Too many earths spoil the broth....

[Al ears]

For some time now I have been very frustrated with a bad 'hum' coming from the woofers when preamp was switched to the phono input. I have scratched my head and made enquiries to both turntable manufacturer and to the maker of my amp / phono preamp to no avail.

Today I decided to play with earth wires in the mains plugs and what do I find?

Upgraded mains plugs, I will not mention manufacturer, are the culprits. On opening the plug I found their is not one earth wire connected but two. I detached both from the plug to the power supply to phono preamp and voila! No more hum.

Reconnected one and all is well still.

Question. What the hell is that extra earth wire there for in the first place?

Still, whatever, I can now play vinyl without woofers looking like they are going to jump out of the cabinets. Result!!

Moral:- Don't trust upgraded mains cables.

 

[chebby]

Upgraded mains plugs, I will not mention manufacturer, are the culprits. On opening the plug I found their is not one earth wire connected but two. I detached both from the plug to the power supply to phono preamp and voila! No more hum.

Reconnected one and all is well still.

Question. What the hell is that extra earth wire there for in the first place?

Still, whatever, I can now play vinyl without woofers looking like they are going to jump out of the cabinets. Result!!

Moral:- Don't trust upgraded mains cables.

I think we should know just so some people will not have to repeat your experience.

 

[Al ears]

Upgraded mains plugs, I will not mention manufacturer, are the culprits. On opening the plug I found their is not one earth wire connected but two. I detached both from the plug to the power supply to phono preamp and voila! No more hum.

Reconnected one and all is well still.

Question. What the hell is that extra earth wire there for in the first place?

Still, whatever, I can now play vinyl without woofers looking like they are going to jump out of the cabinets. Result!!

Moral:- Don't trust upgraded mains cables.

I think we should know just so some people will not have to repeat your experience.

You may have a point there chebby so I will name the guilty party:-

ClearerAudio Copperline Alpha.

 

[davedotco]

The mantra for any player is that each component, be it turntable, power supply, arm, cartridge should be earthed once and once only. This is relatively straightforward, well most of the time anyway, until you get to the issue of the phono stage.

The same rule applies here too, but it can be a little more complicated. All electronic (hi-fi) components will have a ground (earth) as part of the circuitry and a ground for the casework. These are not necessarily the same thing, ie not all grounds are created equal.

It is not uncommon in a phono stage for the two grounds to be separate, the circuit may, for example 'ground' through the phono leads whilst the case 'grounds' through the mains lead, this is just one example, there are plenty of others.

The cable situation though may be different, the cables are often screened which is connected to the earth pin on the plug, then of course the phono stage itself is is connected to earth via the usual yellow/green core. Why disconnecting one of the cables, probably the one earthing the phono stage, makes sense if the phono stage is already earthed via the turntable, leaving the screen on the cable earthed to reject RFI.

Difficult to be sure without hands on but I suspect some simple variation on the above.

 

[stevebrock]

Think I understood that !

 

[davedotco]

Think I understood that !

If you look at the arm lead from your Series IV, you should have two earth connectors terminated with spades. One is a single cable that earths the body of the arm, the second, coming from the 2 phono plugs earths the cartridge, minimising static etc.

It gets more complex with metal bodied cartridges, they can ground via the phono leads or by metal to metal contact with the arm, ok if the body is isolated from the signal ground, but a pain otherwise

Take a look at the cartridge below, not yours but a moving magnet type, see the metal tag that exits the body of the cartidge and grounds to the green terminal? Can make life very interesting...!

 

[Al ears]

Think I understood that !

I didn't but it's true. As I said to many earths though you wouldn't know it. Plus throw in the fact that SME arms have two earth leads, it all gets a bit confusing even for an old-timer like myself.

Oops, just read previous posts and it is correct, all SME arms have twin leads. This however was not the fault in my set-up.

 

[davedotco]

Think I understood that !

I didn't but it's true. As I said to many earths though you wouldn't know it. Plus throw in the fact that SME arms have two earth leads, it all gets a bit confusing even for an old-timer like myself.

Oops, just read previous posts and it is correct, all SME arms have twin leads. This however was not the fault in my set-up.

I was talking generally about the different earthing requirements of many players, your issue is clearly about your mains leads.

Out of interest, did you ever use your phono stage with the supplied (standard) mains? Also, what kind of (mains) plug and socket is used?

I know you have solved the issue but it would be interesting to know what caused it, I'm a bit anal about such matters...*wacko*

 

[Al ears]

Think I understood that !

I didn't but it's true. As I said to many earths though you wouldn't know it. Plus throw in the fact that SME arms have two earth leads, it all gets a bit confusing even for an old-timer like myself.

Oops, just read previous posts and it is correct, all SME arms have twin leads. This however was not the fault in my set-up.

I was talking generally about the different earthing requirements of many players, your issue is clearly about your mains leads.

Out of interest, did you ever use your phono stage with the supplied (standard) mains? Also, what kind of (mains) plug and socket is used?

I know you have solved the issue but it would be interesting to know what caused it, I'm a bit anal about such matters...*wacko*

Ooh 'er. The mains cable was employed, in fact I got two for the vinyl side of system, as they were a cheap deal and for some reason the second-hand phono preamp didn't come with a mains lead. Cleareraudio use a good old-fashioned MK plugs.

I was initially a bit concerned that I might have to start stripping down the turntable to look inside for any extra earth wires to disconnect, checking the mains cable themselves was way down on the list but easiest to rule out so started there first, luckily. ;-)

 

[davedotco]

Think I understood that !

I didn't but it's true. As I said to many earths though you wouldn't know it. Plus throw in the fact that SME arms have two earth leads, it all gets a bit confusing even for an old-timer like myself.

Oops, just read previous posts and it is correct, all SME arms have twin leads. This however was not the fault in my set-up.

I was talking generally about the different earthing requirements of many players, your issue is clearly about your mains leads.

Out of interest, did you ever use your phono stage with the supplied (standard) mains? Also, what kind of (mains) plug and socket is used?

I know you have solved the issue but it would be interesting to know what caused it, I'm a bit anal about such matters...*wacko*

Ooh 'er. The mains cable was employed, in fact I got two for the vinyl side of system, as they were a cheap deal and for some reason the second-hand phono preamp didn't come with a mains lead. Cleareraudio use a good old-fashioned MK plugs.

I was initially a bit concerned that I might have to start stripping down the turntable to look inside for any extra earth wires to disconnect, checking the mains cable themselves was way down on the list but easiest to rule out so started there first, luckily. ;-)

Standard IEC?

Do you have a meter to do a continuity check to see what is connected to what? Having two earth wires is sensible enough, equipment ground plus a screen ground but normally the screen will be left floating at the amp end...*unknw*

I know I am wierd, but I love this sort of problem solving...*wacko*

 

[Al ears]

Think I understood that !

I didn't but it's true. As I said to many earths though you wouldn't know it. Plus throw in the fact that SME arms have two earth leads, it all gets a bit confusing even for an old-timer like myself.

Oops, just read previous posts and it is correct, all SME arms have twin leads. This however was not the fault in my set-up.

I was talking generally about the different earthing requirements of many players, your issue is clearly about your mains leads.

Out of interest, did you ever use your phono stage with the supplied (standard) mains? Also, what kind of (mains) plug and socket is used?

I know you have solved the issue but it would be interesting to know what caused it, I'm a bit anal about such matters...*wacko*

Ooh 'er. The mains cable was employed, in fact I got two for the vinyl side of system, as they were a cheap deal and for some reason the second-hand phono preamp didn't come with a mains lead. Cleareraudio use a good old-fashioned MK plugs.

I was initially a bit concerned that I might have to start stripping down the turntable to look inside for any extra earth wires to disconnect, checking the mains cable themselves was way down on the list but easiest to rule out so started there first, luckily. ;-)

Standard IEC?

Do you have a meter to do a continuity check to see what is connected to what? Having two earth wires is sensible enough, equipment ground plus a screen ground but normally the screen will be left floating at the amp end...*unknw*

I know I am wierd, but I love this sort of problem solving...*wacko*

Yes standard IEC.

I have had to chop the earth lead at the plug but have reconnected thin screen wire which does appear to be floating as cannot see it on opening IEC plug.

 

[davedotco]

That your phono stage does not separate signal and chassis earth, so is earthed back to the player by the SME arm cable. So connecting to earth by the mains lead will produce the classic earth loop.

Or it is being earthed by the phono lead to your pre/main, or posibly you player is mis-aligned with respect to Uranus.

 

[Al ears]

That your phono stage does not separate signal and chassis earth, so is earthed back to the player by the SME arm cable. So connecting to earth by the mains lead will produce the classic earth loop.

Or it is being earthed by the phono lead to your pre/main, or posibly you player is mis-aligned with respect to Uranus.

Quiet possibly the rings of Uranus are the major cause of earth loops, I would recommend we all come down to this planets level and disconnect from earth completely.

My player could, with the right material get right up your anus. Particularly if you are a digital freak.

I had the power to nullify earth and I did so.