antiquity fuzz build problems

[lemrey]

i'm having some frustrating issues building the antiquity fuzz.
i can get some sound out of it but it's unpleasant to say the least.

voltage readings seem to be OK except on Q2 C and E which are identical
and I think that's just bad. what could be the reason?

im using stock components except 2N5088 instead of 2N5089
im positive i got the transistor pinout right
i also tried with different transistors, and switched some caps too.
i tried using a fixed resistor instead of the 2K gain pot

[lemrey]

I breadboarded the circuit anew, on a different part of the breadboard but the results are similar.

when the gain pot is turned to minimum i can hear some decent, but low sound.
as i turn it the other way, i can hear only an apocalyptic buzz when strumming hard :\

voltage readings: (9 volts)

Q1 2N5088
C: 1.95 V
B: 0.6 V
E: 0

Q2 2N5088
C: 1.25 V
B: 1.95 V
E: 1.25 V

[lemrey]

I noticed that changing the 5.6K resistor alters the voltages on both Emitter and Collector of Q2 (shouldn't be like this right?)
whereas changing only the 8.2K resistor does not :\
so I managed to bias Q2 Collector by altering the 8.2K resistor with a much lower value,
but the circuit outputs enormous amounts of hiss which I am not able tame
not even with a small cap on Q2 Collector / Base as seen in ROG Sili Face designs
this happens with the gain pot set at half, and even with a fixed 1k resistor in place of the pot.

[Brymus]

You should post the schematic your working from.

[lemrey]

eheh i tought it was pretty famous :x here it is

[lemrey]

I checked everything over and over.. everything is stock except 2N5088 instead of 2N5089 and a 1k pot instead of the suggested 2k.
the only relevant difference is Im using a 1k pot, I think that's what makes it angry..

by adding a 1k series resistor to ground after the first lug of the pot, I can now get some sound out of it,
even if there's much hiss. part of it has been tamed with a cap on Q2 C and B

so probably the issue is the pot, has anyone a better solution i can use in place of the 1k pot I have?

[slacker]

You haven't accidentally used a 470K Ohm resistor instead of 470 Ohm have you? That would mess up the biasing of the second transistor.

[phector2004]

Doubtful... He's getting 1.25V on the collector...

I think most likely, there's a short somewhere between Q2s E and C

You can simulate a 2k pot by putting a 1k resistor in series between the pot and ground, but you'd only have half the sweep (ok if you're just trying to get it to work until you get your hands on the right part!)

Got any pics of your breadboard? Are the rows shorting, by any chance?

[LucifersTrip]

This is another Fuzz Face variant, so unless you can get Q2's C voltage close to 4.5v with Q2's collector resistor close to 8.2K, you will not have a great sound.

As suggested by the others above, there's a chance of a short or mis-wiring...And of course, there's always a possibility that one of the components is a dud....or you accidentally put a wrong component in there (ie 470K instead of 470)

The 1K pot is most likely not the problem.

[Brymus]

If everything is good,no shorts or mis wiring.
Try making the 5K6 a 25K pot or trimmer and see if you cant bias in a better sound.

[phector2004]

I quickly simulated this in Falstad... I think Slacker might be right... Q2's C should be much higher (~5V)    I spoke too soon!

[lemrey]

I used the right resistor (470 ohm).. checked lots of times for shorts or miswiring but I found none.
I breadboarded the whole thing twice in different parts of the breaboard
using a different layout so I really don't know what to think :\ I tried different caps and transistors too.

I simulated the circuit using the 'falstad' applet and the readings are totally different from mine
(reproducing the very same circuit I have on the breadboard) this is curious

by adding a series resistor 1k to ground after the gain pot I could bias the circuit with the 5.6k resistor
switched it with a 10k, 20k, 46k, 56k and the voltage on Q2 collector had yet to reach 4.5v (4.15v) but the sound wasn't satisfying, not a bit

so thanks anyway, im givin up
i'll check out some other fuzz

[LucifersTrip]

so thanks anyway, im givin up
i'll check out some other fuzz

since you're so close, how bout just switching to a stock si Fuzz Face...we know that works & we know the correct voltage readings

[user]

can anyone post soundclips?