PNP NPN fuzz face clones

[hendriko]

ok...this schematic for the roger mayer classic fuzz has PNP transistors in it but the negative of the battery goes to the ground...
is the battery drawn in the wrong way?

http://geofex.com/Article_Folders/fuzzface/fftech2.gif
http://www.geocities.com/CollegePark/Library/1355/rmclassicfuzz.gif

has anybody build either of these?
what's the difference (tone wise - i can tell that a couple of values are different :p)

[Meanderthal]

 That's a mistake in the .pdf file. Notice the + side of the 47uf cap goes to ground in both schematics.

I haven't exactly tried the RM mods(don't remember that bleeder cap on vol), but I imagine it would sound great with the right pair of trannies.

[tcobretti]

Here's a gutshot showing the pos going to gnd.

[Fret Wire]

  I haven't exactly tried the RM mods(don't remember that bleeder cap on vol), but I imagine it would sound great with the right pair of trannies.

The RM mods sound nice, I prefer them to the standard Dallas ckt.

Tcobretti, where did you get the pic? I ask because that's my RM (and my carpet!). I posted that pic along time ago. Has that pic made the rounds around the net? That's an early RM, when he was handmaking them in NYC, and Guitar Galaxy was the exclusive distributer. I bought that when they first came out. Notice how it's called "The Fuzz Face" instead of the Classic Fuzz.

As to the bleeder cap on the vol, that's from one of the later model RM's. Mine's just the Dallas ckt with a 2k fuzz pot and a 1k resistor, along with the corresponding bias values. It still sounds good. The tranny's are BEL AC 128's, and must have been very low leakage, because other than Q2's collector dropping to 3.75v, the voltages still are still good and proportional. My diy versions sound great also.

[hendriko]

The RM mods sound nice, I prefer them to the standard Dallas ckt.

As to the bleeder cap on the vol, that's from one of the later model RM's. Mine's just the Dallas ckt with a 2k fuzz pot and a 1k resistor, along with the corresponding bias values. It still sounds good. The tranny's are BEL AC 128's, and must have been very low leakage, because other than Q2's collector dropping to 3.75v, the voltages still are still good and proportional. My diy versions sound great also.

umm...thats awesome
what's that "bleeder cap" do anyway? does it have any point?

That's a mistake in the .pdf file. Notice the + side of the 47uf cap goes to ground in both schematics.

I haven't exactly tried the RM mods(don't remember that bleeder cap on vol), but I imagine it would sound great with the right pair of trannies.

yea i kinda figured that...just wanted to make sure
thanks.!

im getting the fuzz face matched trannies from smallbear.

Here's a gutshot showing the pos going to gnd.

awesome
i've been waiting to get a pic of that

and thanks also to Fret Wire to even posting that in the first place

[tcobretti]

Sorry if I freaked you out! I save almost every gutshot I see, especially RM pedals, so I'm sure I found yours somewhere along the way.  I have a bunch of RM gutshots in my gallery, most of which you have likely seen.  There are pics there of my newer RM Classic Fuzz, and it has no bleeder cap.  So I guess that was something he tried for a while and changed his mind about.  I just realized that I have seen gutshots with the bleed cap, and that I need to find them for my gallery!

Hendricko, the bleeder cap allows a tiny bit of high freqs to pass the volume pot.  Probly the reason RM did this is because the volume pot on a FF has a tremendous effect on the tone, and he was trying to make the pedal produce highs more consistently.  Since he took it out, I suspect he decided it wasn't serving its intended purpose.  I highly, highly recommend the 47k (or at least a 50k) volume pot, and then you run it wide open.  IMO this setting makes the pedal fuzzier, if a bit quiet.

[hendriko]

so what you're saying is just use a 50k volume pot without the cap?

all the other fuzz face's have a 500k volume....what difference does it make?

also, the "new" classic fuzz in your gallery has that black thing on it (trimpot?) - whats that for?
the old one doesn't have it...so is it necessary?

[Fret Wire]

The lower value volume pot will brighten the fuzz sound a little. The RM mods also brighten up the sound a little too. Personallly, with the RM, I'm fine with the 500k volume, but you may or may not like it, depending on your gear.

The later ones came with a trimpot for cost effective reasons. The older ones like mine were biased, then the final fixed resistor values were then soldered in place. Time = labor = $$, so by going to a trimpot, you only solder once, and adjust until bias until correct. Also, it allows the owner to slightly compensate the bias when the fuzz is being used in warm conditions (onstage..lights), and to also compensate for age, when the trannys slowly leak more with passing time. 

[hendriko]

The lower value volume pot will brighten the fuzz sound a little. The RM mods also brighten up the sound a little too. Personallly, with the RM, I'm fine with the 500k volume, but you may or may not like it, depending on your gear.

The later ones came with a trimpot for cost effective reasons. The older ones like mine were biased, then the final fixed resistor values were then soldered in place. Time = labor = $$, so by going to a trimpot, you only solder once, and adjust until bias until correct. Also, it allows the owner to slightly compensate the bias when the fuzz is being used in warm conditions (onstage..lights), and to also compensate for age, when the trannys slowly leak more with passing time. 

oh ok...i personally like a brighter sound so i guess i'll go with the 50k to begin with

so would you recommend putting a trimpot in?

[Fret Wire]

so would you recommend putting a trimpot in?

That's your call. I bias with pots, then solder in fixed resistor values. If you want to retain bias adjustability, go with trimpots in place of the 33k & 18k resistors. Use 50k & 25k trims. If you use trannys way higher than the gain range suggested in GEO, you may need more than 50k for the Q1 collector trim.

[hendriko]

so would you recommend putting a trimpot in?

That's your call. I bias with pots, then solder in fixed resistor values. If you want to retain bias adjustability, go with trimpots in place of the 33k & 18k resistors. Use 50k & 25k trims. If you use trannys way higher than the gain range suggested in GEO, you may need more than 50k for the Q1 collector trim.

ok...well...i'll see what i do
thanks!

the trannies are from smallbear btw...so i guess theyre somewhere in the "recommended" values