Introducing: Axis Face Silicon Revision 3

[phillip]

Here it is...after an afternoon of soldering a transistor testing!  Lots of thanks to Brett Robinson for the modifications that are highlighted in red on the schematic below!  These two mods make a world of difference in the circuit.  No more horrible "farty" bass thanks to the 0.22uF input capacitor and no more shrill high end from the Silicon transistors thanks to the new 0.047uF capacitor.  The "Smooth" control is a very useful addition to the circuit...it really helps to mellow out the fuzz tone and remove some of the "fizziness" when it's turned clockwise.

I went a little wild Rev. 3 and installed a DC power jack and a white LED, mounted behind a clear lens that mounts nearly flush with the top of the box.

Definitely the best sounding Fuzz Face-style circuit I've ever played...even better than Germanium circuits.  For this circuit I used BC108B transistors.  Q1 has a gain of 191 and Q2 has a gain of 197.  I'm running Q2's collector at 5V for a little more "oomph."  You can try the lower gain transistors as used in the previous Axis Face...a PN2369A in Q1 and a 2N3904, 2N4400 or BD139 for Q2.  The 2N4400 and BD139 would be the best two choices...2N3904s seem to have gains that vary greatly from manufacturer to manufacturer.  The "white face" 3904s that I got from Small Bear all have gains clustered around 125.





Enjoy!
Phillip

[Burstbucker]

Sounds interesting Phillip but I can't see the pics.

All I get are blank squares with a red X in the middle!

8^(

[petemoore]

THey were working yesterday

[MartyB]

Hey Phillip!  Just wanted to say your site is fantastic!

MartyB

[phillip]

Whoops!  I must've deleted them last night when I was doing some cleaning up on my web host.  They should be working again now

Phillip

[Phorhas]

Sweet looking design...I'll have to try it... I find the all-Ge-Fuzz week and not-so-crazy-for-what-a-fuzz-should-be

[Burstbucker]

Thanks Phillip, I now can see those pics!

Very interesting.  I kind of agree with Phorhas in that an all Germanium transistor fuzz is a little less fuzzy than most people like.  I like the one that I built for myself but I don't know if that's the pedal that I'd pick if I were to pick a "desert island" Fuzzbox.  The hybrid fuzz is probably a better all-in-one Fuzzbox.  The Hornet is pretty cool too.

I might try some of your ideas when I tackle my next Fuzzbox.

BTW, how do you do the labeling on the top of your pedals, is that clear labels printed on an ink jet printer?  Looks nice.

I must also tell you how nice your website is, lots of good stuff there, thanks!

[phillip]

Thanks Phillip, I now can see those pics!

Very interesting.  I kind of agree with Phorhas in that an all Germanium transistor fuzz is a little less fuzzy than most people like.  I like the one that I built for myself but I don't know if that's the pedal that I'd pick if I were to pick a "desert island" Fuzzbox.  The hybrid fuzz is probably a better all-in-one Fuzzbox.  The Hornet is pretty cool too.

I might try some of your ideas when I tackle my next Fuzzbox.

BTW, how do you do the labeling on the top of your pedals, is that clear labels printed on an ink jet printer?  Looks nice.

I must also tell you how nice your website is, lots of good stuff there, thanks!

No worries about this one not having enough fuzz...it's all Silicon    I used BC108B transistors because they weren't too gainy (Q1=191, Q2=197), but they still provide enough grind and fuzz to last all day  If you wanted more gain you could even drop in BC109C transistors.  The 109C transistors that I have all have gains between 370 and 420 or so.

Phillip

[BD13UK]

Phillip does it clean up from the guitar volume control ? I found that some of the BC109 FF's were very fizzy sounding and when trying to clean up from the guitar volume they went very bright and brittle so I just wondered if the BC108 or 2N3904's would be a better option.

[phillip]

Phillip does it clean up from the guitar volume control ? I found that some of the BC109 FF's were very fizzy sounding and when trying to clean up from the guitar volume they went very bright and brittle so I just wondered if the BC108 or 2N3904's would be a better option.

Yeah the BC109s don't clean up very well and I also noticed that annoying "fizzy" sound.  The BC108B are low enough gain that they don't have that fizziness and they clean up fairly well from the volume control unless the fuzz pot is wide open, then it doesn't clean up quite as well.

I tested some of my regular BC108 (with no letter suffix) and they are higher gain than the BC109Cs that I have, so I wouldn't recommend them.

The lower gain transistors (PN2369A Q1 & 2N3904 Q2) seem to clean up better than any other transistors that I've tried in the circuit.

Phillip

[WGTP]

Nice design.  What does the .047uf cap in red do, roll off some highs?  

[BD13UK]

Thanks for the info Phillip.

[phillip]

Nice design.  What does the .047uf cap in red do, roll off some highs?  

Yep, say goodbye to those shrill highs

Phillip

[phillip]

BTW, how do you do the labeling on the top of your pedals, is that clear labels printed on an ink jet printer?  Looks nice.

Oops..forgot to answer that one!  The decals are made from the laser decal paper from Small Bear.  I just put a couple of coats of clear lacquer over them once they're dry and they look great!

Phillip