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From: sbhattac@rnd.gba.nyu.edu (Shankar Bhattacharyya)
Newsgroups: rec.audio.high-end
Subject: Making woofers: part 3 (correction)
Message-ID: <6581@uwm.edu>
Date: 25 Sep 90 12:50:26 GMT
Sender: news@uwm.edu
Lines: 29
Approved: tjk@csd4.csd.uwm.edu



I made a typographical error in part 3 of "making woofers".

The error was brought to my attention by a most helpful individual, who also
included some verifying calculations on Dynaudio and Audio Concepts
drivers. I appear to have deleted the message accidentally, in a rush to
get to a class, and I would appreciate another message so that I can get in
touch. I only got a casual look before I took off, and I cannot even
provide a userid to acknowledge the help, or to pursue the calculations.

In any case, my thanks.

The error was in the line for the section "CLOSED BOX FORMULAE".

     Incorrect:   term  =    - 2 + 1/(Qtc *8 2)
     Correct:     term  =    - 2 + 1/(Qtc ** 2) 

Sorry about that. I'm a miserable typist.

Since this gets used to calculate F3, it is obviously of some interest to
get it right. Then:

F3  = Fc * sqrt { 0.5 * [ term + sqrt(term * term + 4) ] }

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Shankar Bhattacharyya, Information Systems, New York University
sbhattac@rnd.gba.nyu.edu
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