Finally Successfully Modded my Dunlop FF!

[zombiwoof]

I've had an early Dunlop FF for many years, and have done some mods from time to time to get it sounding good.  This is the old Dunlop red version with the case-mounted switch, jacks, and separate board.  Stock it sounded horrible, bassy and unlike any good Fuzz Face I've heard.

My first mod was to change out the output cap to the correct .01uf, from the stock .1uf, which was the main cause of the extreme bass (doesn't Dunlop know that it's supposed to be .01? - they must have been looking at those incorrect schematics out there that show .1uf).  And I had an NOS trop fish cap, for extra mojo goodness!  (I can hear some people hear grinding their teeth!).  Less bass, but still sounds like crap.

Next, I changed out the carbon film resistors to carbon comp, which mellowed out the sound a bit (more sounds of teeth-grinding!).  Just wanted to make it like the old ones.  Still no happiness, those stock trannies have to go.

Stock trannies were those skinny fake NKT's that Dunlop supposedly had made for them.  I bet they are just relabeled NTE devices, but who knows?  Got some 2N404's that guys have said can sound good, in the correct ranges, tested myself using the Small Bear/GEO method.  Also replaced the Q1 biasing resistor (33k I think?) with a 50k trimmer in line with a small resistor, to be able to dial in the bias. At this point, after noticing that you lose top end when the volume pot is dialed down from max, and seeing that Mayer puts a small (as I recall, .002uf) treble bypass cap across the volume pot, I did the same (I might have used an .001uf).  I had saved the Mayer schematic from GEO before it got deleted there, glad I did.  Works great, and something I don't see mentioned around here.  Now it sounds closer to Fuzz Face territory, but something is still missing.  Not much sustain, but the tone is balanced better, and there is finally some high end to be heard.  Still not happy, though.

This is the way it sat for quite a while.  I kept my eye out for some better trannies, and finally got some tested ones from an Ebay seller.  I ended up with an NOS AC128k in Q1, and a 2SB176 in Q2, both are within the established gain ranges for those positions.  Biased it with the trimmer, and WHAT DO YOU KNOW, IT SOUNDS GREAT!  Somewhere along the line I removed the treble bypass cap, but I think I'm going to put it back in, for now I'm pretty happy.  Took me some time (although I only worked on it at intervals).

Next, I'm going to have a go with the MXR-sized Jimi Hendrix fuzz, the red germanium one, which has NTE trannies in it that are way out of bias, even with messing with the internal trimmer that's in there.  I've got doubles of those trannies I used in the big red FF, because I bought matched pairs of them, but I'm not sure I can get them to fit in the Hendrix Fuzz (especially the AC128k, with that big heat sink) as it has a pretty tight board.  Might have to get a physically smaller trannie for Q1.  I've got high hopes for this pedal, if I can tweak it in a similar fashion (no, no carbon comps for this one, but I bet it has the same .1uf output cap to replace), as it has a buffer in it that I think is similar to the one in the MXR BC108 Fuzz, to allow it to be used after a wah without problems.  I'll see if it can be made to sound good, and I'll report back, as some other guys here have talked about modding that pedal.

Anyway, just though I'd detail what went into getting the Fuzz Face sounding good, for anyone who might be interested.

Al

[joegagan]

that is a good write-up, thanks.

i have rebuilt or modded many of these. first one was in 98 when i was on the road with my band. that exact circuit board later became the basis for the easyface. i have a soft spot for those big round facey cases