My system hums now

You think you've got it bad?.....  My system Wolf Whistles at my wife whenever she walks by the speakers.

If your system is connected in any way to CATV, disconnect cable at the source to see if it helps.  Detrrmines next steps.

Nick

Is the hum from the electronics boxes or the speakers?

Huge's question is indeed the key one. I have seen threads offering advice on the subject of hum, where the problem turned out to be other sort than assumed by the advisors.

best

David

Good point.  Transformer hum is not the same as earth-loop hum heard at the speakers.

We need a tech-elf to clarify (DB?) but I think it's DC offset on the supply which causes audible transformer hum. A dedicated spur (I have one) will not necessarily eradicate it.

It's interesting to note that Naim have continued to use linear power-supplies with massive toroidal transformers in the Statement amps. I'm guessing that they would have preferred to have used the rather more ubiquitous and less expensive switch-mode power supplies extensively used by other manufacturers, but Naim presumably could only achieve the required performance and sound quality from linear power supplies.

Ergo; we have to put up with the buzzing if we want that sound.

John.

There are other brands that use linear power supplies where there is no transformer hum - in my case I have Bryston 4BSST two two very larger transformers - no hum while at the same time my XPS DR hums away happily (mainly week day early evenings)....

Other brands that use linear power supplies - Musical Fidelity (had one last year - sold now) but no hum - ever...

So it is possible to but power supplies without transformer hum.... since only my XPS DR hums, and not to an extent that it spoils the music, I can live with it - fortunately by the time it gets to 'listen to music' time the hum normally has gone... 

Fernar - torrodial transformers that Naim use because of their high efficiency and therefore good regulation are susceptible to DC saturation and buzzing when saturated by asymmetric mains or DC offset. There are methods that some manufacturers use to eliminate DC offset by using some electronics infront of  the primary of the transformer - but perhaps Naim feel in listening tests this interferes with SQ - perhaps even ever so slightly - and would affect all customers whether they have DC (asymmetric AC) in their mains or not.

Simon

Please don't just assume it's transformer hum, or just assume it's an earth loop until we know whether it's coming from the transformers or the speakers.

The two need different fixes.  Techniques to fix one will have absolutely no effect on the other.  We can advise when we know.

I unluckily had both transformer Buzz/Hum through my Nait XS2 chassis and also humming through my speakers when volume was raised to around 9 - 10 oclock (with no music playing).

I have solved both issues, but i don't think it would be allowed to explain how here

i just wondered if other brands hummed?

My old Yamaha loved to tap dance 

sjw posted:

i just wondered if other brands hummed?

Yes, I've known other transformers hum, and not just in audio power supplies.  However Naim transformers are usually the biggest ones you'll have in your house, and hence they're likely to be the loudest you'll have.

fernar posted:

Other brands that use linear power supplies - Musical Fidelity (had one last year - sold now) but no hum - ever... 

My NAP200 hums... Just a good excuse to play music so that I don't hear it...

Have previously had Musical Fidelity integrated amp and Arcam multi-channel amp that both humed; though Rotel and Quad amplifiers didn't hum.

If the amplifier doesn't know the tune then naturally it hums along.

G

GraemeH posted:

If the amplifier doesn't know the tune then naturally it hums along.

G

I always thought it hummed if it knew the tune but had forgotten the words. 

Huge posted:

Is the hum from the electronics boxes or the speakers?

Boxes, primarily from the HICAP.  Speakers are quiet unless I turn the volume all the way up.

Another detail to fill us in on. Does the hum persist for more than 20 minutes after power on or does it fade away to nothing?

The reason I ask is that it is very common for Naim units to hum when first powered on and be very noticeable and then fade off to nothing after several minutes.

sjbabbey posted:

GraemeH posted:

If the amplifier doesn't know the tune then naturally it hums along.

G

I always thought it hummed if it knew the tune but had forgotten the words. 

Indeed!

G

feeling_zen posted:

Another detail to fill us in on. Does the hum persist for more than 20 minutes after power on or does it fade away to nothing?

The reason I ask is that it is very common for Naim units to hum when first powered on and be very noticeable and then fade off to nothing after several minutes.

Its all the time, but its really not that bad.  I have to listen pretty intently to hear it from 5 feet away, its only when I'm up near it, placing a vinyl on the deck that I hear it.

Reporting it because its net new to me, and I've seen a lot of threads on it.

J.N. posted:

We need a tech-elf to clarify (DB?) but I think it's DC offset on the supply which causes audible transformer hum. A dedicated spur (I have one) will not necessarily eradicate it.

It's interesting to note that Naim have continued to use linear power-supplies with massive toroidal transformers in the Statement amps. I'm guessing that they would have preferred to have used the rather more ubiquitous and less expensive switch-mode power supplies extensively used by other manufacturers, but Naim presumably could only achieve the required performance and sound quality from linear power supplies.

Ergo; we have to put up with the buzzing if we want that sound.

John.

 

John,

Statement has BOTH toroidal and SMPS!

My S1 pre doesn't hum but some of the other power supplies do, occasionally.  However can't be that bad because despite being about 3ft from my ears it isn't distracting.

OK, it's almost certainly due to the waveform shape of the mains.  If the +ve and -ve cycles aren't the same size (i.e. waveform asymmetry), then a residual and varying magnetic flux builds up in the transformer, and the 50/60Hz mains cycle caused the transformer to hum.

This asymmetric wave form can be though of as a distorted wave and a DC component.  The answer is a device to let through the distorted AC wave but block the DC.  there are a number of commercial devices to do this; some use a specific type of filter (N.B. not a mains conditioner or mains filter - they are something completely different); others are in the form of a balanced isolation transformer wired centre tap to earth.