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From: winograd@nbires.UUCP (Steve Winograd)
Newsgroups: net.audio
Subject: Re: single speaker demonstrations?
Message-ID: <264@nbires.UUCP>
Date: Wed, 21-Dec-83 21:10:36 EST
Article-I.D.: nbires.264
Posted: Wed Dec 21 21:10:36 1983
Date-Received: Sat, 24-Dec-83 11:26:48 EST
References: <2279@rabbit.UUCP>
Organization: NBI, Boulder
Lines: 35


I have heard the single speaker demonstration done many times and have
performed it many times for my friends. Every time, it has been immediately
obvious to everyone that having extra, undriven speaker(s) in the room
destroys the sound of the system.

First, the acoustical reason.  The undriven speaker is excited
by sound waves in the air and, working in reverse, generates an electrical
signal which stores energy in the voice coil and/or crossover.  When the
induced field collapses a short time later, it causes the undriven speaker
to reproduce the stored sound.  This reproduced sound is an especially
obnoxious, non-musical distortion which has no relationship to the sound
being produced at that same moment by the driven speakers.  Cancellation,
intermodulation, etc. occur and the music suffers.

Now, for more important matters: how can one compare speakers if only one
set is in the room at a time.  Contrary to what the popular hi-fi magazines
say, people ** can ** remember sounds over a period of time -- it's just a
matter of knowing what to listen for.  Here are some suggestions:

   1. Can you follow the tune?  Try humming or singing along.  If it's hard
      to do, the system probably isn't very good.

   2. Are the instruments in tune?  The most obvious effect of extra
      speaker(s) is that the music goes out of tune.  Try it with solo
      piano music.

   3. Can you follow the beat?  Are the instruments playing together with
      a feeling of good ensemble?  Extra speaker(s) destroy the ensemble.

   4. Most importantly, is the music appealing to your emotions.  That,
      after all, is the whole purpose of music (and hi-fi's)!

Just sit back, listen, and trust your ears!