MXR M238 Iso Brick Power Supply

Product ID: 105381
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  • Power supply for both analogue and digital effects units
  • Ten fully isolated outputs provide quiet, noise-free operation
  • Positive and negative ground compatible
  • Built-in thermal protection prevents overheating
  • Further protection provided against short circuiting
  • Status LEDs provide quick visual cues with regard to unit operation
  • Fixed voltage supply outputs as well as two variable voltage outputs
  • Discrete dimensions allows the power supply to slot into any pedalboard
  • Built to MXR's customary high standards of quality
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Delivery to UK mainland addresses* is FREE on orders over £75 and up to 30kg. (As a guide, a standard electric guitar weighs approx. 3-5kg).

Delivery on orders below £75 are charged at £4.45!

Delivery to Northern Ireland, the Scottish Highlands & Islands, Isle of Man, Isle of Wight and Channel Islands is weight dependant and will be indicated at the checkout

Delivery above 30kg to ANY location will vary according to weight and will be indicated at the checkout

LocationPriceStandard Delivery
UK mainland* FREE on orders over £75 £4.45 on orders under £75 1-3 working days
Northern Ireland, Scottish Highlands & Islands Isle of Man Isle of Wight Channel Islands £12.95 – any order value up to 30kg Over 30kg - please call 1-3 working days
Overseas Please call for details Please call

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The MXR M238 Iso-Brick Power Supply for guitar and bass effects pedals is a small yet perfectly formed must-have for any studio session or gig. Guaranteeing consistent power to your pedals is essential, and you can rest assured that the team at MXR have put their all into the design and manufacture of this diminuitive workhorse. However, busy though your pedalboard may be, the discreet dimensions of the Iso-Brick power enables it to slot into any setup with ease. The Iso-Brick works quite happily with analogue and digital pedals, as well as positive or negative ground inputs.

10 Fully Isolated Outputs

The Iso-Brick puts 10 fully isolated outputs at your disposal. The benefit of fully isolated outputs, means that as there is no common electrical connection between them, ground isolation is assured between power sources. Therefore, unwanted noise loops are eliminated, and for those who like to employ high gain can do so without worrying about their tone becoming swallowed whole by noise. It also means that interference from one pedal can't corrupt the integrity of any other pedal that is connected.

Stable, Low-Noise Voltage Control

As well as individual output isolation, each fixed voltage output is supplied with a stable, low-noise voltage source by employing linear regulators. A hybrid design carries out the task of regulating supply to the variable outputs, in order to simulate the smooth output of an adjustable linear regulator. Thanks to this nifty bit of electronic wizardry, heat and power loss in the circuitry is minimised, whilst preserving the integrity of the output voltage supply - guaranteeing smooth operation throughout the most intense of performances.

Should the unexpected happen, MXR have included an automatic shutdown if the Iso-Block approaches unsafe operating temperatures, and output protection provided against the chances of short circuiting. You can play to your heart's content, safe in the knowledge that your gear is in the best hands.

Selection of Power Supply Options

With varying voltage and current supply options to match the voltage and current requirements of your pedals. For example, digital pedals require more current than analogue pedals. The team at MXR has equipped the Iso-Brick with six 9V outputs: two at 100mA; two at 300mA; and two at 450mA. The 100mA outputs will satisfy the appetite of most 9V analogue pedals; the 300mA and 450mA outputs are more than capable of supplying digital pedals with all the juice that they need.

Two 18V outputs and two variable 6V-15V adjustable outputs are rated at 250mA, which still provides ample power for digital pedals. The variable outputs can be used to simulate "sag" or the effect of a dying battery, which can be used with wide ranging results on your overdrives, distortions, fuzzes, and wah pedals.

Visual Status LEDs

Each output features an LED. When it is BLUE, the connection is working at its optimum capacity. If the output is short-circuiting or overloaded, the LED will switch off. When performing on a dark stage, you can easily identify where any problems may lie, and rectify it quickly. The input supply LED has two states: when it is WHITE there is a good input power connection; when it is RED then there is a bad input power connection.

If you’re looking for an efficient, noiseless and reliable power supply for your pedalboard setup, then the MXR M238 Iso-Brick Power Supply is the perfect choice.

Manufacturer MXR
Model M238 Iso-Brick Power Supply
Input18V at 2 Amps: regulated supply (positive barrel negative center 5.5mm x 2.1mm plug)
Output 6-15V @ 250mA (x 2)
18V @ 250mA (x 2)
9V @ 450mA (x 2)
9V @ 300mA (x 2)
9V @ 100mA (x 2)

(all positive barrel negative center 5.5mm x 2.1mm)
Posted on 09/01/2017 by Stoofer Functionally, this unit is great and stylish - nice.

I would have preferred that the 18V connectors were harder to use by mistake... perhaps having them "physically" away from the others rather than mixed in the middle of the 9V supplies. I've ended up just putting tape over the 18V supplies as none of my pedals can use them in order to avoid a potentially expensive mistake.

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