Univox SuperFuzz Biasing

[Ofek Deitch]

Hi,

I built a SuperFuzz with this layout (below), and was wondering whether I need to bias this circuit if I'm using different transistors?
I'm using 2N5088 and 2N3904, because this is what I had in the moment, and I must say, that I got disappointed when I fired this thing up. I watched a few demos of this on YouTube (Gearmanndude was obviously the best one) and it seems to me that the pedals they used sounded much better.

I'm also using 1N34A Diodes.

This is the layout:



These are the voltages I get: (9v)

Q1:
C. 5.3v
B. 0.67v
E. 0.12v

Q2:
C. 9v
B. 5.3v
E. 4.74v

Q3:
C. 6.0v
B. 3.28v
E. 2.98v

Q4:
C. 3.39v
B. 1.57v
E. 1.0v

Q5:
C. 3.38v
B. 1.58v
E. 10v

Q6:
C. 3.51v
B. 1.13v
E. 0.54v

Thanks!
- Ofek -

[Buzz]

Hi. No expert here, but I think you would be guaranteed to get a different sounding result with the 2N5088.

The original transistor, 2SC828, offers a hFE of 130 - 250, while the 2N5088 offers 300 - 900. Different ballparks.

The 2N3904 gives 40 -300, maybe a better choice, but unfortunately I can't help you bias them.

Maybe replace them with sockets and do it by ear?

Futurelec still sell the 2SC828s pretty cheap if you can handle the wait.

1N34a diodes shouldn't make a major difference as far as I know.

[digi2t]

Recently built one on vero too, except using transistor arrays. http://www.diystompboxes.com/smfforum/index.php?topic=102477.0. Everything is relevant though.

I replaced the 15K on B of the final stage with a 25K trimmer, used a 10K trimmer for octave balancing, and also added a trimmer for the clipping diodes. Mark Hammer's Scoop control is AMAZING!

[LucifersTrip]

except for Q6C, you're pretty close to solidhex's (Fu Manchu)

Q1  6.01    .66      .117
Q2  8.88   6.01     5.41
Q3  6.23   3.27     2.72
Q4  3.1     1.7      1.11
Q5  3.1     1.67     1.11
Q6  5.75   .98       .361

Though, I think you should go with the octave balancing digi2t  mentioned. that can make a big difference.

[digi2t]

Yeah, the octave balancing trimmer makes a really big difference.

As far as choice of transistors is concerned, the 2SC828R`s are good. Although the original units used the Q gain rating, the slightly higher R`s are widely available, and not that expensive. Sifting through them with my Peak meter, I easily found R transistors with gains in the Q range. I matched up a set for Jimi a while back, and he really loved them. They made a heck of a difference in his unit, he shot videos of his Superfuzz, before the 828`s, and after.

2N2222 are great too. In my transistor array version, the TPQ2222 is basically four 2N2222`s on one chip. I tried an MPQ3904 (four 2N3904 array), but the 2222`s won the day. They had a rounder sound, with a slight edge on the sustain. The sustain is especially nice, I get a faint shower of arpeggiating ghost notes ring through on mine as the main note dies away. Supercool.

[electrosonic]

Metal can 2n2222 available here $0.25 each

http://www.goldmine-elec-products.com/prodinfo.asp?number=G19566

Andrew.

[LucifersTrip]

remember, only 2 of the 6 transistors are actually 2SC828

http://www.univox.org/pics/schematics/superfuzz.gif

[digi2t]

Yeah. I was looking at the Shin Ei version.