How can i measure the watts an amp is with a multimeter?

 

Silver Member
Username: Panamanian

Panama cityPanama

Post Number: 232
Registered: Aug-05
How could I measure the watts (RMS) an amp is by using a multimeter?
 

Gold Member
Username: Nd4spd18

Northwest PA

Post Number: 3215
Registered: Jul-06
You cant. Need an o-scope and some big as$ resistors for that (you can't use speakers as the load either).
 

Silver Member
Username: •cam•

Post Number: 690
Registered: Nov-06
What if you had a graph telling you the impedance at different frequencies?
 

Silver Member
Username: Panamanian

Panama cityPanama

Post Number: 233
Registered: Aug-05
The Thing is, I was sold a "new" amp, and it's suppose to throw 300w rms x 2, to power my 300w rms x 2 JBL JBL BANDPASS enclosure with 2 12".

And Althought it sounds good inside, in the outside of the car I can only here the bass within about 3 to 5 meters from the car, (even when the volume in the headunit is loud).

I dont know if it's the enclosure design or lack of power.

The gain also is set to about 60% of the power.
 

Bronze Member
Username: Sept298901

Post Number: 23
Registered: Jul-07
yo im running about the same set wattage wise and that happens w/ my car too, all you can hear is the bass rattling the car from the outside, but from the inside it is so loud i can't even handle it.
 

Silver Member
Username: Philly306

North carolina

Post Number: 406
Registered: Apr-07
why does it matter what it sounds like outside your car? it shouldn't
 

Bronze Member
Username: Sept298901

Post Number: 24
Registered: Jul-07
that was my case in point, who cares what it sounds like outside im only concerned w/ what im hearing. bass
 

Platinum Member
Username: Chaunb3400

Huntsville, Alabama U.S.

Post Number: 12880
Registered: Jul-05
get some sound deadener and enjoy ur music on the inside :-)
 

Gold Member
Username: Juliob

Santo DomingoDominican Re...

Post Number: 4931
Registered: Dec-05
music is very subjective for example i did a lil test, i played a song at 50% (volume of HU) and you could barely hear it outside the car, then i got inside of my house, a piece of wood was rattling, you could hear a lil Boom far away,so is basically impresive how far waves can go
 

Silver Member
Username: Cblaze

Tn Us

Post Number: 103
Registered: Sep-07
i here ya on that one i got a ticket from a state trooper,and it wasnt up that loud,turned out he had a decibel meter,and he said it was going crazy when it thumped
 

Bronze Member
Username: Sept298901

Post Number: 25
Registered: Jul-07
wow, what state do you live in? and whats the decibel limit?
 

Gold Member
Username: Van_man

Boston South, MA

Post Number: 2900
Registered: Mar-06
you can get a rough idea, by finding your voltage at the amp, finding the amp draw off the ground and power (Iuse both readings, and then average), That is of course your meter is able to read DC amps. Most cheap ones cant. They take into acount the amps efficancy, somewhere between 60-80% in most cases, the amps times volts

So like 14.4v X 22a = 314watts. Minus 25% = 78.5.
So 314 minus 78.5 = about 235.5 watts there about.
If you can get the variable of the amps eff. it will give a idea of what you have.

But as M.S. stated, to get a real number, you need some specialized test equipment.
Good luck.

Remember, E=IxR
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