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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 crowding or weighing down your pedal board.

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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 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
All pedals - one year parts and labor warranty.

  • Customer Reviews

Review Snapshot

by PowerReviews
MXRM238 ISO-Brick Power Supply Unit

(based on 3 reviews)

Ratings Distribution

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Reviewed by 3 customers

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Good isolated power supply for the money!

By Victor

from undisclosed

Verified Buyer

Comments about MXR M238 ISO-Brick Power Supply Unit:

After researching the various pedalboard power supplies, the ISO-Brick seemed to offer the best bang for the buck for me. It has a generous number of isolated DC outputs (10 total). I was particularly impressed that there was a generous range of amperage ratings for the 6 dedicated 9V outputs that were available (2x100mA, 2x300mA and 2x450mA). While the 100mA outputs are adequate for overdrives and some other analog pedals, the 300 and 450 mA 9V outputs are particularly helpful for driving digital pedals. I have a variety of TC Electronic pedals, so the additional amperage compared to competing products was an important selling point for me. The ISO-Brick also offers two 18V/250mA outputs, which works great for my Pigtronix Tremvelope. There are also two variable voltage outputs (6-15V) rated at 250 mA. Each of these two outputs have a tiny pot to adjust the voltage and the only marking between 6-15V is for 9V. I would have preferred at least one dedicated 12V output at greater than 300mA to drive my TCE Nova Repeater. Instead, I am using a 9V 450mA output for the Repeater. The lower voltage limits the headroom the Repeater but it is rated from 9-12V and seems to work fine. My ISO-Brick came with ten 26-inch end-to-end DC supply cables. These cables seem to be reasonably good quality. Given the variety of outputs and the potential for confusion when connecting a bunch of pedals, color-coded cables and outputs would have been a nice touch but a little bit of colored electrical tape did the trick for me. I also appreciate that the ISO-Brick has a bright blue LED for each output to verify each is connected to a pedal. All in all, I am very pleased with the ISO-Brick. It does its job for minimizing noise and allows you to connect up to 10 pedals.



By SonnySoul

from Norway

About Me Quality Oriented

Verified Buyer


  • Reliable Performance


    Best Uses

    • High-End Equipment
    • Travel

    Comments about MXR M238 ISO-Brick Power Supply Unit:

    I love it!
    It is easy to understand and is really pedalboard friendly :)

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

    (2 of 2 customers found this review helpful)


    Great value, plenty of power, slight issues with connectors

    By Andrew Meyer

    from Oak Lawn, IL


    • Powerful
    • Small
    • Versatile


    • Cheap connectors
    • Short Adapter Cord

    Best Uses

      Comments about MXR M238 ISO-Brick Power Supply Unit:

      I've had this 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.

      • Was this a gift?:
      • No

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