MXR Micro Amp Review – Best Clean Boost Guitar Pedal?


The MXR M133 Micro Amp is a deceptively simple pedal 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, compressors, and overdrives 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.

Read more about the MXR Micro Amp at

Sound & Performance:

We 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. We scrutinized the sound repeatedly 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 harmonic range.

We switched to a Strat with single coil pickups and were able to find the spot to match the volume of the SG. This 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.

We really liked it on clean tones, too. Playing our Strat with the neck and middle pickups engaged produced an even deeper sound that was pure and true to the guitar’s natural tone.

We tried it on a Jazz Bass, too, to see how it performed. We were very pleased with the extra girth that our bass produced. We felt that it gave our passive pickups a more active presence and beefed up our low-end nicely. Great for slapping and popping. And again, no real coloring of our tone but an overall fatness of amazing tone.

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.


ANNOUNCEMENT: Andy Richardson of ZVex Effects has passed away. Andy's generosity and friendship helped make Best Guitar Effects what it is today. Please check out the Auction for Andy @ running from October 6-12 where you can bid on tons of cool and rare pedals. Or consider making a contribution to the Memorial for Andrew Richardson to help his family during this difficult time. Thank you. ~ BGFX


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