Guitar Pedal - Selectable Diode Tube Screamer





Introduction: Guitar Pedal - Selectable Diode Tube Screamer

Built after the original Tube Screamer 808.

Step 1: Introduction

The Ibanez Tube Screamer is one of the most popular overdrive pedals ever made. Especially popular with blues players, it boosts mids to mimic the sound of a vintage tube amp. Likewise, due to its popularity, it is very commonly modded.

By changing the diodes at certain points in the circuit, you can greatly change the sound of the overdrive. Adding diodes can create a more tube-like asymmetric sound. Similarly, bypassing a capacitor can add more bass response and give additional boost. There is a wealth of modifications and explanations of the circuitry online (, as well as thorough detail of these mods (, so I won't cover that here.

Typically, these mods work by replacing diodes in the circuit with various makes and models to create different sounds. This pedal combines the most common modifications to be able to change on the fly without ever having to open up the enclosure.

Step 2: Designing the Circuit

We will use rotary switches to select between a bank of different diodes to change the clipping stage as well as having switches to turn on/off other mods.

The circuit was designed in Cadsoft Eagle ( to create PCBs of the circuit. The ".sch" file contains the schematic and the ".brd" contains the board layout.

Step 3: Get Parts

The attached images show the parts list and order form, respectively, for the retailers I used.

You may need to find alternatives for some of these parts, but follow the item list and double check against the schematic.

Step 4: Assemble Board(s)

Now comes the fun part. Sorting the parts and soldering is left as an exercise to the reader.

If you choose to get a professionally created PCB, this will be a little easier as everything is labeled. Otherwise, follow the schematic carefully and take your time.

Step 5: Designing Enclosures

To make all the parts to fit properly inside the 125B enclosure, I recommend creating each part in Sketchup When everything aligned the way you want, print out a 1-to-1 view of each side and drill the holes from the template.

If you don't use sketchup, be careful to take measurements and ensure that your parts will all fit, with enough room to wire, and mark out all drill holes prior to drilling.

Step 6: Assemble Enclosure

Wiring is fairly straightforward but very tedious. Try to make the wires as short as possible (there's a lot to fit in this small enclosure) and wire up each component to it's appropriate jumper according to the schematic.

Step 7: Test and Try It Out!

Plug it in before installing the back panel of the assembly and check that everything works right. Check first that the light turns on after pressing the footswitch. Due to the number of components and tight fit of the enclosure, be especially careful of shorting something. If the light doesn't turn on, unplug it and inspect the circuit.

Test playing through it and if everything works right, screw the back panel on and rock on.



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    29 Discussions

    ok it is realy clear how to do but in the end i cant understand where shoul i connect the wires

    Question: why are there three units? I am building this for my son and know nothing about guitars. Thanks!


    This looks pretty damn interesting, although I can't quite figure out how to connect the switches and potentiometers to the jumpers...Do you think it would be possible to draw a separate diagram for that, or maybe add another set of photos?


    Picked up the general guitar gadgets ITS-808 with their mod kit. I received two alternate dual op amp IC's as well as the stock kit IC. Wanted to customize mine in some form. So i created a separate board that bridges pins 2-6 & 8. Leaving 1&7(op amp output) separate i added a 2p6t switch to pick between 4 ICs (the 4th being a TL082 i got on the cheap)

    3 replies

    I have a bunch of TLO72s They're pretty bland chips, but they do have a wide bandwidth, which will be wasted in an audio device. Very clean, low distortion. Perhaps not the best choice to make an overdrive with. They'll clip without any good tone harmonics. So the noise you'll get out of them will be rather one dimensional.

    The diodes clip the signal, not the op-amp. Op-amps only clip when the signal reach the power rails (or close, depends on op-amp), and it sounds very bad, noisy, squeally and probably oscillate like crazy (been there before). The diodes limit the voltage and thus clip it. That's how the TS generates its overdrive sound. You can use pretty much any dual op-amp for the TS without any noticable change in sound.

    Said by the person that has never heard a vintage JRC4558. Before JRC ran them again the vintage chips were going for north of $75 a piece, and plenty of folks were buying them too!

    A beginner's question: can I use the JRC4558 chip in this circuit?

    1 reply

    Any dual op-amp will do the job for you. If you already have a JRC4558, use it. If not, TL072 are very good and quiet op-amps, and they are very cheap. I use them all the time for building overdrive pedals.

    Without a vintage JRC4558 you're not going to get the tone. I have a few and they really are magic.

    3 replies

    I've got a JRC4558, can I use it in this circuit without rewiring it? Thanks!

    You should. The pin out looks correct to me. Vintage JRC4558s are hard to come by though. I am not sure how well all of the new ones stack up. I would suggest you socket the op amp, so you can swap out different ones. Because the tone differences between the different kinds of op amps can be substantial. Some are noisier, some sound more compressed, there are a lot of dual DIP op amps. They're all going to be different too.

    I have published an article about an overdrive distortion box on this site and it is about the best one going. I took it to a music store once and let the owner of the place play with it for a while. When he was done he just looked up, with a glazed gaze, and all he could say was, How much do you want for it? So he was ready to offer me cold hard cash on the spot he liked it so much.

    Thanks! You helped a lot. Hope you sold the patent for a good money :)

    I found a typo on the schematic. IC1B has the inputs reversed. Pin 5 and pin 6 need to be reversed. Still need answer to my previous question about the 8 position switch connections. Not sure if both wipers go to JP-C1. Thanks!

    And now I just need to learn how to read electronic diagrams.
    They've always just been heiryglyphics to me.