GEO - the Guitar Effects Oriented Web Page

Here's the original FAQ.


Everything I can think of about building and fixing electric guitar effects and the amplifiers that they drive after 25 years of hacking on it. This page is an attempt to collect that info into a useful resource online.

Lots of info and experience is collected in these documents that I authored/edited/collected:

NEW! Special offer - I'll trade a toner transfer package, your choice, for a vintage or boutique effects schematic that I DON'T already have. That's going to be tough - there are about 200 in the archive.

I recently found some triple pole/double throw (3PDT) stomp switches. This lets you have true bypass AND a status LED at the same time. Retrofit those old pedals with a status LED. They're expensive ($21 each!!!) but they're the only switches in existance (I think) that will do both true bypass and a status light at the same time. I'll throw in an instruction sheet for how to hook up the switch to do this. Send email if you are interested.

Effects Schematics

NEW! Ok, by request - the schematic diagram for the Fender Blender in .gif format, a Fuzz/Octave blast from the past. This is NOT a subtle, blues tone distortion. (However, it MAY be your father's fuzz!!!.)

You can get a toner transfer sheet package for making your own Blender printed circuit board for $10, or a printed and drilled circuit board ready to solder parts into for $25 (hand etched by the elves that live in my garage, no less!). If enough of you want boards, I'll get them made commercially. If you want board, info package and a baggie of parts to solder onto the board, that's available for $55.

Coming soon --- The Return of The Clone of the Foxx Tone Machine!!!! The FTM is yet another version of a fuzz/octave/tone pedal. This is the standalone version of the circuit in the Foxx Fuzz/Wah, and by an odd coincidence, convergent evolution seems to have made the Experience Pedal people select the same parts and circuit for the fuzz/octave section of their box some twenty six years later!! Send email if you're interested.

Ahah!!! The third member of the fuzz/octave triumvirate arises from the ashes! The old Univox/Unicord/Apollo/etc/etc/etc SuperFuzz is here!! This is a similar circuit to the Blender and Tone Machine, yet another approach to generating an octave fuzz. This thing includes the Mysterion(!) tone shift switch that puts in a 1Khz notch that makes this fuzz sound like it's playing in a hockey rink! As above - toner package for $10, circuit board for $25, circuit board and parts for $60.

I was graciously given the schematic for the TychoBrahe Octavia. You can see the .gif schematic or the postscript schematic. I have also laid out a circuit board, built a clone from parts available from Mouser Electronics, and it sounds GREAT! If you're interested in making your own and want more help than the schematic, send me email.

7/27/96. OOPS. The Octavia schematic lists a 2N3904 transistor - that should be a 2N3906 PNP, not the 3904 NPN. Also, the transformer is used as a step up, so the big impedance winding (probably called the "primary" in the electronics catalogs, is used as the secondary. I'll get the gif corrected. Sorry...

I collect effects schematics. If you're looking for a schematic that doesn't appear in the effects schematics libraries, I might have it, although most of them are dupes. I would very much like to increase the collection of schematics if you could help. If you have a schematic that is not on Leper's Musical Circuits archive (see Links, below), please send me email. Perhaps we can trade some.

I will be setting up a schematics section, but I intend to only put in schematics that are not otherwise available through the Musical Circuits Archive or the Digital Music Zone schematics pages.

Effects DIY Helps

I build a lot of effects for my own use. If you would like to make some effects, I can provide some things to help the process along.

I have

Tube Screamers

The old tube screamers,subject of so much mysticism, are really very simple circuits if you strip away the electronic switching that made the circuit boards complex. I did a circuit board layout which can be made into the signal processing path of the TS9, TS10, or TS808, which differ only very slightly - one board will do any variant with the right parts. This differs from any of the original pedals in that the electronic footswitching has been stripped out and replaced with a DPDT stomp switch for true bypass, which none of the original pedals did.

The schematics in postscript and schematics as .gif are available here on line.

The package includes schematics, parts list, layout, toner sheet/etc. Check the toner transfer section if you're interested in one. The single schematic covers all three, and highlights the parts that are different between them.

As an example of some of the documentation I provide with the Press-n-Peel sheets, here's the box wiring diagram for the screamer pcb.

Note: Ibanez has reissued the TS9. TS9, TS10, TS808, and probably "Tube Screamer" are trademarks of their current owners (not me).


If you're interested in making a clone of the old Univibe phaser effect, I rescued the schematics from an old copy of the service manual. I drew up and formatted the schematics. Jamie Heilman has these in his Musical Circuits Archive on line. I also did a start-from-scratch printed circuit board layout of the 'vibe. That is available here, as well as at the Musical Circuits Archive. Several folks have contacted me as they built their own clones, so we have some good test data on this layout and circuit. It seems to work well.

There are:

Preprinted toner transfer sheets with instructions, diagrams, etc. are available, too.

Note: Dunlop has reissued the Univibe. "Univibe" is a trademark owned by Dunlop (not me).

Fuzz Face

The schematics for the old Dallas Arbiter Fuzz Face are also on line at the Musical Circuits Archive.

Germanium transistors are available for Fuzz Face Clones.

I have two assembled and tested Fuzz Face clone boards left that don't currently have a home (store owner canceled an order...) . There's also a toner sheet package for the Fuzz Face clone. Send email if you're interested. Note: Dunlop has reissued the Fuzz Face. "Fuzz Face" is a trademark owned by Dunlop (not me).


I periodically run into parts useful for building or repairing vintage effects, tube amplifiers, or other musical electronics. When I do, I usually pick these up and keep them in case I need them. If you can't find that special part for a vintage recreation, I might have it here. These things are what I build my own effects out of, so I don't have a lot of them, but I may have a few available at any gven time.

These are in general not the kind of thing you can get at your local parts store/Radio Shack/mail order surplus house.

Links to other effects or amp related places

If you're interested in guitar electronics - building/repairing effects or tube amplifiers, you will want to take a look at: I'm pretty sure there's a hit counter here somewhere... Ah. Here it is.

Authored and maintained, and contents copyright 1995-1996 unless otherwise noted, by

R.G. Keen