What Clean Boost Pedal Does John Mayer Use? – Keeley Katana Clean Boost Pedal Review

by Jay Sandwich

If you look at the state of music industry today, you will see that old school rock is slowly crawling its way back into the mainstream. John Mayer is undoubtedly one of the major contributors to this phenomenon.

Even though his music can hardly be categorized strictly as rock, the point still stands. One of the reasons why this is the case is Mayer’s ability to use modern equipment in order to bring back that retro tone.

His gear selection includes a number of awesome pedals, one which is Keeley Katana Clean Boost. Today we are going to check out this bad boy and see just why it is considered to be one of the best, if not the the best clean boost pedal out there.

Keeley Katana Clean Boost Review

Keeley Katana Pre Amp Guitar Effect Pedal

Clean boost pedals are definitely not the most popular piece of kit these days. For the most part, people are far more interested in using overdrives or even distortions over clean boost.

However, there is a substantial number of guitar players who are sticking with boost pedals in general. After all there is nothing better than pushing the amp so hard it starts biting.

That is something clean boosts do best. Keeley’s Katana offers slightly more than that, though. Even so, whenever it is mentioned the first question that gets asked is why would someone pay that kind of money for a boost pedal?

The answer is simple, because the pedal is insanely good. While there are certainly some tricks to using a clean boost stompbox, it can really make a difference in how your entire rig sounds.


Katana is about as humble as the weapon it was named after. There is nothing flashy about this pedal. You are looking at a standard die cast chassis that features a very clean look.

The finish is snow white and the only thing that breaks up its monotony is the Katana title as well as the Keeley logo at the bottom. In all honesty, that simplicity of design makes pretty attractive.

On a more practical note, you won’t have issues packing this pedal into any pedalboard. all of the ports are exactly where you want them to be. When it comes to durability and build quality, we couldn’t find a single flaw.

These pedals are hand made in USA, making them more than capable of withstanding the horrors of daily use. Just like John Mayer, you shouldn’t run into any issues should you decide to take out your Keeley Katana onstage.


The simplicity of its aesthetics expands to the features as well. There is only one knob on the entire pedal and a footswitch. The knob is used to determine the amount of boost you are adding into the signal.

However, it is a push-pull knob. Once you pull it out, it becomes more aggressive. More on that in the next segment. The real beauty of this pedal is hidden below the surface.

Keeley has designed a very clean and insanely transparent voltage doubling circuit. If you look closely, the pedal operates on the standard 9V power, however the circuit inside doubles that value meaning that you are actually working with 18V.

That translates to massive headroom that is every bit as transparent as you need it to be.


The performance of Keeley’s Katana clean boost is hard to criticize. Everything about the pedal is just great.

Once you link it into your signal chain, you won’t notice it is there until you punch that switch. Even with no boost applied, your signal remains unchanged.

Naturally, when we are dealing with higher end pedals such as this one, true bypass is a must. However, not all of them offer this level of transparency.

The amount of boost Katana delivers is impressive. When you reach for more, you will always get it. Pulling the knob really amps up the boost, which is designed to be used with your amp’s dirty channel.

If you happen to have a good tube amp, or a fairly decent one, Keeley Katana will really push it to its limits. Even so, there are numerous ways you can use this pedal.

Being a clean boost package, you can add some spark to your clean channel without having to worry about tone discoloration or anything similar.

Then again, if you are hunting for a bit of overdrive, there’s enough gain in this circuitry to give you that as well. Keeley’s pedals are always a treat to play around with, but this one is on a whole new level of awesome.

While we might be a little subjective here, we will say that Katana is probably the best clean boost pedal you can score at the moment.


John Mayer’s affinity towards simple effects has left a mark on what we currently consider to be the standard when it comes to tone shaping.

Keeley’s Katana was around for a very long time, but it is arguable that the newly found interest many have for these pedals, has brought it back to the spotlight.

Now, we should address the elephant in the room. This pedal isn’t really cheap. It’s not overly expensive as some guitar effects pedals are, but being a clean boost makes it seem that way to many.

We are going to simply say that it is absolutely worth the investment. Reasons for this are numerous.

We can even put aside the fact that it is a hand made piece of gear and that it is produced domestically in US. Even with that out of the way, it is still worth the price.

For us, it’s all about that transparent boost, tonnes of gain that is easy to handle and most importantly, its clean nature. Where most pedals add a lot but also take something away, Keeley’s Katana only adds.

It doesn’t take away anything from the tone. That a pretty good deal in our book.

About Jay Sandwich

Jay is an ex-shred guitar player and current modular synth noodler from a small town somewhere. Quote: “I’m a salty old sandwich with a perspective as fresh as bread.” No bull.

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