Скачать или смотреть How to Estimate a Car Amplifier's True Power Output (watts RMS)

General Equation for Approximation ONLY...Designed so you can do it in your head!
(Fuse Rating) x (# of Fuses) x (10) ~= RMS Wattage
ex. (25A) x (2 fuses) x (10) = ~500 watt rms @ rated ohm load

*For class A/B amps, some folks suggest using a multiplier of 6 instead of the 10 shown above for class D amps.*
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Some people want me to put the true equation (for if you've got a calculator handy lol):
(Fuse Rating) x (# of Fuses) x (Voltage) x (Amp Efficiency) ~= RMS Wattage

Voltage: Typically 12.6v with car off or 14.4v with the car running
Amp Efficiency: Class D amps typically run from 75% - 90% efficency

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MORE INFO:
This is a very general equation, but it gives you a guess as to whether or not the amp you're looking at will sufficiently power your subs/speakers.

Manufacturer's usually advertise their amps by their MAX ratings to make them appear more powerful than they are. MAX power ratings are not helpful for matching subs/amps because an amp will very rarely reach its MAX output and it sure as heck cannot sustain that amount of power output for very long. The only time you may utilize the MAX power is during a nasty bass drop in a dubstep song :) Therefore, RMS ("true wattage") is the rating you need to look at in order to match amps and subs properly. Keep in mind you also need to know what load (ohms) you plan to wire your subs for...(if you need help with this, please ask).

The estimation equation I give above can also be especially useful if a seller doesn't know the true Nominal/RMS when you're purchasing an amp second hand. HOWEVER, when purchasing a used amp, please keep in mind that the owner may have installed a higher rated fuse than the OEM spec. I find this is commonly done because of the belief that a higher rated fuse will provide you with more power. (Note: Please do not use fuses that are higher than the OEM specified rating...otherwise the fuses will not be doing the job they were intended to do: protect the amp's electronics from high currents ["power surges"].) Sometimes, the manufacturer will put the proper fuse rating by the fuse slot...as it is shown on the amp I'm talking about in the video (25A).

If you have any questions on this topic, please comment!

If you see an error in my work, please also comment to help me rectify the problem!