Questions about using a DMM

Well I was hoping to get some answers here too. Bummer:\

To test for impedance switch the multimeter to the omega symbol Ω. Red test lead goes to the positive terminal, black goes to the negative, obviously.

To test for output, or to set your gain, you switch the multimeter to AC voltage (shown usually as a sine wave). Check for power going to the amp or for a faulty ground, switch your meter to DC voltage (shown as a line with a dotted line above it). You can also switch your meter to continuity to check and see if a circuit, voice coil, or fuse is blown. No need to match up leads, just put them in the 2 spots you want to check and the meter should make a beep noise. Don't check for continuity if a circuit has power running through it though because you can short it out with the leads and blow a fuse in the meter.

As for testing how much an amplifier actually puts you would need a rms clamp meter which operates differently than a multimeter does.

Everything said above is a good starting point.

As for testing how much an amplifier actually puts you would need a rms clamp meter which operates differently than a multimeter does.

Click to expand...

While that is not untrue, there are plenty of threads on this site for setting gains using a DMM. While is not as perfect or easy as clamping to get the power output at a specific frequency, it is close enough to properly set the gains.

These 2 sites will pretty much answer any questions you have about basic/intermediate car audio:

Basic Car Audio Electronics

Car Alarm, Car Stereo, Mobile Video, and Cruise Control Info for Installers

Between the articles, charts, and diagrams, you can look up this info very quickly.

Yes, the radio needs to be turned up to measure the power output from your amp. You are measuring how many volts are coming out of the amp, and using a chart you can convert the volts @ ohm load over to watts output.

These 2 sites will pretty much answer any questions you have about basic/intermediate car audio:Basic Car Audio Electronics

Car Alarm, Car Stereo, Mobile Video, and Cruise Control Info for Installers

Between the articles, charts, and diagrams, you can look up this info very quickly.

Yes, the radio needs to be turned up to measure the power output from your amp. You are measuring how many volts are coming out of the amp, and using a chart you can convert the volts @ ohm load over to watts output.

Click to expand...

^This, especially Perry's site, Basic Car Audio Electronics...that site rocks.

Everything said above is a good starting point.



While that is not untrue, there are plenty of threads on this site for setting gains using a DMM. While is not as perfect or easy as clamping to get the power output at a specific frequency, it is close enough to properly set the gains.

Click to expand...

He wasn't talking about setting the gains at the point, he was referring to actually clamping how much power the amplifier can produce. Just because an amplifier is rated at a certain ouput doesn't mean that's it's exact output, it always varies but if you have a current clamp you can calculate the actual output. Although this reading is practically useless without also measuring THD.

Basic Car Audio Electronics

Click to expand...

OP if you really want to learn more about car audio and electronics in general, definitely visit this site.