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Conference cookie::notes$archive:cd_v1

Title:	Welcome to the CD Notes Conference
Notice:	Welcome to COOKIE
Moderator:	COOKIE::ROLLOW

Created:	Mon Feb 17 1986
Last Modified:	Fri Mar 03 1989
Last Successful Update:	Fri Jun 06 1997
Number of topics:	1517
Total number of notes:	13349

13.0. "Filter phasing" by PIXEL::DICKSON () Mon Feb 20 1984 13:41

Due to space constraints, I am limited to a low-profile front-loading
design for a CD player.  One possibility, for example, is the
Technics player ($600 at Lechmere).  Another is the new Yamaha
player, follow-on to the CD-1 ($600 at Tweeter).

With my present speakers, I probably couldn't detect phase distortion
in the filters, but when I get better ones (I am thinking of Snell-E),
I will, and want to get a player with good filter characteristics.

Could someone who has been through this before tell me:

	1. What kinds of music are good for detecting phase distortion?
	2. What does it sound like?

T.R	Title	User	Date	Lines
13.1		GOLD::WEAVER	`Tue Feb 21 1984 00:21`	9
	Note that the Sears (Sanyo) player has a low profile as well. I have not seen any specs on it. The CD "sliding door" is thinner than 2 CD cases side by side (if my memory serves me correctly). It seems as if the height was 2/3 or less than the Sony CDP 101. I have not listened to it perform, I only looked at a demo in Sears in the Natick Mall. -Dave
13.2		PIXEL::DICKSON	`Tue Feb 21 1984 10:28`	8
	I got a hint from Tweeter about testing filters: play something with a flute solo in it. If the "breathiness" seems to be coming from the same place as the "toot", the filters are doing a good job. If the breathiness is disembodied, the filters are introducing phase distortion. They did warn against a certain Jean Pierre Rampal disk however, as being overly compressed.
13.3		MUN02::ORA	`Thu Feb 23 1984 10:24`	33
	The CD players can be divided into three categories in their phase characteristics: - the "oversampling" players (Philips/Marantz and some others). these do not have any measurable phase distortion. - most other players which have slight phase distortion (but identical on both channels!) - some players of the second category which have just one multiplexed D/A-converter, causing an additional time delay of about 10 microseconds between the channels. I doubt whether one can hear the difference between these different categories. The phase distortion only becomes significant at higher frquencies. Think of , say, a tone of 10 kHz, which has a wave length of about 3.3 cm. I would say that in any speaker, the effective distance of the woofer and the tweeter from your golden ear differs by more than this amount (not even to mention the difference between the distance to the other tweeter). In other words, the phase behaviour of any speaker is by far worse than that of the CD-players. I don't believe that this kind of symmetric phase distortion at very high frequencies is audible. If the "breathiness" of a flute comes from a different direction than the "toot" you must have some amount of ASYMMETRIC phase distortion, or more likely asymmetric frequency response. I think much more important in choosing the player is its error correction capability (I think there is another note/reply on this subject in this file). There are great differences in this area, and with some of the players you really have to keep your disks very clean (which is advisable anyway).