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80A Fuse not blowing at 3000w ?


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Hello. So i have this setup for a year now , I have a 5000w amp with 2x12s runing at 3000w rms at 1ohm . From ohm's law,  at 14.5v and 3000w the current would be around 200A so why is my 80A fuse not blowing? ( running 2agm , around 140ah so voltage doesn't drop lower than 14.4 )

 

I've previously ran my system at 1000w and now I've went to 3000w. It doesn't sound much louder at 3000w than at 1000w ( or i got used to it? ) , so am i missing something?

 

I've set the gains using an multimeter  and square root of 1000w which was 31v and now at 3000w is about 55v taken at the output of the amp using a 40hz test tone at -5db. 

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You need a clamp to see the actual current going through the cable that has the 80A fuse.

 

To reach rated RMS power you need to feed a sinewave and you set the amp gain to get it's output to the threshold of clipping ( scope or DD-1 needed to measure) and using a resistive load. you measure the voltage across the power terminals of the amp as you do the test not when there is no load and the current with the clamp and do the math with that data. Most systems people have run like yours, far below their theoretical limits.

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You cannot do the test with subs because the impedance of subs changes with the signal frequency, You should get a clamp, there are some inexpensive alternatives. You can calculate with it along with the voltage  (measured under load at amp terminals)  input power at whatever level you are playing.

 

Bottom line you are not going to get accurate numbers the way you measure,  assuming a 13.8V input voltage under load and your fuse rating  P=13.8 x 80 = 1104 Watts input power so that the fuse won't blow.

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