Univox - Superfuzz  [schematic]

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

Re: Univox - Superfuzz

Postby Solidhex » 05 Aug 2009, 01:22

Ah

Ok. In that case you would take a look at your dpdt switch. Each side is its own spdt switch. Connect one side as you would normally with the pole connected to lug 3 of the balance pot and its respective "throw" lugs to the tone outputs of the board. The other spdt side of the dpdt is used for switching the leds. You connect the pole to ground, the two "throw" lugs are connected to the anodes of two separate leds. Connect the cathodes of each led to current limiting resistors then connect those to your positive voltage supply.

--Brad
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Re: Univox - Superfuzz

Postby metulmykul » 05 Aug 2009, 08:44

Another question answered that i hadn't got around to asking...

thanks Brad.
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Re: Univox - Superfuzz

Postby Reggiechacha » 05 Aug 2009, 13:25

Solidhex wrote:Ah

Ok. In that case you would take a look at your dpdt switch. Each side is its own spdt switch. Connect one side as you would normally with the pole connected to lug 3 of the balance pot and its respective "throw" lugs to the tone outputs of the board. The other spdt side of the dpdt is used for switching the leds. You connect the pole to ground, the two "throw" lugs are connected to the anodes of two separate leds. Connect the cathodes of each led to current limiting resistors then connect those to your positive voltage supply.

--Brad


Nice one. Thanks very much for your help Brad!
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Re: Univox - Superfuzz

Postby kupervaser » 15 Aug 2009, 11:05

I am still wondering what this intern trimpot really does?

This comes from the byoc manual for the Leeds Fuzz:

There are rumors circulating the internet that this trimpot controls the amount of octave
effect that mixes in with the fuzz. This is somewhat true, but keep in mind that if you used
this trimpot as such, it can cause an unusual noise gate effect at the end of each note on
certain settings. Ideally you want to set this trimpot so that it produces the most noise.
This may seem counterintuitive, but this will produce the longest sustain and the best
sounding fuzz. This will almost always be dead center on the trimpot's rotation (noon) or
just slightly off center. But ultimately, it's up to you....just trust your ears.
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Re: Univox - Superfuzz

Postby Kregg » 15 Aug 2009, 14:39

It looks like it biases the two 22K resistors between the trim and the balance control.
Now, my main perception with most every fuzz I've played my Strat through is, when I use the neck pickup I get an octave effect which is quite often barely present in the bridge position.
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Re: Univox - Superfuzz

Postby R.G. » 16 Aug 2009, 21:20

kupervaser wrote:I am still wondering what this intern trimpot really does?

This comes from the byoc manual for the Leeds Fuzz:

There are rumors circulating the internet that this trimpot controls the amount of octave
effect that mixes in with the fuzz. This is somewhat true, but keep in mind that if you used
this trimpot as such, it can cause an unusual noise gate effect at the end of each note on
certain settings. Ideally you want to set this trimpot so that it produces the most noise.
This may seem counterintuitive, but this will produce the longest sustain and the best
sounding fuzz. This will almost always be dead center on the trimpot's rotation (noon) or
just slightly off center. But ultimately, it's up to you....just trust your ears.

It ain't a rumor. I said it first I believe, and others may have picked it up. This particular
discussion is what amounts to ancient history.

It's a balance control to vary the bias on one versus the other transistor in that face-to-
face pair. It's easy to see what's happening on an oscilloscope. When they are balanced,
you can see that the peaks from both positive and negative half-cycles of the signal are
equal sized. This produces the most intense octave effect.

It may also produce the most noise. That would happen when both transistors are active
at the same time for tiny, tiny signals; that would also account for the "least gated"
note, maybe. I never noticed the noise as particularly varying, but I guess it could happen
if you use noisy resistors and/or transistors.

The point of having that control is to get reliable octave action from mismatched
transistors. That circuit works best with identical transistors. But you can get most of the
effect of identical transistors by using an offset control - which this is - to balance the
low one up and the high one down. There are about a half-dozen variations of this same
circuit in various commercial pedals. Some use the balance control, others just take
their lumps on whether the transistors match or not.

Again ancient history, perhaps a decade ago, I think it was Mark Hammer who suggested
making a front panel control out of the balance control for tuning in the sound on the
fly, since he liked some of the unbalanced settings.

It's worth noting that the "octaving" is done by what amounts to using these two transistors
as a full wave rectifier. While this causes some distortion all by itself, the octave section
is followed by a back-to-back diode clipper, which clips off the top and bottom of the
full-wave-rectified signal. Fuzz and octave generation are done in separate parts of the circuit.

I'm always taken a little aback when I have to realize that each new generation of net
users discovers the internet freshly, not having been part of the history.
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Re: Univox - Superfuzz

Postby kupervaser » 17 Aug 2009, 08:09

Thanx R.G.

Yes, the newbies have to learn a lot yet.

What can you tell me about the delayed blast of hiss about a split second after you hit a note or chord Brad was talking about in the earlier posts. I am experience them too.

Thanx in advance,
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Re: Univox - Superfuzz

Postby scorpion victim » 17 Aug 2009, 15:15

as far as tweaking superfuzz.. On my clone i opted not to externalize the trimpot and im usually the guy that wants to tweak everything. I dunno. I like it in the my one position best. There is something to BYOC's noisy spot statement, but I just dont like it there best. If you mod, the scoop mod has a much more dramatic effect. best bang for your buck. I like the sag/starve effect but i just built one externally boxed control for that instead of adding it to every pedal I own, too lazy I guess.
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Re: Univox - Superfuzz

Postby Enrulado » 18 Aug 2009, 01:02

R.G. wrote:...It may also produce the most noise. That would happen when both transistors are active
at the same time for tiny, tiny signals; that would also account for the "least gated"
note, maybe. I never noticed the noise as particularly varying, but I guess it could happen
if you use noisy resistors and/or transistors.


I think the trimpot was placed there only because of the wide transistor variations ...

.. key is setting noise at minimum values whitout having a noticiable gate ...
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Re: Univox - Superfuzz

Postby Dan N » 18 Aug 2009, 02:35

scorpion victim wrote: On my clone i opted not to externalize the trimpot and im usually the guy that wants to tweak everything. I dunno. I like it in the my one position best..


Same here. Set, forget, and be on your way.
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Re: Univox - Superfuzz

Postby kupervaser » 18 Aug 2009, 08:24

Enrulado wrote:
R.G. wrote:...It may also produce the most noise. That would happen when both transistors are active
at the same time for tiny, tiny signals; that would also account for the "least gated"
note, maybe. I never noticed the noise as particularly varying, but I guess it could happen
if you use noisy resistors and/or transistors.


I think the trimpot was placed there only because of the wide transistor variations ...

.. key is setting noise at minimum values whitout having a noticiable gate ...


But this is totally controversial with the BYOC manual of the super fuzz.
They say you must set it at maximum noise.
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Re: Univox - Superfuzz

Postby R.G. » 18 Aug 2009, 22:36

kupervaser wrote:But this is totally controversial with the BYOC manual of the super fuzz.
They say you must set it at maximum noise.

So they do, apparently.

I'm going to tell you something now:
The moon is made of Stilton cheese, through and through.

I have said it on the internet. Therefore, it must be true, right?
:lol:
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Re: Univox - Superfuzz

Postby Dirk_Hendrik » 19 Aug 2009, 08:37

R.G. wrote:
kupervaser wrote:But this is totally controversial with the BYOC manual of the super fuzz.
They say you must set it at maximum noise.

So they do, apparently.

I'm going to tell you something now:
The moon is made of Stilton cheese, through and through.

I have said it on the internet. Therefore, it must be true, right?
:lol:



But it is!
That's why Armstron et al filled brought only crackers when going there.
Sorry. Plain out of planes.

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Re: Univox - Superfuzz

Postby Kregg » 19 Aug 2009, 14:33

Dirk_Hendrik wrote:
R.G. wrote:
kupervaser wrote:But this is totally controversial with the BYOC manual of the super fuzz.
They say you must set it at maximum noise.

So they do, apparently.

I'm going to tell you something now:
The moon is made of Stilton cheese, through and through.

I have said it on the internet. Therefore, it must be true, right?
:lol:



But it is!
That's why Armstron et al filled brought only crackers when going there.


Now that would have been funny had you written, "Why else would we have sent a tin can full of 'crackers' to the moon?"
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Re: Univox - Superfuzz

Postby kupervaser » 21 Aug 2009, 08:56

Ok, cool, so I finished it. I ended up with 2n2222 transistors. I also tried the 2sc828 but they reduced the gain of the pedal. I find it strange because i measured the transistors and the 2sc828 had a higher HFE than 2n2222.
And i doublechecked the pin layout.
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Re: Univox - Superfuzz

Postby R.G. » 21 Aug 2009, 13:39

After you've done this for a while, you will realize that the number printed on a transistor package is only a very rough guide to what the transistor performance will be.

You will also come to appreciate that when a guitarist says "gain" they really mean "distortion".
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Re: Univox - Superfuzz

Postby Kregg » 21 Aug 2009, 18:11

R.G. wrote:You will also come to appreciate that when a guitarist says "gain" they really mean "distortion".


Stoopid Monkee's* ... Image

* Intentional.
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Re: Univox - Superfuzz

Postby leftwing73 » 24 Aug 2009, 20:25

Anybody have any insight on increasing the output of a Superfuzz? Volume, I mean, not necessarily distortion/fuzz.
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Re: Univox - Superfuzz

Postby R.G. » 25 Aug 2009, 14:45

Put an amplifier after it.

This can be single transistor, JFET, opamp, two-transistor compound, a booster pedal, anything. What you're trying to do it just increase the output voltage. Replicating the last stage would work.

You have to do something after the clipping section, because the clipping section forces the output to a specific level.

Oh. Sorry. You can sub in silicon diodes for the clippers to get it a bit bigger. That may change the clipping sound a bit.
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Re: Univox - Superfuzz

Postby Dan N » 26 Aug 2009, 01:36

leftwing73 wrote:Anybody have any insight on increasing the output of a Superfuzz? Volume, I mean, not necessarily distortion/fuzz.


Sir HC once posted that putting a decoupling cap across the last bias resistor increased the volume. I forget what value he used, but maybe something between 10 and 20 uf parallel with that 1K resistor on E of the last transistor. Worth a try.
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