Date:         Tue, 28 Jan 2003 22:41:48 -0500
Reply-To:     Dennis Haynes <dhaynes@OPTONLINE.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Dennis Haynes <dhaynes@OPTONLINE.NET>
Subject:      Re: measuring impedance of a speaker?
Comments: To: Ben McCafferty <ben@VOLKSCAFE.COM>
In-Reply-To:  <BA5C701E.E2C9%ben@volkscafe.com>
Content-type: text/plain; charset=us-ascii

You can't simply use an ohm meter to determine impedance. The difference
between a resistance measurement and Impedance measurement is that
impedance includes the effects of capacitance, (resistance to change of
voltage), and inductance, (resistance to change of current), when an
alternating voltage or current is applied to circuit. In general,
speakers designed for home use are 8 ohms. Car speakers are usually 4
ohms so they can draw more current at the limited 12 volts available.
Good power amps start off with built in inverters/voltage doublers to et
more voltage/power.

Dennis


-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf
Of Ben McCafferty
Sent: Tuesday, January 28, 2003 7:37 PM
To: vanagon@GERRY.VANAGON.COM
Subject: NVC: measuring impedance of a speaker?

Hi out there,
Any of you stereo buffs:  I need to determine if my home speakers are 4
or 8
ohms, so I can set my receiver properly.  Unfortunately, there is no
marking
on the case or actual speaker anywhere, except "75 watts, magnetically
shielded, design for t.v."

I have a fairly sophisticated digital multimeter, but it only goes down
to
200 ohms for resistance.  Is there another way I can determine what I've
got?

If it helps, they are from Rock Solid Sounds, Worthing, England, Made in
Taiwan.

Thanks in advance,
bmc  :)
Ben McCafferty
ben@volkscafe.com

Volks Cafe
1823 Soquel Avenue
Santa Cruz, CA  95062
831-426-1244
http://www.volkscafe.com