Symptoms
- Constant low hum that's present even with the volume down
- Hum gets louder as volume increases
- Hum disappears if you touch the tonearm or turntable chassis
- Hum is present only when the turntable is the active source
Likely causes
- CommonTurntable ground wire not connectedTurntables have a separate thin ground wire (not the RCA cables) that must attach to a ground terminal on the amp or preamp.
- CommonGround loop between multiple plugged-in devicesDevices on different outlets/circuits can create a small voltage difference causing hum.
- PossiblePreamp or amplifier grounding issueA missing or poor ground connection inside the amp or preamp can cause persistent hum.
- PossibleCheap or unshielded RCA cablesPoorly shielded cables can pick up electrical interference.
- Less commonFaulty cartridge or tonearm wiringInternal wiring issues can introduce noise that grounding won't fix.
What to do
- Locate the thin ground wire coming from the turntable (separate from the RCA cables) and attach it to the ground screw/terminal on the amplifier or phono preamp.
- If there's no dedicated ground terminal, try attaching the ground wire to a metal grounded surface, such as an amplifier chassis screw.
- Plug the turntable and amplifier into the same outlet or power strip to reduce ground loop differences.
- Try a different, well-shielded set of RCA cables.
- Touch the tonearm or turntable's metal parts briefly; if the hum stops, this confirms it's a grounding issue.
- If using an external phono preamp, ensure it's also properly grounded and plugged into the same circuit.
Tools and parts
Turntable ground wire adapterSearch: “turntable ground wire clip”
When to call a pro
If hum persists after properly grounding the turntable and trying different cables, have an audio technician check the preamp or amplifier's internal grounding.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.