I just completed a custom screamer for Rory Connolly, a local guitarist in Houston. I figured I'd share it with the good ol' solder boys here...

The enclosure is a Taiwanese BB from smallbear, and I gave it a coat of primer and two coats of hammered finish black paint. I've found this is the best paint to work with in order to get a decent strong finish without a ton of time and labor. Just spray and go. But now on to what really matters...

The build utilized two off-board mods. The first is obviously the clipping arrangement (more on that below). The second is a Fat control (posted by Kahel at BYOC). This is probably one of the best mods I've seen for the screamer. With the clipping arrangement used in this pedal and the gain available, the fat control is essential for dialing the "right" back into the pedal. Without it, the gain can go from smooth to splatty (think of an old fuzz face with bad transistors) pretty quickly. I'm also happy that I could actually mount the board in this enclosure without having to have it mounted to the pots. I cannot stand having to mount a board to pots.

I use the TL072 in just about every screamer build I do. It just feels better to me. Other component/value tweaks of note...

1. .1uF input cap
2. .15uF tantalum caps for the tone circuit
3. 1M resistor at R3
4. NP electrolytic caps at C2 and C7 replaced with film caps
5. 10uF tantalum cap at C10 (seems to smooth things out a bit)
6. 2K tone pot (all pots are linear...I prefer that sweep over audio taper)

As for the clipping arrangement, Rory wanted a pedal that could go smooth and still do crunch. He wanted some good blues tones, some good high gain crunch, and wanted the pedal to still be able to clean up pretty well. The clippers are arranged on an on/off/on switch, and I used two yellow LEDs on one side, and the other uses three 1N4001s against a single 1N914.

The rear of the board to show the connections.

The board was cut to size and a square of gorilla duct tape was fitted to the back to insulate it (just in case). The board is held in place inside the enclosure with 3M industrial velco.

The connections in the rear are a bit off to me, but this seemed to be the only way to ensure a clean layout inside. Also, this allows the pedal to be placed closely side by side with another pedal since one doesn't have to worry about jacks bumping into other pedals or jacks. Most pedalboards have quite a bit of room between the front and rear of different pedals, but side by side is prime realestate.

I started with a purple LED, but for some reason, it didn't want to work in the pedal. It ended up being very dim and eventually got to the point where it didn't come on at all. Swapping out the LED for this ultra-bright blue one seemed to do the trick.

As with all builds, I'm sad to see this one go, but I've got enough parts to build two more. One will probably go to Rory's studio mate, the other will be a test bed for the 18 volt charge pump I've got planned (with the MAXX1044 chip) and a "blow-out" clipping arrangement using JFETs (1 going east, another going west with another 6 behind it that can be blended in with a pot). If room allows, or if I can find a big enough enclosure, I'll be adding a JFET clean boost in the front as well.

As for the tone in this pedal, it all depends on where the knobs are pointing. In LED mode with the gain over 70%, it gets pretty raw...almost like an OCD or Box of Rock. The fat control is essential...without the bass gets flubby and the mid range and treble get pretty harsh. On the other side of the switch, there is quite a bit of volume loss, but this side is much sweeter. Low gain tones are very musical and can be pushed to break up when you hit the strings hard. The bass notes have a lot of snap and the treble notes compress a bit on the attack and seem to bloom. The pedal goes induces feedback naturally and slowly with a more musical response than most gain boxes. In the middle, the volume goes through the roof. It's easy to get a lot of distortion from the op amp alone...the clippers in either setting smooth this out quite a bit, although there seems to be a mix between the clipping diodes and the clipping going on inside the op amp at higher volume and gain settings. Unless the gain is set to 0, it is essential to play with the tone/fat control mix. There is a lot of range with both of those controls...it's easy to go OCD with finding the right mix. It's not as hard as dialing in a Mesa, but there's still a lot to play with in those two dials.

I gotta say thanks to Kahel for providing a most excellent modification for the screamer circuit. I don't know if I can build a screamer without a fat control now.

Now I'm off to hand this black beauty over to Rory...
Wow way to be a pedal genius. That's pretty impressive. How about some sound clips for those of us who know just enough to get past the basics?
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Wow way to be a pedal genius. That's pretty impressive. How about some sound clips for those of us who know just enough to get past the basics?

No recording gear. I will tell you (again) that the fat control is the best mod for the screamer I've come across. It is amazing where you can take this pedal with that one little control.

Really, if you look at it, it's not that complicated if you've already built or own a tube screamer. There isn't much going on here over the stock tube screamer. The value changes on the key components and the addition of the fat control (which can be found easily on the BYOC web site) made drastic improvements to this pedal over a stock tube screamer. That, and the WIMA caps...far cleaner tone overall than cheaper film caps. If you have a TS-9DX, you can rip out the mode selector or move it to a smaller toggle switch and add a pot for the fat control pretty easily.

I'd like to hear it with a nice buffer in front of it though to see how it reacts. Maybe for my personal build I'll add a buffer (along with the JFET clean boost and 18v charge pump I'm already planning to add).