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In Reply to: RE: " lowered from 620~630 nT to 572~582 nT" posted by Chris O on April 30, 2012 at 11:48:09
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
Follow Ups:
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.
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