]

All clips working with firefox now , Thanks