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MXR M87 Bass Compressor Review (2021)

The MXR M87 Bass Compressor is easily one of the best compressor pedals out there right now. That’s why we here at TONE START are incredibly excited to showcase all of the features and functions of this pedal to you. Without further ado, here is our MXR M87 Bass Compressor Pedal Review. 


  • CHT™ (Constant Headroom Technology) for clean and clear performance
  • A studio classic in an MXR pedal
  • Ten gain reduction status LEDs
  • Tough aluminium housing
  • True bypass
  • Compact design

MXR M87 Bass Compressor Pedal Review
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Below are a list of specifications for the MXR M87 Bass Compressor:

Pedal type


Compression ratio

4:1, 8:1, 12:1, 20:1


True hardwire

Power supply

DC 9 volt

Housing material



4-3/4 (H) x 2-3/4 (W) x 1-9/32 (D) inches


8.4 oz


If you’ve ever used a compressor pedal in the past then you’ll already know how they function. If you haven’t, then you should know they really aren’t too complicated to use. The MXR M87 features five knobs located on the front of the pedal corresponding to: RELEASE, ATTACK, OUTPUT, RATIO, and INPUT.

RELEASE – adjusts how quickly the Bass Compressor returns to uncompressed gain level

ATTACK – adjusts the time the Bass Compressor takes to respond to an input signal and reduce gain

OUTPUT – used to set the desired output level of the Bass Compressor

RATIO – sets the degree of compression, from mild 4 (4:1) to extreme 20 (20:1)

INPUT – adjusts the input signal level relative compression threshold and sets the amount of gain reduction

It really doesn’t take much time to understand how each knob impacts your sound. You’ll be able to have full control over the timing of your compression, and also the input level that triggers it too. On top of that the MXR M87 also features a meter that contains 10 easy-to-see LEDs referring to GAIN REDUCTION.

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GAIN REDUCTION METER – precisely displays gain reduction level and compressor response time when the input signal reaches the compression threshold

The LED meter is great feature that lets you know the level of input that needs to be dialled in. It also shows you when the compression is occurring, and how much compression is there. This is a great addition to the M87 that really solidifies it as a high-end bass compressor pedal.

If you are new to using any sort of compression then the meter is extremely helpful. It allows you have a clear visual indication of how much your signal is being compressed rather than only being able to hear it. This is an awesome touch for newer players.

The last thing we want to mention is the footswitch. You can use it to toggle the bass compression on, or leave the pedal in bypass mode. If you leave it in bypass mode your original sound will remain untouched and intact – just how you would want it.


I don’t think I’m the only one who thinks that bass compression is an underrated and often misunderstood effect.

Out of the box the MXR M87 comes packaged with a user manual, sticker, and a random advertisement pamphlet for other related effects pedals. Pretty standard stuff when it comes to the packaging of effects pedals in recent years. The manual will help you get the unit up and running in only a matter of minutes, but you will have to invest a little bit more time if you want to get the most out of the M87.

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One of the things I love most about bass compression pedals is that they really clean up the sound of your bass. This is one of the reasons why compression is such an important effect to add to your arsenal. Not only that, but they also make the life of your sound guys MUCH easier due to your peak volume remaining consistent during a sound check.

The bright blue LED light indicates whether the unit is turned on, or in true-bypass mode. These two modes can be toggled easily using the pedals footswitch.


The MXR M87 has the ability to fatten up your tone. If you’re looking to shape your sound a bit then the M87 will surely deliver.


Although it’s a bass compressor, it can be used for a variety of different purposes including vocals and guitar. The reason the pedal can be used for a variety of applications is because it’s a great studio-type compressor that is very compact and portable.


The M87 can be powered using a 9V battery, or a Dunlop ECB003 AC adapter/Dunlop DCB10 DC Brick power supply.


Nothing beats an effects pedal that feels solid and sturdy, and one that you know won’t break after two minutes of using it. Thankfully, the M87 feels incredibly well-built and robust. You can just tell this thing was built to last for many years to come. It’s perfect for use at home, on-stage, or on the road. There should really be no issues regarding the overall durability of the M87.

The unit is extremely compact and made from strong aluminium. There should be no troubles finding room for the M87 on your pedalboard due its small footprint.

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Like any other effects pedal how you rate their features comes down to your own personal preference. Hopefully we have given enough insight into the MXR M87 Bass Compressor to give you a good idea if it’s suitable for your needs.

The MXR M87 is a very versatile pedal that can easily tighten up your sound. It’s designed for use both in the studio and on-stage, and is constructed to be very durable and compact. The pedal may look quite intimidating at first due to its appearance, but it really doesn’t take too long to figure it out with the help of the product manual that’s included with the M87.

Overall, I can say with confidence that the MXR M87 Bass Compressor is definitely one of the best, if not the best bass compressor pedals out in the market right now. I strongly urge you to read the rest of the review to see just how much it offers. It’s a true gem that deserves all the praise it has received from the community.


Agree or disagree with our review? Let us know what you think in the comments below!


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