From: John Woodgate
Subject: Re: Bullshit wins v. science
Date: Sat, 9 Nov 2002 07:18:11 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Sat, 9 Nov 2002 11:16:36 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that N. Thornton
wrote (in ) about
'Bullshit wins v. science', on Fri, 8 Nov 2002:
>I hope I've managed to explain better this time.
Yes, you have, but it isn't something new that you discovered. It's due
to the uncorrected group-delay characteristic of your design. Something
which I mentioned is *inevitable* in all loudspeakers since they are
high-pass filters. But the *amount* varies with the configuration.
Clearly, your quest for high efficiency led you to a design that had a
very large amount of group-delay, and probably group-delay variation
But you still say that vented-box loudspeakers are 'designed to be
resonant'. This is misleading: all moving-coil loudspeakers have a low-
frequency resonance and part of *good* design is to control its
unavoidable effects, not only on frequency response but in all respects.
A well-designed vented-box does this quite well, although, **simply
because it is a high-pass filter of at least 4th order**, it has more
group-delay than a closed-box design, which *may* be only a 2nd order
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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