MXR M87B Bass Compressor Blackout Series Pedal

A stealth-finished compressor with MXR pedigree, MXR's M87B Blackout Series bass compressor offers recording-quality compression and a black finish.

The MXR M87B Bass Compressor Blackout is dressed in a stealth finish! These Blackout Series pedals feature a matte black housing with gloss black text and a bright yellow LED. Same great tone and durability with a classy look that will hold down the look and tone of any pedalboard.


- The Bass Compressor provides recording-quality compression with Constant Headroom Technology(TM)
- True bypass switching for keeping your low end tight and clean
- This pedal can be powered by a 9-volt battery, a Dunlop ECB003 9-volt adapter, or the DC Brick(TM), Iso-Brick(TM), and Mini Iso-Brick(TM) power supplies (not included)
WARNING: Cancer and Reproductive Harm -

- Input Impedance: 1 MOhm
- Output Impedance: 600 Ohm
- Max Input Level: +14 dBV
- Max Output Level: +8.5 dBV
- Freq. Response: +/-1 dB, 20 Hz to 20 kHz
- Noise Floor: * -90 dBV
- THD: ** > 0.5%
- Gain: 31 dB
- Compression Ratio: 4:1, 8:1, 12:1, 20:1
- Attack Time: 20 us to 800 us
- Release Time: 50 ms to 1.1 s
- Current Draw: LEDs OFF 14 mA
- Current Draw: LEDs ON 19 mA
- Power Supply: 9 volts DC
Dimensions and Weight in Packaging
Base Item
Shipping Weight: 0.75 lbs
Shipping Dimensions: 6 x 5 x 3 in
Manufacturer Part Number (MPN): M87B

For support or warranty questions, please contact the manufacturer:
Phone: 707-745-2722

Reviewers gave this product an overall rating of 4 out of 5 stars. (1 ratings)
Submitted October 31, 2023 by Russell

"Powerful and transparent"

Overall: 4 out of 5 stars
(see rating details)
Verified Customer zZounds has verified that this reviewer made a purchase from us.
Written by one of our gear experts!
You can do a lot with this compressor thanks to the amount of controls given, and the amount of range the input and output knobs cover. You won't miss having a whole knob for the threshold either, as the four settings cover all the ground you'd want between subtle smoothing and peak limiting. You can dial in a lot of sustain with the release knob as well, but the attack knob is still pretty fast even at the lowest setting (to the left is slowest attack, like on a 1176 type unit). I do wish the attack could be set slower, but it left enough transient for me to work with set all the way down. The input knob has a huge range, so you can comfortably put it in any part of your signal path or behind a loud preamp with ease. This makes this knob very sensitive to adjustments, though. It definitely lets enough low end through and doesn't lose high end, even with very extreme settings. The gain reduction meter is the best feature as only much more expensive units have such accurate metering, so you can really see what you're doing to the signal with it. Overall it's the most transparent compressor I've tried; it brings out detail without pumping or softening the signal, making it ideal for running into an overdrive pedal for more distorted styles. If you like your tone and just want more of it, this is the pedal to get.

Musical Background:

20+ years playing bass

Musical Style:

Hardcore punk
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