MXR M281 Thump Bass Preamp Pedal

Enhance your groove with MXR! The MXR M281 Thump bass preamp helps you punch up your bass signal in the mix with amazing tone-sculpting options to boot.

The MXR Thump Bass Preamp is a tone-sweetening, signal-boosting, and altogether groove-enhancing machine. This pedal was conceived when the MXR design team and our in-house bass players discovered that the Echoplex Preamp's sonic secret sauce made for just as delectable a pairing with bass as it does with guitar. Using that circuitry as a foundation, the MXR team added a simple yet potent tone-shaping interface so that you can dial in the perfect bass sound for the stage and the studio.

Crafting the sound you need is easy. The Echoplex Preamp circuit conditions your signal with a carefully balanced EQ profile, and this pedal's tone controls let you take it from there. The Treble and Bass knobs cut or boost frequencies at 8 kHz and 40 Hz respectively, while the Mid knob cuts or boosts the midrange as set by the Frequency knob, from 250 Hz to 1 kHz. This range of frequencies was selected to give players maximum flexibility and minimal fuss when refining their bass signal.

Check out what the MXR Bass Thump can do:

Whether you need to punch up a solo, boost your signal in a live mix, or sculpt more edge into the sound of a passive bass, the Thump Bass Preamp packs incredible versatility into an MXR mini housing.


- All the tone-sweetening versatility bass players need in an MXR mini housing
- Combines the Echoplex Preamp with a three-band EQ and mid-frequency adjustment
- Punch up a solo, boost your live signal, or sculpt a more aggressive edge onto a passive sound
WARNING: Cancer and Reproductive Harm -

Dimensions and Weight in Packaging
Base Item
Shipping Weight: 0.5 lbs
Shipping Dimensions: 6 x 5 x 3 in
Manufacturer Part Number (MPN): M281

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

Reviewers gave this product an overall rating of 5 out of 5 stars. (1 ratings)
Submitted April 8, 2021 by a customer from
"Best bass booster"
Overall: 5 out of 5 stars
(see rating details)
Verified Customer zZounds has verified that this reviewer made a purchase from us.
Im a guitar player turned bassist, i try to have the same approach for both instruments, so an always on boost pedal is an essential part of the setup. Always loved the microamp+ampeg combo, w the right amount of grain, so when the mxr mini boost came out I immediately bought it. I was using it w my tech 21 vt bass plus a dynacomp mini. It was the greatest combo. Played w it for a couple of years then i got the geddy lee preamp pedal and quit my band and then covid happened. I got this thump pedal right around this period because i always wanted to control of the mid frequency, and so far I haven’t even found a pedal even for guitar that would do this in a musical way. This pedal nails it. The gain is almost as microamp as my mini booster, good enough for me and it really cuts thru any mix, i tend to use the mid freq all the way to the left and maybe a little more depending on the room. Which so far has been mine and one stage. So overall i think this pedal is perfect for me, i dont see my self playing without it. So much that on my last gig i forgot to bring my daysi chain cables so i could only use one pedal w my adapter ibran 3 blocks to get a 9 volt for the tech21 and im so glad i did. Btw the geedy lee preamp is great but lacks a little volume. So the thump is a must
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