How do I stop my pedalboard humming?

Name the noise

Each kind of noise points somewhere different.

Low, steady hum

A deep tone at the mains frequency: 60 Hz in North America, 50 Hz in Europe and much of the world. Usually power, grounding or a ground loop.

Edgy buzz

Hum with a harder, brighter edge. Common with single-coil pickups near lights, dimmers and screens, and with a loose ground wire or jack.

High whine or chirp

A thin, high-pitched or digital-sounding noise, often from a digital pedal sharing power with other pedals.

Hiss

A steady rush, like air, that rises with gain. A little is normal with high-gain pedals, and a noise gate tames it.

Checks, cheapest first

1. 01Guitar straight into the ampUse one cable you trust. Quiet? The noise is on your board, so skip to check 04. Still humming? The cause is the guitar, the cable, the amp or the room, and the next three checks cover those.
2. 02Turn the guitar volume to zeroIf the noise stops, it is coming in through your pickups. Single-coil pickups pick up hum from lights, dimmers, screens and power cables, so turn to face a different direction and listen for it to drop. Humbuckers are built to cancel this kind of hum.
3. 03Pull the cable out of the ampTurn the amp down, pull the cable out of its input, then turn the amp back up. Still humming as loud with nothing plugged in? The hum is in the amp itself, often a tube or the filter capacitors, or in the outlet. Book a tech, and do not open the amp yourself. If the hum gets louder when you touch the strings, or you feel a tingle, stop playing and have the amp and the outlet checked: that can mean a wiring or ground fault.
4. 04Swap the cablesTry a known-good instrument cable and known-good patch cables. A cable with a broken shield or ground wire hums and crackles, and swapping it costs nothing.
5. 05Add pedals back one at a timeRun guitar, first pedal, amp. Then add the next pedal, and the next. When the noise appears, you have found the pedal, its cable or its power.
6. 06Move that pedal’s powerGive the noisy pedal its own isolated output, or try a different output on your supply. A digital pedal on a daisy chain can add hum or whine; if it does, give it an isolated output. Use a supply built for pedals, not an adapter from another gadget.
7. 07Separate audio and power cablesKeep patch cables away from power cables, and cross them at right angles where they have to meet. Keep fuzz and high-gain pedals away from the power supply itself: some supplies, especially transformer-based ones, radiate hum.
8. 08Break the ground loopHum that starts when you connect a second powered device, like a second amp, a DI box, a mixer, or a laptop over USB, is usually a ground loop. Plug everything into the same outlet or power strip, and use the ground lift switch on your DI box if it has one. Never remove or tape over the ground pin on a mains plug: that pin protects you from electric shock.
9. 09Tame the hissHigh gain amplifies every bit of noise. Back the gain off a touch, and put a noise gate after your drive pedals. A gate hides hiss between notes; it does not fix hum at its source. Hiss from the amp itself needs the gate in the effects loop, which the high-gain noise guide covers.

Digital whine, specifically

Digital pedals run on fast clock circuits, and that switching noise can leak into other pedals through a shared power connection. So a digital pedal on a daisy chain can add hum or whine. If it does, give it an isolated output and route patch cables away from it. If a pedal still whines on its own isolated output, test it alone with guitar and amp before blaming the supply.

Common mistakes

• Lifting the safety ground on a mains plug. The hum may stop, and you are left exposed to a dangerous shock. Use one shared outlet or a DI ground lift instead.
• Buying a noise gate to fix hum. A gate hides noise between notes. It does not fix a power or ground problem.
• Blaming the newest pedal without testing. Check every pedal one at a time; the cause is often a cable or a power output.
• Rebuilding all your power for one noisy pedal. A digital pedal on a daisy chain can add hum or whine; if it does, give that pedal an isolated output.
• Zip-tying power and audio cables together in one tight bundle.
• Playing on through a tingle from the strings. Stop, and have the amp and the outlet checked.

Words used here

Ground loop

Two pieces of gear grounded through two paths, usually the mains plug and an audio cable. Current circulates around the loop and you hear it as hum.

Isolated output

A supply output that is electrically separate from the others, which keeps noise from passing between pedals.

Daisy chain

One adapter feeding several pedals through a single cable with several plugs.

Single-coil pickup

A pickup with one coil of wire. Bright and clear, and it picks up hum from nearby electrical gear.

Humbucker

A pickup with two coils wired to cancel hum.

Ground lift

A switch on DI boxes and some other gear that disconnects the audio ground to break a ground loop. The mains safety ground stays connected.

Noise gate

A pedal that mutes your signal when you stop playing, hiding hiss between notes.

Effects loop

Send and return jacks on an amp that place pedals after its preamp.

Tools for this

• Power plannerCheck every pedal has enough current on the right output.→
• Pedal power databaseLook up how much current each pedal on your board draws.→
• Power suppliesFind a supply with isolated outputs for the pedals that need one.→
• The BoardMap your chain in order so you can test it one pedal at a time.→

Related guides

• Do I need a power supply for my guitar pedals?Voltage, polarity, mA, and isolated vs daisy chain, in plain English.→
• Why does my high-gain rig hiss, and where does the noise gate go?Hiss and hum at high gain: find the source, then place and set the gate.→
• Why does my guitar signal cut out or crackle?Crackle, dropouts and switching pops, traced with the wiggle test.→
• Is it fret buzz or electrical hum?The unplugged test, then action, relief and frets in order.→
• The six pedalboard mistakes I see at every gigPower is one of the six, and it is the one that hums.→