Updates to Screamtendo 64:

You can buy the Printed Circuit Board at www.guitarkit.com.

R.G. Keen of  GEO sent me a couple of iron-on PCB transfers for the Screamtendo 64. So, some construction notes for building the Screamtendo 64 from R.G.'s PCB:

A. If you just want a Tube Screamer, those awfully nice Ibanez people make them for a very reasonable sum. They are smart enough not to complain about people posting their schematics, so I don't mind directing you into their capable hands. If you want to build a device tuned to you own bizarre preferences, with better quality capacitors and true bypass, the GEO transfer package is a good place to start. You'll need a suitable drill, and you'll need to do a little research.

B. Read this:  How to build GEO effects (pdf) and this: The Technology of the Tube Screamer. Read them again.

C: To make a PCB you need to be able to drill small holes with precision. A hand-held Black & Decker with a 1/16" drill bit is useless. A 1/32"/ 0.032"/0.7-8mm drill bit with a steady hand & good eyesight  is what you'll be needing. A drill press would help. If you can get an RTS (ready-to-solder) board, or get you mother to do the drilling, go for it.

D. No-Drill method: If you don't have the drill, you could just solder the components to the pads. Everything would be a mirror image. You would have to put the IC on upside-down, by bending the legs in the opposite direction. The DIP switch would be a problem, you could bend the legs into L- shapes poinitng inwards. Caps, resistors and transistors would not be a problem. But borrowing a drill would be easier. Veroboard would be easier than the No-Drill method. Of course you can still buy a TS-5 and do a rebuild.

E.Buy a Hammond 1590BB box. Using old disk drive casings or cornflakes packets will make the job more difficult (I take this back now,  Jim Radmer's site has a really nice harddrive casing). Use small pots to leave room for the jacks at the top. Make sure you can just wedge a  battery between the stomp switch and the casing. With a "Boost" switch and knob, you can go for a vertical ( GEO how to mount parts in a stompbox  ) or horizontal orientation ( The Screamer+ Distortion pedal ) for the box. You can get 4 knobs and 2 footswitches in the vertical orientation using  small knobs and pots.

F. The harder you lean on the iron-on transfer, the bigger the tracks and pads get. So if you overdo it and they overlap, scrape the copper away from anything resembling a short circuit (after etching). Test adjacent tracks with a resistance meter or magnifying glass before you solder. Leave at least a milimeter between tracks or pads. If you don't lean hard enough, patch up the tracks with a permanent (Lumocolor) marker before you etch. The tracks around the DIP switch are a little close together, so special attention there.

G. There are 2 connected pads labelled "OPT" in the documention that comes with the transfer. If you cut the link between the pads and add a switch, you get a diode disconnect switch ("Clean Boost/Compression"). If you use an 8-pin DIP switch, switch 8 happens to be pretty close if you want to drill another pair of holes.

H. N.B. Switch 6 is a Rat-style diode clipper.  See  AMZ Rat schematic for inspiration. Instead of the 1k resistor, use a 1uF (or more) capacitor, negative to the diodes. Use 1N34A germanium diodes. The 1k resistor pulls the voltage down between the opamps too much, and is really not a good thing. Sorry about that folks, but we are constantly learning. The capacitor provides much needed DC decoupling.

I. No reason not to use a 1 meg drive pot instead of a 500k. With a 1 meg boost pot, you could use a 250k drive pot, and still have plenty of gain. You might want to put a cap across the boost pot, maybe 100pF if your boosted tone is too bright.

J. Switch 5 affects the way the tone control works. See  AMZ Rat schematic for inspiration. Actually I shorted it out by mistake once and just liked the sound. You could increase it for less treble (I haven't tried that).

K. The 10k volume pot (100k on the TS9) may be intended to lower output inpedance in the version with no output transistor.

No, you're not supposed to change the switch settings with your teeth in mid-solo. Try all 64 combinations, and keep the setting you like best. Change your mind further on down the road. This gives you the most versatile distortion pedal on the market, at the lowest price on the market. If you just use the first 4 switches, you get a more sensible set of 16 combinations.

Epoxy a DIP switch onto the pcb. Use 6 of the 8 switches, one to increase treble, one to increase bass, one to increase gain, one for asymmetrical clipping, one for a more natural treble tone, and one for a more compressed clipping.

TS-10's are cheap, you can have 2 TS-10 Switchmasters for on-stage flexibility. This may actually be a cheaper option than getting a bigger box and adding footswitches.

Switches 1-4 are pretty straightforward component tweaks. Switches 5 and 6 are more radical hacks to make the circuit work in a way the designer did not intend, so those of a nervous disposition may prefer to stick to switches 1-4. There will be some interaction between 5 and 6, since they connect together.

Switch number 5: This give you a more hifi treble sound when you set the tone to minimum, and a treble boost when you set the tone to maximum. With Bass boost on, Drive at minimum and Tone on minimum, you get a tone similar to the natural guitar tone. This gives you a "transparent clean boost" (almost) which is useful, and does not sound like a Tube Screamer anymore. The tone control has a more narrow range if you do this.

Switch number 6: This only makes a difference at high drive settings. It increases compression and distortion, but reduces output. It is sensitive to the kind of diodes you use. I used 1N34A germanium diodes. If you have any problems disconnect the switch permanently.

Kustom Kolor:

Decreasing the value of the resistor at 1a gives more drive (distortion).

Increasing the value of the capacitor at 2a gives more bass.

The diode at 3a is a silicon diode. A germanium diode gives a more subtle effect.

Decreasing the value of the capacitor at 4a gives more treble boost.

The diodes at 6a are germanium.

Advice for the less experienced:

Wire up one switch at a time with nothing plugged into the pedal, then plug the guitar in and make the pedal still works before adding the next switch. If you apply too much heat to the diodes you can damage them. Don't overheat the 8-pin integrated circuit, or any component attached to it. Keep the wiring short to reduce noise. Go easy on the epoxy (giggle). Don't use switch 6 if you can't get it to work (see "H" above, though).

The changes here are the same for the TS-5, TS-9 and TS-10. It should work for the DMZ Son-of- Screamer too (I haven't tested it though). Some other overdrive pedals are almost identical to the tube screamer, but you are on your own here. The first 3 switches can be applied to may distortion boxes, but component values will vary quite a bit.

Uncanny Tales: When you remove the 220k resistor attached to pin 3 of the opamp as part of the TS-10 -> TS-808 conversion, you will notice that you now have 4 unused holes in a row on the PCB, conforming to one side of a 4-switch DIP switch. There are another 2 unused holes on the PCB to accept pins 5 and 8. Scary concidence, huh?. You can bend up pins 6 and 7 on the switch, and attach it neatly to the PCB. No epoxy needed after all. Realizing that people in the future would want to remove the 220k resistor to add a DIP switch, did Ibanez add the otherwise unnecessary holes in the PCB? There is a hole inside the battery compartment which allows you access the DIP switch with a toothpick. Was the TS-10 designed by time travelling aliens with access to a Screamtendo 64? Anyway the Screamtendo 128 has the extra setting for the flux capacitor...