NAP 200 audible hum

On the assumption this is from the NAP rather than your speakers, this is normal, or at the very least not a sign of a fault.  Will vary in intensity.

Sounds odd to me. I think I'd want to get it checked out.

It will depend on what is putting DC or pollution onto the mains.  You may find it quiet or humming depending on what is on elsewhere.  I have found anyone using a hairdryer or an electric blanket (even your neighbours) to be particular culprits, although the local Smithy used to be bad too - but that would often result in not just noisy transformers but dimming lights as well!

Mike Woodcock posted:

Hi - I’ve just noticed an audible hum from my NAP 200. When I turn it on using the from switch, the is a slight crack followed by an audible hum that doesn’t stop.  The hum is from the amp itself and is not coming through the speakers. If I disconnect those it is still there 

is this normal or is this a trip to my dealer? 

Hate to say it!

Normal!

Plenty of Threads on the Dreaded Hum!

The Good thing is Naim's Large Transformers really swing!

The Bad Thing, humming can be a problem, depending on your incoming electrical source!

I suppose humming is part of Naim’s very nature.

My CDX2, SuperNait2, HiCapDR and 555PSDR produce an audible hum.

I have dedicated mains and our building, a small 3 floors building, is only 2 years old.

Even so, there is an audible hum which may range from nearly inaudible to louder enough to be heard from the sofa (2,5 meters distant).

Richard Dane posted:

It will depend on what is putting DC or pollution onto the mains.  You may find it quiet or humming depending on what is on elsewhere.  I have found anyone using a hairdryer or an electric blanket (even your neighbours) to be particular culprits, although the local Smithy used to be bad too - but that would often result in not just noisy transformers but dimming lights as well!

I could tell anyway when Mrs C was using a hairdryer (could hear the hairdryer), but how do you know when your neighbour is using an electric blanket ?

More seriously, a separate MCB did little or nothing to eliminate 'hairdryer hum' but a dedicated main consumer unit has eliminated it.

Thanks Everyone - It sounds like I’m being paranoid.  I’ll try a different socket - there’s nothing else turned on in the property, I’ve tried it first thing when everything is off.  Just not something I’ve noticed before

Mike

Mike Woodcock posted:

Thanks Everyone - It sounds like I’m being paranoid.  I’ll try a different socket - there’s nothing else turned on in the property, I’ve tried it first thing when everything is off.  Just not something I’ve noticed before

Mike

It unnnerved me the first time I was aware of it but I relaxed after researching on the forum and learning it was not a fault.  Just forget about it, unless you can hear it over silent passages from your normal listening position.  I doubt a different socket will help, and you can't routinely turn things like your fridge and boiler off.  There are potential solutions if it really detracts from your listening enjoyment, but all at a financial cost.

I have an XS2 which hummed from new, researching the forum determined that it is normal. I found it irritating and the hum level would vary. A bit more research led me to a DC blocker. I bought an Isol8 Axis power socket with DC blocking. It does not eliminate the hum entirely,  but reduces it to a much lower and less iritating and consistent level.   There is no discernible difference in sound quality. 

Bob F 

Mike Woodcock posted:

Thanks Everyone - It sounds like I’m being paranoid.  I’ll try a different socket - there’s nothing else turned on in the property, I’ve tried it first thing when everything is off.  Just not something I’ve noticed before

Are you saying that the hum has just started with an amp you already own, or is it a newly acquired amp that hummed from the start? If it’s the former, there could be a problem with the amp, or possibly a new mains supply issue. 

I had a NAP200 and occasionally had transformer hum and speaker hiss.  Fortunately, it did not intrude on the music and I concluded that it bothered me more than the NAP200. 

What I did find, though, is that it varied in intensity based on distance and angle, and in quite unpredictable ways.  Perhaps a minor change to your HiFi rack position will quieten down your listening position.

Completely normal and par for the course with Naim transformers IME. The only thing that cured it completely for me was installing an Airlink balanced transformer which got rid of the DC on the mains radial feeding it. The transformer didn't impact SQ in any way. (Latter was already knackered on the radial and is subject of another thread!)