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From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: Speaker phase and current vs voltage drive
References: <3DBC76E9.F9DA95C2@managesoft.com> <3DBDC5A7.1F5A6706@managesoft.com> <3DBDDB69.3D30001F@webaccess.net> <3DBEA0B1.30E5EEFB@mmm.com.DELETETHIS>
Date: Wed, 30 Oct 2002 00:25:27 GMT
NNTP-Posting-Date: Tue, 29 Oct 2002 16:25:27 PST
Roy McCammon wrote:
> Chuck Simmons wrote:
> > What we normally do is assume that the speaker above the principle
> > resonance is nearly ideally a current to force converter, that is to say
> > a motor. A voltage driver working into a resistor gives a current
> > proportional to voltage. Thus the resistance of the speaker essentially
> > changes the speaker to a voltage to force converter.
> Just speculating. I suspect that the moving coil
> generates a back emf that effectively changes the
> speaker into a voltage to velocity transducer, which
> seems like a good thing.
This is true of a free coil after it has accelerated. In fact, this is
why a low motor constant is highly desirable with transconductance
amplifiers that have little head room. With little head room it is
better to live with high current to get the desired force without the
high BEMF that would exist with a high force constant.
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons firstname.lastname@example.org
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