Uniti Atom - hum

With regard the sq, it sounds as though the Atom is still running in - give it a week or two to bed down.

The hum from the unit suggests you have dc on the mains; Naim devices seem susceptible to that - I think because they use such large toroid transformers. You can try to track down the cause of your dirty mains (but it may be coming from beyond your premises making it impossible) and unplug it. If it's a real bother you can buy DC blockers, but they aren't cheap - expect to pay £400 minimum if you're in the UK or €400 in Europe. No idea about other countries or continents. If you go down that route make sure you use a reputable supplier and that the current/power rating is high enough for the Atom.

My original Atom was an ex demo unit and didn't hum.

2 x replacements both hummed when first turned on 2 months ago

2nd replacement the hum has significantly disappeared over the past month and getting almost silent.

It does seem to take a little time for the Atom to get "on song" and the sound to improve. 

My Atom hums a bit, it's a higher pitch hum than other Naim amps I've had, and not loud enough to be a problem when its not playing. Obviously it doesn't hum in standby, so if I really want silence, I can switch it off.

There's plenty of info and threads on here about how to best deal with hum coming from Toroidal transformers.  It's just a physical thing, shouldn't be heard from the speakers and shouldn't impact overall sound performance. It's usually caused by pollution on the mains from either poor PSUs or faulty equipment elsewhere.  Cheap switch mode supplies, hairdryers, electric blankets, ethernet over mains units, dodgy or old refrigeration units, to name just a few prime suspects. The best solution is to try to fix at source, although it can take a bit of detective work to find the culprit.  If it only happens at certain times then that's often a useful clue...

Yesterday i uninstalled a double socket on the same ring with had the new style USB sockets, no idea if it made a difference, but my understanding is they do have some form of switched mode power logic.

My Nova hum is low, sometimes at night i can detect it, i assume that is mains pollution elsewhere.

Obsydian posted:

Yesterday i uninstalled a double socket on the same ring with had the new style USB sockets, no idea if it made a difference, but my understanding is they do have some form of switched mode power logic.

My Nova hum is low, sometimes at night i can detect it, i assume that is mains pollution elsewhere.

Those sockets with USB power sockets built in are very convenient, but I can imagine a house full of them being a potential noise issue, so I avoid them.

ChrisSU posted:

Obsydian posted:

Yesterday i uninstalled a double socket on the same ring with had the new style USB sockets, no idea if it made a difference, but my understanding is they do have some form of switched mode power logic.

My Nova hum is low, sometimes at night i can detect it, i assume that is mains pollution elsewhere.

Those sockets with USB power sockets built in are very convenient, but I can imagine a house full of them being a potential noise issue, so I avoid them.

Hi CHRISSU, thats why i originally installed one with 3.1V output to two USB, i found in reality anything more that one device or as many fast charge devices now it was useless.

In the end i went with an AUKEY 6 into 1 (2x Fast and 4x Std), it has intelligent charging, never even gets warm (odd) and i quite regularly charge 4 devices at a time, plus most of all its a neat setup and i even use this for holidays

Note the AUKEY i have is about 2 years old

my atom hums, when on and in standby. my house is only 4 years old so I would hope the wiring system is in good shape. I think the only thing with SMPS is the NAS. most other items in the house are new.

Unfortunately the source of the trouble may be coming from your neighbours...

longmanjon posted:

my atom hums, when on and in standby. my house is only 4 years old so I would hope the wiring system is in good shape. I think the only thing with SMPS is the NAS. most other items in the house are new.

Strange that it hums in standby, is is exactly the same hum as when it's awake? For me, the hums starts as soon as you wake it up, and stops as soon as you put it back into standby, which is what you'd expect if it's the main toroidal transformer you can hear.

iangw posted:

First impressions of the Atom is that it is very convenient and easy to use and generally decent sound quality. My previous setup was a Mac mini feeding a Arcam rDac into a PrimaLuna tube amp. The Atom lacks the mid range and top end quality and I seem to have to play my music louder for the unit to sing. Whilst I was not expecting the sound quality to match my previous setup I was hoping for something close but I guess I need to spend more to get it.

 

I wouldn't expect the sound to change much, unfortunately. It's due to the firmware changes they started to make several months back (search on here to find out more). When I first bought my brand new atom, it sounded absolutely amazing from the off, no matter the volume, completely and utterly amazing. Now it's as flat as a pancake and I can't wait to upgrade to something else from a different manufacturer. 

Here in Poland you can get decent DC blockers for ca 70-80 GBP. Check Tomanek

ChrisSU posted:

longmanjon posted:

my atom hums, when on and in standby. my house is only 4 years old so I would hope the wiring system is in good shape. I think the only thing with SMPS is the NAS. most other items in the house are new.

Strange that it hums in standby, is is exactly the same hum as when it's awake? For me, the hums starts as soon as you wake it up, and stops as soon as you put it back into standby, which is what you'd expect if it's the main toroidal transformer you can hear.

It hums in standby only if server mode is turned ON. If it is OFF - unit do not hum in standby.

Also, furniture under Atom can increase the volume of hum (for example if you have a cheap MDF furniture with closed doors under the Uniti).

I had this problem also. And I bought "Vibrapod Isolators (Model 2 For equipment weighing 5.44Kg - 14.5Kg)". I put them under Uniti Atom. And they greatly reduced the volume of hum.

If server mode if off it is basically using no power, so no hum.

Obsydian posted:

If server mode if off it is basically using no power, so no hum.

Exactly

tony123 posted:

Also, furniture under Atom can increase the volume of hum (for example if you have a cheap MDF furniture with closed doors under the Uniti).

I had this problem also. And I bought "Vibrapod Isolators (Model 2 For equipment weighing 5.44Kg - 14.5Kg)". I put them under Uniti Atom. And they greatly reduced the volume of hum.

By the way, you can gently lift the Unit off the table with your hands. And check if the hum reduces while the unit is in your hands (not touching the furniture). If yes - vibrapods will also help.

tony123 posted:

Also, furniture under Atom can increase the volume of hum (for example if you have a cheap MDF furniture with closed doors under the Uniti).

I had this problem also. And I bought "Vibrapod Isolators (Model 2 For equipment weighing 5.44Kg - 14.5Kg)". I put them under Uniti Atom. And they greatly reduced the volume of hum.

I shall take a look at the vibrapod and try lifting the unit first to see if that reduces the problem, as mine is on a unit which is probably built with some choice materials.

well I tried a set of and although it helped the overall sound improve, the hum is still there. I tried a different socket just in case but no change. I shall have to investigate noisy mains from other appliances, but nothing new has been added recently and would that affect it when its in standby?