From: John Woodgate
Subject: Re: Speaker phase and current vs voltage drive
Date: Tue, 29 Oct 2002 04:07:28 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Tue, 29 Oct 2002 06:02:01 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Clifford Heath
wrote (in <3DBDC5A7.1F5A6706@managesoft.com>
) about 'Speaker phase and current vs voltage drive', on Tue, 29 Oct
>Thanks to those who gave partial technical explanations (3 Johns
>and Chuck). Although I understand what you've said, I don't feel
>entirely enlightened. It seems to me that:
>* it's possible to reproduce the SPL fairly accurately,
>* it's unlikely that our technology does,
>* our ears are remarkably competent at hiding deficiencies,
>* a number of justifications are used to avoid thinking
> about it, such as "our ears are not sensitive to phase-shift".
>Though the justifications are likely true, that doesn't seem enough
>of a reason not to attempt a combined mechanical/electrical end-to-end
>analysis that might yield an improvement.
People in the loudspeaker business have been trying to do this for over
70 years. It isn't a simple problem at all.
>> Voice coils are usually spring suspended
>How linear are those springs? The construction techniques I've seen
>incline me to think they get stiffer with greater displacements, which
>would create 2nd harmonic distortion.
Well, if the displacement is symmetrically non-linear, the distortion is
odd-order. Usually, its approximately symmetrical, giving both odd and
even order distortion. But there are several other sources of
distortion. Wolfgang Kleppel has done a LOT of very good work on this,
much of which has been reported to the Audio Engineering Society.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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