earworm said:
ok gonna read the document, thanks for the link!
but ehm...ok, noise is the same as rms, and i assume that "MUSICAL POWER" is the same too?
but what is program then, if its not the peaks and not the normal music...
something in between, but i read it on the back of two speakers, so why wouldn't they just put
"rms and peak" on it......tsssssss
Speaker ratings aren't standardized. I always wonder when I see "Musical Power", because a lot of times I don't see any other rating with that particular wording. If there is no other rating, I assume it's a peak rating. If there is also an RMS and Peak, I assume it's program.
The AES has established accepted ratings, but they aren't universal or required.
Speakers, aside from mechanical failure, fail for two reasons. They get too hot, or they move too far. RMS and program ratings involve thermal testing. Peak ratings are related to overexcursion as well as thermal issues.
Most pro makers use the following AES terms:
RMS/Noise/Continuous- Pink or white noise with limited dynamic range fed to a speaker at the rated power for eight hours, and the speaker doesn't fail. This is basically the most brutal test a speaker undergoes. The voice coil is in continuous motion and receiving constant current, and is constantly hot.
Program (Music Power?)- The equivalent of modern compressed recorded music, for an extended period. Music has wider dynamic range and pauses, and so is different than noise, and the voice coil stays cooler as it gets a little rest during the material. So the actual material can be at a higher level.
Peak- the absolute max the speaker can take, for a very short time, like a snare hit. More power than that, and the coil will probably jump out of the gap. Give it peak power for more than a few seconds, and it will melt.
Program is usually twice RMS. Peak is usually twice program, or four times RMS. If a maker gives an honest assessment of any of the ratings, you can figure out the rest.
It's all about how long the speaker can take what you throw at it.
The other question is what are you really throwing at it?
Remember that program ratings are averaged over time, too. With an average modern highly-compressed CD played through an amp putting out maximum power on the peaks, the amp is usually considered to be putting out 1/8 of it's power over time. So if you have speakers rated at 500W program/1000W peak, and a 1000W/channel amp driving them, and crank a CD through them so the amp is maxing out on the peaks, over time the amp is only putting out 125W, well within the speaker's program capacity. This is why DJs can pump music through speakers all night long, when they would seem to be exceeding the speaker's ratings.
Live music from a band has even lower average power ratings over time. Averaged over a night, a band's or club's power amps will maybe be putting out 1/10 of their rated power.
This seems odd, until you remember that 1/8 power is less than 10db down from peak. If your amp is 10db below clipping, it's only putting out 1/10 of it's power. Watch your console meters over an average night, and see what I mean.
Guitar players are the most dynamic of all. Over a night of playing, a guitarist using a 100W Marshall will probably average less than 1W of output power.
Anyway, I went from speakers to power amps, but they are related.
Click on the topics on the chalkboard.