What's "RMS" ??

[Jason B]

I'm planning my system and I'm clueless to the meanings of all the terms (except wattage )

What does RMS mean? If there is a 1000 watt max on my XS-12 sub can I put more than the 500 watts RMS it's rated for?

[CP3]

I know what it means but I cant explain it. Im sure phil "old wise one" can answer

[spharis]

Stands for Root Mean Squared. Think of it as continual output rating and it make sense.



Here is an explanation off the web so I dont have to type it.

RMS stands for Root-Mean-Squared, and is an indicator of the amplifier's capability. The RMS power output can be sustained, for long periods without any damage to the amplifier itself.

[philwsailz]

I'm planning my system and I'm clueless to the meanings of all the terms (except wattage )

What does RMS mean? If there is a 1000 watt max on my XS-12 sub can I put more than the 500 watts RMS it's rated for?

First, a very simple answer to your question:

Maybe...... you might be able to use an amplifer with slightly more than 500 watts RMS output


A 600w RMS amplifier will work real well with your 500w RMS subwoofer... assuming you do not abuse or misuse the sound system, or continue operation of the stereo at a level that obviously sounds bad.

It has to do with clipping distortion, which happens when the amplifier is running at its maxed out ragged edge. Clipping distortion is bad on speakers, due the the things it does mechanically to a speaker. A 500 watt RMS amplifier will not try to put out that brief or accidental 550 watt signal burst without clipping and distorting, and possibly damaging the speaker. The 600 watt RMS amplifier can do it cleanly.


For sure know this though:
Either setup can blow the speaker and/or the amp with misuse or abuse... You have to listen for the audible signs of speaker distress and distortion and when something sounds bad, know it is probably hurting. Turn it down...

[philwsailz]

Now the long answer:
fine print:
Literally: "ROOT MEAN SQUARE"

The wikkipedia link for anyone who cares to look:http://en.wikipedia.org/wiki/Root_mean_square


RMS is a measure of the magnitude of a varying quantity. Sound is necessarily made of waves. The electrical signal applied to a speaker is in effect a wave, speficically a complex AC signal with both varying frequency, (pitch) and amplitude, (volume). When measured, the eletrical wave-signal is ideally the exact same as the acoustic wave signal.

Okay, enough pure science....


As it relates to us 90% of the time, the use of RMS has come to, or can mean "REAL" i.e. RMS power is the amplifier's real power. For an amplifier, its RMS power output is the real measure by which two amplifiers can be honestly compared. DO NOT confuse this with PEAK POWER. PEAK POWER cannot be measured. It is an artificial specification with no basis in reality. PEAK POWER is often called WLS power. WLS is an acronym for When Lightning Strikes. If an amplifier ever truly was able to provide its advertised peak power output, it would be due to a lightning strike, and probably would not function after passing that amount of power...



Many companies these days adhere to a specification called CEA-2006 which is an even more complete description of the output capabilities of the amplifier, as it specifies operating voltage at the power input terminals, output load, frequency, etc... It takes RMS power output to a different place, and allows a more precise comparison based solely on power output capabilities.




You really cannot measure the power handing of a speaker. That being said, the acoustic sciences are well enough established that any manufacturer has a good idea of what amount of power their speaker will handle, with minimum mechanical or thermal stress, all while sounding more or less consistent without getting ragged or sloppy. In general, this will be advertised as the speaker's RMS power handling. As with amplifiers, two speakers can be compared based upon their power handling. When doing so, always use the RMS value, and not their PEAK value.

When matching up speakers and amplifiers, it is simplest most of the time to make you speaker and amplifer seleciton based on advertised RMS power values, choosing the speaker and amps that have the same power output and handling.

Did I stir up the muddy water and make it less clear?

[philwsailz]

Geez, I edit and edit and edit, and still write a book rather than a simple reply.

Still editing by the way....

[chpthril]

What's "RMS"

Isn't that that psychedelic band from the 80's

[philwsailz]

they get royalties from every stereo product sold, due to the inclusion of the band's name...

[spharis]

You have experienced clipping distortion as well if you have donks where you live.

[philwsailz]

what about bubbles?

[philwsailz]

I had donks once. Doc gave me some penicillin and I got better....

[dogbert]

Focus, guys, focus!

[chpthril]

Great info guys thanks. I hope this next ??? doesn't make matter even more complicated

With regards to clipping, distortion, etc, is it better to have a slightly higher output amp then the driver's rated RMS and keep it in check with volume level, gain, and other settings, OR, a driver with a slightly higher rated handling then the amps output?

[philwsailz]

Great info guys thanks. I hope this next ??? doesn't make matter even more complicated

With regards to clipping, distortion, etc, is it better to have a slightly higher output amp then the driver's rated RMS and keep it in check with volume level, gain, and other settings, OR, a driver with a slightly higher rated handling then the amps output?

Personally I prefer a slightly bigger / higher-powered amp, as in my first post above. Use settings, control, and sobriety to keep the stereo in check and the signal clean.

The smaller amplifer cannot drive the higher-powered speaker to its max potential, and an attempt at doing so will usually lead to clipping.

[buffman]

.... Use settings, control, and sobriety to keep the stereo in check and the signal clean. ...

SOBRIETY now that is funny