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Loud hum on sonos 5 when playing from a pre-amp turntable

  • 21 April 2022
  • 5 replies
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I bought the pro-ject turntable with the pre-amp that was recommended by Sonos to connect to a sonos 5. I was getting a loud low hum coming through the speakers and I couldn’t find a way to ground the turntable to the speaker. I tried buying an upgraded rca cable that didn’t have the grounding wire, the sound quality improved a little but it still has a very heavy low hum. Is there a way that I can ground the other end of the wire to the line in on the sonos 5?

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Best answer by GuitarSuperstar 21 April 2022, 17:51

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Userlevel 7

Under the Line-In settings for the Five, what is the Source Level set to? If you adjust it lower, does it make any difference?

@Sofaman4u I have the same, a very low bassy hum. I have a Audio-Technica Bluetooth turntable (no pre-amp) plugged into the line-in socket of my Five speaker. I had the source volume in the line-in settings at the default setting of level 3. But I felt that wasn’t loud enough for my requirements so I went ahead and set it at 10, thinking I’d get the volume I needed. That’s when the loud hum feedback would kick in even though the louder volume sounded great. I set it back to 3 and the hum went away only to appear intermittently especially on quieter tracks. I have noticed that at any level, the hum would appear on the run off on some select vinyls and not others. Strange. Can you or GuitarSuperstar or anyone in the community tell me if there’s a fix or a workaround to this without having to sacrifice volume? Thanks for reading :-)

  1. get a pre-amp, to put in between the turntable and the Sonos. The Sonos’ line in is designed for a ‘line level’ input, not a ‘phono level’ input. You’re currently under driving it, which can be a source if ‘hum’ when you turn up an amplifier to adjust for that super low input. 
  2. check the ground in your turntable. An improperly grounded device can introduce a hum….although in your case, it’s much more likely the first issue. 

Citizen Spacey,

Do you have any other SONOS speakers in another room (not near the turntable)? If so, play the turntable through the distant speaker and keep the FIVE near the turntable silent. Do you hear the hum now? If not, there is an acoustic feedback issue between the turntable and the FIVE.

Another Another possibility is that there is magnetic field generating device, such as a power supply brick, near the turntable. This can induce hum directly into the phono cartridge -- no record required. One test for this is to hold the turntable arm above the record surface and move it across the record area. If the hum level varies, then there is an external field.

Another test is, if possible, reverse the power plug in its outlet. Do this for both the turntable and the FIVE. You may find a combination that minimizes the hum.

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Also you get very distorted sound if you don’t use the RIAA equalization to reverse the pre-cutting equalization that was applied.

 

https://infogalactic.com/info/RIAA_equalization