Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site allegra.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxl!eagle!allegra!karn From: karn@allegra.UUCP (Phil Karn) Newsgroups: net.audio,net.flame Subject: re: jj's Re: Thoughts on subjectivity and specifications Message-ID: <2251@allegra.UUCP> Date: Thu, 2-Feb-84 20:44:44 EST Article-I.D.: allegra.2251 Posted: Thu Feb 2 20:44:44 1984 Date-Received: Wed, 8-Feb-84 01:47:34 EST References: many, <779@drufl.UUCP>, <2387@rabbit.UUCP>, <782@drufl.UUCP> <2458@rabbit.UUCP>, <2248@allegra.UUCP> <821@drufl.UUCP> Organization: AT&T Bell Laboratories, Murray Hill Lines: 30 Once again, the only fair way to evaluate ANY recording system is to control ALL of the elements of the system EXCEPT for the presence of the recording system under test in the path. For example: 1. Pick an LP record and a turntable. Any record, your choice. 2. Play this record into a digital audio recorder (e.g., the Sony PCM-F1 videotape adapter, since average people can't make CD masters). 3. Requeue the record and digital player and play them in synchronization with levels EXACTLY matched. Getting a turntable to play exactly in phase with the digital player over any length of time will be very tricky. 4. Have a computer (or a confederate you cannot see) randomly switch your speakers or headphones between the two sources (without telling you which is which, or even if a change took place) and record your guesses as to whether the source was switched, and if so, which is which. Of course, if your point is to determine differences between CD players, this is easier. You can just start up two of them playing identical disks, match the levels exactly, then start with #4 above. If you can consistently tell which source you're listening to after many such trials, THEN I'll believe you. I suspect that you will find it impossible to tell the difference unless a) you set the recorder input level too high and clip the A/D converters, or b) the recorder or media is defective. Until you've been at least this thorough, you cannot make your claims. For all I know, you couldn't stand to listen to the Sony because you blew out your tweeters on the previous player. Phil Karn