is there a difference between nominal power rating and rms?

It's all marketing slang... RMS = sustained level at 99.9% of the time, Nominal=when all conditions to meet that figure have been met e.g. Voltage. Effectively you need to meet nominal conditions to meet the rated RMS figures.

never beleive a figure when they state it in PMPO. Always look at thr RMS value.
PMPO is supposed to mean maximum output. But crap 6x9's from JB which states 300watts pmpo most likely means 300 watts of utter distortion. always look at the rms value to get a true figure for how much power the speakers can take or how much power an amp can put out.

EG most head units state they are 4x50watts. this is in pmpo which kinda shows you how piss weak they are and the need for amps. ive found its always best to look at RMS figures when looking at power.

definately check rms value. From what i have read, the MAX power output can only be twice that of the RMS (laws of physics). Its is impossible for it to be more. So i have read.

Cheers,
Cam.

P.S I am not an expert on physics, like i said, tis just what i've read.

This is some good info about PMPO vs. RMS, however wAtchme is actually asking what the difference is between Nominal Power Rating and RMS.

definately check rms value. From what i have read, the MAX power output can only be twice that of the RMS (laws of physics). Its is impossible for it to be more. So i have read.

Cheers,
Cam.

P.S I am not an expert on physics, like i said, tis just what i've read.

Umm dude what about boss amps? 20WRMS x4 or something yet they are rated at 250W x4. True WaTCHME was asking about Nominal and RMS. Nothing to do with P.M.P.O. Yes dude they are basically the same.

cam is right when you are talking quality amps and equipment in general.
Check out a good quality amp and you will see that the max is close to double the RMS rating. However, when the quality goes down, so does the RMS. Boss amps (1000x4) are rated 250 watts max per channel. A mate of mine tested it on an oscilloscope, less than 50 watts RMS.

close enough to right anyways......