Turntable Buzzing Noise despite using grounding cable
I’m hoping experts will give some clue as to why I’ve got humming via speakers when the pre-amp is connected to the turntable, with an earth cable. Any solutions gratefully accepted.
The Problem & Environment
Humming occurs only at high volume.
The amp’s volume scale goes from 0 to 40. Humming is most noticeable around Vol 34.
Humming only occurs on analogue input (i.e turntable).
No humming from CD or Bluetooth audio sources, even at max volume.
The amp is connected to the turntable via a pre-amp.
The turntable is grounded to the pre-amp.
All plugs are earthed (UK plugs).
The multi plug extension lead which carries all three power supplies is grounded.
All RCA connections / cables between amp, pre-amp, amp and ceiling speakers are tight.
I even connected a second ground wire from pre-amp to amp’s steel body. No change in humming.
Set up = Turntable => Pre-amp => Amp => Ceiling Speakers (x4)
My Kit
Turntable = Pro-ject Debut II (NC 507.0). Original cartridge, Ortrofon OM 5E
Pre-amp = Pro-Ject Phono Box E
Amp = Denon RCD-M41 DAB
Ceiling speakers = Bowers &Wilkins CCM662 Passive Ceiling Speakers (x4)
Cables = high quality RCA cables and speaker cables.
I’ve checked Pro-Ject’s own, excellent guide to solving humming.
Posted May 7, 2025, 2:40 PM UTC