Amplifier "hum" help....

First things first...it is a "hum" not a "buzz". The amp in question is a Naim Nait 5si. The hum becomes noticeable at barely 25% of "maximum" volume, and it is transferred to the speakers. I am using exactly the same set up as I did with an Arcam Delta 290 /290P and a Rega Brio, neither of which displayed similar behavior.
I have tried distancing the phono stage and the Rega Neo ttpsu from the amp, and noticed no change.
I f I disconnect everything from the mains bar the amp, then try the amp in various sockets around the house, and the hum is still present, is there any way I can tell whether the "hum" is mains induced, or inherent in the amp itself?
I suppose I could try it next door

 

Run an earth wire from the amp to the mains on a separate socket with just the earth wire if that makes sense.

 

The Nait does not have an "earth" point as far as I know.....

 

I doubt its a power problem, but could be a power supply problem in the amp (bad filter capacitor(s)). Does the hum appear on both channels and does it get louder with volume increase?

 

Yes and yes....it is brand new out of the box! Naim "mystique" can be perplexing....several "sources" state that a level of hum is "normal", and will have no effect upon performance...but because I know it is there it is bugging me

 

Just an "update"....now the Naim has been powered up for a few days it is (in my system) beginning to shine...I have also taken delivery of a pair of Graham Slee hand built Spatia l/s cables to compliment the Slee Lautus interconnect twixt Accession phono stage and amp....installed them last night ,and although not in a critical listening mood(long long day at work) reached at random for an an album and lighted upon Caravan's "In the Land of Grey and Pink"....not too challenging, but it sounded wonderful.
As the wooden hill beckoned, thought I would just try one more record before I turned in, and chose something a bit more "difficult"...and plumped for Emmy Lou Harris's "Wrecking Ball"...the one with THAT Daniel Lanois production....it held me spellbound from beginning to end...guess I am going to have to revisit all those "classic" albums once again!

 

But is the hum still there?

 

Yes...but I forgot all about it...and said "hum" does not seem to be present through the speakers when playing an album as I would hear it in the" gaps" between tracks.(I think).

 

Disconnect any sources and just listen to the amplifier connected to speakers and turned up.
Is the hum present?

 

Will try that this evening when I get home from work

 

Missing ground wire from TT to phono amp and/or phono amp to Naim amp.

 

Readjust your rca cables, ensure they are not touching any power cords, etc. 9 times out of 10 when you insert a new piece of equipment into your system and you hear a hum or new noise that wasn’t there before;, it’s a cable thing. This is why I run an all balanced system as I don’t have these issues anymore:

 

This is where I get confused. There is no ground wire pin on a Rega Turntable. There is no ground wire pin on a Naim Nait 5si.

 

Interesting, most of these items have a separate ground wire. If I remove my TT ground wire, hum appears.

 

The TT ground is down one of the legs of the leadout cable, so at your Graham Slee Accession phono preamp there's no requirement to connect to the ground tag.
The connection between the phono preamp and the Nait continues the signal grounding, in your case the Lautus cable.

What else is plugged into the Nait?

 

Just a Marantz cd6006 ....I think(hope) a "senior moment" may just be the culprit....prior to installing the Naim, I did a big "cable tidy". I used to use two surge protected blocks to accommodate all the plugs for the audio system and the T.v....(including Firecubes, Chromecasts you name it), and they where pretty much connected at random. During my "clean up" I ensured that both systems were independent(run from different mains sockets),and I also removed floor standing house lights(leds) from the "audio block".
When I was finished, I was so pleased at the neatness and clutter free result I just fed the extension block in behind my Atacama shelf unit without thought....including the power blocks for the Graham Slee phono stage and the Rega Neo TTPSU...both of those used to be as far away from any other equipment as possible...now they both just sitting on on a fully occupied 6 way block!
That is the only thing I can bring to mind, and seeing as the "old" wiring scheme(or lack of) allowed both a Rega Brio and an Arcam Delta 290/290p to run without any hum or buzz, could those psu blocks be the cause?

 

The Brio has a symbol on the back indicating that it is double insulated (a square with a square is the symbol), so the ground connected to it is purely signal ground.
The Nait says on the back that it must be connected to earth, so it's a protective ground, and the signal ground is probably referenced to it, either directly, or via a resistor to raise the signal ground above the safety ground.

In theory the Nait should be quieter than the Brio.

The wall wart for the Rega Neo TT PSU will probably be a just step down transformer.
It's basic and it's linear.

Does the power lead from the TT PSU into the RP8 go anywhere near the tonearm cable?
The TT PSU could inject noise into the signal.

 

I will check everything when I get home from from work....thanks to all those who have offered advice to date

 

Is the hum present when using a line source like a cd player or tape deck ?
Do you hear the hum when using headphones at zero volume ?

 

Yet to try the C.D player with the Naim....will remedy that this p.m

 

I would wager your entire system is static charged from vinyl playback. Do you wetwash your LPs? If not... Start wetwashing every LP before playback, especially new LPs. The static humm will slowly go away.

 

Update....I followed the advice given here,.and unplugged everything from the Naim.....even at "11" it was absolutely silent...no hum or buzz whatsoever. I then hooked up the Rega TTPSU....same result....then what I thought might be the deal breaker....the turntable and phono stage....but deep joy...the Naim just behaving itself.
So last thing to connect. The Dali Oberon loudspeakers. And guess what....they seem to be the source of the hum.
I cannot detect any "downside" when a record is playing,and I am glad the amp/turntable/phono stages have been ruled out as the culprit....any ideas on what causes the speaker hum? The Naim is the most powerful amp I have used with the Oberons.....perhaps it is normal?

 

That was a waste of time!
Of course you're not going hear a damned thing if the problem is electrical noise pickup.
As it stands you've ruled nothing out.

How's about doing it all again with the speakers connected, as I suggested earlier?

 

Not with you at all...surely if I plug just the amp (and amp only) into the mains I can rule out the amp as the source of the hum? And then when I reconnect everything one by one and all is well, I could rule out the ancillary equipment? And by connecting the loudspeakers last of all, in finding out that is where the hum emanates from, I have narrowed down things considerably? And then by firing up the cd player, finding all the hum has gone completely, the only conclusion I can draw is that the right hand speaker is too near the turntable cartridge and picking up interference from there?

 

The loudspeakers cannot be the source of the hum!