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Balanced Mains Conditioners

Just wondering if anyone has had any problems with balanced mains conditioners - e.g. transformer hum from the mains conditioner unit itself.  For all the sonic advantages of balanced conditioners, unfortunately the one I purchased suffers from intermittent hum.  A high to low ebb and flow hum that at its loudest can be a major distraction to listening to the music. 

 

aliEnRIK's picture
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Re: Balanced Mains Conditioners

All transformers hum

Mines hidden inside a cabinet so it doesnt distract at all. That said, it doesnt intermittently change frequency. Sounds like yours hasnt been put together very well.

May I ask where you got it and which unit you bought?

If its fairly new it will settle down after a 'run in' time

Anonymous
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Re: Balanced Mains Conditioners

Its a Ben Duncan one.  It does really improve the sound quality of the music (hum put to one side of course).  The hum varies from day to day even hour to hour.  Sometimes its near silent, sometimes its loud enough to distract attention from the music.  Sometimes I can hear the hum when I'm just coming up the stairs to the room where I have the hi-fi equipment.  I've had it about six months. 


Stranger still that apart from the ebb and flow hum another problem is that if my wife plugs her hairdryer into any socket in the house (and the mains unit is plugged into my hi-fi mains that is on its own separate consumer unit) then the conditioner doesn't just hum it make a louder still constant drone which goes on until my wife switches the hairdryer off.  Listening to music when my wife is drying her hair even if she is downstairs is quite difficult. 


 Despite the problems I'm having the sound quality (hum put to one side) of the actual music is very much improved with the unit plugged in.  I'm just trying to clarify if its a problem with my local mains that is being highlighted by the hum of the mains conditioner.


Thanks in advice for any thoughts or advice


 

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Re: Balanced Mains Conditioners

Id have thought a Ben Duncan one would have been well made

Is it possible to tighten the screw/s that are holding the transformer together?

Id be thinking about encasing it somehow

Anonymous
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Re: Balanced Mains Conditioners
Midlife Person:

Just wondering if anyone has had any problems with balanced mains conditioners - e.g. transformer hum from the mains conditioner unit itself.  For all the sonic advantages of balanced conditioners, unfortunately the one I purchased suffers from intermittent hum.  A high to low ebb and flow hum that at its loudest can be a major distraction to listening to the music. 

 

Ha you think you have it bad ive got two amps that both hum!!!!!

It is very very faint mind and does not bother me really attal. On another note i have an Isotek Solous unit which is silent,so i dont know whats goin on with your unit, an earthing problem maybe (google it),otherwise may just be one of its traits !

You cant beat the luxury hifi tho hum or no hum,worth it when the cd's are blasting! 

Anonymous
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Re: Balanced Mains Conditioners

Hi, Thanks for the feedback.  I don't agree that all transformers hum.  With most amplifiers that I've used the transformer is completely silent.  A friend of mine who is an engineer confirms that transformers shouldn't hum at all if all is right with the mains.  I think my conditioner is reacting to some interference present on my mains.  I took the balanced unit round to my friends house, a few doors down and it was totally silent when I plugged it in there.


 Anybody heard of bt lines putting interference in the mains?  We've got an old bt line still connected, although we are on cable and now get the phone through cable.  The bt lines comes in along the garden wall and the cable line is right beside it.  Although we no longer use the bt line it is still connected to our house and the external bt box on the garden wall also runs a telephone line to our next door neighbours house.


 I can't think where else the interference could be coming from.  Yes, the balanced mains transformer is encased.  It seems a very well made product.  I think the product is highlighting that something is putting interference into my house mains supply.

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Re: Balanced Mains Conditioners

Transformers hum due to DC leakage on an AC line


 


Ill not argue about the 'all transformers' comment, ill just post a comment from a company that makes them -


"'The short and simple answer is that many times, transformers hum because of an effect known as 'lamination rattle' or 'winding rattle' caused by DC voltage on the line.


Lam' or 'winding' rattle occurs in all transformers to some degree, that degree being related to the quality of the transformer and the quality of the line voltage."


So although some may seem 'quiet', theyre almost certainly resonating to some degree

Anonymous
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Re: Balanced Mains Conditioners

I can the agree on all 'resonating to some degree'.  I'd seen the DC leakage comment.  I was thinking of getting one of these DC blockers but at £500 a throw I didn't want to throw away more money on yet another product that didn't solve my particular interference problem.  But I am tempted as this might well be the one to solve it.


Thanks for your thoughts on this.

Anonymous
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Re: Balanced Mains Conditioners

Greetings all, first post here. Yes, mine (a 3kVA job - not RA's but similar specs) hums too, not permanently, but often very noisily, and I've had it now for a couple of years. It doesn't help that it is sited next to the CU on a stud wall, which acts as a kind of resonator! I live in a smallish upper flat in NW1 London, so, not too many options re placement. It's one floor below me, so it doesn't bother me, but it's next to my long suffering wife's study, and she's not over the moon about it.

Anyway, a question.  As I understand it, one rule with balanced mains is to plug all your audio kit into it - in my case that includes a pair of Quad ESL57s. This year I intend to get the floor boards up and install a decent ring or radial(s) from the transformer to my listening room. The existing ring attached to the transformer  - well, it's a long story - but I don't trust it. That existing ring uses standard 2.5 flat solid core twin and earth. If you were going to do (or get done) a rewire froim the transformer to the audio units, would you do a ring for the whole lot, or radials for each piece of kit? And what cable would you use? I've experimented doing DIY powercords with lengths of affordable audio grade mains cable - e.g. 2.5 Supra Lorad, Lapp Olflex, Foundation from Missing Link and RS screened. All of these, bar the Foundation, are screened, and I like the sound from the unscreened Foundation best. But it's probable it, and the others I have tried, may not comply with current electrcity regs for an underfloor rewire. So, if I want the job certified, it may have to be T&E.     So - 6mm, or 10mm?

Any thoughts, experience  - most welcome!

Osborn

 

 

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Re: Balanced Mains Conditioners

Hi mains transform hum is a product of A.C. current and loose laminations in the transformer core. The mains supply is swinging between plus and minus 50 times a seconds, this change is the basic principle of how transformes work. Its the magetic field in the tranformer produced when a current is flowing in a conductor, this changing magnetic field acts on the loose lamination. When the A.C. then changes to the opposite polarity an opposing magnetis field then pulls the lamination back causing a sound i.e. mains hum.

Anonymous
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Re: Balanced Mains Conditioners

Hi Nick. You realise that you are fuelling doubts in my mind - as well as Midlife Person's - as to whether our transformers are properly/adequately 'wound' (is that the correct term?). ..Would your explanation account for the hum being intermittent (sometimes mine is totally silent, then, half a minute on, after a gentle crescendo, it can hum for England!)?

I've mentioned the hum to a few techie and sparky colleagues (at least, more techie than I), and they say that the hum is an indication that the transformer is doing its job - and it's a job that needs doing!...

Anonymous
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Re: Balanced Mains Conditioners

my transformer  only hums at 4 specific times of the day, the rest of the time it is near silent.  it's an airlink 2kva model.  at around +/-15mins: 9am, 10:30 am, 16:00  &  22:15 for about the same duration of 3-5mins the transformer will hum.  it's not every day & weekend times are different but all of these times correspond to when a pair of apc ups i'm using on servers show over voltage protection working.  all times seem to correspond to normal surge times in the grid supply.  the over voltage will be present for a short period when many people are shutting down all their electricals for the night, kids going to/coming home from school or when the work shy are watching jk in the morning & boiling their kettles during every break, at the same time the national grid step up supply etc.  the supply here has also improved since a local factory on the same supply closed down.  maybe it's worth checking all your earth's are good.  get a rough idea of who/what shares your local transformer & is there a trend in times that it hum's 

obviously this is just my take on it but given that both of my apc ups(separate spur to audio)  show over voltage protection kicking in at the stated times & then at those exact times the transformer hums then stops at the same time the apc ups's revert back to normal status does seem to indicate the hum is directly related to mains supply over voltage.

Anonymous
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RE: Re: Balanced Mains Conditioners

Hi all,

I'm new here as a result of finding this discussion using google. Sorry my contribution is a bit late buy hey-ho ! My interest lies in the fact that I do contract Design Engineering for Pro-Audio, including Balanced Mains and I know EXACTLY why this transformer hums.

The ebbing and flowing hum is simply saturation of the transformer core as your supply voltage varies. A £5 digital multimeter from Hong Kong on ebay will soon find your mains voltage. I've known mine to be consistently high, as much as 252V, which made cheap 'wall warts' designed in China for the European Standard supply voltage of 230V hum wonderfully. This was typically at night when the reduction in demand caused the voltage to rise.

A good balanced mains transformer such as those I'm associated with will have 'taps' on the primary winding to compensate for this. We have taps at 220, 230, 240 and 250V for example. Just select the one closest to your actual supply voltage.

The hairdryer problem I have met in person once myself. Many hairdryers use a diode in series with their heating element to provide 'half power'. The hairdryer then sucks net DC from the mains causing waveform distortion and a net DC voltage on the mains and especially so if your supply is highish impedance, which your other comments suggest. The only answer is to find a haidryer that doesn't do this. I don't know if the relevant regulations have now outlawed this practice but a new hairdryer may solve that problem at minimal cost.

Regards,  Graham

Anonymous
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RE: Re: Balanced Mains Conditioners

osborn, you say "I've mentioned the hum to a few techie and sparky colleagues (at least, more techie than I), and they say that the hum is an indication that the transformer is doing its job - and it's a job that needs doing!... "

I'd avoid taking advice from ANY of them ever again. Transformers hum if Angel they're badly made and the laminations are loose, so they can vibrate or (b) their core is saturated by overvoltage, overloading or DC content on the supply causing magnetostriction.

http://en.wikipedia.org/wiki/Magnetostriction

Also see my earlier post of 6 Nov 2012.

 

Graham

Anonymous
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RE: Balanced Mains Conditioners

I forgot to mention a source for the term 'saturation'.

http://en.wikipedia.org/wiki/Saturation_(magnetic)

Graham

Anonymous
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RE: Balanced Mains Conditioners

@   Midlife Person  "Anybody heard of bt lines putting interference in the mains?".

On the Planet Zog maybe ?  Smile  You didn't get the idea from Russ Andrews' site did you ?  :wall:

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