Whats the way to figure how minny watts you're amp is really pushing by the fuses?


Gold Member
Username: Taylor17

Kopperl, Texas

Post Number: 1281
Registered: Jan-05
I remember someone saying that the real way to see what you're amp pushes is to like add the total fuse rating's and then do someing... I was just wondering, how you figure this out??
For example, my amp has a fuse rating of 40A x 3.

i wished i knew the answer to that cause i have a 500 max watt amp pushin 2 12 inch 500 watt max subs and i have had one problem with anything the subs sound great.

Gold Member
Username: Taylor17

Kopperl, Texas

Post Number: 1282
Registered: Jan-05
Lol, my amp is only supposed to be a 800 watt rms amp, but I think it is pushing a little more than they say.
3 40A fuses seems a little big to me, but then agen, thats why I'm asking how to figure this up...:-)

Gold Member
Username: Taylor17

Kopperl, Texas

Post Number: 1285
Registered: Jan-05

Gold Member
Username: Carguy

Post Number: 2170
Registered: Nov-04
A fuse size is a good start. If you really want to know, then get a DMM and measure the current flow when the amp is pusing.
To find power, take current reading multiply by voltage on the power wire. The total you get is the power being pushed by the amp.

Silver Member
Username: Fishy

Tamarac Ft.Laud, FL USA

Post Number: 851
Registered: Sep-04
Not a good idea unless you've got an industrial strength multimeter. Most meters are good for 10 amps max(140 watts @ 14v). In addition this method only gives you the amount of power your amp is using, not producing. Power output depends on an amplifier's efficiency as well.

An accurate measurement of an amplifier's output should be measured on well...... its outputs. It would require mesuring the voltage on an output across a dummy resistor and then using the following equations to determine power.

V = I * R


P = I * V


P = V^2/R

See here for more details:


All I can say is good luck finding a big enough resistor if your amp's pushing 500-1000 watts.

Using fuse ratings can tell you the maximum power your amp could produce(P=I*V = fuse rating * 14.4v on a 100% efficient amp) w/o blowing the fuse, but won't help you determine what its actually producing. For exmple I own a 360 watt Xtant with a 60 amp fuse and a PPI pro MOS 2050(~400 watts 2 ohm bridged) that came with a 35 amp guy. Needless to say I would blow that lil sucker every once in a while when I pushed it and ended up using a 40 amp instead.


Silver Member
Username: Southernrebel

Monroe, Louisiana USA

Post Number: 500
Registered: Mar-04
^^^what he said^^^

you can also use the method...w/ a few changes...to find your box rise.

all you need a DMM and a Clamp meter.

Gold Member
Username: Taylor17

Kopperl, Texas

Post Number: 1286
Registered: Jan-05
ok cool. Where could I get some of this equip to do this, and how much do they cost?
Thanks for the help.
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