From: John Woodgate
Subject: Re: wattage meter exists??
Date: Mon, 9 Sep 2002 07:57:15 +0100
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Mon, 9 Sep 2002 20:08:55 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Robert Baer
wrote (in <3D7BF170.74C8F68F@earthlink.net>)
about 'wattage meter exists??', on Mon, 9 Sep 2002:
> Actually, speakers are *current* operates devices: the current thru
>the coil creates a magnetic field which interacts with the permenant
>magnet's field, the resulting force moves the voice coil (and thus the
While your explanation of the action is correct, your conclusion that
that makes it a 'current operated device' is completely misleading and
unhelpful in the extreme.
I was very careful to define what I meant by 'voltage-operated device':
loudspeaker is a voltage-operated device, not a power-operated device,
in the sense that you get the frequency response you want (or are
willing to accept) with constant voltage applied, not with constant
You do NOT get a desirable frequency response if you supply the
loudspeaker with a constant current, independent of frequency.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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