Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83; site utcsrgv.UUCP Path: utzoo!utcsrgv!newman From: newman@utcsrgv.UUCP (Ken Newman) Newsgroups: net.audio Subject: Re: Are all DADs alike?(+ phase response of speakers) Message-ID: <1876@utcsrgv.UUCP> Date: Tue, 2-Aug-83 20:27:32 EDT Article-I.D.: utcsrgv.1876 Posted: Tue Aug 2 20:27:32 1983 Date-Received: Tue, 2-Aug-83 21:11:14 EDT References: <2107@tekmdp.UUCP>, <2435@rochester.UUCP> Organization: CSRG, University of Toronto Lines: 26 There is an excellent article in the July 83 High Fidelity, p. 17, called "CD sound: Trouble in Paradise?", by E. Brad Meyer, president of the Boston chapter of the AES. It seems to hit some interesting nails on the head regarding poor sound quality from some cd disks. He talks mainly about recording techniques being unsuitable for cds. The ringing in square waves from cd players is caused I believe by the very steep filters used to attenuate response above 20 kHz. Remember also a square wave is a very severe test signal and a good square wave at frequency f indicates good response out to roughly 10f. Also the square waves present on most test records probably have some ringing themselves. While we're talking about phase response in speakers, an interesting technique is/was used in the Ohm F speaker. These things have a single driver, a bullhorn-shaped cone essentially that opens downward. The cone is made of several different precision materials of carefully controlled densities, and is excited at the top around its perimeter, causing a circular wave to travel down the cone. Short wavelengths dissipate quickly, and radiate from the top, long wavelengths travel the whole cone and radiate from the full length. The result is a completely phase-coherent cylindrical (360 deg) sound front. What's even more amazing is that this apparently worked (they were kind of inefficient though). K. Newman decvax!utzoo!utcsrgv!newman