Fuzz Face Mods

[kurtlives]

Is the 33K resistor the one Mike Fuller replaces with a pot for the soft mod?

What resistor do I replace for biasing?

http://www.smallbearelec.com/Categories.bok?category=Germanium+Transistors     What's with all the different transistors? WHat are the differences?

[petemoore]

Is the 33K resistor the one Mike Fuller replaces with a pot for the soft mod?
  Not sure what the soft mod is.

What resistor do I replace for biasing?
  instead of the the 18k can be a 20k pot wired as variable resistor.
http://www.smallbearelec.com/Categories.bok?category=Germanium+Transistors     What's with all the different transistors? WHat are the differences?
  Some are NPN some PNP, made here / there / different appearance and slightly different properties I suppose...maybe it just takes more transistors which equates to more time testing to get matched FF sets from one 'brand' compared to the other...not sure.
  See GEO "Technology of the Fuzz Face": Choosing transistors...

[brett]

Hi
I think Pete meant the 8.2k resistor (not 18k).

Many different transistors work ok (especially with the bias pot in place), but the tone will be different in many cases.
I used to like higher hFE than the "magic" 70 for q1 and 130 for q2.  But lately, I've gone off that idea and like the heavier tones available at 50 and 120.
cheers

[kurtlives]

There is no 8.2K resistor.

So is the FF one of those pedals that dosent really need to be biased?

[Dragonfly]

iirc, the "soft mod" is simply a 250k pot on the front end.... lug 3 from the switch...lug 2 to the effect input....lug 1 no connection

may be mistaken though

[soulsonic]

I replaced the input cap of my Dunlop FF reissue with a 1uF film cap and it made it sound much more "boutique-y".

[Dragonfly]

I replaced the input cap of my Dunlop FF reissue with a 1uF film cap and it made it sound much more "boutique-y".

Panda-riffic even ?

[hellwood]

There is no 8.2K resistor.

So is the FF one of those pedals that dosent really need to be biased?

other than transistor selection, its all about biasing (to fart or not to fart)

[soulsonic]

I replaced the input cap of my Dunlop FF reissue with a 1uF film cap and it made it sound much more "boutique-y".

Panda-riffic even ?

I paint all my film caps black and white for a reason!
... welll...not really... maybe I should start? Give it the ol' Panda Mojo.
But seriously, the film cap really sounds good there, and 1uF is still plenty big that the FF still does it's thing, but it does tighten up the extremest of the sub lows a little bit in a way that's nice.

[kurtlives]

So the 18K is the bias resistor?

[hellwood]

So the 18K is the bias resistor?

its for biasing the collector of the second transistor
to  -4.5V

[PerroGrande]

Unless you go with a hand-selected, tested pair of trannies, 18K is rather unlikely to be the actual value you need.  I've fallen into several veritable treasure troves of Germanium PNP transistors recently (adds mojo, hopefully offsetting the mojo loss I incur by loving good op amps),  and I don't think I've used 18K once for biasing...  I setup the circuit with a trim pot, set the bias where I like it, remove the pot, measure the value, then replace with a permanent resistor...

[soulsonic]

The last time I built this sort of circuit, I actually found myself adjusting the collector resistor on Q1 (the 33K one). This seems to adjust whether it sustains good or gates nasty. You could do a 10K resistor in series with a 50K trim pot and probably be able to adjust the circuit to sound good with whatever you stick in there.

[petemoore]

  Sometimes the pot is a little bit touchy, that's why if I have a 10k, I'll add 5k6 or so so then I have bias range between 5k6 and 15k6, a pretty good range for most of the transistors I'd want to use.
  one way, the gating sets in pretty quickly as far as pot rotation amount, the other way makes it gate in a different way, somewhere in between is usually between 4.5v and 6v bias.
  with 'good transistors, the FF [a single stage feedback amplifier] can be biased nicely with a trimpot @Q2CR position [replaces the fixed bias resistor].

[ambulancevoice]

both collector resistors are bias resistors
what i would do is replace both of them (33k and 18k (i thought the fuzz face was 8.2k??) with 100k trim pots
this will allow you to contour the biasing/sound to you liking

[mac]

I replaced the input cap of my Dunlop FF reissue with a 1uF film cap and it made it sound much more "boutique-y".

I did the same thing, poly caps at the input. Also 3 x 685 polys at the gain pot. Bigger board but bigger sound.

iirc, the "soft mod" is simply a 250k pot on the front end.... lug 3 from the switch...lug 2 to the effect input....lug 1 no connection

I prefer this pot over the stock gain pot. It also makes the HBs of my guitar sound better, and increases the input Z for better compatibility with another fxs.

mac

[drewl]

Any quick tips for making mine a little less bassy?
It doesn't "fart out" but is a little too dark, I'd like to brighten it up a bit.
Thanks.

[Dragonfly]

iirc, the "soft mod" is simply a 250k pot on the front end.... lug 3 from the switch...lug 2 to the effect input....lug 1 no connection

I prefer this pot over the stock gain pot. It also makes the HBs of my guitar sound better, and increases the input Z for better compatibility with another fxs.

mac

with lug 1 disconnected it shouldn't work as strictly a "gain" pot...though it will cut a bit of overall gain....more for impedance matching, as you mentioned.  Connect lug  1 to ground and you have a gain control a'la Easy Face. using TWO pots (1st as "soft", 2nd as "gain") is is a really nice mod, BTW.

[mac]

I like the 2-lugs input pot at 10-20k in case I switch from SC to HB, and control gain with the guitar volume.

The "meterless nitroburner" has a 500k pot with all lugs connected, kind of  guitar volume I guess, and variable input cap which I adopted in mine.

But again, the best mod imho is replacing the electros with polys, or "helping" electros with a poly or ceramic in parallel.

mac

[soulsonic]

I'm currently working on a simple little silicon Fuzz Face style thing that will (hopefully) get that cool germanium vibe and feel, but with standard low-noise silicon transistors. And it will have a high input impedance so it will be happy with whatever you plug into it. I'll keep y'all posted.