Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10 5/3/83; site tektronix.UUCP
Path: utzoo!linus!decvax!tektronix!kimr
From: kimr@tektronix.UUCP (Kim Rochat)
Newsgroups: net.audio
Subject: Experiment on audibility of speaker phase response
Message-ID: <1398@tektronix.UUCP>
Date: Fri, 30-Sep-83 02:09:28 EDT
Article-I.D.: tektroni.1398
Posted: Fri Sep 30 02:09:28 1983
Date-Received: Sun, 25-Sep-83 14:07:24 EDT
Organization: Tektronix, Beaverton OR
Lines: 19

My speaker system consists of a pair of Yamaha NS-10m speakers with KEF-T27
tweeters added on.  The Yamaha's have not been modified in any way, and the
crossover to the KEFs is first order at 20kHz.  The position of the tweeters
was derived by comparative listening.  I have no idea what the actual 
resulting phase response is, but it must be pretty good, since I prefer these
to other speakers known to have good phase response.  The important point is 
that the position of the tweeters was easily arrived at.  The movement of the 
tweeters changed the "focus" of the 3-dimensional sonic image, just like 
focusing a camera.  The actual impression was that of the harmonics of the 
instrument being in a difference plane (depthwise) than the instrument
itself.  By moving the tweeters forward or backward, I could make the location
of the harmonics correspond with the location of the instrument.  Anyway, a
movement of 1/4" resulted in a clearly audible difference, which corresponds 
to about 180 degrees of phase shift at 20kHz, relative to the Yamaha speaker.
So, in my experience, high frequency phase shift does impair imaging.

Ps: Equipment I used to have made it more difficult to arrive at a tweeter
    position since the image was not as precisely defined in space,
    so good associated equipment is needed.