OKKO Diablo - handmade guitar overdrive

body, feed, gain, level, tone, headroom switch
Power Supply:
9 volt DC/battery
Internal voltage:
9/18 volt
solid-state, analog circut
Discrete circuit:
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Berfore I said anything I let you know that so far, I've been using this pedal only with the 'Epiphone Standard' and 'Cort M600T' guitar both equipped with the humbucker pickups.

Image of OKKO Diablo overdrive pedal for electric guitar
The OKKO Diablo is one of the most versatile overdrive guitar pedals I know. I was thinking about buying it a few years ago when I watched the video where Gregor Hilden from 'www.gregorhilden.de' played a very melodic solo using it, along with a semi-hollow body custom built Gibson using both the pick and his fingers to demonstrate the whole range of dynamics the pedal is capable of. I wanted to put this video here, but unfortunately couldn't find it on his channel this time.

Here is this video that Gregor kindly allowed to publish on my website

The pedal isn't cheap and is hard to find in most "offline" music stores, especially outside Europe, it costs around 290$ and 340$ for the 'Gain+' version that has an additional drive channel, but only one can be used at a time, having two channels allows quickly switch from one gain setting to another with the help of the additional foot switch. As the operational manual says the 2nd channel doesn't have more gain, but sound a bit "fatter".

I ended up owning the standard one that has only one gain channel, since then it's my favorite stompbox, along with the Boss OD-3 overdrive.
Comparing it to the Boss OD-3, the tone of the OKKO Diablo is a lot edgier or harsher by 'default', although when I pick the strings softly it smoothens the tone a lot.

When playing some crunchy riffs, the crunch feels to me as very 'healthy' and alive, it's literally there, you feel it. To quickly dial up some useful tones look at 'Example Settings' below.


Both the standard and the Diablo Plus have a headroom switch, that activates an internal voltage doubling circuit.


Switching it on makes the pedal to run on near 18 Volts from a regular 9V power supply or a 9V battery, this way the pedal produces a tighter, more distortion like tone, and the volume gets a sensible push.

The feed knob is very usable and this one along makes this pedal very special, just tonight I was listening to the 'Late Mix - You Don't Fool Me by Queen', and decided to play through the mix,I took my 'Cort M600t' guitar, fired up the Diablo, turned the feed knob to about 9 o'clock, and I had it, a Brian May's like tone that easily cuts through the song, consistent and very musical. (I also added some delay on top of the drive effect).

The 'feed' creates the effect similar to one that a treble boost does. A treble boost amplifies and slightly overdrives certain higher frequencies making the sound of a guitar easier to integrate withing a mix, moreover it changes the tone in a way that each note sounds more accented or sharp.

On the other hand, the feed knob cuts off certain lower frequencies in the beginning, before the signal goes through the gain stage, so more higher frequencies become overdriven and leave the pedal from the output. If you turn the feed knob all the way up, it won't filter any bass off and even can subtly boost the bass instead.

This is my favorite control knob, listen how sharp and at the same time soft the Epiphone Std. guitar sounds on the neck pickup:

With a subtle reverb:

And the delay applied:

The adjustments used (in a clock position):
  body: 9     gain: 12     tone: 3
feed: 9 level: 12
18 Volt mode

It's hard to say what the 'BODY' knob does exactly, it subtly changes the sound, but how exactly - can't explain you, what I can say is that at about 9 o'clock the tone is more "singing" and better suited for playing solos, at about 12 to 3 o'clock is well suited for crunchy rhythm guitar.

In addition to all the aforementioned tone controls the OKKO Diablo has 2 internal trimpots for advanced tone tweaking. They are located on the circuit board, in order to access them you'd need to unscrew the bolts at the bottom and remove the lid from the box.

As the operational manual explains the internal PRESENCE trimmer controls high frequencies. Decrease for brighter, increase for darker sounding amps. The BASS trimmer affects lower mids and bass frequencies.

I was satisfied with the Diablo out of the box and never had to tweak these trimmers.

And just in case, here is the factory position of the trimpots on my pedal:
Factory (default) position of the trimmers (trimpots) in OKKO Diablo overdrive pedal

update on Oct 14, 2015

As I said before Boss OD-3 and OKKO Diablo are my favorite overdrive pedals so far, and they perfectly fit together in my signal chain when I need a heavy metal like sound. Usually I put the Boss OD-3 first with the gain about all the way down to push Diablo farther.

Example Settings

(position is indicated in space relative to the numbers on a clock's face)

voltage mode: 9V
body: 12-3   gain: 12   tone: 1
feed: 1                 level: 1

Break through the mix 
(for a neck humbucker)

voltage mode: 18V
body: 9    gain: 3    tone: 1
feed: 9               level: 1


Gibson Les Paul Studio - Soloing - Neck/Bridge pickup

Beautiful, delicious playing by Taco Visser that shows how the OKKO Diablo sounds at different gain levels and with a smooth, ballad like jam track in the background.

The HEADROOM SWITCH is set to Hi (18 volts run internally).

Fender '86 Contemporary Stratocaster - Soloing

Another tasty playing from Taco Visser. This time he shows how the pedal sounds with the strat single coil pickups.

The HEADROOM SWITCH is set to Hi (18 volts run internally).

Not that for some reason his Diablo overdrive pedal has white colored knobs, while they usually black in any other place I saw.

Diablo Gain+ pedal with a Les Paul Guitar

Riffing and various solo elements played here

In this video you can here how the effect sounds with an array of different settings, including both 9 and 18 internal voltages, various tone, feed, body and of course gain.

Note that my Diablo, and Diablos I've seen in many other demos do not produce so much gain, as one in this video, I guess his amp contributes a lot here as well.

With a Les Paul Std and Fulltone catalyst as a booster

Nice blues improvisation, the Diablo is at the low gain

Improvisation with a Hollow Body humbucker equipped guitar

The guitar is Ibanez AS-80.

0-43 seconds: the neck pickup
43~ seconds: the bridge pickup
handmade guitar pedal, versatile, very dynamic, discrete circuit, transistor-based overdrive stompbox, non-IC, IC-free, bass response knob, organic crunch