Do I need double earths?

[Phil Lawton]

Got s slight earthquake buzz from my latest turntable. It’s plugged into a five-gang socket, which itself is earthed.

Does the turntable also need to be earthed or can I removed the earth wire from its plug?

[hifi_dave]

Be helpful to know the turntable, arm, cartridge and amp.

[Phil Lawton]

Be helpful to know the turntable, arm, cartridge and amp.

Clearaudio Concept Signature with Profiler arm, Concept V2 MM cart, Marantz PM6xxx amp, Primare R32 phono stage.

[Barry]

By "slight earthquake buzz", I presume this is an audible effect you hear through your speakers. It sounds as though you have an earth loop; possibly through earthing the metalwork of both the turntable and amplifier, and having a separate ground connection via the tonearm wiring (probably via the shielding of the signal leads).

Earth-loops are notoriously difficult to track down, but I would be reluctant to disconnect the earth wire of your turntable. Do you have a multimeter or continuity tester? If so, check to see if the metalwork of the turntable is connected to either, or both of the shields of the tonearm signal cables.

If you can do that, report your findings so I can advise you further.

[Phil Lawton]

By "slight earthquake buzz", I presume this is an audible effect you hear through your speakers. It sounds as though you have an earth loop; possibly through earthing the metalwork of both the turntable and amplifier, and having a separate ground connection via the tonearm wiring (probably via the shielding of the signal leads).

Earth-loops are notoriously difficult to track down, but I would be reluctant to disconnect the earth wire of your turntable. Do you have a multimeter or continuity tester? If so, check to see if the metalwork of the turntable is connected to either, or both of the shields of the tonearm signal cables.

If you can do that, report your findings so I can advise you further.

Didn’t notice the ‘earthquake’ autocorrect - what a divot.

I can’t see any exposed metalwork on the turntable - am I missing your meaning?

Can’t see anything unusual in the tonearm signal cables. I don’t have a multimeter or continuity tester either.

[Barry]

Having had a look at your equipment list, there are a number of ways an earth loop might be created.

We don't have to worry about the Marantz amp, as all the 6000 series are double insulated and have a two pin mains connector. The Primare R32 has a three pin connector, so its metalwork is earthed. It also has a ground terminal which is directly attached to the metalwork.

I can't find much information about the Profiler arm and how the metal work is earthed/grounded. Does it have captive signal leads, and is there a separate ground wire?

So depending on how the tone arm leads are connected to the R32, including the separate earth wire, it is quite possible to create an earth loop.

[Phil Lawton]

Having had a look at your equipment list, there are a number of ways an earth loop might be created.

We don't have to worry about the Marantz amp, as all the 6000 series are double insulated and have a two pin mains connector. The Primare R32 has a three pin connector, so its metalwork is earthed. It also has a ground terminal which is directly attached to the metalwork.

I can't find much information about the Profiler arm and how the metal work is earthed/grounded. Does it have captive signal leads, and is there a separate ground wire?

So depending on how the tone arm leads are connected to the R32, including the separate earth wire, it is quite possible to create an earth loop.

Tone arm leads are straight into the phono inputs of the Primare and the Earth wire also goes straight into the Primare.

Does this mean the I could disconnect the earth from the Primare?

[Barry]

Didn’t notice the ‘earthquake’ autocorrect - what a divot.

I can’t see any exposed metalwork on the turntable - am I missing your meaning?

Can’t see anything unusual in the tonearm signal cables. I don’t have a multimeter or continuity tester either.

Hmmm - if the turntable doesn't have any exposed metalwork, why does it use a three core mains cable? Can you check to see if it is double insulated? If you look at the label on the back of the deck and see a 'square within a square' symbol, the deck is double insulated.

Also are there just two signal leads on the tonearm, or is there an additional earth lead (usually terminated with a spade connector)?

[Barry]

It would appear the Clearaudio Concept Signature turntable uses an external 12V power supply. How is this connected to the mains?

[Phil Lawton]

Hmmm - if the turntable doesn't have any exposed metalwork, why does it use a three core mains cable? Can you check to see if it is double insulated? If you look at the label on the back of the deck and see a 'square within a square' symbol, the deck is double insulated.

Also are there just two signal leads on the tonearm, or is there an additional earth lead (usually terminated with a spade connector)?

There is a separate earth lead with a spade connector. This is connected to the Primare. Could I instead connect this to the ground connector on the Marantz?

The turntable’s connector for the mains is a small circular thing, as opposed to a kettle-lead connector.

[Phil Lawton]

Just turned on just the amp and Primare and got the earth buzz, without the turntable being switched on.

[Phil Lawton]

It would appear the Clearaudio Concept Signature turntable uses an external 12V power supply. How is this connected to the mains?

It’s a wall wart mains connector.

[Barry]

Connect the separate earth lead to the Primare R32 phono stage, using the ground terminal. If the hum problem persists, then you could try connecting the earth lead to the ground terminal on your Marantz amplifier.

If you still have a hum problem, we will have to look at the turntable's external power supply (unlikely) and to the cartridge/tonearm interface.

[Phil Lawton]

Connect the separate earth lead to the Primare R32 phono stage, using the ground terminal. If the hum problem persists, then you could try connecting the earth lead to the ground terminal on your Marantz amplifier.

If you still have a hum problem, we will have to look at the turntable's external power supply (unlikely) and to the cartridge/tonearm interface.

Will do…means moving the Primare up a level, so I’ll try this on the morrow.

Thanks for all of this, Barry.

[Barry]

Just turned on just the amp and Primare and got the earth buzz, without the turntable being switched on.

That clears the wall wart power supply, which being a DC power supply was not a prime suspect.

We will see if there is any improvement in changing the arm earth lead to the ground terminal on the Marantz amplifier.

[CageyH]

What happens if you disconnect the earth lead from the turn table to the R32?

[Steph Dale]

To be honest, that's probably where I would have started. Some cartridges, cables and/or tonearms have odd earthing arrangements and this would check that the loop/hum isn't due to a parallel earth between the cartridge/arm/turntable and the amp.

Steph

[Barry]

The Concept V2 cartridge uses a metal housing. If this housing is connected to the 'cold' connecting pins of either of the two channels, and the separate arm earth lead is also used, then an earth loop would be formed. But it is not at all obvious if the metal cartridge housing is connected to the signal earth.

[Phil Lawton]

That clears the wall wart power supply, which being a DC power supply was not a prime suspect.

We will see if there is any improvement in changing the arm earth lead to the ground terminal on the Marantz amplifier.

Barry

You were bang on…Clearaudio now attached to the amp’s earth and buzz eliminated.

Many thanks for your help.

[Lawrence001]

Barry

You were bang on…Clearaudio now attached to the amp’s earth and buzz eliminated.

Many thanks for your help.Isn't this the standard set up for a TT to try first? I've always done this (well except where I have a separate phono stage, when I use that - maybe that was the issue here, I should really read the above first [emoji23]).

[Phil Lawton]

Isn't this the standard set up for a TT to try first? I've always done this (well except where I have a separate phono stage, when I use that - maybe that was the issue here, I should really read the above first [emoji23]).

Hi, Lawrence

Yes, I'd hooked the turntable up to the phono stage's earth, which was what I now know was giving the buzz.

Attaching it instead to the amp's earth cured it.

[Barry]

My response is to say: "whatever works". Tracking down hum and buzz problems can be notorious dificult to do, and cure.

In connecting the tonearm ground wire to the earth terminal of the Marantz amplifier means the arm is now earthed by your Primare phono amp via the screening of the phonostage output cables.

Why this should be the solution to the problem I don't know - but as I said 'whatever works'. Now just sit back and enjoy the music. :)