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Path: utzoo!linus!philabs!cmcl2!seismo!harvard!talcott!panda!teddy!rdp
From: rdp@teddy.UUCP
Newsgroups: net.audio
Subject: Re: RAW SPEAKERS
Message-ID: <1036@teddy.UUCP>
Date: Mon, 29-Jul-85 09:01:09 EDT
Article-I.D.: teddy.1036
Posted: Mon Jul 29 09:01:09 1985
Date-Received: Wed, 31-Jul-85 23:21:52 EDT
References: <3177@decwrl.UUCP> <28400013@smu>
Reply-To: rdp@teddy.UUCP (Richard D. Pierce)
Organization: GenRad, Inc., Concord, Mass.
Lines: 44

In article <28400013@smu> mike@smu writes:
>
>Just thought I'd suggest that a smaller woofer is often less
>prone to distorsion, and is often capable of a tighter sound...
>M.H.P.

Why?

First of all, for a given sound pressure level, the amount of excursion
(displacement) is proportional to the inverse square of the radiating
area, so that at a given frequency, an 8 inch woofer must have a total
excursion TWICE that of a 12 inch woofer. Now it turns out that the way
that the VAST majority of drivers are manufactured, small speakers are
subject to the same mechanical and electromagnetic limits that large ones
are. This would then imply that the smaller drivers have higher levels
of mechanically (due to non-linearities in the suspension) and electromagnetic
(due to the size of the linear protion of the magnetic field, the LENGTH
of the voice coil) induced distortions. 

Also, because of there lower masses, smaller cones have higher fundamental
resonances than larger ones. THis also implies (under normal circumstances)
that these mechanical limits will be reached at higher frequencies, where
more real music is occurring.

As far as control over a cone is concerned, then I quote on of my many
laws of acoustics, "The right amount of magnet is the right amount of
magnet". Smaller woofers tend to be severely electro-magnetically
overdamped, resulting in over-controlled and, as a result, relatively
reduced bass performance. This requires either tailoring the response
of the input signal, further exacerbating the excursion problem, or
wieghting the cone to make it more massive (the "Mortite" syndrom)
reducing efficiency, etc., etc., etc.,.....

It might be argued that smaller cones have less breakup problems at
higher frequencies. ALl things being equal, this is true, but much
of this is controllable by appropriate materials technology. It turns
out that the most commonly used cone material, paper, is markedly
unsuited for loudspeaker use (more on this if anybody is interested)

Now smaller cones do have a distinct advantage in angular dispersion
characteristics. If this is what you are talking about, then I agree.

However, one distortion that smaller speakers do reduce is the distortion
of ones living space due to the significantly reduce floor space. :-)