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.
Am l am correct in thinking that Rega and Project turntables are light weight minimalist designs? They certainly look like featherweights in the hi-fi boxing ring…. Maybe that’s why they shy off covers? Highly likely they already know that their design structures are not massive enough to resist external forces unlike decks with heavier more substantial plinths.
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I have two turntables, and I like both. A Sonograph SG-3 and a Kenwood. Both have dust covers that I use to protect the TT when not in use. I had noticed the acrylic dustcover material would attract dust to the cover and would sift through the crevices in the dustcover hinge joints. I ended up solving this by getting a destat source from Amstat Industries to produce a charge to counter the electrostatic attraction of the Acrylic. It is a polonium 210 alpha emitter fixed in a bar array, and gets two sided taped to the inside of the dust cover or base of the TT. Works well; is safe. Not inexpensive because it needs to be periodically replaced as it decays off and looses its effectiveness. but it does destat the dust cover and everything under it including the vinyl record. |
I haven't seen it addressed so far in this discussion so I'll relate an experience I had back in the late 60s / early 70s when visiting my favorite audio emporium. The owner kept a very orderly showroom and a regular dusting of the display components helped keep it that way. On one visit, the owner took me aside to show me a discovery he accidently made while on his dusting routine. If memory serves, I believe the turntable in question was a DUAL 1019 and the cartridge was a SHURE V-15. He played a record with the dustcover down, ran his dusting cloth over the plastic lid and the playback sound changed considerably. He then produced a "ZeroStat", a pistol-shaped device that was used to de-magnetize vinyl reccords prior to playing and activated it over the dustcover. The playback sound returned to its previous character. If I hadn't seen and heard it I wouldn't have believed it possible ! The dusting cloth had magnetized the dust cover enough to cause the tonearm to lighten up its tracking force and the ZeroStat dispersed the magnetic field to restore it to its original tracking force ! I never tried to duplicate the feat at home and had no reason to believe that the owner was playing a trick on me, so, to this day, I play my TT with no dustcover in place. Was he trying to get me to buy a ZeroStat ? I dunno, but I did buy one and still use it on occasion ! |
The zerostat works, but what it does is to reduce static charge, not magnetism. Static charge develops on every LP when it is handled because vinyl is one of several materials that easily accumulates an excess of negative ions on its surface. The magnitude of the negative charge can be great enough to dramatically attract the cartridge, increasing the effective vertical tracking force of the stylus on the LP, causing distortion and even damage. This of course is a pull on the cartridge in the opposite direction from what you observed with a lucite dust cover that got charged up and then discharged. In that case, the charged cover was exerting an upward force on the cartridge. LPs get charged up when you remove them from a paper sleeve or when you touch them with your finger tips after walking across a wool carpet, for examples. |
mylogic I’ve witnessed Arlo Guthrie a few times yapping away, then he says "I know I’m supposed to be singing, but you can’t always do what you’re supposed to do’ And the stories are all related to where he started. You would love a Buckminster Fuller lecture, in 1967 that crazy man took an entire auditorium at Pratt Institute on a meandering thought trip and at the end of the hour slammed it home, OMG, I still remember it like it was last week. Vibrations getting to the surface are all related to the Dust Cover on/off issue, as is this fundamental question about equipment location. https://forum.audiogon.com/discussions/location-of-compoments?lastpage=true&page=2#2757920 Thorens, yeah, they should have had more clearance than that in that model.
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elliottbnewcombjr ‘’Alices Restaurant’’ has all come back to memory! Buckminster Fuller is new ground and has made me look into his history…..’’Spaceship Earth’’ and all that! One of his theories remind me of Linn’s LP12. All the expensive tinkering over the years and upgrades to make this model better and things have not changed in 50 years. l love his logic and this quote from him…. You never change things by fighting the existing reality. To change something, build a new model that makes the existing model obsolete. Why have Linn never built another turntable and try to better the LP12?
l wonder what Fuller would have made of this staying in the past?
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lewn So pleased you are following this very interesting thread, some call it a boring subject….you know! The last few posts are relevant to dust covers, you were just not paying attention but just wanted to reciprocate. elliottnewcombjr was just stating the obvious with ongoing engineering development. Buckminster Fuller was a renown inventor and his views are also relevant to the discussion.See his famous quote posted.
In an earlier post elliottbnewcombjr also stated this opinion on turntable covers…. ’’Impractable TT’s (any TT) without a dust cover is an incomplete solution, an abomination, they should be ashamed of themselves’’ Fullers reasoning is the same…. ‘’You never change things by fighting the existing reality. To change something (that can be improved) build a new model that makes the existing model obsolete’’ Elliott and myself may not agree on everything, but we do agree with Buckminster Fuller and the need for constant development.
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I guess that is "yourlogic". Unfortunately or fortunately, we are not all living in Fuller's geodesic domes. Another prediction of his gone awry. But it interests me that you can read what Elliot wrote about dustcovers vis a vis turntables and in any way conform that thought with Buckminster Fuller's thoughts on anything. The only way I can see that parallel is if you take the dust cover as a modern innovation, which of course it is very much not. Far from it. It is rather more accurate to say that progress in turntable development has included the gradual elimination of dust covers. |
I thought you made your position clear in your first post, no need to say any more! You are right - electrostatic forces are orders of magnitude more powerful than gravity. Another way to create static charges is to rub vinyl with a diamond stylus. Those charges immediately attract dust. Interestingly about 30% of dust extracted from records is diamond! In my opinion the OP raised a good question - should the dustcover be raised or not when playing a record. Clearly this presupposes there is a dustcover and that it is hinged. If your turntable does not have a dustcover, or the dustcover must be removed when playing, this topic is not going to change anything for you. I read up about the Wilson Benesh GMT One System turntable, which weighs almost half a ton and uses lots of materials science, university types and research grant money to minimise unwanted resonances. This behemoth does not have a cover, although it costs house-money! Obviouly they don’t worry about airborne feedback, or dust! For the record (sic) my dust cover is hinged to an outer plinth which only connects to an inner plinth via the sandstone blocks they stand on. Otherwise there is an air gap, a bit like a double-glazed window. |
Stylus rubbing on vinyl is not a cause of static charge. This was shown by Shure Corporation in their published white paper on static charge. I and some other guy here who also owns a static charge meter have repeated the experiment with the same result. No cigar on that idea. My position has been stated twice already. I use no dust cover during play; I completely remove the cover, if the TT has one. But I advocate that each of us should make his or her own decision. My practice is based on my listening tests and my subjective opinion of what sound best. I do agree it’s a fine idea to cover the TT when it’s not in use. For the past many years I’ve had 5 TTs up and running with 6 different tonearms and cartridges, 3 TT s feeding one system and two TTs feeding another separate system. |
@lewn Thanks for that Shure thing! I guess it is in a chapter from 1978 in high-fidelity-phonograph-cartridge-technical-seminar-faq.pdf entitled CHARGES ON THE RECORD--A STUDY OF STATIC ELECTRTCITY ON PHONOGRAPH RECORDS. The only mention of stylus rubbing causing electrostatic charges seems to be "Incidentally, measurements with these instruments will also show that electrification from the direct friction between the diamond and vinyl is, oddly enough, negligible’. The author created static charges initially by rubbing the record surface with cat fur (labelled CAR FUR in the table!) resulting in 30,000 Volts when the record was lifted from the table. Considering he switched cat fur for a more repeatable 10,000 volt probe, I am not surprised the stylus is regarded as a negligible (but not zero) contributor! The seminar reinforced that the most effective way to temporarily remove static is to use a carbon-fibre brush. One was attached to the V15 Type IV cartridge but this approach seems to have gone the way of the dodo. Saved me spending on a Zerostat! Another surprise for me was learning just how much static electrical forces can change the tracking force! All good stuff ... |
