Kicker rms rating

[LoganSF 10+ year member]

so basically the excess excursion would do the most damage? is that what the dude is trying to say?

 

[ahole-ic]

hahaha....although Ive seen some DD's that if you threw across the room would put a whole in the wall and damage everything around it!! thats funny though...I chucked a Lanzar one time
my cvrs were rated for 400 and I sent 550 without distortion...

Did you actually clamp the power or are you just assuming that? I mean no offense to you if you did, it was just a good question to start my post with. Most people do not understand how any of this works. Your 1000 watt amp might only be capable of reaching 1000 watts for instance. If you keep turning the gain up, the peaks of the wave cannot go any higher. You will still only be putting out 1000w peak. The average keeps going up though.

Most people do not understand impedance rise or how to set their gain properly. They don't know how to tell how much power their amp is actually putting out. They just ASSUME how much and then tell everyone on a message board that "x" speaker is underrated. Can you apply 1000 watts to a 100 watt speaker if the power is clean? It depends on the signal. Is the Rms actually exceeded? You have to understand the terms to know. You're not comparing apples to apples.

 

[kr15 5,000+ posts]

Did you actually clamp the power or are you just assuming that?

no, and you are absolutely right. Impedence rise as well as losing a few watts due to lack of optimal wiring (RF has a wire calculater that estimates how much power you lose based on wire guage and length etc.) I said 550 as that was what the fosgate birthsheet said. That is probly on a steady 14.4volt load..so yes you are right, I sent an advertised 550rms...

After reading the clipping article. I have a question. I blew that Lanzar that I said I threw, off less than 300rms despite it being rated for 380rms. In a case like this is that a situation of a company overating the product?

 

[bubbagumper6 5,000+ posts]

Hey DB...why so serious?

haha. The way I understand it, sending a clipped signal means that for a short period of time, the subwoofer is receiving rail voltages (the more clipped, the longer the period of time). So wouldn't that increase the thermal energy the coils would have to dissipate? Thus making a clipped signal push the woofer past it's thermal limits and cause it to fail? I mean if a woofer is rated at 500w, that means it can dissipate 500w worth of thermal energy (heat), so 700w of clean signal would produce a lot less heat than 700w of clipped signal right? Or am I way off base on this?

 

[99grandprixGT 5,000+ posts]

i hooked up a pair of kicker CVR to a RD D9 and it handled them !!!!

 

[DBfan187 5,000+ posts]

Hey DB...why so serious?
haha. The way I understand it, sending a clipped signal means that for a short period of time, the subwoofer is receiving rail voltages (the more clipped, the longer the period of time). So wouldn't that increase the thermal energy the coils would have to dissipate? Thus making a clipped signal push the woofer past it's thermal limits and cause it to fail? I mean if a woofer is rated at 500w, that means it can dissipate 500w worth of thermal energy (heat), so 700w of clean signal would produce a lot less heat than 700w of clipped signal right? Or am I way off base on this?

While the clipped one may die sooner than the other one, both are surely going to die. Once over the thermal limits, it's only a matter of time.

They put those RMS ratings there for a reason people. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[bubbagumper6 5,000+ posts]

While the clipped one may die sooner than the other one, both are surely going to die. Once over the thermal limits, it's only a matter of time.
They put those RMS ratings there for a reason people. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Well then how do you explain people feeding Type R's 1000w rms daily?

 

[DBfan187 5,000+ posts]

Some companies may be a tad underrated.

//content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif I also saw those same people looking for new speakers in the classifieds not long after.

 

[DBfan187 5,000+ posts]

Too much power is the ONLY thing that will destroy a well built speaker. Too high a peak power can cause it to move too far, and cause mechanical failure. Too much RMS power for too long will cause thermal failure.  

A clipped signal will not damage any speaker, if it is at a level low enough so that the heat can be dissipated, and it doesn't move far enough to mechanically damage it.

Take a square wave source signal from any number of test CDs, and play it through your system at a low volume. If you have a power supply on the system, you can play that 100% clipped signal indefinitely, and the system will never miss a beat.

As Rob said, a square wave is not made up of positive and negative DC components. The true makeup of a square wave is the fundamental frequency signal, combined with all of the harmonics of that fundamental.The combination of the many different, but related, sine waves results in a square wave.

You can prove this for yourself by running a low frequency square wave signal into a variable crossover, and look at the output on an oscilloscope. with the crossover bypassed, the square wave will be perfect. But, engage the low pass filter, and begin bringing it down towards the fundamental frequency, and the wave shape begins to look like a slightly clipped sine wave. If you turn the crossover point all the way down to the fundamental frequency, the scope will display a perfect sine wave.

Just something for those with nothing better to do this weekend...

The only thing that thermally damages speakers is power... more specifically: average power over time.
I'll explain...

If you take a given amplifier, let's say 100 watts and operate it just below clipping with music material, the "Crest Factor" of the amplifier's output is equivalent to the "Crest Factor" of the program material.

"Crest Factor" is the difference between the average level of the signal and its peak level. For example, a pure sine wave has a "crest factor" of 3dB, meaning that it's peak level is 3dB higher than its average level. We all know that 3dB represents a power factor of 2, so another way to look at it is that the peak power of the signal is twice that of its average level. So, if we play a sine wave on our 100 watt amplifier, just below its clipping level, the average power (over time) the speaker is needing to dissipate is 50 watts.

A true square wave, by comparison, has a crest factor of 0db, so it has equal average and peak power. Our 100 watt amplifier, playing a square wave, unclipped, into our speaker requires that the speaker dissipates 100 watts of power (twice the heat as a sine wave).

Music has a significantly higher crest factor than sine waves or square waves. A highly dynamic recording (Sheffield Lab, Chesky, etc.) typically has a crest factor of 20dB or more, meaning that its average power is 100 times lower than its peak power. So, if we play our 100 watt amplifier just below clipping with the typical audiophile recording our speaker is only needing to dissipate 1 watt of average power over time.

Modern commercial recordings typically exhibit crest factors of around 10dB, meaning that the average power is 10 times lower than the peak power. So, our 100 watt amp just below clipping would deliver an average power over time of 10 watts that the speaker has to dissipate.

Okay, so what happens when we clip the amplifier (which we all do at times). When the amplifier enters into clipping, the peak power no longer increases, but here's the KEY... THE AVERAGE POWER CONTINUES TO INCREASE. We can often tolerate a fair amount of clipping... as much as 10 dB or more above clipping with a reasonably dynamic recording... a bit less with a compressed commercial recording.

So, if we turn the volume up 10dB higher than the clipping level with our Sheffield Lab recording, we have now reduced the crest factor of the signal reaching the speakers by 10dB... so instead of needing to dissipate 1 watt average, we are asking the speaker to dissipate 10 watts average, and we're probably ok.

If we turn up the volume 6dB past clipping on a compressed commercial recording (or bass music recording), we have taken the crest factor of the signal from a starting point of 10dB to only 4dB, asking the speaker to dissipate an average power of 40 watts instead of 10 watts... that's FOUR TIMES the average power, which generates four times the heat.

SO, in most cases, the reason clipping can damage a speaker really has nothing to do with anything other than an increase in average power over time. It's really not the shape of the wave or distortion... it's simply more power over time.

When someone plays Bass Mekanik clean (unclipped) on a 1000 watt amplifier the average power is 100 watts (10dB crest factor). You can also make 100 watts average with Bass Mekanik by heavily clipping a 200 watt amplifier.

If someone is blowing a woofer with 200 watts of power due to a lack of restraint with the volume control... they will blow it even faster with a 1000 watt amplifier because they will probably turn it up even more and now they have more power to play with... this is the recipe for aroma of voice coil.

When woofers are rated for power, an unclipped signal is assumed. We use test signal with a crest factor of 6dB for power testing and can run a speaker at its rated power for hours and hours on end without thermal or mechanical failure. For example, a W1v2 can dissipate 150 watts average power for eight hours or more with signal peaks of 600 watts. So, we rate the speaker for 150W continuous power. This way, when a customer needs to choose an amp for it, they will hopefully choose one that can make about 150 W clean power... Even if they clip the bejeezus out of that amplifier, it is unlikely that the speaker will fail thermally. This is a conservative method, but it needs to account for the high cabin temperatures in a car (think Arizona in the summer) which significantly impacts heat dissipation in the speaker. A top plate that starts at 150 degrees F is not as effective at removing heat as one that starts at 72 degrees F in the lab... and this affects the ramp up of heat in the coil.

DISCLAIMER: The frequency components of clipping can affect tweeters due to their low inductance and lack of low-pass filtering. Clipping essentially raises the average power of high frequencies to a point that can damage tweeters... Woofers and midranges couldn't care less about these high frequency components because their filtering and/or inherent inductance knocks that stuff out of the picture.

Best regards,

Manville Smith

JL Audio, Inc.

//content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[bubbagumper6 5,000+ posts]

Some companies may be a tad underrated.
//content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif I also saw those same people looking for new speakers in the classifieds not long after.

I guess, but I don't think it's as cut and dry as your trying to make it out to be. I mean I fed my Type R's at least 600w each they did fine. And I've got a BTL on 3kw and it's fine (however it does have all the options so maybe that affects it's power handling?)

 

[DBfan187 5,000+ posts]

A clipped signal carries more average power than a non-clipped signal... this is the only aspect of it that affects a speaker thermally.

It doesn't matter if the signal is clipped before the amp at the preamp level or after the amp.

A sine wave can damage a speaker in a matter of seconds given enough power and in a matter of minutes at fairly moderate output... it depends on the impedance of the speaker at that particular frequency... if the impedance happens to be low, it might go up in smoke in a couple of minutes.

//content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[DBfan187 5,000+ posts]

I guess, but I don't think it's as cut and dry as your trying to make it out to be.

It is. Just give it time and those speakers will go poof.

 

[DBfan187 5,000+ posts]

I would clarify that futher, sprexumn....
The fact that a signal is clipped does not make it inherently damaging... if the average power of the clipped signal is low it won't ever damage a speaker. At higher power levels, the fact that a clipped signal carries more average power over time can result in damage.

The fact that tweeters have low inductance, do not employ low-pass filters and have small, delicate voice coils makes them more susceptible to damage from a clipped signal than a woofer or mid.

Does that make sense?

It just points out that the old statement of an amp that is too small will damage speakers more than a more powerful amp is entirely dependent on the use of each amp... if you clip both amps to the same extent, the more powerful one will blow speakers faster.... but it is possible to make a small amp operated into clipping produce as much average power as an unclipped larger amp (even though the peak power is greater on the big amp).

When you clip an amp you not only increase distortion, you also compress the dynamic range of the signal... the distortion isn't what kills the speakers (except tweeters in some cases)... it's the dynamic range compression that really does it.

Halo1...

Do you mean an inductor? An inductor will make the impedance rise at higher frequencies (reducing power at higher freq's). You can achieve the same result by filtering the amp's input signal via a low-pass active crossover. The latter is more desirable because it does not introduce resistance like the inductor and is much more precise.

Best regards,

Manville Smith

JL Audio, Inc.

right there

 

[bubbagumper6 5,000+ posts]

That was a good read...I'm still trying to understand everything in it...

I have no doubt that if I fed my BTL a 3kw sine wave for hours on end, that it would die. But like that article says, music is much, much different. They rate subwoofers using a sine wave for reference right? So according to FI a BTL could handle a 2kw sine wave indefinitely? So 3kw music would have to have a much higher crest level right? So the speaker's not actually seeing 3kw when playing music right?

 

[DBfan187 5,000+ posts]

you're getting it //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif people never think of 'time' being part of it