Impedance Meters
Impedance Meters

In this video, we look at the impedance meter - an invaluable bit of kit when installing or fault finding speaker lines in commercial audio systems.

It's very different from your multi-meter - watch the video to find out why an impedance meter is an asset to your toolbox!

An impedance meter is a device for measuring loudspeaker lines on constant voltage 100 Volt line PA systems. It's an essential tool for any audio engineer installing a new audio system or measuring a line on an existing system where there might be a fault.

An impedance meter sends out an AC signal on a one kilohertz tone and gives you a proper reading of all the loudspeakers on the line, helping to fault-find systems very quickly. You can't do this with a multimeter because they are only designed to measure resistance and you'll just end up measuring the primaries on every transformer in every loudspeaker and the reading will be extremely low.

Our video shows the TOA ZM104A which is a very popular meter. There are others available and although some are Digital, this one is Analog and it’s very simple to use.

Once you’ve set the meter up (see the video for more information), you’re ready to check the load on the speaker lines. For example, in a small system with a 15 watt cabinet speaker and a 20 watt projection speaker, we know the load should be about 35 watts on that line. A simple calculation tells you what reading to expect when you connect the probes to the speaker lines so you can quickly see if there is a potential faulty speaker or wiring fault at which point you would need to investigate further.

A simple walk around the system listening for the meters’ one kilohertz tone though each speaker may be enough to identify a non-working speaker or differences in volume where an incorrect tapping has been selected.

An impedance meter is also useful to find out the total load on the amplifier to prevent overloading.

For more advice, please call us and we’ll be pleased help.