Speaker impedance measuring meter

KenLayton

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When connecting or troubleshooting speakers connected to a jukebox (or any sound system or amplifier) you should use a "speaker impedance meter". It uses a special test frequency and along with the built-in computer inside it, calculates the actual impedance of the speakers connected on a line. If connected to an individual speaker, it will measure the impedance of that.

MCM Electronics has several of these meters they sell.

# 72-6948 is currently on sale until November 30th this year for just $129 by using "source code" G116 at checkout.

http://www.mcmelectronics.com/product/72-6948

# 72-7420 is a better quality one.

http://www.mcmelectronics.com/product/GOLD-LINE-CONNECTOR-ZM1-/72-7420

# 72-7900 is even better.

http://www.mcmelectronics.com/product/GOLD-LINE-CONNECTOR-ZM1P-/72-7900
 
Thanks Ken! Great timing, I was just looking for one of these. I had a couple of amplifier's output transistors fry recently. They were still under warranty, but the dealer suggested I get one of these because my meter isn't as accurate. My meter was showing 8.61 ohms, wonder how far off that really is.
 
These testers are especially helpful when you are checking external speaker lines that connect to an amplifier (like a jukebox amp for example). Like say when you have two 8 ohm speakers wired in parallel on one channel. That would be 4 ohms total impedance seen by the amplifier. So the tester should read around 4 ohms.

I've seen many cases lately where speakers are advertised as "8 ohm compatible". If you measure them with the impedance tester, they will show they are actually 6 ohms, not 8. If you were to wire these actual 6 ohm speakers in parallel, that would be 3 ohms. Many amplifiers don't like a 3 ohm load and will fry.
 
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