Schumann Two Face fuzz.

[digi2t]

I decided to start a new thread. The other thread I started, to which Gus made some very interesting contributions, took a different direction on my breadboard, and I would like to keep that separate.

Well, thanks to jerms over at the DAM forum, I finally got to trace the Two Face. I'll tell you right now.... not for the faint of heart. The amount of el cheapo wire that's stuffed into the enclosure is hallucinatory. Take a look.....



I also had a request for a close up of the knobs, so here are some more shots, including the fuzz, and clean board. The 12vac to +/-12vdc board is identical to the PLL, or Lion.















And of course, my trace,





Going to breadboard this in the coming weeks to validate the trace. I've been playing with this over the past few days, and it's a little reminiscent of the Skyripper, but more menacing. It's noisy, buzzy, with lots of Velcro stuff going on. Has settings for oscillation induced screaming, and much of it is interactive with the guitar's volume. Just a plain weird-ass box.

I love it.  

I'll will try (I mean try) to put together a video of this unit in action. I'm not really happy with the videos out there now, since they don't show the guitar volume interactivity, which is important. It just so retarded though, I don't know where I'll start.  

EDIT: I've added the power pin numbers to the LF351 in the schematic. I forgot before, sorry.

[Keppy]

Sweet! I think there's an error on the schem, though, as the clean pot is completely bypassed. Looks interesting!

[digi2t]

Sweet! I think there's an error on the schem, though, as the clean pot is completely bypassed. Looks interesting!

Don't think so. Probably just not clear the way I've drawn it. The instrument input is split between the two circuits, and the clean out (when switched on) is injected to pin 4 of the bypass switch.

Check that, and tell me if I'm wrong.

[soggybag]

Schuman must be a very interesting character. I can't decide if the construction is purposely crude, or he has some motor, or visual issues, or he's decided that neatness and organization are not important to him. I love the outside of the box. The graphics and knobs are unique.

Choosing the run from 12vac is a interesting.

Looks like this is two fuzz faces driven from an op-amp buffer. One FF is PNP, and the NPN. Does it have three outs? I only see two. I'm not getting the usefulness of having a -fuzz, and +fuzz coming out of two jacks. I would think to mix the two.

[italianguy63]

purposely crude, or he has some motor, or visual issues

Ha! 

After seeing so much of Pickdropper's work.  This thread has me feeling a lot better about my own work.

MC

[soggybag]

I'm trying to understand if somehow Schumann finds it easier to work like this, prefers to work like for a reason, or works like this due to circumstance.

There seems to be the wider community of stompbox people. Then there are the outliers. I would put Schumann in the group with Bocorelli, and Wyllie.

[Keppy]

Sweet! I think there's an error on the schem, though, as the clean pot is completely bypassed. Looks interesting!

Don't think so. Probably just not clear the way I've drawn it. The instrument input is split between the two circuits, and the clean out (when switched on) is injected to pin 4 of the bypass switch.

Check that, and tell me if I'm wrong.

The pot labeled "CLEAN" has two lugs in use, and there is a solid line connecting them.

[digi2t]

Freakin' hell!!! Now I see it.

The 101 cap is in the wrong place. It should be where the solid line is.

Thanks guys. I'll update it soon.

[~arph]

I wonder how long it takes this guy to get the units to actually work when he thinks everything is soldered up. It looks like an accident waiting to happen. Nightmare to debug as well..

[Govmnt_Lacky]

I wonder how long it takes this guy to get the units to actually work when he thinks everything is soldered up. It looks like an accident waiting to happen. Nightmare to debug as well..

I wonder how many of these he actually SELLS. I really do not know much about Schumann products except for what Dino has dabbled with. I mean... is this guy moving a lot of pedals? Is it primarily a cult-ish following? I just dont see how he could be selling a lot with that workmanship 

[~arph]

Yeah, it just amazes me that someone that is pretty decent at circuit design and had an eye for aestethics on the outside of the box makes such a terrible mess of the insides. He must be getting a lot of repairs too..

[digi2t]

Here's the updated schematic, with the cap corrected. Thanks guys! 

[Keppy]

Awesome! Thanks again, Dino!

[soggybag]

I still don't get the purpose of having two inverted fuzz outs each at their own jack. You'd have to have a stereo setup to get anything out it. I would think there would be a way to mix them.

[~arph]

There is, you dan choose to split/link them. The mixing is done with the level controls

[soggybag]

Thanks, that makes more sense. Looking at the schematic had the idea that each fuzz channel went to it's own jack.

I just read about it on the Schumann site. Sounds like each Fuzz Face only supplies the positive or the negative portion of the wave, which is very interesting. Sort of a push/pull Fuzz Face pair.

[~arph]

I don't think it's acting on the halves of the wave. By the looks of it one side is a negative ground fuzz and the other a positive ground fuzz. There should be some pretty intense settings when combined ( some 20V peak-to-peak )

[Keppy]

I just read about it on the Schumann site. Sounds like each Fuzz Face only supplies the positive or the negative portion of the wave, which is very interesting. Sort of a push/pull Fuzz Face pair.

I don't think it's acting on the halves of the wave. By the looks of it one side is a negative ground fuzz and the other a positive ground fuzz. There should be some pretty intense settings when combined ( some 20V peak-to-peak )

Check out the sensitivity pots. With the wipers to the left, the base of the first transistor is biased to ground, meaning it is off until it the base is driven positive (NPN) or negative (PNP). Moving the wipers to the right allows for some voltage feedback through the 100k resistors like in the Fuzz Face, but since that feedback is divided by the 100k resistor and the 15k sensitivity pot, it will never be biased as far on as a Fuzz Face. It looks to me like they will always have a push/pull arrangement, with the option of a coring/gating effect with the sensitivity pots turned down.

The opamp boosters, reduced feedback, and lack of emitter bypass caps also would seem to guarantee that it sounds nothing like a Fuzz Face, even though it really looks like one. Er, two.

Who's gonna be the first to scope it?

[digi2t]

Well, I have the fuzz section on the breadboard. It actually sounds "better" that the unit jerms lent me. I suppose the transistors might have something to do with that. I'm going to have to update my schematic again, some of my pot lugs are backwards. I also left out a resistor, and cap on the clean circuit.

Here's a video on the fuzz section. This fuzz is a nightmare to demo, because of the sheer amount of textures available. Every little nudge on just about any pot, including the guitar, changes the tone of this beast. I apologize in advance for the excessive rambling, but this thing is one part Skyripper, one part Uglyface, and one part Christine. In the wrong hands... humanity is lost.

Trying to get the clean section working now. To be continued......

[UKToecutter]

that is a noisy, glitchy, fuzzy horrible mess.
Which means I like it!!!!!