Univox - Superfuzz  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...

Re: Univox - Superfuzz

Postby Jan1966 » 20 Jul 2019, 17:31

Dibya wrote:2sc828 are rare gens , can I use something else?

Yes. Try experimenting with what you have got.
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Re: Univox - Superfuzz

Postby Nocentelli » 20 Jul 2019, 22:24

Pretty sure any Si BJT in a similar hFe range (200-300ish) would do, 2N3904 are probably the most common/easily available.
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Re: Univox - Superfuzz

Postby digi2t » 21 Jul 2019, 00:36

2N3904 tend to be too hot. 2N2222 works better. Gains in the 150 to 180 range, with Q4 and Q5 matched. If you can find 2N2219's, even better.
No matter how many times I cut it, it`s STILL too short!
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Re: Univox - Superfuzz

Postby jalmonsalmon » 21 Jul 2019, 02:42

digi2t wrote:2N3904 tend to be too hot. 2N2222 works better. Gains in the 150 to 180 range, with Q4 and Q5 matched. If you can find 2N2219's, even better.

matched pair for Q4 and Q5 cause more of the upper octave thing?
I made one of these years ago, seems to work good but I would like to revisit this pedal and get it the best it can be
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Re: Univox - Superfuzz

Postby aionios » 22 Jul 2019, 12:09

jalmonsalmon wrote:
digi2t wrote:2N3904 tend to be too hot. 2N2222 works better. Gains in the 150 to 180 range, with Q4 and Q5 matched. If you can find 2N2219's, even better.

matched pair for Q4 and Q5 cause more of the upper octave thing?
I made one of these years ago, seems to work good but I would like to revisit this pedal and get it the best it can be


Correct. The octave trimmer (found on most Superfuzz layouts) can compensate somewhat for this, but you do want them to be as close as possible.

digi2t wrote:2N3904 tend to be too hot. 2N2222 works better. Gains in the 150 to 180 range, with Q4 and Q5 matched. If you can find 2N2219's, even better.


An original Superfuzz that I measured had the following transistor gains:
Q1: 124 hFE
Q2: 95 hFE
Q3: 143 hFE
Q4: 62 hFE
Q5: 50 hFE
Q6: 52 hFE

I found my clone sounded dead-on to the original with 2N3904 in Q1-3 (measuring the to make sure they are in the sub-180 range) and 2N3903 for Q4-6, with Q4 and 5 being matched. But any of the types Dino mentioned will work as well. The 3903 was readily available (drying up now though) and much cheaper than the 2N2222 when I did it last year.

The 3046 transistor array was hit or miss. I tested a few that were in the low 40's for gain - that's too low for the Superfuzz and it doesn't sound right. If you know the transistors are in the 60-100 range then it'll work, but it's not necessarily a drop-in solution.
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Re: Univox - Superfuzz

Postby Manfred » 22 Jul 2019, 16:05

An original Superfuzz that I measured had the following transistor gains:

What is the measuring collector current of HFE meter?
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Re: Univox - Superfuzz

Postby digitalzombie » 22 Jul 2019, 17:10

So are we still going off the schematic from page 1 of this thread, or is there an updated schematic in one of the many broken image links?
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Re: Univox - Superfuzz

Postby digi2t » 25 Jul 2019, 12:35

aionios wrote:The 3046 transistor array was hit or miss. I tested a few that were in the low 40's for gain - that's too low for the Superfuzz and it doesn't sound right. If you know the transistors are in the 60-100 range then it'll work, but it's not necessarily a drop-in solution.


The best array results that I've had are with the TPQ2222. They are also sold under the MPQ2222 moniker as well. These are quad NPN array IC's (four 2N2222's), of which I use them for Q1, 2, 3, and 6. Another quad IC's that works well is the RFT B360Dc, which I see come up on EBay quite often. The "c" suffix is the gain range, which according to the datasheet puts them in the 56 - 140 range. A tad lower than the TPQ/MPQ series, but they can be had quite cheap in some cases (especially in Europe), which means you can buy a bunch and audition them. Now... do the array IC's provide any tonal advantage over sorting out four individual transistors? Not really I suppose, but I guess I'm just really lazy, so if I can avoid the work of sorting transistors, I'll take that out any day.

As for "dualling" the Q4/5 section, using supermatch exotics such as the 2SC1583 or LM394 aren't the ticket. The gains are way too high, and the octave just doesn't bloom correctly. They tend to make chord work rather muddy and overly compressed as well. 2N2913/15/17 work very well indeed. The 2N2913 has been my "go to" for this section for a while now. Gain range for this series is 60 - 250, with the average for any I've ever bought sitting right in the wheelhouse at 150. Using the balancing trimmer is highly recommended, as you may actually wish to "detune" this section a bit. With an overly strong octave, it can be detrimental to chord work giving them too much of a ringmod'ish feel.

Three final mods that I find to be most beneficial;
1) Lifting the clipping diode pair, just a bit, from ground. I use a 10K trimmer, but I find lifting between 1K and 2K gives the fuzz a bit more meat and body, without sacrificing any of the saw edge.
2) Tone pot, rather than tone switch. This is a taste object. If you like to switch between two distinct tones, than stay with the switch. If (like myself) you prefer to "set and forget", then a tone pot is better. It allows to tune into all the in between tones that the switch system can't give you.
3) Replace the 15K Q6 base to ground resistor with a 25K trimmer. Adjusting the Q6 collector voltage via the trimmer can help finalize the tonal and output quality of the Superfuzz. With Q6 in the 125 to 175 gain range, the trimmer should give you a usable collector voltage adjustment range of 2.7V to 7.2V. I find that 5.75V is the best balance between great tone and all out roar. YMMV.

Here's my version (just right click and "open image in new tab" to get the full image);

Image
No matter how many times I cut it, it`s STILL too short!

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