DC Brick for a board of analog pedals; Iso-Brick, or the Mini Iso-Brick for a small board, the moment there's a digital pedal on it, because the isolated outputs are what stop the hum. All three MXR supplies are on our wall as of September 25, 2026, the DC Brick and the Mini Iso-Brick at $105.99 each and the Iso-Brick at $179.99, each with Dunlop's ECB009 18-volt adapter in the box.
- What isolated means, and why a daisy chain hums
- The three on our wall, side by side
- MXR M237 DC Brick
- MXR M239 Mini Iso-Brick
- MXR M238 Iso-Brick
- What a board of our Boss and MXR pedals draws
- Which one is yours
- Questions about the MXR bricks
- Voltage, current and the lights
What Isolated Means, and Why a Daisy Chain Hums
A daisy chain puts one supply's ground into every pedal, and a digital pedal on that chain hums. MXR's answer is isolated outputs: Dunlop rates all ten on the Iso-Brick and all five on the Mini as fully isolated, for analog or digital pedals, positive or negative ground.
Asked which power problem he sees most on the boards that come in, Paul's answer was short: "Daisy chains, not isolated power bricks."
The DC Brick is the plain one: eight 9-volt outputs and two 18-volt outputs, short-circuit protected, not isolated, right for a board of analog pedals. Dunlop's manual shows where the shared ground bites: the M237 is not compatible with positive-ground pedals, and plugging one in may cause a short circuit. That is the whole decision. Count the digital pedals on the board. None, DC Brick. One or more, an Iso-Brick.
The Three on Our Wall, Side by Side
Dunlop's MXR catalog lists four power supplies, and three of them are on our wall. The fourth, the Iso-Brick Pro, is the big-board unit, with a 9V output at 1.5A for a multi-effects processor and an 18V link output at 2.0A that feeds a second brick; Dunlop's own store showed it out of stock on September 25, 2026, and when Dunlop has it available we can order one, in 1–2 weeks at most, final sale. Prices are ours.
| DC Brick | Mini Iso-Brick | Iso-Brick | |
|---|---|---|---|
| Isolated | No | Yes | Yes |
| 9V outputs | Eight, an average of 150 mA each, 1200 mA in total | Four at 300 mA each | Six: two at 100 mA, two at 300 mA, two at 450 mA |
| 18V outputs | Two, an average of 400 mA each, 800 mA in total | One, switchable 9V or 18V, 800 mA | Two at 250 mA |
| Variable voltage | None | None | Two outputs, 6V to 15V, 250 mA each |
| Positive-ground pedals | No | Yes | Yes |
| Price | $105.99 | $105.99 | $179.99 |
| Pick it for | An all-analog board, and the most outputs for the money | A small board or a travel board with a digital pedal on it | A full board, a positive-ground fuzz, or a pedal you want to starve on purpose |
MXR M237 DC Brick
- Outputs: eight 9V, two 18V, none isolated; up to 2000 mA in all
- Protection: short-circuit and overload protection, a red LED on each 9V output that lights on a short; not for positive-ground pedals
- Price: $105.99
The DC Brick is Dunlop's revamp of the DCB10, and for $105.99 you get ten outputs, the most of the three for the money, plus a red light that tells you which cable or pedal shorted.
What you don't get is isolation. The DC Brick's outputs are not isolated from each other, so it is the supply for a board of analog pedals; a digital pedal that hums on it wants the Iso-Brick. See the DC Brick.
MXR M239 Mini Iso-Brick
- Outputs: five, all isolated; positive and negative ground, analog or digital
- Splitter: the included splitter cable runs two pedals from one output, if both want the same voltage and together stay under its rating
- Price: $105.99
Same price as the DC Brick, half the outputs, and every one of them isolated. That is the trade, and the moment there's a digital pedal on a small board, it is the right one. The Mini Iso-Brick is the size of a candy bar with five isolated outputs, four at 9 volts and 300 mA and one switchable to 18 volts at 800 mA, enough for a digital delay or a multi-effect.
It is the supply for a small board or a travel board: five isolated outputs with real current, and the 800 mA output covers a digital delay or a multi-effect. See the Mini Iso-Brick.
MXR M238 Iso-Brick
- Outputs: ten, all isolated; positive and negative ground, analog or digital, with noise-reduction circuitry
- Variable outputs: two, adjustable from 6V to 15V, 250 mA each
- Price: $179.99
The Iso-Brick has ten isolated outputs, including two at 18 volts and two variable from 6 to 15 volts, which run a fuzz at a starved-battery voltage on purpose. One caution from the manual: not every analog pedal will operate below 9V, so check the maker's range first.
The six 9-volt outputs are rated in pairs, and Dunlop's rule is that a pedal's mA rating must not exceed its output's, so the digital pedals go on the 300 and 450 mA pairs. It is the only one of the three with room for ten pedals, and, with the Mini, one of the two that accept a positive-ground pedal. See the Iso-Brick.
What a Board of Our Boss and MXR Pedals Draws
Every Boss compact on the wall except the adapter-powered TU-3S runs on a 9-volt battery or Boss's PSA adapter, sold separately, and the current draw decides which one you'll want: the DS-1 and SD-1 sip 10 mA and last on a battery, the DD-8 pulls 100 mA and the RV-6 95 mA, which is adapter territory. Here is a six-pedal board from the wall, every draw from boss.info.
| Pedal | What it is | Current draw | Price |
|---|---|---|---|
| Boss TU-3 | Chromatic tuner | 20 mA; 80 mA in High Brightness mode | $109.99 |
| Boss SD-1 | Super OverDrive | 10 mA | $69.99 |
| Boss DS-1 | Distortion | 10 mA | $69.99 |
| Boss CE-2W | Waza Craft chorus, all-analog | 25 mA | $241.99 |
| Boss DD-8 | Digital delay | 100 mA | $197.99 |
| Boss RV-6 | Reverb, digital effects with an analog dry path | 95 mA | $153.99 |
Add the six together and the board draws less than any one of the Mini Iso-Brick's four 9V outputs is rated to carry by itself, so the Mini runs it, with the SD-1 and DS-1 sharing one output through the splitter cable. The DC Brick could carry the current, too. What it can't do is keep the DD-8 and the RV-6, both digital, off the ground the other four share, and a digital pedal on that chain hums.
An all-analog board is where the DC Brick earns its keep. Boss calls the CS-3 a classic analog compressor and builds the BD-2W, CE-2W and DM-2W on all-analog circuits, and the Carbon Copy's audio path is completely analog: CS-3 20 mA, BD-2W 18 mA, CE-2W 25 mA, DM-2W 35 mA, Carbon Copy 26 mA. The five together draw less than the 150 mA average Dunlop gives a single DC Brick 9V output, with three 9V outputs and both 18V outputs still open, so the $105.99 buys outputs instead of isolation. A Duke of Tone on one of the 18V outputs, 6 mA and no battery option at all, runs with the extra headroom Dunlop describes at 18 volts.
The rest of the Boss wall, by draw: DS-2 15 mA, TR-2 25 mA, HM-2W 30 mA, MT-2 30 mA, TU-3S 30 mA, TU-3W 50 mA, CH-1 55 mA, BF-3 60 mA, FZ-5 60 mA, OC-5 60 mA, DC-2W 65 mA, DD-3T 70 mA, RE-2 75 mA, SL-2 95 mA, SY-1 115 mA, and the XS-100 at 160 mA, adapter only. The whole wall with prices is on Boss pedals in Glens Falls. The drives on that board are compared in Boss DS-1 vs SD-1, and the tuner in Boss TU-3 vs TU-3S vs TU-3W.
Which One Is Yours
- All-analog board, or the most outputs for the money: the DC Brick, $105.99.
- Small board or travel board with a digital pedal on it: the Mini Iso-Brick, five isolated outputs and a splitter for a sixth pedal, $105.99.
- Full board, a positive-ground fuzz, or a pedal you want to starve on purpose: the Iso-Brick, ten isolated outputs, two of them variable from 6V to 15V, $179.99.
- A multi-effects processor and room to grow: the Iso-Brick Pro, special order.
Bring the board. All three bricks are on the wall during shop hours, the Carbon Copy and the Duke of Tone are on the floor to play through an amp, and the MXR patch cables and ribbon patches hang beside them. Call or text (518) 217-8695 and we'll hold one for you.
Questions About the MXR Bricks
How much is an MXR power supply?
$105.99 for the DC Brick and for the Mini Iso-Brick, $179.99 for the Iso-Brick, as of September 25, 2026. The Iso-Brick Pro is a special order.
DC Brick or Iso-Brick?
DC Brick for a board of analog pedals. Iso-Brick, or the Mini Iso-Brick for a small board, the moment there's a digital pedal on it, because the isolated outputs are what stop the hum.
Will a digital pedal run on the DC Brick?
It will power up; a DC Brick 9V output carries an average of 150 mA, more than a DD-8 or an RV-6 draws. The problem is the shared ground, not the current: a digital pedal on that chain hums.
Does it ship?
Yes, within the U.S. Rates are on the shipping policy page, or pick it up at the shop, free. For Canada or anywhere else, contact us for a quote first.
What warranty does it carry?
Dunlop covers its electronics for one year from the date of purchase, directly or through the selling dealer, and asks you to register the product within 14 days of purchase to activate it. Keep the receipt.
Voltage, Current and the Lights
Three rules from Dunlop's manuals. Match the voltage: a 9V pedal fed 15V or 18V can be damaged, and Dunlop recommends staying at or below the maker's stated requirement. Watch the current: a pedal's mA rating must not exceed the output's. And read the lights before you pull plugs: on the DC Brick a red LED on a 9V output means that pedal or cable has shorted; on the Iso-Bricks the output's LED goes dark on a short or an overload, and the unit resets itself 5 to 10 seconds after the cable comes out.
When a hum survives an isolated supply, the supply is not the problem, and Dunlop's own troubleshooting step is the useful one: run the pedal off a battery. If the noise stays, it was never the supply. A Kramer aluminum-neck bass came through the bench with odd noises and buzzing that did not track with the pots, jack or switches; cleaning and a check of the connections and grounds did not stop it (the Repair Vault entry).
The bricks, the pedals and the MXR cables hang in MXR, sorted high to low. The rest of the cable wall is on guitar cables in Glens Falls, and buying MXR from us, warranty and special orders included, is laid out on Dunlop and MXR in Glens Falls.
All three bricks are on the wall now, next to the Carbon Copy and the Duke of Tone.
Paul's Guitar Hideout is located at The Shirt Factory in Glens Falls, NY. Use the Cooper Street entrance and take the stairs up. If stairs are difficult or you're bringing in something you don't want to carry up, call or text us and we'll arrange access.
The Shirt Factory
71 Lawrence St., Suite 201B, 2nd Floor
Glens Falls, NY 12801
Wednesday–Sunday, 12–5 PM
(518) 217-8695 · info@paulsguitarhideout.com