transformer hum buzz - is UPS a solution

Never, EVER use an UPS for powering an audio system. It will suck the life out of it. Make sure you're not having a grounding problem or a wacky electrical device inducing the hum over the power lines.

ps. my 250DR eventually settled after humming (a pulsating hum) for a couple of weeks.

When I added a balanced mains transformer to my system this virtually eliminated the hum on both my 555 and 250. Improved SQ also (to my ears)

Thanks for your comments!

Alanbass1 i don't think this is easy to install such device - can you tell me where to search these online? How did it improve the SQ ?

Dan.S that is why I asked my question. Did you try an UPS unit before?

A prominent hum from the transformer is often due to imposed DC on the mains, and a DC blocker should fix completely. Several members on the forum have reported using such devices, both commercial and DIY, and reported success with the hum while not noting any adverse effect on sound quality. If yours has only partial success with the hum and has an adverse effect on sound quality it might be that the device is a poor one, although of course this is only conjecture. 

While waiting for people with such experience to respond it may be worth giving more details of your system, and in particular the DC blocker you have tried.

IB, I have advised him on a DC filter in another thread, but for some reason the one he has destroys the sound (it’s claimed)   I wonder why this filter manufacturer is able to be successful if that’s the case,  but maybe we will never know.      As to the OP question of using a UPS ......   obsolutly not,   I can’t speak for all UPS but the one I have has nothing in its circuitry that will block DC & the Naim transformer inrush current will probably damage it.  As for running the Naim on ghe battery phase,  it will probably not be able to do that 

Same problem here -solved it with PS Audio Humbuster (DC filter).

Mike-B posted:

IB, I have advised him on a DC filter in another thread, but for some reason the one he has destroys the sound (it’s claimed)   I wonder why this filter manufacturer is able to be successful if that’s the case,  but maybe we will never know.      As to the OP question of using a UPS ......   obsolutly not,   I can’t speak for all UPS but the one I have has nothing in its circuitry that will block DC & the Naim transformer inrush current will probably damage it.  As for running the Naim on ghe battery phase,  it will probably not be able to do that 

Further to Mike’s post, most UPS reconstruct the mains waveform cycle relatively quite crudely and in doing so cause higher frequency harmonics to be added on the UPS mains. For most devices this is of no consequence and I would expect a degree of filtering, but this is not at all desirable for sensitive audio circuitry. In other words the reconstructed mains on many UPS is quite noisy.

S

Slawek,

I found an Airlink Transformer’s balanced power supply to work well in our system.

For all the history, look up a thread called,” Suffering from those transformer hum blues?”

Hope this helps, FT

Hi,

I recently purchased a hicap dr to go with my supernait 2 and it hummed badly in my house but was silent at the dealers. Having read many posts on this forum I bought an airlink balanced transformer and guess what.. it made no difference whatsoever. 

The hicap was returned to the dealer but the balanced transformer has burned a hole in my pocket. I'd be careful about blindly buying one without a home trial as they're not the cure all which some would have you believe.

I like the naim sound but the experience has made me feel that I can't make any further upgrades as don't know what combination of components will hum. It's a pity but see my only option now is to move to another manufacturer.

BTW, my bare SN2 is totally silent so it seems to be pretty random which transformers actually hum.

Thanks for all your input. I know it could be annoying when no solution can work with such good sounding equipment. 
I replaced my naim to audiolab but the hum although very slight (more weght/very solid casing) was still there but the sound was much worse and I gave it back to the dealer.

T38.45 did you hear any SQ difference? are the dynamic and upper parts of the scale still the same? The one I've checked was Polish Tomanek DC Blocker quite cheap one. It seems to me others on this forum say any DC blocker can degradate the sound and (supposedly) Naim dissuades/revives this kind of a solution.

The rest of the equipment are dynaudio emit 20 and arcam airplay.

Would be a solution to place the amplifier in a closed rack? Anyone tried?

slaw posted:

Thanks for all your input. I know it could be annoying when no solution can work with such good sounding equipment. 
I replaced my naim to audiolab but the hum although very slight (more weght/very solid casing) was still there but the sound was much worse and I gave it back to the dealer.

T38.45 did you hear any SQ difference? are the dynamic and upper parts of the scale still the same? The one I've checked was Polish Tomanek DC Blocker quite cheap one. It seems to me others on this forum say any DC blocker can degradate the sound and (supposedly) Naim dissuades/revives this kind of a solution.

The rest of the equipment are dynaudio emit 20 and arcam airplay.

Would be a solution to place the amplifier in a closed rack? Anyone tried?

SQ wise I didn‘t realize an impact. The tip for PS Audio came from my Naim dealer!

slaw posted:

Thanks for your comments!

Alanbass1 i don't think this is easy to install such device - can you tell me where to search these online? How did it improve the SQ ?

Dan.S that is why I asked my question. Did you try an UPS unit before?

I purchased an Airlink 2000 va stand alone unit direct from them online. Plugs into a wall socket so absolutely no hassle setting it up

alanbass1 posted:

slaw posted:

Thanks for your comments!

Alanbass1 i don't think this is easy to install such device - can you tell me where to search these online? How did it improve the SQ ?

Dan.S that is why I asked my question. Did you try an UPS unit before?

I purchased an Airlink 2000 va stand alone unit direct from them online. Plugs into a wall socket so absolutely no hassle setting it up

...and did it continue to work for you?

Phil

Hi Slaw,

To answer a couple of your questions, it was the airlink 2000 transformer which I purchased and it was pretty much silent as could only hear it when I put my ear next to it. It's a bit of an ugly beast though so would need to be hidden somewhere if it made any difference and you wanted to use it long term.

As to putting the amplifier in a closed cabinet, I tried building a wooden box which fitted over my hicap, leaving it open at the the back in order to let any heat out. It made a slight difference but not enough to stop me hearing the noise. You might have more luck with a closed cabinet but would have to try.

Using the airlink 2000 also caused a change to the sound of my system. Bass notes appeared to be fuller and I had more clarity in general which was good but it came at the expense of kick drums getting lost in the mix somewhat. In the end I preferred the overall sound with it removed.

Pedropete posted:

Hi,

I recently purchased a hicap dr to go with my supernait 2 and it hummed badly in my house but was silent at the dealers. Having read many posts on this forum I bought an airlink balanced transformer and guess what.. it made no difference whatsoever. 

The hicap was returned to the dealer but the balanced transformer has burned a hole in my pocket. I'd be careful about blindly buying one without a home trial as they're not the cure all which some would have you believe.

I like the naim sound but the experience has made me feel that I can't make any further upgrades as don't know what combination of components will hum. It's a pity but see my only option now is to move to another manufacturer.

BTW, my bare SN2 is totally silent so it seems to be pretty random which transformers actually hum.

The other piece of advice was to switch off all other appliances inside the house (particularly those on the same ring main as the audio equipment) and then tun them back on one by one to see is anything inside the house is causing mains asymmetry.  If so fix that first, as if the cause is inside the house, then a Balanced Isolation Transformer may well not make any improvement to the transformer hum (actually there's a possibility it could make it worse).

It's probably still worth you doing this test

Hi Huge,

I already tried turning off everything in the house including the rest of my system, heating, fridge etc. Only thing powered was the hicap and I tried it in various different rooms / sockets with no change to the buzz. Maybe I have a giant mutant bee inside which likes to sleep at the dealers : )

I've pretty much given up with it now as have wasted too much time and am not willing to throw any more money onto the fire trying to fix it. Like some other forum members I was a bit undecided whether the hicap dr was actually an improvement to the SN2 so the hum made the choice easy.

In the end all is good as have learned a lesson and will leave my system alone for now, be happy with what I have and enjoy the music.

Damn you ugly active atc's, leave me alone, I still don't want to elope with you.... yet.

Had a similar problem with my supercap2,  drove me nuts.  it was dirty mains but only certain times of the day.  

When we moved house, I ended up putting in a balanced isolating transformer in the basement and ran 3 cables to the room, a bit of overkill, but if your pulling in 1, why not pull in 3 ( 1 for each ATC and 1 for the rest of the boxes) , just ensuring they have sufficient segregation between cables.

worked a treat, but a messy job. luckily its a fixer upper we moved into.

contemplated UPS, and looked at the av units that turn AC to DC and back again.  a lot of money for no guarentees.

Isol-8 not do a axis-dc block?  I was going to try but never got round to it.

iam amazed that the number of hum related issues, in 50yrs of having audio equipment ive never had any issues. ive had at least 7 different in coming supplies it that time.  it seems they relate more to naim equipment that others . iam not convinced it is a dc problem but a positional issue either external  or internal of the unit,    

audio1946 posted:

iam amazed that the number of hum related issues, in 50yrs of having audio equipment ive never had any issues. ive had at least 7 different in coming supplies it that time.  it seems they relate more to naim equipment that others . iam not convinced it is a dc problem but a positional issue either external  or internal of the unit,    

What causes your doubt? In the vast majority of cases that I’ve read of on this forum, some action to block DC on the mains is said to have cured the hum. I know that isn’t proof, but it is pretty good circumstantial evidence. Of course there can be other causes, and the occasional fault with a transformer occurs, cured by changing it or the unit.

Incidentally, it is not universal to Naim: my Musical Fidelity P270, which has a pair of very large toroidal transformers inside (being a dual mono design) does exactly the same thing, with the most classic of symptoms: an intermittent loud hum that comes and goes. However it was not until fairly recently that I’d read of these problems on this forum, and haven’t yet got around to building a DC blocker.

cant believe there are many that have hum that is caused by dc  .   in industry we  had this problem with transformers and the main reason was loose laminations etc with shell tranformers and contactors, sometimes slight repositioning the fixing bolts alittle solved it ,screening plates also helped too. toroidal  --- twisting it on its bolt alittle... 

Slawek,

Sometimes we needs to find a good compromise which suites the best to our situation. If you want to really cure the problem by “electric gadgets” - try IsoTek, they are quite famous in audio- electro market. I have tested them power-block Evo3 Sirius, after all I chose Atlas unfiltered power-block.... 

Kacper 

audio1946 posted:

cant believe there are many that have hum that is caused by dc  .   in industry we  had this problem with transformers and the main reason was loose laminations etc with shell tranformers and contactors, sometimes slight repositioning the fixing bolts alittle solved it ,screening plates also helped too. toroidal  --- twisting it on its bolt alittle... 

First thing I did with my amp was open up and tighten etc...   however, the irregular intermittent nature, with the way it comes on and goes off, doesn't fit with that sort of cause, but perfectly fits DC on the mains caused by something else on the circuit - which need not necessarily be within the home.