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Re: Speaker impedances



At 08:46 6/10/97 -0500, Garry Hemminger wrote:
I have been given a large subwoofer by a student, and it looks like a
fairly expensive speaker which I coulds make good use of in class with
either a stereo receiver, or a bass guitar amplifier. However, I
have no specs for this speaker. Can anyone suggest a simple way to
determine its impedance? And how necessary is it to know the
impedance?

*****************************************
Gary Hemminger

If you have a taste for heroic experimentation ( or a 1:1 isolation
transformer) you might try stringing a 40 watt incandescent lamp,
a ten ohm 5 watt resistor and the subwoofer in series across
120 volts 60 hertz.
The voltage across the 5 watt resistor is a measure of current, and
together with the voltage across the sub woofer provides an indication
of impedance at this spot frequency. A phase measurement would be
useful.
Comparing with a known speaker would be desirable.

The considerable health hazard of this setup is evident.

Regards
brian whatcott <inet@intellisys.net>
Altus OK