- Typical MXR build, solid, sturdy and well-made
- Very easy to use
- Sounds very transparent
- Can drive tube amps into natural overdrive
- Can be used as a booster to further fattening your overdriven sounds
- Limited usage due to the nature of the design
- No EQ settings available to compensate any frequency band while boosting
Hello there, and welcome back to yet another guitar pedal review! As you may have noticed, I have started purchasing guitar pedals, mostly overdrives, distortions, and boosts, to test with tube amps and reactive loads in a direct recording setup. I wanted to try as many pedals as possible and document my experience here. However, I eventually would like to stop, as producing these videos and articles takes a lot of time. 🙂 This time, we are going to continue with yet another legendary pedal that has stood the test of time, the MXR Micro Amp! As I always do, I will provide as many details as possible about this company and the pedal, along with a brief demo video, in this MXR Micro Amp review.
Table of Contents
TL;DR
If you own a tube amp or a tube preamp, chances are you know how it feels to have the opportunity to alter the characteristics of them by using ovedrive, distortion and booster pedals. It almost feels like an endless game of tone chasing!
I think most guitar players go through this phase once in their lifetime and they keep buying and selling guitar pedals to find the best combination! It’s always fun!
While going through this phase, I realised I had never tried a clean, transparent boost pedal with my tube amps and wanted to give it a go. MXR Micro Amp is possibly the first option that came up to my mind. Despite being designed and released in the late 70s, MXR Micro Amp is still widely available on the market thanks to Dunlop’s attempt to re-issue this legendary pedal at relatively affordable price tag!
MXR Micro Amp is possibly the easiest to use, lean and transparent booster pedals out there. It offers +26dB clean boost which you use to beef up your clean tones, push them into the overdrive zone and also add a lot of volume and thick body to your already overdriven and distorted guitar sounds!
Using this pedal on extremely high-gain settings is not the wisest thing to do. However, when used with clean settings along with single coil pickups, it can really add that body to your sound without adding any colour or characteristics to your base tone.
It also works with overdriven and distorted sounds really well, however, one should always consider how much headroom your guitar and rig features before you use the pedal. When you have some headroom to fill, MXR Micro Amp will definitely add its magic!
cigilovic.com totally approves the timeless MXR Micro Amp pedal to any players who are seeking a relatively affordable transparent boost pedal. However, I’d like to mention that if you are bedroom player like me, you may need such a volume change while you are playing on your on.
I would personally go for traditional overdrives and distortions to add some colour to my guitar tones rather than having the ability to boost the volume.
Let’s start with a brief introduction to the legendary MXR brand for those who are unfamiliar with it.
About MXR
Since its founding in 1972, MXR has been a trailblazer in the world of guitar effects, helping define the tone of modern music through decades of innovation, grit, and unmistakable sound. Born in Rochester, New York, the brand was founded by engineers Keith Barr and Terry Sherwood, who envisioned a new generation of compact, durable, and great-sounding pedals for working musicians. The result? A lineup of rugged stompboxes that became staples of the stage and studio, earning MXR a place among the most iconic names in guitar history. From analogue classics to modern innovations, MXR pedals are trusted by bedroom players and arena headliners alike. Whether you’re chasing vintage warmth, crystal-clear modulation, or aggressive distortion, MXR delivers the tone you can count on. 
A Legacy of Iconic Pedals – Analogue Innovations
Over the decades, MXR has produced some of the most sought-after and enduring effects in the industry. Here’s a look at a few of the standout models that have shaped its legacy:
Phase 90 (1974)
The original MXR release is still one of the most popular phasers of all time. With its signature swoosh and single-knob simplicity, the Phase 90 helped define the sound of Eddie Van Halen and countless others.
Dyna Comp (1976)
A legendary compressor that delivers smooth sustain and signature “squash.” Essential for funk, country, and lead guitar tones.
Micro Amp (Late 1970s)
A clean boost classic, offering up to +26dB of gain with just one knob. The Micro Amp is perfect for pushing amps, balancing guitar volumes, or giving solos a transparent lift. It’s still a go-to tool for tone shaping today.
Distortion + (1975)
One of the first distortion pedals ever made, delivering gritty, amp-like drive. Used famously by Randy Rhoads, it remains a favourite for vintage rock tones.
This fuzzy, glitchy pedal combines heavy fuzz with a sub-octave effect for chaotic, synth-like textures. Famously used by Jimmy Page on Led Zeppelin’s “Fool in the Rain.”
Flanger & Chorus (Late 1970s–80s)
Warm, lush modulation pedals that offer rich depth and movement. The MXR Flanger and Analogue Chorus became key components of ’70s and ’80s guitar tones.
Carbon Copy Analogue Delay (2008)
A modern classic featuring warm, bucket-brigade repeats and built-in modulation. Its lush, vintage-style echoes made it an instant favourite across genres.
A hot-rodded take on classic distortion, this pedal delivers rich, saturated drive with modern tweakability.
A 10-band EQ with dual output, which allows -/+12dB gain adjustment per band!
Signature and Artist Series
MXR has collaborated with iconic artists to develop custom pedals tailored to their unique tones, such as the EVH Series, including the EVH Phase 90, Flanger, and 5150 Overdrive, inspired by Eddie Van Halen’s gear, Zakk Wylde Series, built for high-gain riffing and soaring solos, Timmy Overdrive (Mini, a compact take on the legendary transparent overdrive, done in collaboration with Paul Cochrane, Slash Octave Fuzz, Kerry King EQ, and more. 
Powered by Dunlop
In the 1990s, MXR found new life under Dunlop Manufacturing, Inc., which revitalised the brand while preserving its analogue soul. Under Dunlop’s stewardship, MXR continues to expand its product line, blending vintage character with modern features and maintaining the brand’s reputation for durability, reliability, and tone. Today, MXR remains a trusted name for musicians around the globe, from weekend warriors to world-famous headliners. No matter the genre or playing style, MXR has a pedal that fits your sound.
MXR Micro Amp
The MXR Micro Amp (model M133) is a clean boost pedal designed to increase the gain of your guitar signal without altering its tone. It features a single knob labelled Gain, which controls the amount of signal boost, up to +26dB.
Introduced in the late 1970s by MXR Innovations, a company that helped pioneer compact stompboxes during the golden era of analogue gear. The Micro Amp debuted around 1979, a few years after the company’s breakthrough pedals like the Phase 90 (1974) and Distortion + (1975). The idea was to provide a simple, no-nonsense boost solution in the same compact format. 
Jim Dunlop acquired MXR in the mid-1980s after the original company went bankrupt in 1984. Dunlop reissued many of MXR’s iconic pedals, including the Micro Amp, with modern reliability while staying true to the original designs.
The reissued Micro Amp (still known as M133) kept the same minimalist design: just a single Gain knob, a hardwire bypass footswitch, and a durable metal chassis. It became a go-to tool for players needing clean volume boosts, for solos, amp-driving, or balancing guitar outputs. It’s been quite popular as it is one of the easiest to use transparent boosters out there on the market – It doesn’t colour your tone much, making it ideal for pushing tube amps into overdrive or just lifting your level for solos. Before we jump to the review section, let’s first have a look at the tech specs briefly.
Tech Specs
| MXR Micro Amp | Tech Specs |
|---|---|
| Type | Boost |
| Gain | Up to +26dB |
| Controls | Single Gain control |
| Switch | Hardwire Bypass |
| Input Impedance | 1MΩ |
| Output Impedance | 470Ω |
| Maximum Output Level | +6dBV |
| Noise Floor | -80dBV |
| Gain Control | +0.5dB to +26dB |
| Frequency Response | 20 Hz to 20kHz |
| Current Draw | 2.5mA |
| Power Supply | 9V DC (centre negative) |
| Made in | China |
Before we jump to the MXR Micro Amp review section, let’s listen to the demo I prepared for this pedal. For the demo, I used the already-recorded loops that I stored in my Boss RC-5 pedal, as I just wanted to do a very quick demo. In these loops, I used my FGN Boundary Odyssey, Cort M600, Fender American Standard Strat, Ibanez AR300 and Epiphone SG Custom Ebony guitars. 
Apart from the guitars, I used my usual setup featuring my Marshall JVM410HJS, Two Notes Torpedo Captor X SE, RME Babyface PRO FS and Genelec DP8020 DPM. For the effects, I also applied the Valhalla Room Reverb plugin in the post. I also experimented with different channels on my JVM 410HJS to show you what this sounds like on a clean channel, as well as crunch and overdrive channels as a boost.
Sound Demo (no talking)
Review
As you can see, it’s one of the leanest, simplest to use pedals I have ever tested! It comes in a standard MXR packaging, including a pretty solid box. This is pretty much the standard for all MXR pedals I have purchased so far. Standards are good! 🙂
In the box, you will have the pedal, a quick guide booklet, a warranty and serial number leaflet, an MXR sticker and 3M pads for the pedal. The quick guide, as with all the MXR pedals, is just a general guideline on MXR pedals. I have never had any manual or any specific document for the particular MXR pedal that I have ever owned. 
So it doesn’t come with a manual. Would you ever need a manual with a pedal like this? Highly likely no!
The pedal itself features a pretty solid chassis, standard input and output, with the power in (on the right side). Somehow, MXR places the power input on the right side of some of the pedals. Even though the pedal feels pretty sturdy and solid, it’s very lightweight. If you have the pedal brand new, there will be 3M pads included in the box content, and I highly suggest you use them. Otherwise MXR Micro Amp may just move freely on your pedalboard easily as it’s feather light!
When I first got this pedal, I was using a slightly different rig. I had a Marshall JVM410H along with a RedSeven Amp Central reactive load and IR loader, and was using this to boost the OD1 and OD2 channels. My initial expectation was to increase the volume up front and hit the front end of the amp a little harder. So while using this on an already high-gain channel, I couldn’t really discover the full potential of this pedal. However, after having played with my JVM410H as well as with the JVM410HJS (Satriani signature) on the lower gain channels and clean channels, I was pretty surprised with the results, as the pedal was adding a lot of juice and drive to those channels.
As you can hear in the demo video, even while using a high-output pickup (FGN Boundary Odyssey), it doesn’t greatly distort the sound on the clean channel. But definitely adds some body and slightly pushed-clean characteristics to the sounds. I think it’s extremely transparent and doesn’t really add any colour to the overall characteristics of your guitar and amp. When you use a tone setting on your amp that is clean or slightly overdriven, there’s a lot of headroom you can fill with the MXR Micro Amp. Especially if you are using a tube amp, you will see how much drive it can add to a mildly overdriven channel. In this scenario, it’s possible to use most of the gain the pedal generates on top of your signal. However, when you have a distorted channel, for instance, a crunch or distortion channel on your amp, it’s not going to yield great results.
You can easily hear all these flavours in the demo video above. I think ideally, one should use Micro Amp to push a clean or an overdriven channel into a thicker, creamy and juicy tone setting by setting it around noon or 1 o’clock. You can still push it further, but it would be a better fit for a Stratocaster or Telecaster-type guitar. Based on my experience with tube amps, tube preamps, distortion, overdrive and booster pedals, I strongly believe the more headroom your guitar has by default, the wider the range of any type of those pedals will become usable.
Even though I didn’t record this demo with my Marshall SV20H a.k.a. the Baby Plexi, I did test it for a while. I think it is an excellent choice with Plexi-type amps as well. Usually, Plexis starts to generate some overdrive (depending on your pickups) around 5 or 6 on the Loudness Controls. So from there, you can easily push it further and add a lot of body and natural overdrive by using a Micro Amp!
Verdict
As you may have guessed already, I have a lot of positive vibes with this extremely simple yet effective pedal by MXR. I think there’s no doubt it stood the test of time and is still used by many guitar players. I can wholeheartedly recommend the MXR Micro Amp to anyone seeking a transparent yet powerful boost. I have purchased several MXR pedals so far, such as the MXR 10 Band EQ, Micro Amp, Custom Shop Phase 90, Uni-Vibe and Thump Bass Preamp pedal (Hopefully will feature them all here!).
I’m a big fan of their pedals and the consistent quality they offer every time. There has never been a bad surprise from any MXR pedal so far! The only thing I dislike about the MXR pedals is that, in my opinion, they are slightly overpriced here in the EU. As far as I know, they are all made in China (nothing against that!), so the costs are reduced already. However, the price tag is slightly higher than what I feel comfortable with. But I still buy them! 🙂
I totally understand their approach, though. They carry a big brand and the name, so they are trying to hold that position on the market. Wish they cost a little less so I could buy a lot more MXR pedals. Back to Micro Amp! Although I recommend this pedal without any doubt to any guitar player, I would like to add that if you are just a bedroom player like me, chances are you may not need this flexibility in your rig. In my opinion, Micro Amp is a better fit for musicians who gig and need the extra volume level during their performance. 
When I utilise boosters and overdrives, I usually aim to get different gain characteristics so I can get a lot more out of my tube amps and preamps. I don’t need a different volume level during my solos because, at the end of the day, I just play for myself at home. I hope I have been clear with what I am trying to say! 🙂
Pricing & Availability
Luckily, like most of the MXR product line, the MXR Micro Amp is widely available at any music shop and basically at any store! I got mine from a local website here in Slovakia, Alza.sk. I believe they supply a limited number of musical instrument products via Muziker here. But as I said, you will be able to find this pedal anywhere. Micro Amp is available at Thomann, Reverb and Amazon on any day of the year!
Check out MXR Micro Amp on Thomann here
You can also check out your local marketplace on Facebook, eBay or any other local websites specific to your location for the used ones, as well as Reverb.com. It’s not always easy to find used ones for a good price, as it’s very easy to buy a brand new one at an affordable price tag.
Check out MXR Micro Amp on Reverb here
Also, please check out Amazon, as MXR pedals are widely available and might be a better option for some of my visitors.
Check out MXR Micro Amp on Amazon here
Thanks for visiting my blog and supporting me so far! I will hopefully see you in the next review here!
