i just aquirred 2 12inch L7's (4ohm if that matters) and a power 1500bd...it says on the box that it puts out 1500watts at 2 ohms....so how much power will each sub be getting?

 

That depends...I'm going to assume 1500 is peak (and not peak to peak), and I will also assume that it really rated 1500 watts at 2 ohms. If that is the case, then in a perfect world with a sine tone as the signal, your subs would be 750 to each sub if you wired them parallel. In the real world resistance changes depending on the frequency, the sub, and the enclosure, but for car audio applications the 750 figure will do.

 

Oh one more thing; if you check out this thread I started a while back, you can learn more about voltage, current, resistance, and of course wattage.

http://www.acura-tl.com/forum/showth...ghlight=SPLITZ

good luck!

 

Well since this is a rockford fosgate amp and rockford is notorious for underrating there amps i would say you have a very good chance of getting 750w rms to each speaker... of course that is probably @ 14.4v.. so @ 12v i would say you are looking @ 700w rms....

 

but splitz is absolutely correct... but splitz i think you went a little deeper than he wanted...

 

thanx guys..still kinda confused...but aslong as i get atleast 700 watts to each thats fine...thanx

 

Like shaw said the Fosgates are pretty well underrated. The 1500bd should produce somewhere around 1600 watts. Your subs will defiently move with that amp.

 

on the test sheet it says it produces 1718watts...but something aobut 74% efficiency...i dont know what the standard for efficiency is...but that doesnt sound too good

 

Shaw,

I cant help it...I've been reading too much of Southbounds posts!

Splitz

 

74% is pretty damn good. SOme amps are only about 50% effiecient. If I am correct effiency is the % of power produced and lose to heat. So 74% is really good I think. I have a 500BD which is about 73% effiecient and test sheet says it produces 648 watts.

 

cool thanx..i thought i was getting a deficient amp

 

hmm...deficient probably isnt a word...

 

Yeah, efficiency is a rating of OUTPUT POWER DELIVERED TO THE LOAD vs. THE POWER DRAW FROM THE POWER SUPPLY (battery/alternator)

So for an easy example... If an amp puts out 750 watts RMS into a given load, and if that amp states that it is 75% efficient... that means that it would have to draw 1000watts from the battery/alternator power supply in order to produce that 750 watts to the speakers. The 250 watt discrepancy is dissipated as heat as "dnd" correctly pointed out. REMEMBER that this is only valid for RMS ratings (the equivalent of DC power and heat). Peak power is always misleading. Because in the example above, the step up power supply required to produce that kind of wattage could sag signficantly when in true rms mode... thus making the effiency factor less than stated.

The efficiency factor can also usually be a method of determining the classification of the amp. CLASS A amps typically sound the best, but are VERY inefficient. CLASS B amps are the most efficient without going into unconventional CLASS C or D amps which are VERY efficient, but lack sound quality. CLASS C amps are typically used in RF amplifiers where resonant tank circuits are used to reproduce the part of the signal that is missing due to the lack of initial bias. CLASS D amps are used in subwoofer amps where LOTS of power is required and sound quality/clarity is not that detailed. CLASS D amps are very efficient because they are actually square waves with a varying duty cycle which is then converted to a quasi-sinewave through elaborate encoding/decoding/filtering techniques, etc. The fact that the output devices are swinging between saturation and cutoff to make the square wave, means that very little signal or heat is dissipated across these transistors themselves. Most of the voltage and current ends up at the load. However, these amps would sound VERY harsh at higher detailed frequencies to a trained ear.
I guess they are acceptable to many people down in the bass ranges where the ear is not as sensative to direction or detail.

CLASS AB is the typical compromise used for an amplifier of good sound quality and good efficiency. It's idle current is biased between the state of "FULL ON" during the absence of an input signal (class A) and the "FULL OFF" state without an input signal as in a CLASS B amp. There's just enough quiescent (idle) current to keep down the crossover distortion between the push-pull pair of output transistors at low signals, and at the beginning of each cycle, while still remaining quite efficient.

Hope this helps, even though some of you probably don't care to know all of this... I KNOW THAT ALL YOU WANT IS GREAT LOUD MUSIC! So do I! But sometimes it helps to know how to achieve it without being sold a BS story by some salesman...

Good luck!
SB

 

thanx for the info...im probably gonn have to read it over a few times before i fully get it tho...hehe