UnitiServe Power Supply related to hum on 555, 552 and 300 Power Supplies?

Posted by: GeeJay on 09 February 2014

My UnitiServe went wrong during the week (refused to hold data buffer and only dim orange lights flashing at the Ethernet socket - no green light at all). Controlled shutdown and reboot has resulted in 'blink of death' (as another forum member called it).

 

Anyway, long story short is that I've taken the UnitiServe and its power supply back to my dealers to be repaired.  The thing is that since removing the US, I no longer get the hum I used to on my 3 power supplies (555PS, NAC-552PS and NAP-300PS).

 

Coincidence, or has the US power supply been feeding electrical noise (with subsequent transformer hum) onto my separate radial circuits all along?

 

Will be putting the US on a separate part of the house mains when it gets back from repair.  Also still not sure why standard US power supply is SMPS - aren't these known to be noisy, and the reason that all other kit uses conventional transformer-based PSs?

 

Posted on: 09 February 2014 by hungryhalibut

I prescribe a linear power supply, as shown in my profile. For $399, it will make the sound a lot better, and the hum issue will be banished. 

Posted on: 09 February 2014 by GeeJay

Thanks HH.  Appreciate rapid response

 

Know that forum rules forbid discussion of 3rd party PSs (but I'd be lying if I said I hadn't also had some similar thoughts!), but I do wonder why the only piece of kit in the whole range that's fitted as standard with SMPS is the UnitiServe?  Can't quite get the logic....

 

Wondering if any other forum members have also lost 'hum' when their USs removed from the same circuit as their other kit?

 

 

Posted on: 09 February 2014 by hungryhalibut

It's beyond me why Naim won't supply a decent power supply with the UnitiServe, but they won't. Luckily, there are other alternatives. If you don't change over, don't plug the US into the same circuit as the rest of the equipment.

Posted on: 09 February 2014 by analogmusic

Either they feel it doesn't make a difference or it's just mind boggling.

 

there is a power supply for every thing except US?

 

why did they not make it compatible with the NAPSC or Hicap/flatcap at least

Posted on: 10 February 2014 by hungryhalibut

I asked Naim about this and the response was that if I wanted a Naim server with a better power supply I should get an HDX. In my view it should be supplied with something decent in the first place: a modified Napsc would be ideal. The current pile of junk that comes with the Serve can't be that cheap as it has a special filtered mains lead to stop interference from the power supply entering the mains. I'd have thought it was much better to address this by using a liner supply in the first place.

Posted on: 10 February 2014 by james n
Originally Posted by analogmusic:

Either they feel it doesn't make a difference or it's just mind boggling.

 

there is a power supply for every thing except US?

 

why did they not make it compatible with the NAPSC or Hicap/flatcap at least

It's got a reasonably hefty current draw (beyond the normal CAP capabilities) so the little switching PS is a cost effective approach for powering this item - adding a linear supply out of the box would make it too expensive. I'm sure if there was enough demand for a US linear PSU then Naim would introduce something but as Nigel and others have found, the 3rd party market seems to be covering this quite well 

Posted on: 10 February 2014 by hungryhalibut

And probably at a quarter of what Naim would charge.

Posted on: 10 February 2014 by james n
Originally Posted by Hungryhalibut:

It's beyond me why Naim won't supply a decent power supply with the UnitiServe, but they won't. Luckily, there are other alternatives. If you don't change over, don't plug the US into the same circuit as the rest of the equipment.

Or just move it elsewhere in the house. I can see the need for the US to be on the rack if used as an S/PDIF source but in UPnP server mode, i'd put it and any attendant switch / router hardware elsewhere, away from the system. This may also take away the need for a linear supply ?

Posted on: 10 February 2014 by analogmusic
So a switch PSU can supply adequate current?
 
I am not an engineer, I really have no idea about these issues
 
 
 
 
Originally Posted by james n:
Originally Posted by analogmusic:

Either they feel it doesn't make a difference or it's just mind boggling.

 

there is a power supply for every thing except US?

 

why did they not make it compatible with the NAPSC or Hicap/flatcap at least

It's got a reasonably hefty current draw (beyond the normal CAP capabilities) so the little switching PS is a cost effective approach for powering this item - adding a linear supply out of the box would make it too expensive. I'm sure if there was enough demand for a US linear PSU then Naim would introduce something but as Nigel and others have found, the 3rd party market seems to be covering this quite well 

 

Posted on: 10 February 2014 by james n

The US power supply is very efficient at what it does from a size, heat dissipation and cost perspective and is an ideal unit to supply what is effectively a small audio computer. Switching supplies tend to get bad press - mainly as they can affect the other mains powered equipment around them. Naim attempt to counter that with the filter block they incorporate into the power lead.

 

Done properly switching supplies can work very well (Linn Dynamik, Devialet, Chord etc)

Posted on: 10 February 2014 by james n

Good to see you around Allen. Trust you are well