MXR Micro Amp Review – Best Clean Boost Guitar Pedal?

Review of: MXR Micro Amp

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Last modified:September 26, 2016



The MXR M133 Micro Amp is one of those deceptively simple pedals that can have a huge impact on your sound. If you’re seeking a solution for extra volume and dynamics, a good clean boost might be for you. Does the MXR M133 give you the best boost for your buck? You’ll find out in our MXR Micro Amp review.

But first, let’s talk boosts, overdrive, and compressor pedals to find out if this is the solution you’re looking for.

MXR-Micro-Amp-Review-Best-Clean-Boost-Guitar-Pedal-03When people want a booster pedal, they usually just need more volume. A good clean boost pedal delivers just that. It’s great for matching the volume of two different guitars or for kicking up the sustain of an overdriven amp. We’ll get into what the MXR Micro Amp can do later.

A compressor differs primarily in that it increases perceived loudness by evening out the volume of your playing. This effect differs in that you lose a sense of dynamics, the ability to control volume levels by playing softly or aggressively, but it’s great when you want every note to be equally heard. Watch out for extra string noise though.

An overdrive can boost your signal with its level and gain controls, but these effects typically add a mild to extreme coloration of your tone. You want your pure guitar tone to come through, a nice clean boost does the trick.

The MXR M133 aims to offer you a simple clean boost of volume without coloring your tone at all. Let’s see how it performs.

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Sound & Performance:

I first put this pedal in front of an already saturated amp and kicked it in for some leads from our humbucker-equipped Gibson SG. Going from a crunchy rhythm tone into a Micro Amp powered solo feels great. The volume increase is definitely there. You might find yourself wielding too much power with this thing. But the extra surge in volume can help you find the sweet spot where your amp breaks up into silky smooth tube saturation.

Switching the effect on and off for an A/B comparison really helps you take notice of the great increase in sustain and volume. Notes ring out longer and come alive with harmonic overtones. There is some serious magic in this little box.

The boost is clean enough to satisfy the tone obsessed. I scrutinized the sound repeatedly during my A/B comparison and found very little coloration. You could almost say there is a slight mid-range boost which could be due to the increased volume in general. Either way, a nice fatness comes from the simple increase in loudness and harmonic range. It’s also killer for a solo boost. Put an MXR Carbon Copy or Seymour Duncan Vapor Trail in your chain after it or in your amp’s effects loop for some analog delay, and you’ll be in tone heaven!

I switched to a Strat with single coil pickups and was able to find the spot to match the volume of the SG. The Micro Amp is great for those of you who switch guitars during live shows and want an easy way to match volume without relying on a clunky volume pedal.

I really liked it on clean tones, too. Playing my Strat with the neck and middle pickups engaged produced an even deeper sound that was pure and true to the guitar’s natural tone. The little extra boost the M133 offers will help take your amp from clean to dirty by pushing it into overdrive.

I tried it on a Jazz Bass, too, to see how it performed. I was very pleased with the extra girth that the Micro Amp produced. It gave my passive pickups a more active presence and beefed up the low-end nicely. It’ll certainly beef the sound of any instrument you plug into it. And again, no real coloring of tone but an overall fatness of amazing tone. So while it’s typically categorized under guitar pedals, bassists should check it out, too. MXR nailed it with this pedal. That’s why the Micro Amp is a classic!

So what’s the verdict?



The MXR Micro Amp is an exceptional pedal. It takes your solos to news heights by kicking your amp in the sweet spot. It lets you match the volume of different guitars with ease. And it magnifies the natural character of any instrument you play through it. The M133 is a great value, a possibly a must-have pedal for those searching for the perfect boost pedal. The MXR Micro Amp can help bring out the true character of any guitar you play through it.

Thanks for checking out our MXR Micro Amp review.

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