How do you figure out watts rms using only the amps fuse rating?
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How do you figure out watts rms using only the amps fuse rating?
fuse ratings are based on amps... so P=IV.... amps x voltage = rms power
my kenwood 8105D has a 60A fuse.
at 2 ohms, that's 60A x 120 volts = 7,200watts :eyebrow:
doesn't make any sense. Even if half of that wattage was turned into heat, that would still be 3,600 watts. The kenwood is rated 500wrms at 2ohms with 1,000 peak.
so.......:eyebrow:
I plugged the numbers into a wattage calulator. lol
I put 60amps into 4 ohms and it gave me 120V.
I think I did it wrong. I think you use the car battery voltage and the amperage rating for the fuse.
14.4V x 60A = 864watts
Let's say the kenwood is only 70% efficient. 864 - 30% = 604.8watts
This might mean that this amp will take about 605wrms before it catches fire???
I think???:confused:
This calculation is only an estimate of what the amplifier is capable of putting out. No, it does not mean that at the watts you come up with the amp will catch fire. Fuses blow slowly, and they will handle more than their rating says for brief moments. Some fuses blow more slowly than others. With music playing the amp will rarely be at maximum output unless you run it wide open all the time.
The problem is how do you know amplifier efficiency? The difference between 60% and 75% could change the estimate. I do get suspicions when a company X makes a claim about the RMS power of their product that's completely out of line with comparable amplifiers that use a similar fuse size.
Ya think?! :eyebrow:
Generally, yes. It's not an exact representation of power output by any stretch of the imagination.Quote:
14.4V x 60A = 864watts
Let's say the kenwood is only 70% efficient. 864 - 30% = 604.8watts
This might mean that this amp will take about 605wrms before it catches fire???
I think???:confused:
It's a rough estimate of maximum continuous power the amp should be capable of. This approximation is usually reserved for the ultra-budget amps that you KNOW are listing inaccurate specs.
04murdalanche commented that your amp is no where near capable of rated power -- if it were the 8104 I wouldn't argue, but it APPEARS the 9105/8105's are improvements on the old amps, and I wouldn't be surprised if it actually DOES do rated power.
This. Not to mention, you have no idea what the efficiency is, if the manufacturer put the correct size fuses, if it does rated, etc. There's a whole list of reasons why this method is inaccurate, but it will typically get you in a ballpark. The same ballpark you would be in if you just went off of manufacturer's ratings.
get an oscope/dmm/clamp meter /thread
yea because i have looked at some old school us made amps that had amps that had 120 amps but max current draw was over 250 amps trying to find the manual now lol
Let a professional do it for you.
Yes.