MXR M-238 Iso-Brick

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$127.81 to $179.99

5.0 (57)

2 Critic Reviews

9 Reviews

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17 community setups

17 wishlisted

160 saved

Page last updated Jul 04, 2026

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4.0 (64)

$179.99

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4.5 (20)

$179.99

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4.6 (224)

$179.99 New

$158.39 Used (Like New)

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5.0 (119)

$127.81 80 available New

$110.00 15 available Used

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5.0 (12)

$179.99

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5.0 (4)

$179.99

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$166.00

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£169.00

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Price History

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Description

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Introducing the MXR M-238 Iso-Brick, your reliable companion for a noise-free, versatile, and efficient pedal power supply. This compact and lightweight powerhouse is designed to accommodate a broad spectrum of pedal types, ensuring smooth gig after gig performance without overcrowding or weighing down your pedalboard.

This power supply sports 10 fully isolated outputs effectively eliminating the dreaded gig-ending ground loop noise. Each output is meticulously engineered to handle a variety of voltage and current requirements, giving you the freedom to run analog or digital, positive or negative ground pedals.

Two unique variable outputs can be adjusted from 6V to 15V at 250mA, offering the ability to simulate voltage "sag", a sought-after effect by vintage tone enthusiasts. Crafted in a robust and lightweight housing, the Iso-Brick Power Supply comes with power on/off and connection status LEDs, ensuring your pedalboard runs reliably and quietly gig after gig.

Key Features:

10 fully-isolated outputs for noise-free operation
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
Two adjustable variable outputs from 6V to 15V at 250mA for emulating voltage "sag"
Compact and lightweight housing designed for durability
Power on/off and connection status LEDs for ease of use
Versatile design suitable for both analog and digital pedals
Suitable for both positive and negative ground pedals.

Product specs

Type	Pedalboard Power Supply
Inputs	18V DC (AC adapter included)
Outputs	2 x 9V 100mA, 2 x 9V 300mA, 2 x 9V 450mA, 2 x 18V 250mA, 2 x Variable 6V to 15V 250mA
Connectivity	2.1mm barrel, center negative
Isolated Output	Yes
Height	1.8"
Width	4.7"
Depth	2.9"

FAQs

Does the MXR M-238 Iso-Brick Power Supply provide isolated outputs?: Yes, the MXR M-238 Iso-Brick features 10 fully isolated outputs, which help eliminate ground loop noise and ensure quiet operation for your pedalboard.
What types of outputs does the MXR M-238 Iso-Brick offer?: The Iso-Brick provides a variety of outputs: two 9V 100mA, two 9V 300mA, two 9V 450mA, two 18V 250mA, and two variable outputs ranging from 6V to 15V at 250mA.
Can the MXR M-238 Iso-Brick power both 9V and 18V pedals?: Yes, the Iso-Brick is equipped with multiple 9V and 18V outputs, making it versatile for powering different types of pedals on your board.
What is the size of the MXR M-238 Iso-Brick Power Supply?: The MXR M-238 Iso-Brick measures 4.7 inches in width, 1.8 inches in height, and 2.9 inches in depth, making it compact for easy integration into your pedalboard setup.
Does the MXR M-238 Iso-Brick come with an AC adapter?: Yes, the Iso-Brick includes an 18V DC AC adapter, ensuring you have everything needed to power your pedals right out of the box.

Videos

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jimdunlopusa

MXR Iso-Brick Power Supply

jimdunlopusa

NAMM 2015 - MXR Iso Brick Power Supply | GEAR GODS

Trey Xavier

MXR iso-brick power supply unboxing / demo

therockstudio

GearReview MXR Iso-Brick

Theo Browning

MXR ISO Power Brick M238 Before & After Sound Comparison Demo

T Moody

MXR ISO brick test

chris tian

Are Isolated Power Supplies Legit? - MXR Isobrick Demo & Tutorial

Andrew Siemon

Reviews

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PROS

Compact design easily fits under pedalboards
Reduces hiss and noise compared to daisy chain power supplies
Offers multiple voltage outputs for versatile pedal powering
Two adjustable outputs (6V to 15V) ideal for specific voltage needs
Can power high-demand pedals like Strymon
Eliminates noise issues from off-grid or backup power sources
Solid build quality ensures reliability
Includes necessary DC to DC cables

CONS

Adapter and DC connectors feel flimsy, may need replacement
Short power cord requires extension in many setups
Power cords perceived as thin and not robust
Some difficulty fitting connectors in tight pedalboard setups
Potential for power surges damaging pedals
Not all outputs support 9V, limiting the number of pedals powered

Owner Insights

We analyzed real musician discussions from forums and Reddit to find what players love, question, and tweak about MXR M-238 Iso-Brick.

Features and functionality

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The MXR Iso-Brick includes variable voltage and 18V ports, which some users mark with colored tape to avoid accidental misconnection with 9V pedals.
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Owners appreciate the compact size of the MXR M-238, which offers multiple outlets despite its small footprint, making it suitable for densely-packed pedalboards.
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The Iso-Brick's 18V-only outputs are inconvenient for users without 18V pedals, requiring stepdown adapters for compatibility.
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The power plug on the mini Iso-Brick can be loose, causing disconnections with minimal movement, affecting its reliability during use.
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User experience

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Owners report that the Iso-Brick has been reliable for 5+ years, even during tours, with no major issues except for potential user errors in connectivity.
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Some users mention that the Iso-Brick ceased functioning after a few years, but this seems to be an isolated issue, possibly related to the wall adapter.
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Some owners experienced noise issues with the Iso-Brick, leading them to switch to alternatives like the BBE SupaCharger for quieter operation.
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Comparisons

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The Iso-Brick is noted to be more reliable than the DC Brick, which can suffer from interference and noise due to its daisy chain design.
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Some users recommend the Truetone CS-12 for its robust IEC14 connection and expansion capabilities, suggesting it as an alternative to the MXR M-238 for those needing more outlets.
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Owners who switched to the Friedman Power Grid 10 note its standard D-plug and no-frills power output as advantages, despite its higher price point.
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Use cases and applications

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The Iso-Brick is trusted by professional touring bands and has been used successfully in pedal trays within racks, indicating its reliability in demanding environments.
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Bedroom players find the MXR M-238 sufficient for static setups, appreciating its reliability when not subjected to frequent movement.
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A user successfully used both older and newer versions of the Iso-Brick, with one functioning reliably for over 10 years in different performance settings.
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Build quality

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The adapter's small jack connection is seen as a potential weak point, susceptible to damage from accidental tugs, with users preferring the sturdier IEC14 connection.
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Users report the power cable is thin and prone to fraying, causing mid-show cutouts and even minor electric shocks due to exposed wires.
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Critic Reviews

MXR Iso-Brick review | MusicRadar

musicradar.com

The MXR M-238 Iso-Brick is hailed as a power-packed solution for pedalboard enthusiasts. With 10 fully isolated outputs in a compact form, it accommodates a range of pedal power needs, from 9V to 18V. Its user-friendly design, powered by an 18V wall-wart, ensures a quiet, ground loop-free experience, making it a no-brainer choice for those looking to consolidate their pedal power supply. The review praises its versatility and value, but notes no significant drawbacks, making it a highly recommended option for guitarists seeking reliable power on their boards.

positive

Full Review

MXR M238 ISO Brick Review - Premier Guitar

premierguitar.com

The MXR M-238 Iso-Brick is a highly praised power supply unit, offering a compact and quiet solution for pedalboards. With ten fully isolated outputs, it's designed to eliminate noise and accommodate various voltage needs, including DSP pedals. The inclusion of international adapters makes it travel-friendly, and its stress-reducing features, like easy setup and voltage conversion, are notable highlights. While the review finds no faults with the unit, its versatility and convenience make it a standout option for musicians on the go. Overall, a stellar choice for those seeking reliable power with flexibility.

positive

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5.0 out of 5

Based on 9 Reviews and 57 Ratings

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drivingyen

6 months ago

Great Power Supply for pedals!

Overall very solid i heard people say the input jack to connect it to power was floppy but its not the case for me. its overall solid

Preferred Settings + Usage:

i use 18v to 9v adaptors to use more pedals

Roles:

Guitarist

Genres:

Rock Alternative rock Indie rock

juan_ferrari2006

633

about 1 year ago

Insanely great for what it was made of

Doesn't make any noise at all, and that's cool. A must-have for those who wants to build a pedalboard

Roles:

Singer Guitarist Composer

Genres:

Rock Latin Metal

henrico_gouvea

215

about 6 years ago

Great power supply

Compact and beautiful. Solved some of the unwanted noise and effects deviations I had with my previous non-isolated supply. Not sure why my delay pedal interacted with this power supply generating other noise. But I believe it can be fixed by better arranging the cables.

hamnotthefood

397

about 4 years ago

Great

Keeps my power clean, keeps my pedals powered, keeps my board lit up, I can’t complain.

Roles:

Singer Guitarist Bassist

Genres:

Rock Funk / Soul Jazz

axeman

224

over 10 years ago

Best Power Supply I've ever used.

Now when it comes to power supplies, what is there really to say? Does it provide power and is it reliable? Yes and yes. But to me, the big selling point to this one is not only does it have 9v and 18v plugs, but you can also adjust the wattage of each level. Why would you want to do that? Have you ever played a Big Muff or a ProCo Rat with a battery that's dying? Well to get that sound, you can just turn down the voltage to get something similar. Considering this has 8 9v slots on top of the volt adjusting, it justifies the price to me. Not to shabby at all for $150 brand new. You won't be disappointed.

foolishgenius

245

about 8 years ago

well worth every penny

one of the most intuitive pieces I lay claim to. Isolated power (and voltage) to fit virtually every piece you own. The only drawback is that all power pins come in one size but beside that, super solid investment.

miguel_angelo

984

almost 8 years ago

Small and POWERFULL

My whole board is powered by this little beast. 2x18V outputs and 2 variable voltage outputs allow for further experimentation with some pedals. No noise whatsoever.

Roles:

Guitarist

Genres:

Rock Orchestra Folk, World, & Country