Demagnetisation?

Gusboll

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Acquired a tune-up disc that includes a track that is supposed to do a "...demagnetisation regime to reduce the detrimental effects of magnet build up."

How does this work, does it matter or is it all nonsence?

Currently listening to: Frank Zappa - Purple Lagoon
 

Mooly

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The theory goes something like this...

To demagnetise an object you actually magnetise it in ever decreasing amounts. Remember tape head demagetisers that you plugged into the mains or "old" CRT monitors and TV's. They were examples of pretty powerful demagnetisers that are nothing more than an electromagnet. The demagnetising action occured in the case of the head demagnetiser by you the user pulling the thing away slowly. In the case of the TV a "thermistor" passed a high current when cold and as it heated due to this current its resistance increased and the current fell away to zero.

The audio test CD plays ever decreasing tones in the vain hope that the decaying signal will remove "stray" magnetism from any ferrous components. The levels and fields produced haven't a hope of doing that. Many parts are magnetic and many components have leads that are magnetic. If you deliberately magnetise say a resistor or capacitor or transistor then playing these tracks won't do a thing, you need something 100's of 1000's times more powerful.
 

Cpt.Issues

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That CD sounds a bit fishy IMO. Reminds me of the pen you supposedly drew onto round the edge of a CD to reflect stray photons back into the laser or some rubbish like that :roll:
 

Rob998

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LOL, I got an "ultimate system set-up disc" free with A.N. Other HiFi mag a couple of months back. Some of it was fairly interesting info/demonstrations about phase, positioning, soundstage & a 360 degree test. However one track was a "Burn in & Demagnetisation" which was a mix of white noise, rising & falling tones etc. It gave my speakers & ears a workout I suppose, but I didn't feel there was any improvement to my system afterwards and I haven't had any great urge to administer a repeat another dose of the medicine! It did have some very nicely recorded & esoteric music tracks at the end though, so that made up for the snake oil (albeit freely supplied snake oil)!
 

Gazzip

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Cpt.Issues said:
That CD sounds a bit fishy IMO. Reminds me of the pen you supposedly drew onto round the edge of a CD to reflect stray photons back into the laser or some rubbish like that :roll:

Does anybody else on the forum still have several CD's in their collection with a series of "anti-vibration" holes that they drilled around the spindle centre hole on the advice of WHIFI mag about 18 years ago? No? Only me? Are you all sure.....
 

AKMH

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I have been using the Densen Demagic demagnetizer CD for my system with good results, roughly every 2 months. I recall that WHF gave this a 5 star review around a decade back. Had the opportunity to buy a copy for £10 from HMV in Picadilly Circus during a trip to London about 10 years back. It worked very well on my previous Marantz/NAD/Bose HiFi and I still use it on my current set-up.
 

Trefor Patten

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I too regularly (about once every 2-3 months) use the Densen Demagnetizer and find it brings the sort of improvement I used to get when unplugging all my connections and plugging them back again, i.e. everything got marginally better- timing, bass extension, clarity, the lot. I also stick it into the optical drive of my computer on the grounds it does no harm, so why not, and notice an improvement in delivery of all digital files to my dacmagic. Some will tell me it is a placebo effect, to which I reply that a friend who is a professional classical musician came to visit one afternoon after I had run the disc to ask if I had upgraded something, as the system sounded more 'real'. 8)
 

chebby

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My hifi always seems to sound better after I have cleaned it - and the living room around it - and sat down afterwards with a cup of tea to relax.

It's all to do with mood.

I could experiment with running the vacuum cleaner for 15 minutes next to the hifi or hanging a duster over the system, but I am sure it's just my feeling of satisfaction that does the trick.
 
A

Anonymous

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chebby said:
My hifi always seems to sound better after I have cleaned it - and the living room around it - and sat down afterwards with a cup of tea to relax.

Just like my car is always smoother and quieter right after I've washed it :)
 
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Anonymous

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Found this on the web, it tries to give an explanation on the science behind this:

http://www.stereophile.com/content/demagnetizing-tracks-does-it-really-works-1

A so-called "demagnetizing track" consists of a sinewave with an amplitude that decays to zero. I put such a signal on Stereophile's Test CD 3 to allow readers to try it for themselves -- see http://www.stereophile.com/features/424/index8.html.

As to why a decaying tone might (note I said "might") have a beneficial effect, this is exactly what you do using, say, a tape-head demagnetizer to demagnetize the tape path components on an analog recorder. The AC signal destroys any residual DC magnetism, then as the tone decays (or is removed to an "infinite" distance), the component is left in an unmagnetized state.

So: _if_ the components in someone's audio system contain ferrous materials and _if_ those ferrous components are in close enough proximity to the signal path to matter (some resistors have steel leads, for example), and _if_ those components have somehow become DC magnetized, and _if_ the decaying tone is of a high enough level, and _if_ it produces an AC magnetic field in the proximity of the affected components, it _might_ have a beneficial effect.

A lot of "ifs" but a 1978 AES paper from some Kenwood engineers showed measurable distortion from ferrous materials in close proximity to an amplifier's signal path. I don't think it coincidence that most good-sounding high-end electronics use aluminum rather than steel chassis.

John Atkinson
Editor, Stereophile
 

stephennic

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Hi,

I to have a densen demag. It seems to make the sound on my hifi system a little cleaner or give it slightly extra clarity when I use it every couple months, a similar affect when I clean my cds.

Cheers

Steve.
 

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