Humming From Grounded Turntable

[ashor]

Hi All

I have an issue with a humming Audio Technica LP5X Turntable that I can't quite get my head around.

It's not so noticeable through the speakers (unless I crank the volume up) but I do most of my listening via headphones, where it very present and really annoying.

I'm confident it's a grounding related hum and I know it's the TT as it only happens when I switch it on (it has it's own dedicated wall socket).

I'm bypassing the TT's in-built Phono Stage with an external Rega A2D MK1.

What's weird is that the hum is most noticeable WHEN I CONNECT THE GROUNDING WIRE.

I've tried connecting the TT Grounding Wire directly to the external Rega Phono Stage - HUM!!

I've also tried connecting the TT Grounding Wire directly to my Denon PMA-600AE - HUM!!

Any ideas / advice would be gratefully received.

TIA

 

[Gray]

For test purposes, with the Rega out of the equation, what's the situation?

In other words, AT using its own phono stage, direct into Denon amp, ground wire connected.

 

[ashor]

For test purposes, with the Rega out of the equation, what's the situation?

In other words, AT using its own phono stage, direct into Denon amp, ground wire connected.

Hi Gray

Thanks for your response.

I'll give it a try and report back.

 

[Al ears]

If it is a ground loop issue you have too many grounds.
Is the mains cable to your turntable grounded?
Unfortunately this seems more of an issue when turntables have built in phono preamps.
If you have an external one and I assume there is one in the Denon as well, then why buy a turntable with one inbuilt.
Do yourself a favour and sell the turntable and buy a straightforward one.

 

[ashor]

If it is a ground loop issue you have too many grounds.
Is the mains cable to your turntable grounded?

Hi
The power cable for the TT is plugged directly into a mains wall socket.

I considered just not grounding the TT, but is that wise / dangerous?

*I'm in the UK, so it's a 3 pin plug that is earthed.

 

[Al ears]

Hi
The power cable for the TT is plugged directly into a mains wall socket.

I considered just not grounding the TT, but is that wise / dangerous?

*I'm in the UK, so it's a 3 pin plug that is earthed.

No, not in my opinion.
Try removing the earth wire from the turntable mains socket temporarily and see what that does.
the turntable will still be earthed but not via the mains cable.

 

[ashor]

If it is a ground loop issue you have too many grounds.
Is the mains cable to your turntable grounded?
Unfortunately this seems more of an issue when turntables have built in phono preamps.
If you have an external one and I assume there is one in the Denon as well, then why buy a turntable with one inbuilt.
Do yourself a favour and sell the turntable and buy a straightforward one.

Well, maybe I wouldn't have done had I known it would be an issue.

No, not in my opinion.
Try removing the earth wire from the turntable mains socket temporarily and see what that does.
the turntable will still be earthed but not via the mains cable.

Sorry, it's not wise or it's not dangerous?

Also, I'm very nervous about removing the earth wire.
Isn't that potentially dangerous for someone with no clue about electrics?

 

[Al ears]

Well, maybe I wouldn't have done

Sorry, it's not wise or it's not dangerous?

Also, I'm very nervous about removing the earth wire.
Isn't that potentially dangerous for someone with no clue about electrics?

It may be the only way to resolve your issues, and no it is not going to blow anything up.
If you don't want to do this then replacement of turntable might be only other avenue out.
try what @Gray says and if you still have hum you certainly have too many earths.

 

[Gray]

*I'm in the UK, so it's a 3 pin plug that is earthed.

Are you even sure that the earth pin is actually being used though?
(If it's got the square within a square symbol on any label (maybe near where the mains lead enters) then it's double insulated and won't be using an earth).

If there is a mains earth connected to the TT then you're right to be nervous about permanently removing it. Don't.
The TT may (or may not) otherwise have another path back to earth via the Denon - but it's wrong to rely on that for continued safety.

 

[Al ears]

Are you even sure that the earth pin is actually being used though?
(If it's got the square within a square symbol on any label (maybe near where the mains lead enters) then it's double insulated and won't be using an earth).

If there is a mains earth connected to the TT then you're right to be nervous about permanently removing it. Don't.
The TT may (or may not) otherwise have another path back to earth via the Denon - but it's wrong to rely on that for continued safety.

I acknowledge your input but would disagree with it on safety grounds.
It may be earthed through the mains cable but doesn't actually need to be.
Note many non UK plugs do not actually have an earth.
The issue seems to be too many earths creating a ground loop.
The only way to resolve that is to remove one or more.
The whole set-up the OP has seems to hinder this, unfortunately.
If you are really concerned talk to a professional electrician and tell him you have too many earths in a system and how you rectify this.

 

[DougK1]

I bet there's a moulded plug on the mains socket end so any earth detaching will either require replacing the plug or a strip down of the deck to disconnect at the other end. Try Gray's advice in post 2 first and report back

 

[ashor]

I bet there's a moulded plug on the mains socket end so any earth detaching will either require replacing the plug or a strip down of the deck to disconnect at the other end. Try Gray's advice in post 2 first and report back

Will do.
Hopefully I'll get a chance later today.

 

[camcroft]

I also have a AT turntable. I do recall the other week as being classed as landfill turntables by someone on here. I love mine.

 

[ashor]

I also have a AT turntable. I do recall the other week as being classed as landfill turntables by someone on here. I love mine.

I think that was a reference to the lack of available parts to repair them if / when they go wrong. It was probably on a thread I started, as I'd come by an AT-LP5 with a bent tonearm previously, and was looking to get it fixed. (I got that for nothing and have since sold it for spares.)

It's all very well slating one brand or another when money isn't an object. Personally, I thought upgrading was well beyond what I could afford and I was pretty content with my AT-LP3 (which, I would add, delivered faultless service for 4.5 years).

Did I want a better TT? Well, yes, but don't we all?!

Then the LP5X came up for £255 at Richer Sounds in the sale in December. It's got many 5* reviews and the price was right for me.

I sold my LP3 for £130 so (with the money I got for free TT with the bent tonearm) the LP5X cost me about £60, which I thought was a bargain.

For what I paid, it's a great Turntable. Yes, it has the hum (for now) but it also has a 2-year guarantee for faults (and I can claim for Up to 6 years under Consumer Rights). If it lasts that long, I think I would have got my moneys worth (and then some) and the chances are it will last much longer.

As an aside, I've dealt with Audio-Technica customer & technical services on 4 or 5 occasions over the last 4+ years and they have always been superb which (from what I've read) isn't always the case with some higher-ticket brands.

I bought the LP5X with my eyes open and (as the saying goes) "you pays your money and you makes your choice".

 

[Al ears]

I think that was a reference to the lack of available parts to repair them if / when they go wrong. It was probably on a thread I started, as I'd come by an AT-LP5 with a bent tonearm previously, and was looking to get it fixed. (I got that for nothing and have since sold it for spares.)

It's all very well slating one brand or another when money isn't an object. Personally, I thought upgrading was well beyond what I could afford and I was pretty content with my AT-LP3 (which, I would add, delivered faultless service for 4.5 years).

Did I want a better TT? Well, yes, but don't we all?!

Then the LP5X came up for £255 at Richer Sounds in the sale in December. It's got many 5* reviews and the price was right for me.

I sold my LP3 for £130 so (with the money I got for free TT with the bent tonearm) the LP5X cost me about £60, which I thought was a bargain.

For what I paid, it's a great Turntable. Yes, it has the hum (for now) but it also has a 2-year guarantee for faults (and I can claim for Up to 6 years under Consuner Rights). If it lasts that long, I think I would have got my moneys worth and the chances are it will last much longer.

As an aside, I've dealt with Audio-Technica customer & technical services on 4 or 5 occasions over the last 4+ years and they have always been superb which (from what I've read) isn't always the case with other brands.

I bought the LP5X with my eyes open and (as the saying goes) "you pays your money and you makes your choice".

enjoy!

 

[ashor]

For test purposes, with the Rega out of the equation, what's the situation?

In other words, AT using its own phono stage, direct into Denon amp, ground wire connected.

Okay...so I removed the A2D pre-amp to some improvement.

However...! The best result is when the pre-amp is removed AND the grounding wire is removed.

Just as an aside...does the TT have to be grounded...I mean what are the consequences?

Apologies if I just crossed the line into "Stupid Question Land."

 

[Gray]

It may be earthed through the mains cable but doesn't actually need to be.

If it's got a mains earth, then it needs a mains earth 👍

Note many non UK plugs do not actually have an earth.

Of course you're right, loads of 3-pin plugs don't use the earth pin* - plenty have plastic pins.
But if they're not earthed, it's because they don't need to be.

Wherever there's a ground loop, the loop must never be broken by removing a mains earth.

*And as it happens, this turntable uses a mains adaptor, so wont be using the earth anyway 🙂

 

[Gray]

...does the TT have to be grounded...I mean what are the consequences?

Well you've reported that the consequence for you is an improvement with it disconnected.
There's no safety issue with that.

Just to be clear, you can of course forget talk of mains earth - your turntable is powered by low voltage DC.

Is the turntable placed well away from potential interference sources such as mains transformers? - not placed on top of the amp for example.

And presumably the cartridge comes pre-wired - so that should be all correctly connected....

 

[Al ears]

Well you've reported that the consequence for you is an improvement with it disconnected.
There's no safety issue with that.

Just to be clear, you can of course forget talk of mains earth - your turntable is powered by low voltage DC.

Is the turntable placed well away from potential interference sources such as mains transformers? - not placed on top of the amp for example.

And presumably the cartridge comes pre-wired - so that should be all correctly connected....

So you are ruling out an earth loop??

 

[Gray]

So you are ruling out an earth loop??

All we know for sure is that he's got a hum where there should be silence.
No mains earth.
A hum remains with the ground wire disconnected - in which case, where is the loop?

 

[Al ears]

All we know for sure is that he's got a hum where there should be silence.
No mains earth.
A hum remains with the ground wire disconnected - in which case, where is the loop?

Presumably the turntable is earthed somehow.

 

[nopiano]

Okay...so I removed the A2D pre-amp to some improvement.

However...! The best result is when the pre-amp is removed AND the grounding wire is removed.

Just as an aside...does the TT have to be grounded...I mean what are the consequences?

Apologies if I just crossed the line into "Stupid Question Land."

Mains earthing via a 3-pin plug, which is a safety feature, is completely different to the ground/earth flying lead from a turntable. That’s only to reduce noise/hum. If connecting the lead increases noise then disconnect it and pop some tape over the end and tuck it out of harms way (don’t cut it off, as other systems may need it!)

As mentioned, not every 3-pin plug has the earth connected, but if the item is double-insulated an earth may not be necessary.

 

[Gray]

Presumably the turntable is earthed somehow.

Yes, it's got a terminal that connects via spade and separate ground wire in his RCA cable, to the amp terminal.

When we say there should be silence....at least as silent as a phono stage can be.
(Hopefully there's no residual hum that comes with that model).

 

[Fandango Andy]

Hi All

I have an issue with a humming Audio Technica LP5X Turntable that I can't quite get my head around.

It's not so noticeable through the speakers (unless I crank the volume up) but I do most of my listening via headphones, where it very present and really annoying.

I'm confident it's a grounding related hum and I know it's the TT as it only happens when I switch it on (it has it's own dedicated wall socket).

I'm bypassing the TT's in-built Phono Stage with an external Rega A2D MK1.

What's weird is that the hum is most noticeable WHEN I CONNECT THE GROUNDING WIRE.

I've tried connecting the TT Grounding Wire directly to the external Rega Phono Stage - HUM!!

I've also tried connecting the TT Grounding Wire directly to my Denon PMA-600AE - HUM!!

Any ideas / advice would be gratefully received.

TIA

It looks like all the obvious questions about the earth wire have been asked. Here are a few thoughts:

Is it new? has it worked ok before and this has just started or has it always been like this? if new take it back to the shop to see how it reacts with other equipment.

There is a switch to go between internal and external phono. Does that move freely is it engaging properly?

Does your amp have a phono stage? if it goes have you tried that to see if the problem is with Rega Phono Stage?

That looks like a spare headshell and cartridge in the picture, have you used both, is the noise the same?

Have you mention it has it's own dedicated wall socket, as it uses an external transformer this probably doesn't help. try plugging your phono stage to the dedicated wall socket. try, amp, phono, and TT on the same extension lead.

Finally. unplug everything else in the house, especially the TV and Router and including the fridge freezer. If that solves the problem, turn each thing back on one at a time to see where the interference is coming from.

 

[good_enough]

Has the ground been run TT to pre-amp and on to amp? I'd want to be sure that all components share a ground. If the turntable has a mains adapter feeding it, as I surmise is the case, then the ground on the TT can in principle float to any level. We should be aiming to have all components' grounds at the same potential. Running TT - pre-amp means TT+pre could be at a different potential to the amp. Running TT - amp means TT+amp could be at a different potential to the pre.