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From: peters@cubsvax.UUCP (Peter S. Shenkin)
Newsgroups: net.audio
Subject: Re: A Question on Equalizers
Message-ID: <314@cubsvax.UUCP>
Date: Wed, 20-Feb-85 20:45:46 EST
Article-I.D.: cubsvax.314
Posted: Wed Feb 20 20:45:46 1985
Date-Received: Tue, 26-Feb-85 07:16:09 EST
References: <2677@sdcc3.UUCP> <>
Reply-To: peters@cubsvax.UUCP (Peter S. Shenkin)
Organization: Columbia Univ Biology, New York City
Lines: 19
Summary: 

A parametric equalizer is one which, for each stage, has three continuously
variable pots:  one for frequency, one for dB of boost or gain at that
frequency, and one for sharpness of the band around the frequency over which
the boost or gain will apply.  A typical parametric equalizer will have
four bands, for bass, low-mid, high-mid and high frequencies, and the
frequency controls on adjacent bands generally have quite a bit of overlap.
The central bands give a boost or gain contour with the general appearance
of a gaussian (I'm sure you EE's know what it really is; perhaps a
Lorentzian?), and the outer bands usually give the same, though these are
sometimes set up with a shelving contour, in which case the band-width
control really refers to sharpness of roll-off or "roll-on".

Parametrics are very versatile, and I don't doubt that many recording 
engineers prefer them for "eq'ing" vocals, for instance.  But I'm
sure that many would take issue with the idea that they are *necessary*
in the recording process.

Peter S. Shenkin         cubsvax!peters
(Columbia Univ. Dept. of Biol. Sciences)