The fuzz tone I've been looking for - Triclops Fuzz

[lars]

Ever since I read that the Smashing Pumpkin's Siamese Dream album owed a lot of it's fuzz tones to an MSA pedal steel guitar fuzz unit, I've been trying to find out what that fuzz circuit was. I finally settled on the fact that it must be a version of the Jordan Bosstone, specifically the Sho-Sound Nashville version. But I know the EHX Microsynth was also used heavily on the album as well, most likely in combination with the MSA unit to get those really heavy, gated fuzz riffs (sorry Big Muff).

One of the fuzz pedals I breadboarded a while back was an ESR Graphic Fuzz. I didn't have a 741 available for the circuit, so I used a curious IC from a Cadillac 8-track player labeled "DM90", made by AC Delco. Since it was an 8-pin metal can IC, I figured it could be an old 741, so I tried it out.
It worked!
Kind of. The only way to get it to really work well was to put a 10k pot between pins 1 and 5 with the wiper to ground. I thought I was adjusting the offset null, but I was getting this heavily gated fuzz sound, nothing like a 741. It made it sound more like the fuzz tones from a Microsynth. Well, the Microsynth is full of OTAs, so I figured that must account for that unique gated fuzz sound. I ordered a CA3080 and put it in the ESR Graphic Fuzz circuit. This time I set up a 10k pot just on pin 5 to V+ for the gate bias. It worked almost exactly like that old "DM90" IC from the 8-track, so that must have been an old metal can OTA (unfortunately that original metal can IC from the 8-track is dead. If you ever see one for sale anywhere, BUY IT! You can make some incredible fuzz tones with it).

Now back to the Bosstone circuit. I breadboarded that up and got it sounding the way I wanted, then also breadboarded the modified ESR graphic fuzz circuit with an OTA chip in it and ran the two in series.

And there was that fuzz tone! It took a little bit of tweaking on the amplifier bias control, and the filter control, but at full tilt this thing produces a sound that I've only really heard on songs like Cherub Rock. Especially for solos, it changes the way the guitar "feels". I'm worried to disassemble the components to try to put it on a pcb, but I'm going to make sure to document all the connections. I'll have to hand-draw the etch because there are some mods, and I have yet to see an accurate ESR graphic fuzz pcb layout (if there is one I'd like a link ).

Here's a picture of the breadboard mess (I am the world's worst breadboarder). I can't believe it makes any sound at all. I'll try to get a soundclip up as well, while it's working :

I've since decided to call this project the "Triclops Fuzz" in recognition of Triclops Sound Studios in Atlanta, where Siamese Dream was recorded.

[brucer]

It's crazy genius that you know where to start chasing down this circuit, never mind nail it.  Major kudos to you.  Looking forward to sound clips and pcb progress.  Nice work.

[Thomas_H]

Keep it on the breadboard and just draw a schematic.
I'll make that PCB and send it to you to compare to the breadboard circuit 

[midwayfair]

Don't take it off the breadboard even if you're certain you know what's there! You'd be surprised how easy it is to forget a connection when you go to write the schematic or to have made the "wrong" connection on the breadboard that got the sound you like. Take voltages as well, and if you have the inclination, measure the hfe of your transistors to be sure everything's duplicable.

This is one of the holy grail fuzz tones for sure.

[RobA]

Don't take it off the breadboard even if you're certain you know what's there! ...

+1 on this. At this point, I leave things on the breadboard until I get back and have verified the PCB. I've had to pickup a few extra breadboards but it's a small price to offset the frustration of not being able to figure out what went wrong in the transfer to PCB.

[derevaun]

Awesome! There's also this breadboard pcb. Because, sometimes, all you need is a prototype 

[lars]

Awesome! There's also this breadboard pcb. Because, sometimes, all you need is a prototype 

Thanks for this link. That looks very interesting for a project like this. I'll have to take many, many close up pictures so that if I do mess up my connections, I'll have an exact reference. I can't loose this tone!

I have measured a lot of the components in this circuit, including the hfe's on the transistors. It looks like it works best with an hfe around 200 for Q1 and 150-ish for Q2. Lower hfe values tend to get too mushy and wooly sounding with the attack on full. The real key to this circuit is the OTA in that ESR circuit. Jordan bosstones are a bit hollow with not much low end typically. The OTA in the ESR circuit has a ton of bass by itself. Put the two together and you get this nice, full-spectrum fuzz sound, with plenty of midrange definition.

The one odd part is going to be figuring out the power supply. Right now I have to run two separate 9v batteries, since the ESR circuit can't have the negative battery lead directly attached to chassis ground. Since both circuits probably have very limited draw though, I'm sure two batteries would last several months in there, so not much of a hassle.

[lars]

Ok, here's a quick demo of the fuzztone of this mess. Once again I'm just using my Thomas organ amp, recorded into garageband. I added a little bit of layering and post processing like a touch of flanging, but all the fuzz tones are just this breadboard circuit.
[soundcloud]https://soundcloud.com/larsjm/custom-fuzz[/soundcloud]

[selfdestroyer]

Great job Lars! I can't wait to build this... sounds amazing. Im thinking a nice duel pedal with it and a opamp BMP would destroy all that is SP.

Cody

[lincolnic]

Yeah, if a PCB ever exists for this, you can add me to the list of people who'll want one. (I bet the entire forum probably wants one...)

[cooder]

Sounds awesoooommmmeee!!! I would love a board too if it comes into existence...

[lars]

I'm gonna try to knock out a hand-drawn layout tomorrow, so expect to see those great 70's-style curves. It's overall a really simple circuit, with only two transistors, the CA3080, 12 resistors, 8 caps, and two diodes. The four pots will be labelled:  Volume, Attack, Bias, and Filter.

*Update* I'm gonna give the freeware version of Eagle a try, and see if I can make a legit layout for this

I made several modifications today (carefully) to get the Bias and Filter controls to behave. The sweet spots were very narrow with the stock values, and most of the rotation would cause the effect to not work at all, or not do anything to the sound. Now I've got them dialed in to where you get usable tones throughout the entire sweep. These two controls make for a really interesting tone-shaping combo. Instead of the usual treble to bass, these work together to control more of the "presence" and "feel". I was able to drop the second volume pot entirely (it was pointless), so this probably improved the noise level a little bit as well.

The more I jam with this, the more I realize that it's a soloing machine. Something about the upper registers on a Strat just seem to sing, and it's actually easier to play high on the neck, if that makes any sense. I would love to hear this on a vintage JCM800 half-stack.

[GrindCustoms]

Man! That sounds killer!

Congrats on everything, that is surely one thing to build!

[Guybrush]

Amazing work!

I've only very recently started delving into the world of the Pumkins SD fuzz debate mess so I was really happy to see this.

Would love to buy a PCB if and when one is available.

[Cortexturizer]

Sounds good!!
Also, I love the topic's name, it's good to know that some of us have succeeded!