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Thread: How can i measure the watts an amp is with a multimeter? |
    
Silver Member Username: Panamanian
Panama city
Panama
Post Number: 232
Registered: Aug-05
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| Posted on Sunday, September 23, 2007 - 08:52 pm: |
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How could I measure the watts (RMS) an amp is by using a multimeter? |
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Gold Member Username: Nd4spd18
Northwest PA
Post Number: 3215
Registered: Jul-06
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| Posted on Sunday, September 23, 2007 - 11:29 pm: |
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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
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| Posted on Monday, September 24, 2007 - 01:19 am: |
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What if you had a graph telling you the impedance at different frequencies? |
Silver Member Username: Panamanian
Panama city
Panama
Post Number: 233
Registered: Aug-05
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| Posted on Monday, September 24, 2007 - 11:00 am: |
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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
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| Posted on Monday, September 24, 2007 - 05:26 pm: |
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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
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| Posted on Monday, September 24, 2007 - 09:26 pm: |
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why does it matter what it sounds like outside your car? it shouldn't |
Bronze Member Username: Sept298901
Post Number: 24
Registered: Jul-07
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| Posted on Tuesday, September 25, 2007 - 10:45 am: |
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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
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| Posted on Tuesday, September 25, 2007 - 12:17 pm: |
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get some sound deadener and enjoy ur music on the inside  |
Gold Member Username: Juliob
Santo Domingo
Dominican Re...
Post Number: 4931
Registered: Dec-05
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| Posted on Tuesday, September 25, 2007 - 02:20 pm: |
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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
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| Posted on Thursday, September 27, 2007 - 11:14 pm: |
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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
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| Posted on Friday, September 28, 2007 - 03:00 pm: |
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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
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| Posted on Saturday, September 29, 2007 - 12:13 am: |
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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 |
