thanks bro! great info. couple questions though??1.) So class a/b's are really ineffecient at low volumes?? why is that??
It is analagous to doing a pushup. In the fully down, or fully up (for analogy, switched on or off) positions, you exert the least effort. a class D amplifier basically has the devices in one of the low-effort states or the other, and uses averaging to acheive an output that seems (and is) somewhere in between. the class B (and AB) largely operates the device in ONLY the high effort zones. class A, in this example, would be closest to someone sitting on your back while doing pushups. (the technical: a switch is either dropping 0V or passing 0A, giving 0W of loss in either state. an analog state in between these two is dropping some voltage and passing some current, leading to an amount of power being used. for low outputs, the device is dropping much more voltage then required, which means it uses more power then required, thus a reducution in efficiency from the best case)
2.) What does "effecient" in terms of amps mean??
power out vs power in. eg, if it takes 10W to output 1W, you have 10% efficiency.
3.)when you say "15A rms" is A=amps???
RMS, when correctly applied to voltage or current means "the equivilant DC value that could be used in a power calculation." eg, if you have a voltage or current that changes over time, its best to use an RMS value, as that will allow accurate calculation of power. This makes most sense for line voltages that have AVERAGE values of 0, but still provide power. "RMS" is also incorrectly applied to power ratings to mean "average" power. pretty much everytime you see "Watts RMS" you really are just seeing "Watts, average".
4.) So when you double the wattage which is what I would be doing ( i want the jl 1000/1) there really is a bigger gap in D's effeciency compared to a/b's ineffeciency?
pretty much, yes.
5.) So with that info would you suggest definitely getting a class D sub amp since that is where the majority of your wattage is coming from???
if that is your design goal. I personally have had bad luck with class D, and it seems like many of the "Amp repair" threads are issues with class D amps, though that may simply be due to the widespread nature. My issues occured during non-extreme conditions. That said, I would still go with Class D for woofer applications. in terms of sound quality, i've found that changing settings has the biggest effect. I had found that my class D amp was muddy, and switched to a class AB. later I found my class AB to be muddy and switched to my class D. in both cases resetting settings fixed that issue.
6.) Lastly with the 1000w amp pulling lets say 25A full volume for a class D why do you have to have a 100 amp fuse???
the fuse is there to protect the wire, not the amp. the amp will use its own fuse. a smaller fuse could be used to provide added protection to the wire in short circuit conditions, but is not required.
