Univox - Superfuzz [schematic]

[digi2t]

Very astute observation. Makes perfect sense.

How about my "boost the autowah signal when using a dry input (no fuzz)" theory sound? Wouldn't that make sense in this application?

Would this be a valid method for a Superfuzz build? I mean, putting the gain stage at the end, instead of the beginning does help reduce the hissy swell effect. But, then again, it wouldn't be a true Superfuzz, now would it.

[astrobass]

You might be right about its usefulness when pushing a dry signal into the auto-wah, but I don't know. Depends on how loud the auto-wah is.

An auto-wah is going to have an envelope detection block followed by an active filter stage, so it shouldn't need a boost to bring it up to unity afterwards.

A boost in front of it to make it more sensitive is a common trick though. I'm not familiar with the full schematic of the effect in question so I don't know where the auto-wah section is in relation to the fuzz and boost sections. If the auto-wah is between the two or before them both, then I'd say the boost is just marketing. If it's after both the fuzz and boost and the fuzz can be bypassed but the boost is always on, then it's going to be there to make the auto-wah more sensitive.

[astrobass]

Oh, and whether it's valid or not, that's up to your ears. I'd put a clean boost before and after, use a trimmer to control gain at each stage, tweak them for usability and noise level. You could even use a nice dual op amp like a TL072 to accomplish both.

[frank754]

I just finally built one of these and got it to work. I used all MPS6531 transistors, 1N4001 diodes, 10uf 50v caps, and 50k audio (log) pots. There was one important error in one of the schematics going around for Q4 & Q5. Both transistors need the resistors from base to rail as 100k and base to ground as 22k.
A few things I've noticed that if anyone knows, please clear me up on this. (1) The manufacturer schematic has a .002 cap in parallel to the 47k resistor at the collector of Q1. The one I used didn't - would adding it help anything?
(2) It also shows the resistor going to the base of Q3 as 150k, where mine was 270k - should that matter?
Also, if I switched to germanium diodes, would the musician friend I'm sending this too appreciate the sound a lot more?

[astrobass]

Germanium diodes will reduce the output, increase the compression, and generally sound a bit softer. You might find putting two ge diodes in series yields a similar output, similar compression and still get that softer clipping. But 1N4001 diodes are slower and softer sounding than typical si diodes like 1N914s, so the difference may not be dramatic.

You could use a simple spdt to provide a choice between two sets of diodes.

[frank754]

Thanks, I'm still researching for parts and additional mods for my next build. Basically, I plan to try the germanium 1N60P diodes rather than the 1N4001's for a more classic sound, it seems that's recommended by most over the silicon. They have them at Futurelec, and I'm trying to get very close to the classic build. My build with all MPS6531's has lots of gain, but I'm also planning (this time) to go with all 2N2222's except for Q6, and use a 2N3904 there for its higher gain in the last "recovery" stage before output. I'm going to test the hfe of Q4 & Q5 for the best match so a trimpot won't be needed. I also have one more question: a lot of folks like the "Fuzz Face" sound as well, so what's the best simple mod or switch I can add to make this also have the capability of getting that sound as well? Is a switch to bypass the clipping diodes what I'm looking for, or something else earlier in the circuit? Will have to scour all 19 pages of this thread once more, as so many of you folks have had some great ideas.

[astrobass]

The Fuzz Face is completely unrelated. This pedal won't ever sound like it because the way they work is fundamentally different.

But the Fuzz Face is also a tiny circuit requiring two transistors, and fits on a postage stamp if you're determined. So you could feasibly fit both in the same box in all likelihood.

This does bring about the question of how to combine the two, though. You could go simple, just have a DPDT mode switch, and leave off the volume controls for each pedal, with a volume control AFTER the DPDT FF/SF selector, but INSIDE the circuit controlled by the bypass foot switch. That'd save a pot and make the box less confusing to operate, you'd just have one level, and then you'd have the SF's tone controls, and then you'd have the FF's tone controls. You could landscape orient the box, use a larger enclosure (1590D or BB) and group the controls such that the position of the SF/FF selector points at the set of tone controls that are active.

Though, the FF's controls suck. Just fix the Fuzz control at the maxed out setting, and replace the input cap with an input blend cap.

Or put them in separate boxes. The cost of two 1590Bs isn't more than a couple bucks more than a single 1590BB or 1590D. I'd put them in separate boxes. The FF is a really worthy circuit to experiment on. Socket the transistors and try all kinds of different ones. The D*A*M Meathead is a GREAT derivative if you're looking to use silicon transistors, and has many of the common mods baked in (mild voltage sag, fixed Fuzz, bridging cap).

[frank754]

Yes, I figured that, even though I've seen NPN circuits for the Fuzz Face (the orig. PNP versions have an opposite ground). It would add more pots and switch poles (2P3T for the footswitch or an extra elsewhere?) and be cramped in a small box. I'm planning to use the BB, since I can get it in colors for around $9.00. After looking all through this thread, the two or three simplest and possibly most worthy mods, would be a switch to bypass the clipper diodes completely, then possibly additionally to that a 10k ("Tetxure") pot from the low end of the diodes to ground. And the third mod would be to cut off the "octaving" using an SPST switch cutting of the input to either Q4 or Q5 after to cap and just before the 470 ohm resistor going to either Q4 or Q5 (but just one of them).

[frank754]

Looking at the D*A*M Meathead, it's a small circuit and actually could fit on the same board as the SuperFuzz circuit. At first I was thinking of a switch to choose between the two, but a friend suggested a way of sometimes feeding (combining) one into the other in series. That would require two footswitches, one for each, and then if both were in the on position at the same time the signal would feed from one to another (for example from the SF into the DF) if they were wired that way. Has anyone experienced working with a box that did this, and what suggestions would you have (the order of the two circuits and problems that might come up)?

[astrobass]

No idea if that'll work or do something that you like the sound of. You'd want to build each circuit up separately and then try them in each way to see what sounds better or if they even sound good together at all.

[frank754]

Yes, it will have to be an experiment. I first thought of putting the two in parallel, but some intuition doesn't ring true about that being able to work well at all (correct me if you think otherwise). So probably I'll just run one first (the superfuzz circuit which has a lot more tweaks) and then follow it with the meathead (which to me has been described as a tool to add a varying amount of heavy "dirt" to the waveform). Also, I think 2 footswitches would be too busy of a layout for the user and would likely end up being too closely spaced (for comfort while playing) as well, so now I'm thinking just to add 2 toggle switches so that the user could bypass one, the other, or neither. Bypassing one or the other would allow choosing between the two, and bypassing neither would feed from one into the other before the output jack.

[astrobass]

Okay, so the Boss FZ-2 Hyper Fuzz is basically this pedal plus an extra fuzz mode and an active tone stack. There are other differences but those are the interesting ones. Fuzz II is the extra mode, and it's what Electric Wizard used on Dopethrone.

Looking at the schematic, the Fuzz II mode provides a filter, a boost, and then hits that tone stack. Obviously the tone stack is also important. So how bad would it be to add that as a circuit block?

Turns out, not so bad. I drew up that part of the schematic in Eagle, using a TL071 and TL072 instead of the (now out of production) op amps used by Boss. The op amps don't appear to be overdriven at all, so tonal characteristics between different op amps should play a relatively minor role. The PCB fits into 1.5" x 1.5". So I etched one up, figured it'd be best to start off with a modular approach and then bake it into one big PCB later if it all works well.

I've got it populated, but not connected to anything. Going to do the off-board wiring tonight and if it gets me into the ballpark of what I'm after, I'll post the schematic, layout and etching mask here. I'm going to include a DPDT bypass toggle so that I retain access to the "standard" Superfuzz.

If I fail miserably, I'll also post details of what doesn't seem right about it. But I think it should be pretty straight forward.

[astrobass]

Alright, it's not quite there.

Using the schematic here:
https://www.freestompboxes.org/viewtopic.php?f=11&t=868

I took everything from the parallel 1n and 10k resistor, through to the switch. I think. Since that only uses IC1A and not IC1B, I swapped IC1 for a TL071, and for IC2A/B I used a TL072. I've attached what I've got in Eagle for the schematic.

I found that it drops output dramatically. Thinking I need to verify my schematic, and maybe swap the TL071 for a TL072 and use ICB as a gain recovery stage.

If anything leaps out at anyone, please let me know. Once I solve this, I'll post my PCB layout and mask. For the time being it wouldn't be useful though.

[astrobass]

Wait. Fuck. I misread the labelling on the switch on the original FZ-2 schem, that's Fuzz I mode. Shit.

Still looking it over for errors in the transcription. Shit.

[astrobass]

Okay, so I'm using this schematic right now. There's still a small volume drop when it's engaged, but it does sound nice. I'm going to re-work it to use a dual op amp in place of IC1, so that there's a clean boost at the end. Once I've had a chance to etch a new board and test it I'll share that.

[astrobass]

Can a mod please delete my previous post? I uploaded the wrong image. Need to Preview more often.

THAT ASIDE:
Okay, so I'm using this schematic right now. There's still a small volume drop when it's engaged, but it does sound nice. I'm going to re-work it to use a dual op amp in place of IC1, so that there's a clean boost at the end. Once I've had a chance to etch a new board and test it I'll share that.

[HoboRizla]

Hi guys.
As I said, Ivlark layout works good!
I made a little recording to test my Superfuzz with my home made PP-18 amp.
Love it!

https://youtu.be/WILSs1_TRzY?t=3m1s

Rizla

[Gila_Crisis]

@ Astrobass: I already added once that EQ circuit from the Boss Hyper Fuzz to a superfuzz "pimped" clone (if you search the pots you'll find a schem of it). For more clarity I like to use an OPA2132 or a OPA2134 for its opamp.

[astrobass]

@ Astrobass: I already added once that EQ circuit from the Boss Hyper Fuzz to a superfuzz "pimped" clone (if you search the pots you'll find a schem of it). For more clarity I like to use an OPA2132 or a OPA2134 for its opamp.

Neat!

I actually went a little further with it and posted a thread in the DIY forum as it was getting off topic here. I made the thing into its own effect and added a second dual op amp, using one side as input buffer and the other as a gain stage on the output. So it's a standalone tone stack/boost.

The TL072 at 18V does a great job, and it actually does nice things with a lot of fuzz pedals and older designs like the Electra, which lack really robust tone controls. Tames the highs and does a good job of shaping the high and low end response. The boost capability is also really nice to have, you can put it in front of a fuzz to slam it harder, or at the end of the chain to provide a low impedance, high volume signal through a long patch to the amp.

I'm super pleased with how it turned out, and as soon as my shipment of 3PDTs arrives, this thing is making a permanent entry onto my pedal board.

[fauxjazz]

Built a Super Fuzz on Vero. Circuit works fine and was quiet quiet. Have since rehoused it in a small enclosure but experiencing some hum issues. Any ideas what could be the cause of this? At present the circuit is sat directly beneath the jacks (almost touching) but is wrapped in insulation tape. Don't think they making contact with anything but could the close proximity to the transistors be the cause? Any advice appreciated.