Earthing conundrum

Posted by: Willy on 02 June 2018

Starting point:

LP12, Lingo2, Ekos, DVXX2 Mk2, Prefix, 52, 52PS, Supercap, Snaxo362, 250*3, A5 DBLs. Hydra, radial off dedicated Consumer unit.

Having gone active recently I wasn’t happy that the system wasn’t coming on song as I’d expected as the Snaxo run in. I (erroneously) put this down to losing the supercap off the Prefix to power the Snaxo. Set about looking for another supercap and ended up with a …..Superline. Now I’ve read enough to know there are circumstances where a Superline simply, for whatever reason, will not work however I purchased at a price that would enable me to move it on if it didn’t cooperate.

Next step was to call by my dealer who removed the prefix, fitted a second hand BNC terminated armlead (checked out first with a multimeter) and also a second hand Trampolin 2 that had just arrived in.

Took it home. Plugged it in. It hummed like a bugger. Hmmmmmm.

Borrowed my sons Planar 3 (fitted with a Denon MC) from upstairs and plugged that into the superline. No hum.

Took my LP12 back to the shop and left it with them to investigate. No hum there but thay reckoned it was a bit off. Tracked it down to the Ekos which was then dispatched to Linn for a service.

Called in to collect my TT refitted with a newly refurbished Ekos. First had a listen to a LP12/Lingo4/EkosSE/Krystal combination. Rather good. Then my own turntable. Actually not that far behind in performance terms. Well pleased. At this stage my turntable was fitted with a new Linn T-Kable, just left it on.

Took LP12 home. Plugged it into the superline. It hummed like a bugger. Hmmmmmm.

Tried it both straight into the Superline phonos and also with adaptors into the Superline BNC inputs. Hummed on both.

Changing the capacitance: 1µF reduced the hum a bit, 4.7 µF reduced it some more, 10 µF no more than 4.7.

Procured a pair of K boards for the 52 and fitted them. Plugged the turntable into them. Hummed like a bugger. (Superline totally isolated from system). Must admit I wasn’t expecting that.

Tried my LP12 in my son’s 42/hicap/140 system. No Hum!

Borrowed my son’s 42.5/hicap (fitted with MC boards) installed in my system taking my 52 out of the picture. No hum!

Reinstated my 52. Borrowed a 52/supercap/burndy/snaic. Set about replacing first my 52PS with the Supercap, then the snaic, then the burndy and finally the 52. Hummed all the way.

Borrowed a LP12/EkosSE/Arkiv/Radikal/Urika and tried that into my system. Didn’t hum. (Unfortunately it had a mishap on the way here and the antiskating wasn’t functioning properly so we couldn’t do a proper evaluation).

Let’s summarise:

My LP12 into the Linn amp and speakers in Lyric is fine.

My LP12 into 42/hicap/140/mission 700s is fine.

My LP12 into 42/hicap/supercap/snaxo362/250s/dbls is fine

Rega Planar3/Denon MC into superline/52/52ps/supercap/snaxo362/250s/dbls is fine

My LP12 into superline/52/52ps/supercap/snaxo362/250s/dbls hums.

My LP12 into K boards/52/52ps/supercap/snaxo362/250s/dbls hums.

My LP12 into superline/alternate(52/supercap)/supercap/snaxo362/250s/dbls hums.

My LP12 into K boards/alternate(52/supercap)/supercap/snaxo362/250s/dbls hums.

My dealer called out briefly (fitting me in on a Sunday afternoon as he was then off on Hols). We started with the K boards (isolating the Superline from the system). Jigged up the turntable and checked it out internally. All fine.

Using a multimeter we have continuity from the Topplate to the arm lead earthing tag (that then connects to phono binding post on the back of the pre). The top plate itself is connected via the Lingo to mains earth. This should be the single earth reference point (no other source connected to the system). However, we discovered that connecting an addition wire from the top plate to the 52 phono binding post, in effect in parallel with the arm lead earthing wire, significantly reduced the hum. Due to time constraints that’s as far as we got on that occasion.

Sunsequently I added the Superline back in. Had to move the additional earth wire so that it connects from LP12 top plate to the superline binding post (armlead earth wire still connected to 52 binding post).

Despite significantly reducing hum it’s not eliminated. Audible with volume past about 1 o’clock position.

Sound of the system is not what I’d expect it to be. Also seems to be somewhat variable.

So, before we give up and revert to the prefix, consigning the superline and K boards once more to the secondhand market has anyone any idea wtf is going on here?

Willy.

Posted on: 02 June 2018 by Richard Dane

Willy, these hum issues with record players and phono stages can be a real pain to solve. However, I think your Superline is probably fine. How do we know that? Well, when you tried another deck - your son's P3 - it was fine without hum. The problem is probably how the LP12, PSU, arm and cart are set-up and earthed (or not). Do you have the extra flying earth lead from the Linn arm cable connected up to the LP12 chassis? What happens if you disconnect or de-solder it?

Posted on: 02 June 2018 by Willy

Internally the "little" flying lead from the armlead plug is connected to the subchassis, and then then on to the cross member bolt which is connected to the Lingo earth. I did try disconnecting the flying lead but it made no difference to the hum. What spurred me on to that was that my prefix has no such lead so in theory I didn't have an signal to mains earth connection at all. Never seemed to bother it.

Willy.

Posted on: 02 June 2018 by ken c

Great system! so you still have Hicap powering snaxo right?

doesn't seem to be superline issue since "...Rega Planar3/Denon MC into superline/52/52ps/supercap/snaxo362/250s/dbls is fine" and also that "My LP12 into K boards/52/52ps/supercap/snaxo362/250s/dbls hums"

seems the combination of your LP12 and NAC52 may be the issue here as evidently:

My LP12 into the Linn amp and speakers in Lyric is fine.

My LP12 into 42/hicap/140/mission 700s is fine.

My LP12 into 42/hicap/supercap/snaxo362/250s/dbls is fine

I take it the NAC52 doesn't hum with any other source?

just for good measure -- perhaps also change main connections -- i.e. plug it elsewhere -- I doubt this is the issue but worth trying anyhow.

wish it were possible to try an alternative 52 or even 82?

hope you get it sorted!

enjoy

ken

Posted on: 02 June 2018 by Willy

Ken,

Snaxo always powered by my supercap.

I did swap out my 52/52PS/Burndy/snaic for a totally different 52/supercap/burndy/snaic. Both hummed.

Have tried on house ring main instead of dedicated radial and still hums.

Unlikely to be Superline issue as (a) the rega works into it and (b) get hum also with K boards in the 52 (that's two different pairs of K Boards in two different 52s)

However the LP12 works fine into two other pre-amps (a Linn and a 42/hicap)

Only other source is a DacMagic100 fed from my PC. No Hum.

Also tried my phone via a 3.5mm to din connector and again no Hum.

Willy.

Posted on: 02 June 2018 by ken c

Hmmm... tough one!

long short... when you used a different 52, did you use its own cables or did you simply swap it in and use your cables?

enjoy

ken

Posted on: 02 June 2018 by Willy

ken c posted:
Hmmm... tough one!
long short... when you used a different 52, did you use its own cables or did you simply swap it in and use your cables?
enjoy
ken

Swapped the cables as well as the 52 and power supply.

Willy.

Posted on: 02 June 2018 by james n

Willy posted:

Only other source is a DacMagic100 fed from my PC. No Hum.

Willy - was this plugged into the 52 whilst you were trying the different combinations that gave the hum ?

Posted on: 02 June 2018 by Willy

james n posted:
Willy posted:

Only other source is a DacMagic100 fed from my PC. No Hum.

Willy - was this plugged into the 52 whilst you were trying the different combinations that gave the hum ?

James, Have tried multiple combinations with the DacMagic connected to the 52 and disconnected. Disconnecting it slightly increases the hum when present. When no hum is present disconnecting makes no difference. Whilst connected have tried it in the Ground and Lift positions but not noticed any difference with that.

Willy.

Posted on: 02 June 2018 by yeti42

If you unplug the lingo from the mains but connect evreything else on does it still hum?

Posted on: 03 June 2018 by feeling_zen

Are you able to go back to basics and sanity check your mains earth? Earthing is not all equal. In some countries, 1 Ohm qualifies as earth but that's useless from an audio perspective.

Ask a sparky to come over and measure the earth potential. Once that is confirmed to be normal, then go back to troubleshooting.

Posted on: 03 June 2018 by Willy

yeti42 posted:
If you unplug the lingo from the mains but connect evreything else on does it still hum?

Unplugging the Lingo makes no difference to the hum. Even tried a second lingo and it made no difference.

Willy.

Posted on: 03 June 2018 by Simon-in-Suffolk

Interesting one.... it does sound like possibly cartridge left and right ground are some how joined and forming a weak earth loop ... assuming it’s a not a mains earth loop. So I’d be inclined to (if you can) disconnect one of the channel signals to see if the hum goes away. Then if it does you have narrowed it down to bad cartridge wiring, or faulty cartridge.

Posted on: 03 June 2018 by Willy

Simon-in-Suffolk posted:
Interesting one.... it does sound like possibly cartridge left and right ground are some how joined and forming a weak earth loop ... assuming it’s a not a mains earth loop. So I’d be inclined to (if you can) disconnect one of the channel signals to see if the hum goes away. Then if it does you have narrowed it down to bad cartridge wiring, or faulty cartridge.

Simon, Just tried that but actually but unfortunately made no difference. Thanks for the suggestion.

Willy.

Posted on: 03 June 2018 by audio1946

is your mains feed /earth ok

Posted on: 03 June 2018 by Simon-in-Suffolk

Willy posted:
Simon-in-Suffolk posted:
Interesting one.... it does sound like possibly cartridge left and right ground are some how joined and forming a weak earth loop ... assuming it’s a not a mains earth loop. So I’d be inclined to (if you can) disconnect one of the channel signals to see if the hum goes away. Then if it does you have narrowed it down to bad cartridge wiring, or faulty cartridge.
Simon, Just tried that but actually but unfortunately made no difference. Thanks for the suggestion.
Willy.

Ok so you disconnected both signal and signal return for a channel?.. did the hum stop for that channel, but carry on in the other?

If so therefore you have now appeared to narrow it down to a mains earth ground loop issue then... so it looks like the signal returns on your TT are possibly earthed for some reason...or open circuit with some sort of capacitive coupling to ground. To determine the latter, disconnect the signal returns to see if there is a difference.

Posted on: 04 June 2018 by Willy

Simon-in-Suffolk posted:
Willy posted:
Simon-in-Suffolk posted:
Interesting one.... it does sound like possibly cartridge left and right ground are some how joined and forming a weak earth loop ... assuming it’s a not a mains earth loop. So I’d be inclined to (if you can) disconnect one of the channel signals to see if the hum goes away. Then if it does you have narrowed it down to bad cartridge wiring, or faulty cartridge.
Simon, Just tried that but actually but unfortunately made no difference. Thanks for the suggestion.
Willy.
Ok so you disconnected both signal and signal return for a channel?.. did the hum stop for that channel, but carry on in the other?
If so therefore you have now appeared to narrow it down to a mains earth ground loop issue then... so it looks like the signal returns on your TT are possibly earthed for some reason...or open circuit with some sort of capacitive coupling to ground. To determine the latter, disconnect the signal returns to see if there is a difference.

Yesterday I only disconnected the signal from one channel (pulling cartridge tag from cartridge). Made no appreciable difference.

Just tried again but disconnecting signal and ground on one channel. Still humming on both channels at speakers.

Tried with both signal earth tags disconnected (signals connected) and again still humming on both channels.

Would appreciate any further troubleshooting steps you can think of.

Willy.

Posted on: 05 June 2018 by yeti42

Have you tried the house power rather than your dedicated radial?

The TT is on a wall shelf, try it on the Fraim. Bit of a long shot that one but my superline used to pickup radio Moscow (attenuated with a 1nF cap plug) until I moved the system from steel framed racks to Fraim. My surmise is that the steel rack was acting like a passive aerial element to the arm leads. It did this with both a Rega 300 and an Aro. earthing pre or SL to the rack didn't make much difference, nor did moving the system across the room.

I take it you've tried every combination of earth wires connected and disconnected by now.

Posted on: 06 June 2018 by Willy

yeti42 posted:
Have you tried the house power rather than your dedicated radial?
The TT is on a wall shelf, try it on the Fraim. Bit of a long shot that one but my superline used to pickup radio Moscow (attenuated with a 1nF cap plug) until I moved the system from steel framed racks to Fraim. My surmise is that the steel rack was acting like a passive aerial element to the arm leads. It did this with both a Rega 300 and an Aro. earthing pre or SL to the rack didn't make much difference, nor did moving the system across the room.
I take it you've tried every combination of earth wires connected and disconnected by now.

Tried it on the house ring and no difference.

On a quadraspire wooden shelf so I don't think it's likely to be a factor, especially since on the same shelf it works fine with a 42/hicap. Indeed that is the most perplexing thing here that the 42/hicap is fine but either of two 52/power supply combinations is problematic. Still out of curiosity I'll give it a bash.

Tried a lot of earthing combinations with no joy so far. One more I'll give a go, emulating mp prefix connectivity, disconnect earth from arm cable to subchassis and connect flying lead to signal earth (with a 4 pin din) into the 52ps. Will be in town this afternoon (chauffeuring Mrs Willy to her charcoal drawing class) and will pick up a din plug.

Have also initiated a conversation with Naim Support.

Willy.