From: utzoo!decvax!duke!harpo!npoiv!alice!rabbit!jj Newsgroups: net.audio Title: Re: Digital vs. analog Article-I.D.: rabbit.616 Posted: Sun Jul 18 21:59:49 1982 Received: Mon Jul 19 01:08:26 1982 I must admit that I find it difficult to reply to the article by Kim Rochat, although not because the arguements are difficult to refute. They are, in fact, not that difficult to refute, to another signal processing person. Disgegarding the opinion statements about Golden Ears, I will begin my comments by addressing the statements about rise time in analog equipment. It is indeed limited, and quite severly, (in a record, for example) after several passes through the playback device. (This statement holds for magnetic recording, also, but a discussion of the causes is beyond this note). In addition, records, which do generate signals with a very high rise time, most often do so (even in the case of the best records and cartridges) as a result of tracing distortion or mistracking. Even if the signal being reproduced does have an undistorted risetime on the order of 10us, the transducer that reproduces it and the travel through the ear will spread it out, due both to filtering and dispersion. There have been several, although few and far between, papers that have discussed the variability of DISTORTION with respect to signal risetime. Most transducers, do, in fact, have measurable non-linearities that arise during highly slewed parts of the signal. These non-linearities have been shown to be perceptable.Regarding the recording of digital at half speed: There are indeed converters that are capable of converting at 100kHx. The converter is not the problem. STORAGE of the information is the problem. Your scheme of slowing down the digitization of the signal will do the following: 1) Make no difference whatsoever in the Digital sense 2) Introduce a distortion of about 2% due to the nonlinearities in the magnetic recording process. 3) Limit the dynamic range to 60-65dB OR introduce low frequency distortion as a result of compression/expansion. 4) Introduce the most annoying (to me) problem with magnetic recording tape: Head Scrape/Flutter. This bizzare process is the result of sliding a tape, with a finite coeffecient of friction, against the tape head. It has nothing to do with the flutter due the drive system, etc. This is the process that causes the "closed in' sound that is often attributed to magnetic recording. 5) Double the storage required for the signal. To summarize. Your method of making digital recordings would eleminate the beneficial aspects of digital recording, without making any change in the problems involved.