How to read rms wattage with a multimeter

[trevino_88 0]

Im about to set up my components but they are 100rms how would i know how manywatts im sending to the component with my digital multimeter thanks guyz

[Julian 641]

you need something that will do AC amps

(Volts)x(amps)= watts.

Also its usually not necessary to calibrate using a DMM because you can easily tell when there is clipping, most of us do it by ear.

[KU40 173]

You're not going to be able to do it accurately enough with that. Music is too dynamic and the response time of a dmm is too slow to get an accurate reading of just how high the voltage got.

Just set the gain by ear.

[kirill007 52]

You can use pink noise and a multimeter.(correct me if i'm wrong.)

[smgreen20 3]

Roughly a 50 or 60 Hz tone at 0dB set to repeat on the HU.

The math is 100 watts x 4 ohms = 400, square root the 400 = 20

So you'll want to set your gains until the amps speaker outputs read 20 vac.

Disconnect the speakers, when doing this, then turn your volume up on the HU to about 75%

This is not the best way, but for the most part it will get you close enough. There are other factors to take into consideration too, you'll want to know what the amp actually does just before distortion starts on both the amp and the HU (that's why the 75% volume on the HU- most are clean at that volume), and use the amps birth sheet (if it came w/one) to find out the actual power output it has. Set all sound settings to flat. The only settings you'll want engaged is the crossover and slope.

[kirill007 52]

Roughly a 50 or 60 Hz tone at 0dB set to repeat on the HU.

The math is 100 watts x 4 ohms = 400, square root the 400 = 20

So you'll want to set your gains until the amps speaker outputs read 20 vac.

Disconnect the speakers, when doing this, then turn your volume up on the HU to about 75%

This is not the best way, but for the most part it will get you close enough. There are other factors to take into consideration too, you'll want to know what the amp actually does just before distortion starts on both the amp and the HU (that's why the 75% volume on the HU- most are clean at that volume), and use the amps birth sheet (if it came w/one) to find out the actual power output it has. Set all sound settings to flat. The only settings you'll want engaged is the crossover and slope.

That would be a bad way to set up a full range amp.

The amp doesn't puts out power equally throughout the whole freqeuncy range. (certainly not if u still have a subsonic on )

[Sir-Lancelot 216]

Or you could just use your ears.

Honestly people make clipping out to be more then it is.

Your ears wont lie, If it sounds like shit turn it down.

[kirill007 52]

Or you could just use your ears.

Honestly people make clipping out to be more then it is.

Your ears wont lie, If it sounds like shit turn it down.

Some people are a bit deaf. (i mean people don't hear distortion before it is some heavy distortion.)

[KU40 173]

Stand 10 feet away from the car with the trunk open. Hearing distortion is helped immensely when your ears aren't overloaded.

[smgreen20 3]

Roughly a 50 or 60 Hz tone at 0dB set to repeat on the HU.

The math is 100 watts x 4 ohms = 400, square root the 400 = 20

So you'll want to set your gains until the amps speaker outputs read 20 vac.

Disconnect the speakers, when doing this, then turn your volume up on the HU to about 75%

This is not the best way, but for the most part it will get you close enough. There are other factors to take into consideration too, you'll want to know what the amp actually does just before distortion starts on both the amp and the HU (that's why the 75% volume on the HU- most are clean at that volume), and use the amps birth sheet (if it came w/one) to find out the actual power output it has. Set all sound settings to flat. The only settings you'll want engaged is the crossover and slope.

That would be a bad way to set up a full range amp.

The amp doesn't puts out power equally throughout the whole freqeuncy range. (certainly not if u still have a subsonic on )

Yea, I guess It didn't hit me that he's doing the upper end of the freq chart, most people are always asking for the most part about the sub amp. I use 2 tones for the HI's, 1000Hz and 4000Hz, and adjust somewhere in between the difference. It's too complicated for me to explain how I do that.