Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!sri-unix!sri-spam!mordor!lll-tis!lll-lcc!well!rab From: rab@well.UUCP (Bob Bickford) Newsgroups: rec.audio,sci.physics,sci.electronics Subject: Re: Mercury Filled Speaker Wire Message-ID: <4139@well.UUCP> Date: Mon, 5-Oct-87 04:26:35 EDT Article-I.D.: well.4139 Posted: Mon Oct 5 04:26:35 1987 Date-Received: Thu, 8-Oct-87 01:47:45 EDT References: <3816@watdcsu.waterloo.edu> <578@uthub.toronto.edu> Reply-To: rab@well.UUCP (Bob Bickford) Distribution: rec Organization: Whole Earth 'Lectronic Link, Sausalito, CA Lines: 27 Xref: mnetor rec.audio:3569 sci.physics:2387 sci.electronics:1495 jeff t. segawa writes: + Maybe the source of a lot of these + "looks good on paper, sounds awful" sort of problems have a lot to + do with the WAY these measurements are taken. For example, as I recall, + turntable speed accuracy measurements are done by playing 1Khz test + tones. Servo motor powered turntables cope with this type of material + well, since tye stylus drag, and hence, the load imposed on the + turntable's motor, is constant. Now get this same turntable, and try + playing a real record, with it's varying degrees of modulation, on it. + Hit a loud passage, and the stylus drag builds up. Platter slows down, + servo tries (too late) to compensate. I had a turntable like this. + With most types of top 40 music, it sounded OK. Couldn't figure out + why piano music always sounded somehow off key. Naturally, the spec + sheet told me that the turntable had nearly perfect speed accuracy, + and it did, so long as I played 1Khz test tones. If nothing else, + this incident taught me the value of trusting one's own ears. If you are able to detect *ANY* variation in the speed of *ANY* turntable based on "stylus drag", then it's time to chuck the thing in the trash. Run the calculations yourself if you don't believe me; the effect of the stylus is *at least* three orders of magnitude below normal frictional forces (bearings, etc.). Tell me you have a magnetically levitated platter running in a vacuum chamber, and I *might* believe that the effect of the "stylus drag" could be detected. Try to think before you say things like that, okay? Robert Bickford {hplabs, ucbvax, lll-lcc, ptsfa}!well!rab