Speaker hum from turntable

footman · 27 Jul 2015 at 10:53

I have a Project Carbon turntable, there is mild speaker hum as soon as the input is selected on the amplifier.
This is intensified as soon as I touch the tonearm and if I move the arm across the area of the turntable there is a crackling noise from the speakers.

I've checked the RCA cable connections and the earthing connection and they are OK, disconnecting the earthing cable does nothing to stop the hum.

Ideas gratefully received.

EYEREX · 27 Jul 2015 at 12:29

One of my old turntables always had a hum and the only way i could fix was to get a 6ft length of copper rod and place in the ground and run the clean earth to the tunrtable

Ps have you tried a different amp as sometimes it can be the amp adding the hum and not just a case of not having a clean earth

footman · 27 Jul 2015 at 12:56

I've only got the one amp, there's no hum on any of the other inputs.

Cosimo · 27 Jul 2015 at 13:35

Check the cartridge wire connections.

This may help:

http://www.vinylengine.com/turntable_forum/viewtopic.php?f=42&t=58516

footman · 27 Jul 2015 at 14:23

thanks I'll have a look

Cosimo · 28 Jul 2015 at 11:54

footman said:
thanks I'll have a look

Any luck in getting rid of the hum?

footman · 28 Jul 2015 at 16:36

I've had a look but to my untutored eyes the wiring seems OK. I might give Richer Sounds a bell.

kitfit1 · 29 Jul 2015 at 20:50

How tight are your phono Plugs ? if they are very loose and not a very tight tight fit, that will almost certainly cause hum, regardless of how good your earthing may or may not be.

shadychopper · 29 Jul 2015 at 21:53

footman said:
I have a Project Carbon turntable, there is mild speaker hum as soon as the input is selected on the amplifier.
This is intensified as soon as I touch the tonearm and if I move the arm across the area of the turntable there is a crackling noise from the speakers.

I've checked the RCA cable connections and the earthing connection and they are OK, disconnecting the earthing cable does nothing to stop the hum.

Ideas gratefully received.

I get a slight hum If I connect my earth to my phono stage but not when connected to my amp but it sounds to me like the wiring in the arm needs looked at If its cracking while moving across the turntable. A little hum while picking up the arm is quite common I believe.

footman · 30 Jul 2015 at 08:04

kitfit1 said:
How tight are your phono Plugs ? if they are very loose and not a very tight tight fit, that will almost certainly cause hum, regardless of how good your earthing may or may not be.

They are as tight as can be.

shadychopper said:
I get a slight hum If I connect my earth to my phono stage but not when connected to my amp but it sounds to me like the wiring in the arm needs looked at If its cracking while moving across the turntable. A little hum while picking up the arm is quite common I believe.

Yes that's certainly weird that it crackles when the arm is moved, I haven't had a chance to talk to Richers yet but I will.
Thanks for the replies

oldbag · 30 Jul 2015 at 08:17

I have a carbon and don't get hum - keep the deck away from the speakers and keep the rca cables away from the power cables if you can. Also make sure the earth is correctly connected both ends to the amp post and the deck post.

Kei · 30 Jul 2015 at 09:18

I had an almost identical set of symptoms when the earth bonding inside the tonearm itself had detached itself. (SME 3009) Had to dismantle and repair the wiring in the arm.

footman · 30 Jul 2015 at 09:29

oldbag said:
I have a carbon and don't get hum - keep the deck away from the speakers and keep the rca cables away from the power cables if you can. Also make sure the earth is correctly connected both ends to the amp post and the deck post.

The speakers are wall mounted and well away from the turntable.

Kei said:
I had an almost identical set of symptoms when the earth bonding inside the tonearm itself had detached itself. (SME 3009) Had to dismantle and repair the wiring in the arm.

Interesting, it's under warranty so I think I'll take it back.