Okko Diablo Gain + Review

Okko Diablo

Okko Diablo

Now, this is a pedal I’ve been curious about for years — there are a number of clips on YouTube but the astonishing thing is, they all sound wildly different from each other!  As if they are playing completely different pedals.  Both beautifully warm low-gain tone and fizzy, bashing hard rock tone have been sighted.  This pedal was a mystery, and I am hoping that I can uncover that mystery for you in this review.


If you are afraid of too many knobs, then you’ll want to run away.  In addition to the familiar Gain, Volume and Tone, there are Body and Feed, and “+” knob (I’ll write that as Plus in this review) acts as the 2nd gain setting.  If that’s not enough, there are two internal trim pots for Bass and Presence.  To top it all off, there is a rocker switch on the back that changes the voltage setting — 9v vs. 18v.  The pedal itself takes 9v (the manual warns not to try 18v).

Let’s tackle the easy one first.  The Tone knob controls the treble frequencies and it’s placed just where the “hair” of the overdrive tone resides.  It’s a very powerful control that can fundamentally change the character of the overdrive.  Turn it up, you get more high-end fizz and hair.  Turn it down, you get dark & warm.  I really wish all tone knobs worked like this.

The Feed knob controls the input volume and pre-gain bass.  The pre-gain part is important, as the low frequencies have the biggest impact on the incoming signal strength/volume and can dictate, in this case, how much the pedal distorts the signal.  If you turn this knob all the way counter-clockwise, you get very thin sound, approaching the your-guitar-through-a-pocket-transister-radio sound.  To add even more authenticity, your guitar signal can crackle, too, probably because the incoming sound has such little volume and is barely making through the pedal’s circuit.  You can use this to a musical effect, consider it your lo-fi sound.  On the other end, the sound can get very full and possibly muddy depending your amp/guitar/pickup combinations.  But you can turn up Tone to compensate, too, if it gets muddy.

The Body knob is subtler compared to the two above — this controls the saturation/compression.  Counter-clockwise, your pedal remains uncompressed, giving you bigger dynamic range, while turning it clockwise makes it more compressed and gives more sustain.  The impact on tone itself is somewhat minimal, with the clockwise motion adding saturation in the last 1/4 of the range — it just sounds more distorted.  But in general, you really won’t hear a huge difference as you twist this knob.  Impact on the dynamic range/compression isn’t subtle, though, and this is another feature I wish all other dirt pedals pulled off.

I’m going to generalize here, but when you’re playing rhythm guitar and strumming chords, dynamics is a good thing, as the note attacks retain their loud peaks and translate into your strummed rhythm cutting through the mix and giving definitions to your chords.  But when you’re playing single-note lead, you’ll want some compression and sustain, otherwise your notes will just disappear into the mix after the initial attack.

The two internal trim pots are also on the subtle side.  Bass is post-gain low-end, so it obviously depends on how much bass is coming in based on the Feed setting.  The internal Bass mostly affects the fullness of low-end available, and even if you set it all the way up, you can always reduce the heft by reducing the Feed knob.  The Presence control affects the “air” range — ultra-high frequencies above the reach of Tone control.  Interestingly, the range affected by the Presence control really doesn’t sound distorted.  I was pleased about this, as a lot of dirt pedals intentionally roll off ultra-high frequencies because it results in ugly fizz that goes “shhhhhhh!”  But with Diablo, I can turn up this Presence control all the way up, and even my Strat’s bridge pickup doesn’t sound harsh or piercing.  It just gives a sense of air and clarity.

The Voltage switch has a very noticeable impact on the tone.  9v sounds darker and compressed compared to 18v, which sounds bigger, more dynamic, but less sustain.  18v has noticeable volume boost, too, but not only that it does have a frequency extension — highs get higher and lows get lower.  The trade-off is the sustain and saturation.  Again, 18v is great for rhythm work, 9v makes it easier for leads.

The Plus knob can be confusing.  It works to add a certain amount of gain and slight low-mid bump to make it sound fuller.  But think of it this way — Diablo has a finite amount of gain, and the Gain knob full access to all of its range.  So when the Gain knob is set to max, then Plus knob will do nothing, regardless of where the knob is set.  But assuming you have the Gain knob set somewhere lower — then the Plus knob can act as the 2nd setting for the Gain knob that you can activate it with the 2nd footswitch.  So Diablo Gain + doesn’t have a boost or additional gain stage.  It simply allows you to have two different settings, one low and one high, that you can switch with a foot switch.

Phew!  That covers all the notable features of this pedal.  All of the above affects what you can get from where your Gain knob is set.  If you’re set at 18v, Tone and Feed all the way up and Body all the way down — that has a very different sound from 9v/Tone set low/Body set high, even if the Gain knob hasn’t moved.  This is one deep pedal, and the more you get to know it, the more great sounds you can coax out of it.  Definitely not a one-trick pony.


So, with all this flexibility, it can be quite mind-blowing to try and figure out whether this pedal meets your needs or not.  So let me share some fundamentals about this pedal’s sound that doesn’t change:

  • The overdrive character leans toward a classic, vintage vibe.  If I have to associate it with one school over other, I’d say this one is in the “Tweed” camp.  It doesn’t strike me as a Marshall, Vox or Mesa.
  • This pedal sags.  Sag is the softening of pick attack that’s common in old-school overdriven tube amp.  The sag is beautifully done — it really feels natural.
  • Diablo is voiced warmly.  Tone and Presence all the way up, Feed low, 18v, Strat bridge pickup — it still doesn’t sound harsh.  Muddy, yes, we can get there, but harsh?  No.  You can get thin when you turn Feed low but not harsh.
  • Diablo is responsive.  Even in 9v and every knob turned to max — you can still pick softly and get it to reduce its distortion.

The above four points are very important as you consider exploring this pedal.  If you turn up Gain & Tone and hit your strings hard, you can get quasi-hard-rock territory, but high-gain is still not this pedal’s forte.  If you’re looking for tightness or fast pick attack, you won’t find it here.  I wouldn’t describe it as clear and open either, because even with Tone up, Feed, Gain and Body low, there’s still the sag, which gives a warm impression.

So, now that you know what this pedal isn’t — then you can dive neck-deep into the vast array of sounds this pedal can offer.  You can set it to 9v and turn up Gain and Feed for a warm break-up that’s great for some slide work.  18v, Body & Feed low, Tone high and you get bright yet non-piercing rhythm tone.  It’ll particularly delight blues players adept at varying the amount of dirt with picking strength — 18v, Body low and it just responds in way that feels natural and organic.  As long as what you’re looking for is a variation of vintage Fender style sound, this pedal will deliver.


So now the mystery is resolved.  The reason this pedal sounds so vastly different from player to player, video to video is because 1) its range is bigger than that of most pedals of this kind, and 2) it responds to player more, thus what this pedal sounds like reflects more of the player than other pedals.  That said, this pedal is not a complete chameleon and I would say that its strengths are the dynamic response, organic sag and warm character.  It serves roots, blues and classic rock really well.  Players who can appreciate subtlety can get more out of this one than those who just hit barre chords hard, though it won’t sound bad doing the latter by any means.  The controls are wonderfully interactive, so once you understand what they do, then you’ll be able to harness its wide range to dial in the exact sound you’re looking for.


7 thoughts on “Okko Diablo Gain + Review

  1. Thanks for this. I have this pedal and I am a “keep it simple” kinda person. I bought this pedal thinking it would be versatile, but with versatility comes complexity. I am new to using effects so it was even more of an issue since I didn’t know what I was doing. I have read the manual, but this was a more thorough, application driven explanation i.e. what is good for rhythm and what is good for lead.

    • Glad you found the review useful. I aim to write these so that reading it really gives you a sense of how the pedal works — videos and even manuals are often insufficient. Enjoy the pedal!

  2. Great review thanks, explained a lot. One thing that surprises me about this pedal is that I can’t seem to get a cleanish boost from it, especially with humbuckers, always hairy. Any ideas?

    • Thanks for your kind words. As far as your question, your input is too hot, you’ll have to back off on your guitar volume. Or pick softly, but that’s not always a good option depending on the music/song.

      • Yes that’s what I’m doing, just surprising that with gain at zero it still breaks up a lot. thanks for the reply!

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