Lovepedal Silicon Fuzzmaster - a couple of simple questions

[alex_spaceman]

I found the schematic for this pedal and would love to have a crack at it but have a couple questions.



First off, would love to make it NPN. Would 2n3904s be a good like for like substitute? Would then swap ground and +9 as well as elec caps.

Second question - what's the deal with the diode/led/etc bit on the top left? Also doesn't seem to translate to the vero version I found along with the original schematic



Thanks in advance!

Alex

[digi2t]

2N3904 is the NPN complementary to the 2N3906, so I don't see any problem trying it.

As for your second question, it seems to be that there should be a little line continuing on, leading to the "V+". The "V+" corner (for lack of a better term) is what is powering the circuit, with the LED taking it's power after the 330R resistor, and filter caps.

Hope that helps,
Dino

[nocentelli]

Also doesn't seem to translate to the vero version I found along with the original schematic

I think it's just that IvIark has left off the 100n cap (C13) as superfluous, and omitted the LED and associated resistor (R4) since most vero builders might well do the on/off LED wiring entirely off-board. I breadboarded this circuit with 2N3904s, and it.......










....sounds exactly like a 2N904 fuzzface.

[IvIark]

Alex the pedal is already negative ground.  You'll notice the usual power connections for a silicon Fuzz Face have been reversed so the Q2 base and collector resistors go to ground instead of V+, and Q1 emitter and the fuzz components around Q2 emitter go to V+ instead of ground.  This then allowed Sean to use PNP 2N3906s but keep a negative ground.  I've not got the faintest clue why he'd want to mind you, but there you have it.

As nocentelli said I omitted the 100n filter cap because I always do as I really don't see the point in wasting one, but if you really want it verbatim then you can put it next to and in parallel with the 220u.

If you want to use 2N3904's instead of buying in the 2N3906's especially, then you'd just need to connect ground to the bottom row instead of the top, and move the 330R so instead of it going from the diode to the bottom row, it goes from the diode to the top row (just shift the 100n over one column to the right).  Everything else in the layout would then remain the same and in the orientation shown.

[Tony Forestiere]

I got 6 2N3906 in a bag at RS for the price of 1 2N3904. They are cheap. I would try the circuit as is. Good luck.

[Yonatan]

I built it as is, very sweet and dynamic sounding. 

Note if you are buliding it as is (PNP with negative ground), just don't leave off the 220u filter cap like I tried doing.  It whinned horribly!

[alex_spaceman]

Hi guys, thanks a lot for your help. Should have both 06s and 04s, in which case I'll stick with the original design.
From the demos I heard t does indeed very fuzz face-y and dynamic, so might just be the right silicon brother to my Ge FF
Will report back once done with the build!

Ps: IvIark, I didn't realize the blog was from someone active on here. Great blog, lots to look at on it!

[alex_spaceman]

Last quick silly question: ran out of 330R - 390R ok? Guess it wouldn't really make a difference?
Thanks!

[nocentelli]

390r will be fine.

[Plexi]

Very nice sound fuzz, with a touch of od..love it!
A very dynamics, not like any silicon FF.

I used B1K pot, what you suggest to get more subtle drive increasing?
It's a strange kind of Drive control, that act's in conjuction with blend knob.

[Mark Hammer]

Stick a 100k trimmer or pot in series with the 100k feedback resistor between Q2 and Q1.  Or, try a 250k trimmer and identify two audibly different added resistances that could be selected with a 3-position toggle.  The added resistance willintroduce a certain degree of glitchiness that some folks find appealing about extreme fuzzes.  Reverting back to only 100k gets you stock tone.

[Plexi]

Thanks Mark, as always.
I'll be tweaking around that 100k feedback resistor and will see how it goes...