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Forum Home > Layout Gallery - GuitarPCB Build Documents, Mods and Tips > Aeon Drive - Crunchy OD

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This brand new version takes modding to new realms with the on board A/B pads.

More on that coming soon here.

While this circuit is based off of a stripped down version of the Tubescreamer  it just sounds good compared to many of the other varieties.


We have enhanced our version to sound its absolute best!

Aeon Overdrive Build Instructions

Check the Forum for answers to many questions before posting a troubleshoot thread.

Do not miss the Easy Pedal Wiring Guide.

Namely the expansive Tips, Tricks and Tutorials section and the consolidated Crash Course Guide.

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Tone Mods Courtesy of Tonmann:

The stock circuit itself should sound excellent on most rigs however if you wish to experiment...

The tone is a basic filter and not an active tone control so it will work either CW or CCW. It is your preference. Some people are used to brightest to the right however I see it as a simple cut to create an "apparent" bass boost since you cannot add gain to the tone circuit. In reality you are not boosting the bass frequencies but cutting the high frequencies to make the bass seem louder compared to the treble. Stock is brightest CCW. So simply put if you want brighter CW simply reverse wires from lugs1 and 3. Again it will work in either direction CW or CCW. Since this is a passive filter you cannot technically add anything, only remove. The direct of your preference of the cut is up to you.

Of the five capacitors in the audio part of the circuit (C1 - C5) three control bass frequency response (C1, C2 & C5) while the other two (C3 & C4) control the treble frequency response.

C1.  With the values given the bass frequency response is flat for the lowest frequency your guitar will produce (just above 80Hz for standard tuned guitar).  Making the value of C1 larger won't do anything as you can't make the bass response "flatter" than it already is.  Making the value of C1smaller will start to cut bass frequencies going into the op amp.  An exact capacitor value is impossible to calculate as the input resistance of the op amp plays a role - a 4558 op amp could have an input resistance as low as 300kΩ while a TL072 has an input resistance of about 1TΩ (a million, million Ohms).

Putting my head on the block, I would suggest a value of 4n7, if not 2n2 before you started to notice any large difference in the amount of bass cut. 

C5. Very much the same as C1 i.e. the bass response is flat for the given values of C5 and the volume pot.  To reduce the amount of bass at the output you would need to make C5 somewhere around 22n before you would notice any difference; you could also lower the value of the Volume pot to 10k.

C2 is responsible for setting the amount of gain at bass frequencies; making C2 larger will increase the gain - smaller values will reduce the gain of bass frequencies.

A value of 1µ should provide more than enough bass gain and that is a good starting point - at 10µ you would have maximum gain so any value larger would be irrelevant.

Since we are now talking about the µF range, you will probably be using electrolytic capacitors.  In this case it is important that the +ve lead of the capacitor is connected to the right hand pad (looking at the build instructions) of C2.

Another possibility is to create an "apparent" bass boost since you cannot add to the circuit.  In reality you are not boosting the bass frequencies but cutting the high frequencies to make the bass seem louder compared to the treble.

Increasing the value of C3 (220n, 470n) would do this.  You could also increase C4 but this would start to change the characteristics of the Tone pot (a Treble Cut pot would be a better description).

If you wanted to create an "apparent" bass cut you would increase treble frequencies by making C3 smaller (removing C3 altogether would give you the maximum amount of treble).

I would strongly advise using sockets when tweaking any component value.  Although the circuit boards are not exactly fragile, constant soldering and desoldering could lead to broken or lifted copper traces.

October 30, 2012 at 1:53 PM Flag Quote & Reply

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