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A post over on the dreaded Audiogon makes me interested in attempting to build a home made coil degausser to degauss LPs with.
Anyone with some experience welcome to comment.
Anyone ROFL also welcome to comment. (It takes all kinds...)
Follow Ups:
Degaussing is only for permanent magnets. Carbon black is non-ferrous and non-magnetic, same with vinyl. They are prone, obviously, to being charged up.
From Furutech's description for its LP demag device.
"Demagnetizing LPs How can an LP be magnetized? It’s plastic! The fact is that pigment added to the plastic during the manufacturing process is the culprit. The minute amount of ferrous material in the pigment causes LPs to become magnetized. Testing at the Tokyo Nanotechnology center with a IHI Gauss meter showed that after an LP was treated with the deMag the magnetic field of the LP was lowered from 620~630 nT to 572~582 nT (nanotesla: a unit of magnetic field strength,1 Tesla = 10,000 gauss)."
You have to admit that a nanotesla is pretty weak, especially a few mm away. And lowering just a tiny amount from 625 to 580? That a human being could perceive anything like this truly stretches the imagination.
The turntable platter, motor belt and nearby transformers, copper wiring etc. of a system would have magnetic properties that would likely totally swamp out this tiny 45 nanotesla reduction in record field strength.
However, I can easily see and hear (SNAP, CRACKLE, POP) the thousands of volts stored up in the record from static electricity.
What is the lower limits to human sensitivity, especially when a cartridge, phono section, and preamp will further amplify any magnetic changes (via EMI inductance). Since a typical MC cartridge has a mere 3 millivolt output and that has to be amplified to about 2 volts at the preamp outs, please elucidate what the lower limits of human sensitivity is, especially in consideration that the lower dynamic range of an LP would be significantly lower than 3 millivolts, at least by 40 to 45 dB for a typical LP.
Stu
And fixing a static-y LP is very noticeable.
Yes, everything matters and everything is audible, however some are much more so.
If you wish to devote the time, money and energy to effect a 7.5% reduction in a microscopic magnetic measurement in each of your 1,000's of LPs (leaving 92.5% of the original magnetism to torment your soul and cartridge) more power to you.
I have better ways to spend time and money, like getting rid of static.
that you are jumping to conclusions based on the numbers when you have yet to even try the tweak. A 6.5% lowering is significant when compared to, say, distortion figures in an amplifier, and no one quibbles about a manufacturer claiming that.
In my experience, degaussing an LP is usually of greater import than using a Zerostat. But I tried it before dismissing the idea, and later acquired a Lakeshore gaussmeter to measure what I heard.
But of course, YMMV and you are most certainly entitled to think what ever you want.
Stu
6.5% reduction is about 0.6 dB. Not a big deal, even if the noise or distortion is loud to start with and is not masked. The tweak may work, but the explanation given is highly suspect.
The effect is relative to the magnetic fields in the cartridge itself, as they will determine the relative level of this noise to the desired audio signal. Different cartridges will have different susceptibilities to low level residual magnetism. It would be necessary to measure the spatial distribution of the residual magnetism or otherwise obtain a frequency spectrum of any resulting noise before one could tell if any masking were taking place.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
You are confused with the math. Comparing an amp with 7.5% distortion to one with 1% distortion is a 6.5% "point" improvement, however it is a 87 percent improvement. Yes, this is significant.
If an amp has 0.12% distortion at one watt, an 8% improvement will give you 0.11% distortion at one watt. Yes, there are quibbles about a manufacturer claiming that that is significant.
Which model of gauss meter did you purchase? Do you average the reading over the entire LP or does the whole thing have a positive and negative pole?
I have a Lakeshore gaussmeter. It is still manufactured and you can look up the specs on the internet. It does not really indicate poles but I swept the surface of an LP before and after degaussing.BUT, why should you care about the measurements? after all you don't measure the amount of static on your LP's do you?
Stu
PS : Dr Amar Bose, on the introduction of the Bose 500 watt per channel receiver way back when, claimed that a distortion figure of 5% was adequate and any lower would not be audible. Average distortion figures for tubed gear measures about .5%, transistorized gear significantly lower than that, at least at the 1KHz point normally referenced.
So, as you can see, depending on which piece of gear you measure 6.5% improvement, it could be rather significant, but then again you avoid the issue of what is the limits of human sensitivity..... That limit is the true determining factor of what numbers are truly significant
Edits: 04/30/12
I got into LPs in the late 1970's. By 1983, the record companies started making records out of absolute crap, pinecones and sand to sell their new-fangled CeeDees. Those disks were so full of static, especially in the winter, they would drive me nuts. I hate static.
Ferrous materials are creeping into everything, like resistors. There are a lot of things to demag.
older than you and started collecting vinyl in the late 60's. The fascinating thing about degaussing LP's, for which I have yet to understand, is that degaussing actually lowers the level of the pops and ticks resulting from surface damage. You can take a very scratchy sounding disc, where the surface noise is so great the music is barely audible and actually hear the music (the scratches are still presence, just lower in volume). It is the weirdest damn thing.
I demonstrated this effect to a local radio DJ who collects bootleg Jazz stuff and he was stunned at the difference, especially since the station had desktop degaussers for their cassettes.
I got into the degaussing thing for tapes, and always had a hand held Geneva degausser, so it was a simple thing to run the degausser over the LP while still in the jacket. Perhaps it helps to lower static, too, but I notice the difference in sound: better dynamics and clarity.
The Genevas are relatively more expensive about $75 to a $100, and one model is more powerful at 2800 gauss. I can't tell the difference between the lower powered version. I also find them in garage sales as bulk tape erasers, should you care to experiment.
Stu
You assume that removing the static electricity from an LP is worth doing because the static charge is sombig, but don't think demagnetizing the LP is not worth doing because the LP is not magnetic, which you later changed to "the magnetic field is too small." You assume removing the static charge will make more of an improvement than removing the magnetic field. That's why they call these things, uh, controversial.
You should try it, they sound pretty good.If you have played a record with a big static charge you would notice they have a tendency to pop and crackle when played.
And a LP has its own gravitational field, and yes, I also think it is too small to affect playback.
Edits: 04/30/12
Nobody is disputing that LPs have a static charge. The issue is whether they also have a magnetic field that affects the sound. It seems reasonable to assume that ultra sensitive modern cartridges, esp. Moving coil types, are probably susceptible to small magnetic fields.
The rave reviews of the Furutech LP demagnetizer seem to indicate that not only are the nanotesla not swamped out by nearby electronics but that the effects of the demag are rather large. Counterintuitive, huh?
Edits: 04/30/12
I don't consider 6moons to be a credible source of information. Are there other reviews?
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
I also suspect you don't trust Positive Feedback, either. ;-)
I suspect you probably don't trust Soundstage, either.
Got an old Radio Shack Bulk Tape Erasure unit laying around that was all the rage ~15 yrs ago? Back then it was used for degaussing CD's. I still use it from time to time on my CD's and it does have a positive effect.
I've tried degaussing my records with the RS unit a few times and the results seem to be a slight reduction in background noise, cleaner treble response and image solidity but as always and of course, YMMV.
~
Back in my college day a bunch of us thought about making our own degassing coils.
The bulk wire and associated parts cost more than just buying a degassing coil.
You can still get one for about $40 at Fry's
I don't want to know why you think vinyl can be magnetized.
for anyone who wants to know how spinning vinyl can lead to magnetization issues, here is something from the degaussing thread on the vinyl forum:
"We have a medium very much prone to static build-up. Thus charged, we spin this medium at up to 500RPM for CD and a bit slower for vinyl. From Rowland’s experiments we learn that such activity creates its own magnetic field. With magnetisable particles embedded in the CD structure, label print ink and colorants to make basically clear vinyl look black, we have permanent magnets on our hands. For LPs, the magnetic field of the spinning disk is in very close proximity to the sensitive structure of the cartridge and thus influences the pickup."
so the problem is that records can get a static charge, when the charged record spins it creates a magnetic field, and the magnetic field can be picked up by the cartridge.
-andre d
"we spin this medium at up to 500RPM for CD and a bit slower for vinyl.
33.33 RPM is quite a bit slower than 500 RPM. Good reason to be suspicious of the entire argument, IMO.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
It's not the RPMs per sec it's the angular velocity. The angular velocity of the outer rim of the LP is relatively high and the surface area of the LP is considerably greater than a CD, about 4 times greater. And we don't known the minimum velocity required to produce the effect.But one has to wonder, ESP. In the case of the CD, even if it is degaussed prior to play, why doesn't the magnetic field reemerge after say 5000 revolutions?
Edits: 04/28/12 04/28/12
The angular velocity is constant; the linear velocity varies linearly with radius at a fixed rotational speed.
Thanks for the correction.
personally i am not as interested in figuring out why it works as i am in IF it works. if the process works as its proponents claim, then its probably worth doing. imho.
-andre d
TV CRT degaussing coils are dirt cheap these days as they are totally unnecessary with flat screens. Seen them as cheap as $10....
Stu
Most any old color CRT TV has the coil loop around the outer
perimeter of the CRT. I've taken them out before taking to
a recycler, they work well. If too big, just twist and
double the loops. They are normally energized at turn on and
only for a couple seconds. I've never made one, but I think
they used just 2-4 loops in the coil. Not sure on voltage
used, so I'd use a variac to start.Or you can get one of those hand-held tape erasers for
under $20.
Edits: 04/26/12 04/26/12 04/26/12
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