dunlop fuzz face

[ruispeeds]

Hi there,

i have a dunlop fuzz face and i've decided to mod it, so i put 2 dpdt switches to alternate between the  Ge nkt275 stock transistors and new 2n5087 Si transistors, but it doesn't sound as i was expected, they have some kind of hiss with the fuzz pot all the way up.
What can i do to solve this?
Thanks in advance.

RS

[Papa_lazerous]

bias?

[ruispeeds]

I've tried to bias both of the trimpots but the hiss presists.
I've just no idea!!!

[Papa_lazerous]

have you checked the Ge transistors for leakage?  maybe thats the hissing

[petemoore]

  5087's are high gain transistors, more than likely that's what's up with the noise factor.
  Fairly sure were talking about PNP's ina pos Gnd FF.
  Also the bias, probably off by a good bit because of the gain and leakage being different for each transistor.
  See Piggyback thread, use 8pin IC socket and trimpot as Q2collector resistor...anytime you change a transistor in the FF the bias should be checked.

[ruispeeds]

OK, thank you for the advise, i will try to check all that, and pay attention to biasing.
Thank you very much Pete.
RS

[brett]

Hi
with the silicon transistors, try a 220 ohm resistor off the emitter of Q1.  That should fix it.

[ruispeeds]

Thak you very much Brett, i will try that.

[drewl]

Since I was down to only one GE transistor I used a SI in the Q1 spot and the GE in the Q2 position and put a 500 ohm pot on the emitter of Q1.
That little trick really worked and improved the sound alot- Thanks.

Although......
the other GE transistor I had which I broke the base lead off, the case appears to be connected to the base.
It's a funky GE (general electric) PNP germanium painted black....so I'm gonna try and solder a lead to the case so I'll have 2 germaniums to play around with.

[nightingale]

Hi,
If I remember correctly, one of the trim pots is wired as a variable resistor in series on the input of the red Dunlop FF's.
Probably to make the circuit work better w/ a wah or whatever? I would go easy on adjusting that trim if you want to keep the input impedance to FF spec.  I have one at home, I will try to take another look at it tonight.

best,
ry

[joegagan]

Hi,
If I remember correctly, one of the trim pots is wired as a variable resistor in series on the input of the red Dunlop FF's.
Probably to make the circuit work better w/ a wah or whatever? I would go easy on adjusting that trim if you want to keep the input impedance to FF spec.  I have one at home, I will try to take another look at it tonight.

best,
ry

depends when it was made. the pre 99 red FF reissues had much more 'standard' ff circuit. very easy to mod into a monster, just put a 2n3906 in Q1, 20 k trim pot in place of the 8.2k at Q2 collector. change 22uf at Q2 emitter to 47 uf, try a 2k pot instead of 1k for fuzz pot (or 2k resistor to ground, who needs the fuzzpot anyway>?) you might need a better germ trans for Q2 but some of the stock ones were actually pretty good sometimes.

in the post 99 dunlop reissues ( circuit board mounted to SPDT sw) they added a bunch of junk , probably an attempt to make them more temp stable. I tried for a while but could never get one of these to sound any good to my ears. if you are getting one on ebay try to get the seller to open it up and tell you if the circ board is mounted in the old location or on the switch.

can't beat the look of the little round stage pie staring up at you....