I got my XPS (DR) however.........

OK, so here the set up (after following some sound advice) - 272, 250DR, XPS (DR) with Powerline and driving a set of Focal Diablo Utopia III (on loan). I'm still waiting for delivery of the rack, so its sitting on the old glass shelves.

The sound is simply stunning and the improvement since adding the XPS this week is huge. However, I get a hum from the XPS - Definitely not through the speakers.  

Pinged off a quick email to Naim who tell me and I quote, "it is quite normal to get a physical hum from any of our “big transformer” devices if the mains supply to it isn’t clean". There are pages and pages of comments on this topic and from what I've seen, very little agreement on how to resolve it.

I do have an IsoTeK somewhere but I was told to dump it when I first got "infected" with the Naim Virus!

So, any thoughts?

Steve

 

 

 

 

Original Post
wenger2015 posted:
Steve GTX posted:

Do you mean, run a mains supply from the consumer unit to the outlet?

 

Hi Steve GTX...thats probably the best option....otherwise it's hire a generator 

By the way congratulations on an excellent system,  I'm sure it must sound stunning 

Steve GTX posted:

How do I know if that is the issue? If the mains supply to the house is not "clean" running another cable won't make any difference.

It there a test I can do? 

Take the XPS to the "West Wing" and plug it in to the closest circuit to the fuse box that hopefully has nothing else on it (if so, try to unplug everything you can, but definitely find another circuit if there is a computer, large appliance or fluorescent lights on the circuit).  Does it hum there?

I'm having my supply split at the incoming mains tails and a dedicated consumer unit and cables run in. Will this cure the hum of a big toroidal transformer.....maybe not, but it's worth a try. Anything to stop the general household electronics from messing with the hifi supply can only be a good thing. 

Thanks, I'll give it a go but I'm really surprised that it's that sensitive - I shudder to think what's connected to the ring mains on the ground floor. Just in the living room I've the HiFi, Sky box, DVD, Apple TV, Sonos Connect, NAS Drive, TV. and I'm sure there is the odd table lamp (odd meaning more that one, not strange or an even number of them). 

What about using the IsoTek?

 

Thank you  Mark, 

That is how I've got it now. The XPS is connected directly to the Wall socket with a Powerline, along with the 272 & 250.

I'll get the electrician around to see what my options are - I've just had a new consumer unit installed and getting a new cable to it will not be easy 

 

 

When I was running the 272/XPSDR/250DR they stacked best in that order top to bottom.  I noticed the 272 liked air above it, but really didn't notice much difference in swapping the positions of the XPS & 250.  I did notice a fairly marked improvement of having an extra empty layer of Fraim at the bottom.

The dedicated circuit did improve things for me, but my XPS (and my HCDR for my SL) still had a slight hum afterwards.  The improvement in musicality, though, was quite noticeable.

Steve GTX posted:

Thank you  Mark, 

That is how I've got it now. The XPS is connected directly to the Wall socket with a Powerline, along with the 272 & 250.

I'll get the electrician around to see what my options are - I've just had a new consumer unit installed and getting a new cable to it will not be easy 

 

 

You don't have the 272 connected to the mains, do you?

Just to give you an idea of how essential I think the dedicated line is, I would consider installing the line prior to the XPS and a larger step than the XPS.  That isn't to belittle the XPS in any way, as I think it makes a vast improvement on the 272, but after doing it I find the dedicated circuit fundamental to the performance of my system.  I highly recommend it.

A dedicated spur often improves SQ, but it will not necessarily obviate the transformer-hum of Naim power-supplies, no matter how much effort is put into removing potential suspects from one's own ring-main.

That's my experience anyway. 

John. 

Steve GTX posted:

HH,

Having re read my earlier reply, I quite understand why you asked.

You do know that this is all your fault, after all, it is your plan I've been following .

Ah good; as you have seen your post implied that. But of course, owning a 272/250 you are a top man who would never make such an error. 

As to a dedicated line, do it. It takes all the rubbish from other stuff off the mains and will improve sound quality. We run our wire round the outside of the house buried under the flower bed, using 10mm2 steel walled armoured cable. You should get a separate small consumer unit installed. We have no hum at all.

Regarding a stand, have the 272 at the top with the XPS below, and it's important that the Burndy doesn't touch the wall, floor or other wires. Make sure you arrange it into the right shape before plugging in, so that there is no strain on the connections. 

In general, a dedicated mains supply won't silence mechanical transformer hum.  The hum arises for one of two reasons:

A  (Rarely) because the transformer is just a noisy one.
B  (More often) because the mains supply is asymmetric (positive 1/2 cycle isn't equal to negative 1/2 cycle).  Reducing the wire resistance won't affect this.  If a dedicated supply does reduce the problem then you're causing the problem inside your own home, so fix the problem where it's being caused!

Adam Zielinski posted:

The thing is - there is no practical method of getting rid of a transformer hum.

By practical I mean one with decent return on costs / effort ratio.
...

That depends...

If you already have a radial circuit, get an electrician to install a balanced isolation transformer wired CTE.

If you have skill with a soldering iron, build a 'DC blocking filter'.

Otherwise the cost is of the order of £1000(GBP) up.

I use two Isol-8 axis blocks in my system and these cured DC-induced transformer hum for me. Before I had them the Supercap and the XPS I had  used to drown out quiet musical passages. To be quite honest I've not detected a drop of in SQ and if there has been a slight change for the worse, these ears can't hear it and it's more than compensated with all that transformer hum banished .

As usual best remedy is to try the solution yourself. I find there's a lot of folklore out there, some based on fact, some just passed around rather than directly experienced. That's the scientist in me speaking!

Adam Zielinski posted:

The thing is - there is no practical method of getting rid of a transformer hum.

By practical I mean one with decent return on costs / effort ratio.

All my power supplies hum, my CDX2 hums, even my NDX hums - but never at the same time

Hi Adam

You might like to check the thread in the post that is two above yours.  

Huge's post below yours suggests a very similar train of thought.

Best regards, FT

Hi FT

Certainly - I remember that post well. I already had an interesting discussion with my electricians on that.

But it would seem we have not yet found a foolproof solution for my system. The current thinking is that my gear is hooked up to a different phase than the rest of the equipment which isolates it well from fridges, hairdryers etc. But that phase seems to be picking up interference from other building equipment in the basement (water pump, heating pump...).

Adam

liam posted:

My xpsdr hummed so much I sold it!

Well that is certainly a pedestrian solution - you should have rewired your entire house or failing that, bought a different one.

Have you no commitment to sonic excellence?

Brexit Schmexit - I think we need to focus on bigger issues...

(Disclaimer - the above statements are pure hyperbole for comic purposes, and are not meant to be taken in any other spirit.)

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