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MXR M87 Bass Compressor Review

Compressors fit into a range of effects that apply to dynamics. In musical terms, the dynamics are about how quiet or how loud a signal is. A compressor’s function is to affect and controls dynamics.

It changes the dynamic of the signal and hence the volume. In other words, it squeezes or compresses the range of a signal.

So, let’s go through our in-depth MXR M87 Bass Compressor Review to find out more about one excellent option that could well find a place on your pedalboard…


How does it work?

It will reduce the volume of notes that are too loud within a range that you have set. Once you reach the apex of the range, the compressor prevents the volume from going any higher. This also has the effect of allowing quieter notes to be boosted. That also means that the overall volume will be higher.

Is there a difference?

Yes, there is. Using only a relatively modest amount of compression can give your bass a bit more. A smoother tone but still with plenty of punch. However, use too much, and your bass sound will become flattened in tone and rather lifeless. Too much, and you lose that ‘edge,’ and the compression will become very noticeable.

Compression has even more of an impact when used by bassists who slap. The playing style can be notoriously uneven in output. It wouldn’t have worked well without compression. The more dynamic and aggressive the playing, the more compression has an influence. But as we say, don’t overdo it.

Unglamorous as it is…

It is one of the best effects pedals for bass guitar these days, especially on stage. At one time, it was a studio-only thing. Now we can carry them around. It isn’t the most glamorous of effects, but it is one of the most necessary. No matter what style you play, it is easily one of the best bass pedals you can buy.

This MXR M87 Bass Compressor comes from a company with a pedigree for producing great pedals in other areas, especially for guitar. But how do they get on when it comes down to the engine room of the band? We’ll find out, but first, let’s get to know MXR.


They were originally set up in 1972 in New York by a couple of school friends. Initially, they worked out of a basement apartment. However, it didn’t take long for them to make their mark.

The famous Phaser…

Their first serious attempt at a pedal produced the four-stage Phase 90. This was a pedal used by Eddie Van Halen on his first two albums. They followed this up with the Dyna Comp. This also met with success and became one of the most sought after compressors of its time.

Two years after the Phase 90 came the two-stage Phase 45. Another successful phase pedal with a different sound and was aimed at a different market. The MXR M87 Bass Compressor has become another successful compressor from MXR. So, let’s have a closer look…

MXR M87 Bass Compressor
Our rating:4.4 out of 5 stars (4.4 / 5)


There are a good number of bass guitarists whose only contact with a compressor might be in a recording studio. No shame in that. It is only relatively recently that there have been quality portable options available for everyone.

MXR’s aim with the M87 was to put studio quality compression on your pedalboard. It certainly offers a range of functions with plenty of controls that put you in charge of the sound.


Otherwise known as “Constant Headroom Technology” will make sure there is adequate headroom. Headroom is a measure of voltage swing above what you would usually use. Having plenty of headroom allows you to use a signal that is much stronger but without any distortion.

What you don’t want to happen when using compression is for your bass to lose its character, in other words, to alter the sound. The sound of the bass is paramount. And the transparency of the M87 will not let your sound be compromised by the compression you use.

The Build

Certainly can’t argue with the styling of this pedal. It has a certain chic to it with its white finish. However, it might not look quite so good after a few months of heavy stomping. But new and out of the box, it looks great. And to add to its style, it has a blue LED that illuminates when the pedal is active.

Durable and light…

It has a strong all-aluminum build measuring 2.6 by 5.5 by 4.4 inches. Aluminum means it is also going to be lightweight. The ¼ inch jack sockets for in and out connections are placed on either side. The footswitch also has a sturdy build quality.

Five control knobs that are positioned for easy use and an LED panel with ten lights. They are easy to see and tell you when the threshold of your compression has been reached. Likewise, it features True Bypass. A fairly standard build quality that is tough enough to do the job.

The Controls

The control knobs are not too big to make them difficult to use. Sometimes on some pedals, you can hardly get your fingers in between the knobs for slight adjustments. There should be no problem with these.

There are five controls, each handling a different aspect of the sound. Attack, Ratio, Release, Output, and Input. As a group of controls, it makes it a simple operation to fine-tune the sound you are looking for. Furthermore, these controls, along with the LED display, make it one of the best bass compressor pedals on the market today.

Illuminated LED…

The LED display we have mentioned shows the status of the threshold of what you have previously set. This we feel is an important inclusion. Not only does it show how close you are to your threshold, but it also acts as a guide to your playing style. You will be able to pick out the areas where you exaggerate the action. Quite useful in developing better techniques.

The Performance

Certainly, an area that is the real issue. Someone once said that “a bass compressor should be felt rather than heard.” Quite right. This is one of those times that you are going to have to sit down and work out how to get the best sound for you.

The M87 is completely transparent. This will let the dynamic range of your instrument excel until you reach the threshold. As we have already said, you will know when you are reaching the threshold via the status LEDs.

You will have plenty of headroom to work with, courtesy of the CHT. There will be some variations, though, with certain instruments.

Active or Passive pickups?

You will get a hotter signal if you are using a bass with active pickups. Therefore, it has to be taken into account whether you are on a passive or active bass.

However, we have to say it is one of the more expensive pedals you will come across. But it is just a case of deciding how much improvement it will make to your overall sound. If it makes a big difference, it is a small price to pay for a premium bass compressor.

MXR M87 Bass Compressor Review – Pros and Cons


  • Good strong aluminum build.
  • Nice looking design.
  • Easy to use controls.
  • LED display to tell you when you are reaching your threshold.
  • Completely transparent sound.
  • Good headroom.


  • Some may consider it a little expensive.

Looking for Something Else?

Effects pedals aren’t the only way to improve the sound of your bass guitar, but they certainly can help. So, have a look at our in-depth reviews of the Best Bass Distortion Pedals, the Best Bass Amps, the Best DI Boxes for Bass, the Best Jazz Bass Pickups, and the Best Precision Bass Pickups that you can buy right now.

Likewise, you may find it’s time for a new bass guitar. If so, check out our in-depth reviews of the Best Bass Guitars, the Best Acoustic Bass Guitars, the Best Beginner Bass Guitar, the Best Short Scale Bass Guitars, and the Best Left Handed Bass Guitar currently available in 2023.

MXR M87 Bass Compressor Review – Final Thoughts

If you want the best sound you can get from your bass; then the reality is that you need a good compressor. Having a quality compressor will work wonders for your bass sound. It will flatten out those little power surges that you automatically get at times.

MXR M87 Bass Compressor

If you and the people you work with expect a quality performance with no booming peaks and disappearing troughs, you will need a compressor. This is an essential bass pedal that offers plenty of scope to create the sound you want. In fact, it could well prove to be the missing link in your sound.

Until next time, as always, it’s all about the bass.


To find out all about Art as well as our other writers, check out our About Us page.

5/5 - (16 votes)

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About Corey Hoffman

Corey is a multi-instrumentalist who has played in numerous bands over the years, some good, some not so good. He has also written countless songs and recorded five albums in professional studios across America. Today he is a hobby musician but still loves the guitar after over 15 years of playing.

He considers his writing as a way to share what he has learned over the decades with younger generations ad always can't wait to get his hands on the latest gear.

He lives just outside New York with his wife Barbara and their two German Shepherds, Ziggy and Iggy.

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