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From: andrew@inmet.UUCP
Newsgroups: net.audio
Subject: Re: Orphaned Response - (nf)
Message-ID: <1055@inmet.UUCP>
Date: Thu, 15-Mar-84 00:07:57 EST
Article-I.D.: inmet.1055
Posted: Thu Mar 15 00:07:57 1984
Date-Received: Fri, 16-Mar-84 07:55:48 EST
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#R:hpfcla:-1310000600:inmet:2600050:177600:1621
inmet!andrew    Mar 12 09:18:00 1984

> 2.  Extra speaker in addition to the normal stereo pair.  Most people
> thought that the change that occurred when the other speaker was brought
> into the room was incredible.  They thought the sound was muddier and
> more veiled.  This is how Casey explained it: (paraphrase)
> 
> "Well, a speaker has a woofer and a tweeter, so what else must it have?
> Well, it has to have a crossover.  Now, tell me, what's in a crossover?
> Well, things like resistors, capacitors, and...AHA! Capacitors! And
> now what do capacitors do? They store charge.  The active speakers
> excite the extra one, and cause the woofer to vibrate in sympathy with
> the music.  Current is generated in the voice coil of the moving woofer,
> and this in turn charges up the capacitors in the crossover.  They
> charge for a little while, then they decide to discharge whenever they
> damn well please, and cause the tweeter to become active all of a
> sudden, generating some sound that is not only greatly distorted, but
> way out of phase."

This isn't quite as far-fetched as it sounds.  THE AUDIO AMATEUR ran an
article a few years back entitled "The Not-Quite Passive Radiator".  The
premise of this article (sorry, I no longer have it) was basically:  When
using a conventional woofer as a passive radiator, an R-L-C network could
be attached to it to 'tune' its response by reinforcing the voice coil
current at desired frequencies and opposing it at others.  Casey's premise 
is not all that different; he also takes into consideration the effect on
the tweeter.
 
Andrew W. Rogers, Intermetrics    ...{harpo|ima|esquire}!inmet!andrew