How to Power a Pedalboard

Powering a pedalboard means feeding every pedal on the board the voltage, current and polarity it was designed for, from one organized power system instead of a pile of wall warts. Get it right and the board is quiet and reliable. Get it wrong and you get hum, buzz, pedals that cut out, or in the worst case damaged circuits. EarthQuaker Devices puts the core rule plainly: "You want to always ensure the voltage from your power supply unit (PSU) matches the voltage of the pedal. Not doing so may damage the pedal."¹

The decisions that matter are three. First, what each pedal needs: most want 9V DC with a center negative plug, but 12V, 18V, 24V and even 9V AC pedals exist. Second, how much total current your board draws, since digital pedals in particular are hungry. Third, whether you share power across a daisy chain or give each pedal an isolated output. This page walks through each of those, the hardware involved, and the noise problems that show up when something is mismatched. For the bigger picture of laying out a board, see How to Build a Pedalboard.

What each pedal needs: voltage, current and polarity

Three numbers describe a pedal's power requirement, and all three appear in the pedal's manual or product page.

Voltage is the electrical pressure the pedal expects. Most pedals take 9V DC, but JHS Pedals notes that "a few other common power requirements" include 12V, 18V and 24V DC, and some pedals, like the Line 6 DL4, require 9V AC power². AC and DC are not interchangeable: a pedal built for DC will not run correctly on an AC adapter and vice versa. Some pedals accept a wide range. The 29 Pedals FLWR "will accept 7.5 to 35 volts of AC or DC in either polarity with absolutely no change in tone or power to the circuit"³, and the Master Effects DC3 uses a standard boss-style 9 to 18V power supply⁴. But range tolerance is a feature of specific designs, not a general rule.

Current, measured in milliamps (mA), is how much the pedal actually consumes. A supply must deliver at least this much; more is fine, less is not. A pedal will not "use up" extra current, it simply draws what it needs. The Master Effects Super Four Hundred, for example, uses a standard boss-style 9V power supply (2.1mm, center pin negative) and requires a minimum of 150mA⁵.

Polarity describes which part of the barrel plug is positive and which is negative. The industry standard, set by BOSS-style pedals, is 9V DC with a center negative 2.1mm plug. Donner states the same requirement from the other direction for its Circle Looper: "a voltage of DC9V, an internal negative and external positive polarity, and a current of 500mA or more"⁶⁷. Plugging a center positive supply into a center negative pedal can damage it, which is why polarity reversing adapter cables exist.

The parts: supplies, cables, adapters and mounting

A pedalboard power system has a few building blocks.

• Power supply: the unit that converts wall AC into pedal-friendly DC. Options range from a single 9V adapter to multi-output brick supplies.
• Daisy chain cable: one plug that fans out to several barrel connectors, letting one supply feed several pedals⁸.
• Adapter cables: Tech 21 notes that as pedalboards grew, "high power switching power supplies with daisy chains, adapter cables to reverse polarity or change the voltage" appeared⁸⁹. These let one supply serve pedals with different plug sizes, polarities or voltages.
• Current doubler: for pedals with higher power requirements, the Voodoo Lab PPAP Current Doubler Adapter "accepts any cable with a 2.1mm plug" and combines two Pedal Power outputs into one¹⁰.
• Mounting hardware: supplies are fixed to the board with brackets or dual lock. Aclam's Power Supply Support is a dedicated mounting accessory for pedalboards¹¹, and Vertex makes an AC power module that "makes it easy to connect two independent power supplies on your pedalboard, eliminating the need" for multiple external AC cords¹².

Many pedals also run on a 9V battery. Dunlop's MXR range, including the Phase 90, can be powered by "a 9-volt battery, a Dunlop ECB003 9-volt adapter, or the DC Brick, Iso-Brick, and Mini Iso-Brick"¹³. Some pedals power up the moment a cable is plugged into the input jack, as Suhr notes for the Shiba Drive: "Connecting a cable to the input jack will power up the pedal"¹⁴, so a pedal left patched in will drain its battery even when unused.

Installing the supply

West Coast Pedalboard lays out the installation sequence¹⁵:

1. Mount the supply using a mounting kit, either brackets or dual lock.
2. Connect the power cable before permanent mounting.
3. Run cables loosely at first.
4. Test the whole rig.
5. Secure cables with a cable clamp kit.

One adapter or many: daisy chain versus isolated power

These are the two main architectures, and the choice drives both cost and noise.

Daisy chain power

A daisy chain connects several pedals to one supply through a single cable. Tech 21 calls it an "economical way to power multiple pedals from a single supply," and notes that switching versions can run on 100-250VAC worldwide⁸⁹. Often the chain starts from a spare output on a pedal you already own: "Often, the chain's main source is the extra female jack on the good ol' tuner pedal"¹⁶.

The limitation is electrical. As Voodoo Lab's Darrin Fox explains, "Daisy chains force every pedal in your rig to share a single electrical path. That means they share the same ground and" the same noise floor¹⁷. There is also a hard compatibility limit: "Any pedal needing to see a positive ground CANNOT be daisy chained with standard 'boss-type' neg-tip adapters (which 99% of effects use)"¹⁶. Vintage-style positive ground fuzz circuits fall in this group.

Isolated multi-output supplies

An isolated supply gives each output its own separate power source. Voodoo Lab describes the benefit directly: "True isolation effectively gives every pedal on your board its own dedicated power source"¹⁷. On the product side, the Pedal Power 2 PLUS "isolates every output," which "eliminates tone-robbing interaction between other effects" by breaking unwanted ground paths⁹. Tech 21 lists the familiar examples: "Pedal Power, Dunlop DC Brick, Cioks and others"⁸⁹, and Voodoo Lab's current lineup includes the Pedal Power 3, 3 Plus, X4 and X8¹⁷.

Isolation costs more than a daisy chain, but it is the standard answer for larger boards, mixed analog and digital pedals, and any rig where hum is a problem.

Digital pedals and current

Digital pedals are the main reason current planning matters. Tech 21 warns that "Digital pedals, however, consume much more power (80mA and above) and you may find out at the worst possible moment" that a supply or battery cannot keep up¹⁸⁹. On batteries the situation is worse: a digital pedal can drain one "in about an hour"¹⁸. JHS Pedals gives the planning numbers: "most standard pedals require less than 100 mA. Digital pedals often require a much higher current to operate correctly," generally 200 mA to 1000 mA².

Supplies exist for exactly this case. The Voodoo Lab Pedal Power Digital is "a linear (analog) power supply for high-current DSP-based pedal effects and accessories"¹⁹. Notably, it is not a digital switching supply despite the name: Voodoo Lab says it "keeps pedals free from high-frequency noise that occurs with digital 'switching' power supplies"¹⁹. The Pedal Power 2 PLUS likewise "uses an audiophile quality linear supply for consistently stable, clean, pure power"⁹. Linear supplies are heavier and cost more to build than switching supplies, which is part of what you pay for in an isolated brick.

To size a supply, add up the current draw of every pedal (from each manual) and compare the total, and each individual output, against the supply's ratings. A pedal like the Blackstar ID:X Floor, which "uses a standard 9V 500mA pedalboard friendly power supply"²⁰, needs an output rated for that full 500 mA, not a typical 100 mA output.

Common power problems and their causes

Hum and buzz. General Guitar Gadgets identifies the core issue: "The main problem is hum and buzz noise added to the audio signal in some pedals or situations," and advises that "the power supply should be well filtered and regulated," noting that most wall warts are not²¹. A cheap unregulated adapter is the most common source of power noise on a small board.

Ground loops and stacking drives. Shared grounds on a daisy chain let noise circulate between pedals, and "stacking drive pedals with a daisy chain can boost the hum"⁸. Isolated outputs break those paths⁹.

Underpowered pedals. A pedal asked to run on less current than it needs may work until it does not: digital pedals in particular can fail mid-gig¹⁸. Symptoms include LEDs dimming, screens glitching or the pedal resetting. The fix is an output with enough rating, or a current doubler combining two outputs²².

Wrong voltage or polarity. Mismatched voltage can damage the pedal outright¹. Reversed polarity can do the same; check the barrel symbol printed near the jack before plugging in an unfamiliar adapter.

Positive ground pedals. Vintage-style fuzz circuits that need a positive ground cannot share a standard daisy chain with negative tip pedals at all¹⁶. These need their own isolated output or a battery.

A note on unusual power designs

Not every pedal fits the standard model. Creation Audio Labs' FUNKULATOR includes "a built-in power boosting circuit that takes standard 9V pedal power and steps it up to 36V or even 72V for headroom"²³, meaning it accepts ordinary 9V while running its internal circuit at much higher voltage. Pedals like this are why reading the manual before buying a supply matters: the label on the jack does not always tell the whole story of what the circuit does with the power it receives.

For how power fits into the wider picture of connecting a board, see Pedal Signal Chain Order and True Bypass and Buffers.

Pedals on this page

Donner Circle Looper

Donner · Drum

$179.99 list price

MXR Phase 90

MXR · Phaser

$99.99 list price

Suhr Shiba Drive

Suhr · Overdrive

$249 list price

Questions