In my informal "experiment", I first yanked an LP from its paper sleeve (in order to be sure it got charged up) and measured the charge on one surface, 11kV. Then I treated that surface with my 40 year old zerostat and measured the same area again, 0.1kV. Then I played the LP and measured the same area yet again, 0.2kV. That is the definition of "negligible". And the very small increase in charge density may well have been due only to my handling of the LP after playing it. However, you are not alone in your previous belief that the diamond stylus rubbing on vinyl causes static charge. Several makers of the very expensive static charge removal devices (not the relatively cheap Zerostat) parrot this belief in their advertising brochures.
Some thoughts on dust covers
Over the course of time there have been many discussions concerning the subject of dust covers. They tend to revolve around the central question: Should the dust cover be down or up while playing records? Some of these discussions have been nasty, consequently I have refrained from participation. It is hoped that I can provide some common sense that was given to me by someone of unquestioned authority many years ago. During college and after, from 1970 to ~1980 I worked in HiFi retail, selling high end lines of audio equipment. One of these lines was Thorens. Sometime around 1977 or 1978, if memory serves, Thorens introduced their new TD126, as a top of the line TT with their own arm and I sold the first one at our store to very good customer. He came back very unhappy after the first night of frustration with it. The problem was that with the dust cover closed some of his favorite records were hitting tangentally on the very back were the platter came closest to the dust cover when it was in the closed position. I called the manufacturer's rep and he set up a three cornered phone call with himself, the Chief Engineer of Thorens at the time, and me. I don't recall the man's name, but it doesn't matter, it is what he said that matters, then and now. The Chief Engineer explained that the problem was caused because the hole in the offending records was slightly off center so there was an eccentricity as such a record rotates about the spindle. The solution was simplicity itself, the dust cover should be removed always when playing records. That the intent of the cover is to protect the turntable when not in use. I pointed out that we lived in a semi-arrid environment (San Diego, CA) which is dusty to which he replied that if the environment was too dusty for records it should also be considered unhealthy for people to be breathing the air. He recommended are filtration, not dust covers to address environmental concerns. The rep asked about air bourne feedback from speakers and the Thorens guy laughed and said that if that was a problem in a given system, relying of the dust cover was a very flimsy and ineffective solution and that proper measures should be instituted to provide meaningful distance and isolation to ameliorate the problem. So the often offered extremes: a) Always play your records with the dust cover down, or b) put the dust cover away in it's box and never use it, should both be recognized for what they are are - not solutions at all. First principles: Identify the problem(s), seek solutions and alternatives, prioritize.
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It seems the 30,000 Volts recorded by Shure corresponds to the breakdown voltage of air in a Californian winter - with a very low relative humidity of 10%. Shure's measured voltage dropped dramatically when the record was placed on the grounded platter (much of the field migrated to the platter side) and returned as soon as the record was lifted. Prima facie it seems that when you played your record, it doubled the charge so I am keeping an open mind on whether the rubbing stylus can create charges. Charges attract dust like crazy, and dust down to smoke-size particles and even down to a few microns may be significant. If I remember, I now run my carbon-fibre brush both before and after playing to try to remove fresh dust before the records goes back into its anti-static sleeve. I am still waiting for an ultrasonic cleaner to arrive from China! In modern physics theory, electromagnetic and gravitational forces have hugely different magnitudes. About 1,000,000,000,000,000,000,000,000,000,000,000,000 times different! Which explains how plastic combs can pick up paper on a dry day, and charged records can significantly affect stylus tracking forces. That Shure seminar was not too keen on Zerostat-like devices: "Another form of active ionizer is in the form of a pistol-shaped, device, which produces positive ions when the trigger is pulled, and negative ions when the trigger is released. This device is effective for large charges, but it is hard to avoid leaving residual charges on the record since there is no way of detecting the zero charge condition" which accords with your measurement. |
"Prima facie it seems that when you played your record, it doubled the charge" First, 0.1kV to 0.2kV is a range where the meter is not very accurate and readings are not very repeatable. The meter never reads zero, for example. So the difference between the two readings may not even be statistically significant. Second, like I said, it is much more likely that my touching the LP had more to do with the difference, if it was even real. Third, such a low amount of static charge is inconsequential even if real. The problem we are addressing has to do with charges far in excess of 100V (0.1kV). 10kV (or 11kV in the specific case I noted) is 100 times higher 0.1kV. Do you have a background in this field, or are you a physicist or other scientist? If so, feel free to point out the error in my thinking. Since you don't have access to my meter, you could not have known its quirks, so I don't mean to criticize you for that. I don't know why you compare "electromagnetic force" to gravity. First, the magnitude of the difference as you express it has no meaning unless you know the relevant parameters for the source of the EM force, in the case of EM, and the sizes of the objects that experience gravitational attraction and the distance between them, in the case of gravity. But also, electrostatic attraction is not identical to electromagnetism. The point about the Zerostat is only that if used properly it will reduce the charge to a harmless level. And it costs a lot less than most of the modern alternative gadgets. Some flat earthers maintain that what we experience as gravity is due to electrostatic attraction. They have to resort to such an explanation, because if the earth were flat, it would not be massive enough to account for the gravity we do experience. |
@lewm I don't know why you keep posting on this either--you've covered it soup to nuts and, at this point, you won't change anyone else's mind who disagrees. @dwette Having a custom cover made of acrylic to protect the TT is not expensive--i had one made for my custom Jean Nantais table for $120. I remove it when i play but i have a second TT, an old Sony DD from the 70's that has a hinged dust cover that i just put up when i play LPs and have both removed it and played LPs with it down and i can't tell the difference in any position, although i would probably unhinge it and remove it if that were convenient when i play LPs. |
I don't need a dustcover, nor do I even want a dustcover. Whether it's $120 or $350 it won't make a difference for anything anyway, IMO. But as I mentioned earlier it's also impractical for me. There is really no way I can site one on my turntable that would make any sense and not become a total PITA. This photo shows that acrylic mat on the platter. I just remove it when I play records.
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