..amp is? I have an amp, I dont know anything about it. When I get home I can get numbers off of it or even pictures of it. Without seeing it or knowing anything about it, is there a way to know how many watts it is?

 

The only way to really find out is to get the model number and search the web.

 

Thats what I was thinkin, when I get home Ill look for the number. Thanks!

 

This is the same one I have. Is it worth using on anything? I just want a sub and know I need an amp too. Someone gave me this one and I have no idea what to do with it. or if it even works. Anyway to test it? Thanks!

 

take it to a local stereo shop. they should test it for free

 

Testing true RMS power output takes equipment the average shop will not have.

However, if they have an oscilloscope, clamp meter, and DMM they can give you a good ballpark figure. In fact, if you can get a hold of an oscilloscope, clamp meter, and DMM it is pretty easily.

 

I once heard that you can get a ballpark figure by taking the fuse rating, multiplying it by 14.4 (voltage, engine running), then mulitplying it by the amplifier's efficiency.

Efficiency is tricky, and it varies by class: A/B or D. I think a good ballpark figure is that class D amps are maybe 70-80% efficient at best, and A/B amps are maybe 60% efficient. Multi-channel amps are usually class A/B and Monoblocks are usually class D.

Example:
My Alpine MRD-605 monoblock is fused for 60A. It's a monoblock and is infact class D. So...
(60x14.4)x0.75 = 648w

This is actually pretty close to the birthsheet which said 631w @ 14.4v

My Audiobahn A6004v 4 channel amp is rated at 600w total rms power. It's fused for 60A, but is a class A/B amplifier. So...
(60x14.4)x0.60 = 518w

This is slightly under rated RMS power, which doesn't surprise me because it didn't come with a birthsheet or a CEA 2006 certification. It's Audiobahn...

This is just a guideline. so take it for with a grain of salt.

 

Oh good god, im going to try reading this one again in the morning when my brain doesn't feel like its gonna explode haha. Thank you though.

 

Ha, a quick summary of what Chris said: Multiply the number listed on the fuse by 14.4 and you will have a general rating for your wattage.

 

Times efficiency.

It'll put you in the general area...assuming your efficiency guess is semi accurate. For instance, JL's old class D amps were like 50% efficient. On the other hand, there are A/B's that are in the 70% area.

Also, this way assumes the amp is capable of drawing as much current as the rated fuse capacity. However, this is hardly ever true. With cheaper amps, the fuses are usually a good bit above what the amp is capable of pulling with out some sort of failure. On the other hand, many high current amps use slow blow fuses (well some use no fuses at all, lol) so the amps is capable of drawing well over the fuse's rated value for short periods of time.

 

So True...

I simply listed a general way to "guess-timate" an amp of unknown wattage. And, you list good info about fusing and efficiency. Good Post.

 

Teamwork, it's nice when it functions correctly.