Univox - Superfuzz  [schematic]

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

Re: Univox - Superfuzz

Postby stonew » 26 Aug 2009, 16:20

good!!! :applause: :applause: :applause:
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Re: Univox - Superfuzz

Postby leftwing73 » 28 Aug 2009, 17:58

Thanks guys. I tried that decoupling cap and while it did massively increase output, it also caused a piercing whine. Would playing with the biasing resistor to feed more voltage to the transistor in the last stage help? I'd like to try to keep the circuit as close to original specs as possible. I a/B's my Superfuzz with an original and while the tone was dead-on accurate, the output of mine was noticeably lower. I'm using metal film resistors, metallized poly film caps, don't know if those contribute to lower output?
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Re: Univox - Superfuzz

Postby Bside2234 » 28 Aug 2009, 18:31

I did the decoupling cap also and didn't like it. It was obnoxious. Mine has plenty of output though. I get unity volume around 12-1 o'clock. Maybe go through your components to make sure all your resistors and caps are the right value.
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Re: Univox - Superfuzz

Postby R.G. » 29 Aug 2009, 16:47

leftwing73 wrote:Thanks guys. I tried that decoupling cap and while it did massively increase output, it also caused a piercing whine. Would playing with the biasing resistor to feed more voltage to the transistor in the last stage help? I'd like to try to keep the circuit as close to original specs as possible. I a/B's my Superfuzz with an original and while the tone was dead-on accurate, the output of mine was noticeably lower. I'm using metal film resistors, metallized poly film caps, don't know if those contribute to lower output?

Put a resistor in series with that decoupling cap. The piercing whine is the unit oscillating due to feedback through the wiring and/or power supply.

It is entirely possible you have transistor(s) inserted in reverse. Transistors have very low reverse gain. Did you look up the pinout for the transistors you used and ensure the right pin in the right hole?
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Re: Univox - Superfuzz

Postby danargyle » 31 Aug 2009, 05:26

hey guys, sorry for the noobish question. i wanted to know how do i wire a dual colour LED for the dpdt tone switch?
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Re: Univox - Superfuzz

Postby Solidhex » 31 Aug 2009, 08:34

You want to get a bi color led that has a common anode preferably. Since all you need to change the tone switch on a Superfuzz is a spdt you can use a dpdt switch to change the tone and activate a corresponding bi color led color. Let's assume you already have your tone switch wired up. The pole wired to the 3rd lug of your "balance" pot, the throws wired to the two different tone outputs from the board. You would then wire the other pole to ground. The other two throws would be wired to the cathodes of your led. The common anode would be wired to a current limiting resistor then to your positive voltage supply.
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Re: Univox - Superfuzz

Postby danargyle » 31 Aug 2009, 14:47

Solidhex wrote:You want to get a bi color led that has a common anode preferably. Since all you need to change the tone switch on a Superfuzz is a spdt you can use a dpdt switch to change the tone and activate a corresponding bi color led color. Let's assume you already have your tone switch wired up. The pole wired to the 3rd lug of your "balance" pot, the throws wired to the two different tone outputs from the board. You would then wire the other pole to ground. The other two throws would be wired to the cathodes of your led. The common anode would be wired to a current limiting resistor then to your positive voltage supply.


Thanks! great explanation, i got it now.
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Re: Univox - Superfuzz

Postby leftwing73 » 31 Aug 2009, 15:02

R.G. wrote:
leftwing73 wrote:Thanks guys. I tried that decoupling cap and while it did massively increase output, it also caused a piercing whine. Would playing with the biasing resistor to feed more voltage to the transistor in the last stage help? I'd like to try to keep the circuit as close to original specs as possible. I a/B's my Superfuzz with an original and while the tone was dead-on accurate, the output of mine was noticeably lower. I'm using metal film resistors, metallized poly film caps, don't know if those contribute to lower output?

Put a resistor in series with that decoupling cap. The piercing whine is the unit oscillating due to feedback through the wiring and/or power supply.

It is entirely possible you have transistor(s) inserted in reverse. Transistors have very low reverse gain. Did you look up the pinout for the transistors you used and ensure the right pin in the right hole?


Thanks RG, I'll give that a shot. I guess I'll start small and just increase the resistor value until the whine stops.

The transistors are oriented correctly. My pedal reaches unity gain, so it's not a drastic difference between mine and the original, but I think it does need more output.
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Re: Univox - Superfuzz

Postby R.G. » 02 Sep 2009, 23:54

You could also try putting a 0.1uF ceramic cap and a 100uF electrolytic across the +9V on the board. That might help; but the position you place the 0.1uF will have some sensitivity for how much good it does.
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Re: Univox - Superfuzz

Postby iamadamb » 31 Oct 2009, 05:15

i built one of these off of mikes veroboard layout and i have a problem...

it sounds great but i have this loud popping when its switches on and off.

i used the beavis audio true bypass/w led but i also put a 1M resistor from before the input cap to the ground.

i thought doing that would stop potential pops...

should i remove the resistor all together? (maybe it screws up this circuit?)

or should i put a lower or higher resistor from input to ground? (500k or 2.2m?)

any help would be a lifesaver

thanks in advance
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Re: Univox - Superfuzz

Postby yeeshkul » 01 Nov 2009, 09:50

I always use 2M2 and I believe the higher values should work fine too. The value is that massive because you do not want to let it suck your input signal however the xxM resistor is still capable to shunt the unwanted DC voltage carried to to input by a leaky input cap. The thing is you have to put it between the switch and the input cap - not right on the input socket, that wouldn't solve the problem. First of all remove the LED if you use one and check it for popping. Lowering the pulldown value will cause a bigger loss of the input signal, 1M is the bottom of what you shall use.
I've built a few superfuzz clones so far and haven't had a trouble with any popping so far. I believe you will find a bug/cold joint or whatever to get rid of it easily.
By the way my last built sonded horrible - i was checking the PCB side with magnifying glass the whole evening, changed one tranny, I was doing desperate simulations in LTSpice and stuff and in the end ... i found out i forgot to solder one resistor leg. Those things happen.
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Re: Univox - Superfuzz

Postby yeeshkul » 01 Nov 2009, 10:02

R.G. wrote:You could also try putting a 0.1uF ceramic cap and a 100uF electrolytic across the +9V on the board. That might help; but the position you place the 0.1uF will have some sensitivity for how much good it does.

Do you mean the shall be as close as possible?
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Re: Univox - Superfuzz

Postby devastator » 30 Nov 2009, 18:07

Hi,

I made a zvex octane 2 , the same schematic of the Univox superfuzz execpt the fact he used 2N3904 , sound cool but really messy with chords (you can hear the octave up in the sound) .

There's a way to erease the octave up with a pot or a footswitch ? First time I plugged it there wasn't octave up , just a full fuzz sound.
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Re: Univox - Superfuzz

Postby jimmyjames » 01 Dec 2009, 16:32

Hi

I'm building Mike's stripboard layout for my first attempt at a build. I've got most of what I need but am not sure about the switching. Do I need an SPDT for the On/Off footswitch and a DPDT for the Tone footswitch and bicolor LED or do I need a DPDT and a 3PDT respectively?

I know there are some references to this in the above posts but I'm still a little confused. Any help for a complete ignoramus would be very much appreciated :)
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Re: Univox - Superfuzz

Postby Dan N » 01 Dec 2009, 22:06

3PDT for on-off/power for the led, and a DTDT for the tone/bi-color led.
Dick joke has expired.
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Re: Univox - Superfuzz

Postby yeeshkul » 01 Dec 2009, 22:16

devastator wrote:Hi,

I made a zvex octane 2 , the same schematic of the Univox superfuzz execpt the fact he used 2N3904 , sound cool but really messy with chords (you can hear the octave up in the sound) .

There's a way to erease the octave up with a pot or a footswitch ? First time I plugged it there wasn't octave up , just a full fuzz sound.


Switch to the bridge pickup, turn the tone control all the way down, play above the 12th fret and hold the pick short. This is the way to get octave from Superfuzz.
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Re: Univox - Superfuzz

Postby hairyandy » 02 Dec 2009, 02:18

yeeshkul wrote:
devastator wrote:Hi,

I made a zvex octane 2 , the same schematic of the Univox superfuzz execpt the fact he used 2N3904 , sound cool but really messy with chords (you can hear the octave up in the sound) .

There's a way to erease the octave up with a pot or a footswitch ? First time I plugged it there wasn't octave up , just a full fuzz sound.


Switch to the bridge pickup, turn the tone control all the way down, play above the 12th fret and hold the pick short. This is the way to get octave from Superfuzz.


You mean the neck pickup. The neck pickup with the tone rolled off produces the roundest tone and in turn is easiest for any octave fuzz to create the octave.

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Re: Univox - Superfuzz

Postby jimmyjames » 02 Dec 2009, 12:48

Dan N wrote:3PDT for on-off/power for the led, and a DTDT for the tone/bi-color led.


Thanks for the advice Dan. Much appreciated.
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Re: Univox - Superfuzz

Postby yeeshkul » 05 Dec 2009, 10:02

yeah, i mean neck pickup. :slap:
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Re: Univox - Superfuzz

Postby jimmyjames » 18 Dec 2009, 16:01

Hey guys. Another rookie question: how do I tell which direction to put the 10uF polarised electrolytic capacitors into Mike's veroboard layout?

Any advice would be much appreciated.

Thanks.
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