Mains hum - earthing?

[mkp1969]

So after 72 hours of owning an Ultra I think I'm going to have to return it.
It's a superb piece of kit, beautifully made and, largely very good at what it does.
I, however, have found that mine introduces horrible hum into the phono stage of my Naim NAIT 50 amplifier.
After hours of plugging and unplugging the only way to rid the phono stage of the hum is to completely power off the Ultra. No amount of moving the ground wire from amp to Ultra to mains ground would fix it. Quite simply if the Ultra was plugged in, the hum found its way to the phono stage. Disappointing but from what I've read here there may be some real concerns about the Ultra and its grounding.
I'm going to try a Pro Plus instead as I really like the software and the Roon Readiness. Hoping that I don't get the same issue.
I'll miss that lovely screen though.

 

[Valentino]

This is the rear of your amp, right? Is your RCA to DIN cable ok?

 

[mkp1969]

Yes, I've tried three different RCA to DIN cables on it. Sadly the hum remains

 

[harkpabst]

Which input did you use?

 

[mkp1969]

I've tried the Ultra into both the DIN inputs. Even with the Ultra bit connected to the amp, as soon as I power up the Ultra, there is hum on the phono input of the amp. It's like the Ultra is producing noise on the mains that the phono stage is picking up. As soon as I unplug the Ultra from the power, the hum disappears.

 

[Valentino]

In the OP you write "from what I've read here there may be some real concerns about the Ultra and its grounding." That is new to me. Could you point me to posts mentioning this?
...
I would not be surprised if the NAIT 50 doesn't like the back to mains noise from the Ultra's SMPS. The NAIT 50 a very old school construction. It could very well be that a Pro Plus is a better solution since you can substitute it's standard smps with a linear power supply if necessary.

 

[harkpabst]

This is not a commonly known issue. If anything (and as you already found out yourself) it's usually rather the other way around, that the phono input on the Ultra picks up external noise.

The hum cannot be injected through the Ultra's line output, if this itself remains silent, of course.

 

[mkp1969]

This is not a commonly known issue. If anything (and as you already found out yourself) it's usually rather the other way around, that the phono input on the Ultra picks up external noise.

The hum cannot be injected through the Ultra's line output, if this itself remains silent, of course.

Yes the hum isn't coming from the Ultra's outputs. I think as the other poster mentioned it's likely the phono stage of the Naim is not enjoying the switched mode PSU of the Ultra.
It's a shame as I really like the Ultra's abilities and look.

 

[mkp1969]

In the OP you write "from what I've read here there may be some real concerns about the Ultra and its grounding." That is new to me. Could you point me to posts mentioning this?
...
I would not be surprised if the NAIT 50 doesn't like the back to mains noise from the Ultra's SMPS. The NAIT 50 a very old school construction. It could very well be that a Pro Plus is a better solution since you can substitute it's standard smps with a linear power supply if necessary.

I may be confusing the grounding with multiple reports here regarding noise on the Ultra's own phono stage. Regardless, I think you're probably correct regarding the SMPS. I have a Pro Plus ordered. I will see if it makes a difference. I may yet keep the Ultra and use it as a headphone system elsewhere on the house.

 

[mkp1969]

Update: I tried the Ultra again with the Naim but it seems that if the Ultra is plugged in in the same room I get the dreaded hum through the Naim's phono input. My house is over 100 years old and it doesn't have the best electrics so I'm resigned to not using the Ultra on the system.
I am, however, keeping it. I've set it up in another room as a headphone system (pretty much a bargain alternative to a Naim Uniti Atom headphone edition) using its phono input with another turntable and so far, fingers crossed, it's absolutely fantastic.
I have a Pro Plus arriving this afternoon for the NAIT - let's hope they like each other!

 

[Saponetto]

Early winter tests using the Ultra made me think that its internal smps "transmit" some noise through the power cord.
Since those cold days, I had to shield and keep it away off from any line level cable.
Hoped it just was bias, but it was not.

 

[mkp1969]

So finally, Pro Plus is here and it's getting on great with the Naim. I will of course pick up a linear power supply for it at some point.
They sound great together, getting on like a house on fire (unlike the cassette deck which was originally next to the Naim which literally was on fire this morning - caps decided they had had enough).

 

[freaknout]

I know you've sorted this but I wanted to let you know that I have an Ultra into a Nait 5i and it's absolutely fine.

Naim are very sensitive to signal grounding, there will be something in the Nait 50s manual about it no doubt. I've found you can elimate most issues by having the whole system plugged into the same power outlet. The system will then share the signal ground.

 

[mkp1969]

I know you've sorted this but I wanted to let you know that I have an Ultra into a Nait 5i and it's absolutely fine.

Naim are very sensitive to signal grounding, there will be something in the Nait 50s manual about it no doubt. I've found you can elimate most issues by having the whole system plugged into the same power outlet. The system will then share the signal ground.

I did resolve it completely by linking the Nait's grounding post directly to the earth pin of a UK plug and plugging that into the power outlet, following some advice from the Naim forum. I'm keeping both Wiims though as the Ultra is like a budget price Atom Headphone edition - sensational value for money - and the Pro Plus sounds gorgeous through the NAIT.

 

[HansD-NL]

"I did resolve it completely by linking the Nait's grounding post directly to the earth pin of a UK plug and plugging that into the power outlet" --> In that case the ground connections inside the Nait 50 are not up to spec which is a shame...

 

[freaknout]

I did resolve it completely by linking the Nait's grounding post directly to the earth pin of a UK plug and plugging that into the power outlet, following some advice from the Naim forum. I'm keeping both Wiims though as the Ultra is like a budget price Atom Headphone edition - sensational value for money - and the Pro Plus sounds gorgeous through the NAIT.

Great.

Am really happy with the Ultra in the office and Pro into my 272 when needs must

 

[mkp1969]

"I did resolve it completely by linking the Nait's grounding post directly to the earth pin of a UK plug and plugging that into the power outlet" --> In that case the ground connections inside the Nait 50 are not up to spec which is a shame...

I think this is Naim's usual configuration. Most of their components have a ground mode switch for use with a Naim amp. It's not ideal but the amp sounds amazing so I can live with it.

 

[HansD-NL]

I think this is Naim's usual configuration. Most of their components have a ground mode switch for use with a Naim amp. It's not ideal but the amp sounds amazing so I can live with it.

I don't know exactly what you mean by "a ground mode switch" since I'm not really familiar with Naim products but to lift the ground on a interconnect path between devices (pre en power amps for example) it only is possible with balanced connections since unbalanced connections have only 2 conductors both needed for carrying the signal.

 

[freaknout]

I don't know exactly what you mean by "a ground mode switch" since I'm not really familiar with Naim products but to lift the ground on a interconnect path between devices (pre en power amps for example) it only is possible with balanced connections since unbalanced connections have only 2 conductors both needed for carrying the signal.

Here is the excerpt from my Naim NAC272 manual. Hope it helps.