Aion Electronics Fractal Overdrive Quick Start Manual

Fractal Overdrive
Pearl OD-05 Overdrive

Overview

enhance the resonant peak of your specific guitar and amp. You can even get a scooped-mids sound if that's
what you're shooting for, something that's pretty rare in an overdrive.
The circuit has a lot of familiar things in common with others you've seen, but in this implementation they
don't always behave how you expect. This is not quite a Tube Screamer where you can tweak just about any
part and get something good out of it! The original designers balanced the stock circuit very well, but if you're
modifying it, you may find that if you change one thing on one end you may need to change something clear
over on the other end to make the first thing sound good.
Specific modification ideas can be found on page 3. If you're the type to socket every component on a PCB
and experiment by swapping parts in and out, this circuit will keep you busy for a long time and you will
undoubtedly be rewarded with something you love. If you do end up with something interesting, make sure to
send in a build report!
Controls & Usage
• Drive controls the amount of gain from the op amp that is fed through the feedback clipping diodes.
• Level is the output level of the effect.
• Frequency sweeps through the midrange from 100Hz to 4kHz, setting the frequency that is either
boosted or cut by the EQ Gain control.
• EQ Gain is the boost or cut of the frequency set with the Frequency knob. It provides up to +/-15dB gain.
At the center position, it's a flat response and the Frequency knob has no effect.
• Clip is a clipping diode switch to allow you to use different combinations of diodes.
PEARL OD-05 OVERDRIVE / FRACTAL OVERDRIVE
The Fractal Overdrive is a clone of the Pearl OD-05 Overdrive,
a strangely obscure effect from the early 80's when Pearl (yep,
the drum company) briefly dipped into the effects pedal business.
The result was a line of very well-engineered pedals that
unfortunately never got the attention they deserved.
The interesting thing is, even 30 years later this pedal still is
relatively unknown. There are no commercial clones of this pedal
and it's relatively unexplored in the DIY scene (with the exception
of BYOC's Parametric Overdrive project). But those who have
played through one universally praise it for its tonal flexibility.
The OD-05 has a standard feedback-diode clipping stage like
a Tube Screamer, but the magic is what comes in front of it: a
parametric equalizer that allows either a cut or boost of up to
15dB in a range from 100 Hz to 4 KHz. With this flexible pre-
clipping EQ, you can get some incredible sounds out of it. You
can crank the mids for a cocked-wah sound, or tune the circuit to
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