This is a modified Tube Screamer that I built for a guitarist I did a recording project with earlier in 2010.

So what is it? This is a Tube Screamer 808 clone with a set of simple mod switches. The 3 knobs on the left and the circuit inside are the same as a Tube Screamer 808. The middle two switches flip between the “vintage” ts808 circuit and the more modern ts9. Since the difference was only two resistors, I was excited to hear the difference, and switch between them. Unfortunately it turns out the main difference between the two circuits is the opamp used and not the circuit design. I spent a long time switching between the two settings and there is a difference, but it is very subtle. The 808 setting smooths the highs slightly the 9 has a tighter low end than the 808.

The 3 right most switches, change the diodes in the Tube Screamer’s clipping section, essentially changing the distortion. The “S” setting on the right of all the switches is the stock tube screamer silicon 1N914 diode, common in many other guitar pedals. The “G” setting on the top two switches replaces the 1N914 with a germanium 1N34A diode. Flipping the first switch filters out some of the low end, and can clear up the tone a little bit depending on your amp. The second switch filters out the low frequencies similar to the first switch and some top end leaving a more midrangey sound. At the same time this switch also changes the distortion tone, giving it a little more bite, and the way the sound decays, creating a slightly more clipped, gritty sound. The final switch, changes between a symmetrical and an asymmetrical clipping by completely removing a diode and replacing it with bare wire. This mellows out the high end and the distortion a little. Because the way diodes work there will be a pop and a volume difference when you flip any of the right 3 switches so they are not really good for switching while playing but, choosing the tone you like for the particular song/set you are playing.

The knobs and switches are labeled using small pieces of paper that are taped on with scotch tape. Originally I planned to use some classy slide off decals, the kind that are used on fancy models, but it was a total pain in the ass and didn’t work at all. First the ink printed poorly and didn’t dry very well into the paper, then when I dipped it in water all the ink dissipated. Even after that the decal peeled right off the pedal when it dried. I know people have done this with great success and I have some ideas as to where I messed up, but it is not something I want to revisit anytime soon.