I used my dmm to check the voltage coming out of my speaker terminals, with the gain set at about 75% I get a reading of 130 volts ac. If I interpreted the formula correctly, my amp produces 8,450 watts at 100 percent efficiency under a 2 ohm load, and 33,800 at .5 ohm load. I don't know how efficient this amp is under these conditions, so I still don't know what kind of power it produces or if I even did the math correctly. I used this formula ( power=voltage squared divided by resistance.) My amp is an MA audio hk4000d. It is significantly louder at .5 ohms, but I don't really have any idea as to what wattage it is actually producing.
If my math is correct, shouldn't the amp be putting out about 89.5 volts, considering it is only rated at 4,000 watts at 2 ohms? Should I lower the gain until it reads 89.5? How much will that effect SPL? (I could care less about SQ in this truck!) Or does more voltage simply equal more power/ higher SPL? I removed all the impedance protection and over/under current protection and was running about 15.5 volts dc to the amp when I checked it.
Thanks in advance to anyone who can offer some advice, sorry for the long post!
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Gettin' deafer by the day.......96' GMC yukon-Eclipse CD 5442HU
MA Audio HK4000D-Digital Designs 9515F
150+db with one woofer...DD rules!!!!
here is you're answer d43m05, amplifiers put out an a/c current.
I forgot to mention that I also had my HU volume at level 70 out of 80. That is the point where the voltage coming out of the amp began to drop. I am assuming this is where my HU clips. Does this sound right to you guys?
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Gettin' deafer by the day.......96' GMC yukon-Eclipse CD 5442HU
MA Audio HK4000D-Digital Designs 9515F
150+db with one woofer...DD rules!!!!
Resistance is a measurement of opposition to current flow and it produces a voltage drop. This is all in relation to DC circuits (straight power). The output of an amplifier is AC (wiggly power) and the Ohm rating of your speaker circuit is impedance, which is in relation to alternating waveforms.
I can't help you with the calculation, but a multi meter wont tell you anything except AC voltage and that isn't going to stay constant with music, maybe with a test tone.
ddsubman wrote:
If my math is correct, shouldn't the amp be putting out about 89.5 volts, considering it is only rated at 4,000 watts at 2 ohms?
Your math is right, but something else might not be is my bet. You should really be using an o-scope to look at the waveform instead of a DMM. You can find the highest unclipped signal this way but you still won't know exactly what the impedance is during testing. You can't get an absolutely precise reading using a speaker because of the fluctuating impedance, so if you want to know the precise power output of the amp you will have to bench test it using a dummy load in a more controlled procedure.
You most likely already saw that a tone at 50 Hz gives a different output reading than a tone at, say, 65 Hz. And that you can almost just breathe on the gain and find a substantially different output reading at the high end... At this point, doing this in the vehicle using a DMM, I would say you should adjust gain down to the 89 volt reading. What tones are you using for the signal source and is it prerecorded or did you make a CD?
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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
stevdart wrote:
What tones are you using for the signal source and is it prerecorded or did you make a CD?
I used a prerecorded bass mechanic cd with 20 sec. test tracks. The amps output voltage peaked at 44hz. At any frequency above or below ,the voltage would drop. I set the gain at 89.5 volts and the sound quality is better, but the spl is not as loud as it was before at 130volts. Would I be better off to leave it at 89.5 for ride around and increase it to 130 for comps? I would like to put it on the term lab and check it at both settings, but I don't have time to drive for an hour to get to my "local" audio shop! LOL Maybe I'll just wait for the next NSPL/dBdrag show and make a run at each gain setting....
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Gettin' deafer by the day.......96' GMC yukon-Eclipse CD 5442HU
MA Audio HK4000D-Digital Designs 9515F
150+db with one woofer...DD rules!!!!