What's "RMS" ??

I was going to say that the last graph looks like some ppl's heart rate. Right 1lab?

Your right it does but it usually represents some type of artificional intelligence when that persons brain clips their heart rate so bad. Unfortunately I am too much of a newbie to determine who's brain wave is causing so much clipping but I do know it is related to IQ problems. IMO this person again has a low IQ and I would bet > they are well under 50

Sorry Phil and Mike for the RMS interuption.
Please continue.

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?

Oh hell You just gave me a refresher for a course I had in 1978 at SIU

[Graham Morris]

clipping

Hi Graham-

Clipping in the laymans terms is when the amplifier is trying to put out a larger output waveform than it can. The input waveform cannot be fully replicated at the speaker terminals, as the amp does not have the output voltge amplitute necesary to recreate it.

The result looks like the second and third pictures above.

Clipping can be a contributor to thermal failure of the speaker due to excesive heat. At any point that the output signal is flat, as in the clipped off tops and bottoms of the output, the amp is producing a DC voltage output at a constant voltage. DC voltage in a speaker does nothing more than create heat.

Loss of damping is a problem; damping is simply put the ability of the amp to smoothly control the woofer's motion. When one loses damping, the woofer can travel to extreme displacements, beyond its design intent. This can sound bad on its own, but can also cause other things. Many voice coils are aluminum, and if one hits the bottom of the motor structure, it will bend and probably rub or even get stuck. If it gets stuck, the voice coil will for sure over-heat with applied signal, as it cannot turn the electrical energy into motion, only heat.

PHil
Thanks I know understand how an underpowered amp that clips can damage a speaker. Just causes heat and no movement. I had always struggled to see how it did.

Many thanks

[spharis]

Clipping is caused 90% of the time by cranking the gains all the way up or going over 75% of a head units volume.

[philwsailz]

Basically, no or maybe.
It comes down to gain matching all parts so that they hit clip at the same time.

High-end stuff will clip, so the goal is the same, regardless what equipment you have.
In general, wire will not affect clipping...

[da.bell]

So, getting higher end equipment/wires/... will reduce the chances of clipping?

[philwsailz]

Don't know if Phil said it or not, but clipping can be caused at numerous points throughout the signal as it passes through. Head units, eq, and the amp. Most everyone can hear clipping if they know what to listen to.

Well put.

And no, since the discussion started with RMS as a tpic, I did not go into it.

Spharis is right.

[philwsailz]

MB-8's = 150 watts RMS/ 4 ohm driver
Pro 60's = 150 watts RMS/ 4 ohm driver

MX700.5 = 85 watts x 4 @ 2ohms = about 45-50 watts x 4 @ 4ohms (correct me if i'm off Phil )

I'l say go with the ZX850.4 (215 x 4 watts RMS @ 2ohms) for 2 reasons: more power per chnl @ 4 ohm and not having the sub pounding away when the tower speakers are cranked up.

These are only the my thoughts that are based solely on street smarts Let's see what the experts say

I agree with CHP...

I am going from memory, as I am typing from the Atlanta airport, but I seem to recall that the 850.4 is good for 150 W RMS into 4 ohm load, according to CEA-2006 specs. That will be a prefect amp for your speakres if my memory is correct.

Since you are going for the higher power on the tower, go with a KICKER ZX400.1 digital amp if you are using the KICKER marine sub(s) or I may have other recommedations if you intend to go with a different woofer. If you have no amplifier for your in-boat speakers, the MX700.5 is nice, as it has 4 channels of full range power, and 420 watts RMS of digital subwoofer power.

[chpthril]

You guys are the best... That's why I love this board... Such a wealth of useless information...

with something factual thrown in every once in a while

[Lunchbox]

You guys are the best... That's why I love this board... Such a wealth of useless information...

[chpthril]

Thanks for the explanations! I was kinda under that impression but wasn't really sure.

I was going to go with the MX700.5 (Kicker) for my tower speakers and sub. I'm leaning towards Pro 60's and MB8's for the tower. Is this a good amp or is there another one better suited? I don't want to go crazy, I just want good clean sound for hanging at the sand bar and boarding. Not trying to win any contests.

MB-8's = 150 watts RMS/ 4 ohm driver
Pro 60's = 150 watts RMS/ 4 ohm driver

MX700.5 = 85 watts x 4 @ 2ohms = about 45-50 watts x 4 @ 4ohms (correct me if i'm off Phil )

I'l say go with the ZX850.4 (215 x 4 watts RMS @ 2ohms) for 2 reasons: more power per chnl @ 4 ohm and not having the sub pounding away when the tower speakers are cranked up.

These are only the my thoughts that are based solely on street smarts Let's see what the experts say

[Jason B]

Thanks for the explanations! I was kinda under that impression but wasn't really sure.

I was going to go with the MX700.5 (Kicker) for my tower speakers and sub. I'm leaning towards Pro 60's and MB8's for the tower. Is this a good amp or is there another one better suited? I don't want to go crazy, I just want good clean sound for hanging at the sand bar and boarding. Not trying to win any contests.

[spharis]

Don't know if Phil said it or not, but clipping can be caused at numerous points throughout the signal as it passes through. Head units, eq, and the amp. Most everyone can hear clipping if they know what to listen to.

[da.bell]

That's mean!

I have not idea what you are talking about.

[philwsailz]

\
Can you please explain what clipping is and how clipping causes damage?

Hi Graham-

Clipping in the laymans terms is when the amplifier is trying to put out a larger output waveform than it can. The input waveform cannot be fully replicated at the speaker terminals, as the amp does not have the output voltge amplitute necesary to recreate it.

The result looks like the second and third pictures above.

Clipping can be a contributor to thermal failure of the speaker due to excesive heat. At any point that the output signal is flat, as in the clipped off tops and bottoms of the output, the amp is producing a DC voltage output at a constant voltage. DC voltage in a speaker does nothing more than create heat.

Loss of damping is a problem; damping is simply put the ability of the amp to smoothly control the woofer's motion. When one loses damping, the woofer can travel to extreme displacements, beyond its design intent. This can sound bad on its own, but can also cause other things. Many voice coils are aluminum, and if one hits the bottom of the motor structure, it will bend and probably rub or even get stuck. If it gets stuck, the voice coil will for sure over-heat with applied signal, as it cannot turn the electrical energy into motion, only heat.