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MXR M238 ISO-Brick Power Supply Unit   

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The MXR Iso-Brick Power Supply is small and light with tons of quiet, noise-free DC power on tap ready to run a wide range of pedal types without cro...Read More

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See All MXR Amplifiers & Effects Power Supplies

Power your pedals without any hassles and save some much-needed space on your pedal board.

The MXR Iso-Brick Power Supply is small and light with tons of quiet, noise-free DC power on tap ready to run a wide range of pedal types without crowding or weighing down your pedal board.

Each of the Iso-Brick Power Supplys 10 outputs is fully isolated, eliminating gig-ending ground loop noise. Whether analog or digital, positive or negative ground, this power box has you covered. The MXR team broke down these 10 outputs to accommodate a variety of voltage and current requirements: two 9V outputs at 100mA, two 9V outputs at 300mA, two 9V outputs at 450mA, two 18V outputs at 250mA, and two variable outputs adjustable from 6V to 15V at 250mA. The two variable outputs can be used to emulate voltage sag, a drained battery effect sought by many vintage tonechasers.

On top of all that, the Iso-Brick Power Supply comes in a small, lightweight housing thats built like a tank. Features power on/off and connection status LEDs. Put this little box on your pedal board to make sure it runs reliably and quietly gig after gig.

  • Pedalboard-friendly size
  • 10 fully-isolated outputs
  • Quiet, noise-free operation
  • Powers a wide range of pedal typesdigital and analog, positive and negative ground
  • (2) 9V outputs @ 100mA, (2) 9V @ 300mA, (2) 9V @ 450mA, (2) 18V @ 250mA, and (2) variable outputs adjustable from 6V to 15V @ 250mA
  • Variable outputs can be used to emulate drained battery effect

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Review Snapshot

by PowerReviews
MXRM238 ISO-Brick Power Supply Unit

(based on 2 reviews)

Ratings Distribution

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  • 1 Stars



Reviewed by 2 customers

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(4 of 4 customers found this review helpful)


Good for the price, minor issues with some pedals

By Andrew Meyer

from Oak Lawn, IL

About Me Quality Oriented

Verified Reviewer


  • Good Value
  • Powerful


  • Inconsistent Performance

Best Uses

    Comments about MXR M238 ISO-Brick Power Supply Unit:

    I got mine brand new on eBay (most sites won't have them in stock for at least a month), had it about a week now. I mainly got it because I added an MXR 10-band to my board and didn't want to deal with a separate 18v power supply on top of my old One-spot. Pros: this thing puts out a lot of power for the price; the 10 inputs are well thought out, and provide a lot of flexibility. It's smaller than I was expecting, and could easily mount underneath my pedalboard. My One-spot wasn't incredibly noisy, but the Iso-brick seems to have cut out some of the little hisses and squeals I would get when running a lot of effects.

    As for the cons, they don't have to do with the unit itself so much as the adapter and DC connectors. The cord on the adapter is only about 5 feet long, which means I'll have to run an extension cord out to my pedalboard in most gigging situations. It also feels pretty flimsy; nothing like the beefy cord on my One-spot. If it actually were a decent length, I'd probably worry constantly about it getting damaged. The DC connectors feel just as flimsy as the adapter cord, and don't seem to fit the inputs on my Boss and Electro-Harmonix pedals; when running them right into these pedals, the LEDs light up very weakly and the pedals are very noisy, if they work at all. I've currently got my One-spot's daisy chain running from the Iso-brick to remedy this, as it seems to make a more solid connection. I'll probably be buying better connectors in the future.

    Overall I'd still say it's a good buy; just be prepared to replace the DC connectors as they may not fit all pedals perfectly.

    • Primary use:
    • Personal
    • Was this a gift?:
    • No

    (3 of 3 customers found this review helpful)


    Excellent product on first impressions

    By KDMD

    from Corvallis, OR

    About Me Quality Oriented

    Ask me a question


    • Good Value


      Best Uses

        Comments about MXR M238 ISO-Brick Power Supply Unit:

        I just picked this up from my local music store. I'd been waiting for it to be released for some time now as it looked like a great value and on first impressions it would appear to be as expected. I had some concerns that it might be too tall to be mounted under a pedaltrain board, but that is no problem. I have it mounted under a pedaltrain PT JR with the stock mounting brackets and it fits fine. The bracket only had to be bent very slightly to get the bracket to screw down flush to the underside of the board as they're designed for the slightly shorter voodoo lab power supplies. Screwing it in was all the force needed to bend it down. It holds the unit in place snugly. I would technically give this a 4.5 star rating because of only two complaints. On the pedaltrain board, once mounted, the upper row of plugs are too close to the board rail to use the straight plugs on the cords, so you have use the right angle side on the unit and the straight plugs into your pedals. The lower row is clear to use either, though.

        The only other complaint is the power cords seems a bit flimsy, not a robust, rubberized cord but rather just a thin wire AC adapter. Doesn't seem to be a bid deal, though, as I am running seven pedals on it currently and I get no noise and reliable powering of all of my pedals. Bottom line, I'm glad I waited on this unit to be released (my backup plan was a voodoo lab 4x4) which thus far seems to be an excellent value.

        • Primary use:
        • Personal
        • Was this a gift?:
        • No

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