Here is why

ravaneli

I am sorry I just found this. Could have helped a lot. Here is a source with better reputation than mine, or the omniscient H9.

http://www.monstercable.com/mpc/stable/tech/A2420_Some_Facts.pdf

I don't expect any of the people with the insults to change their position, but there are many random readers that should know the truth.

Joe08867

Raveneli, you really need to read it again.

From your link:
An Experiment into Distortion
All it should take to clear up the DC question is to put a large stiffening cap in series with a speaker. Then
hook your speaker to your car battery. No DC will flow because DC doesn't flow through a cap. Now hook
the speaker to your amp with the cap in series and turn up your amp until it starts to clip. The clipped
signal will go right through the cap. We all know that caps don't pass DC, right? So now that we are on
the right track let's get back to the facts. When an amplifier clips a signal, it causes the generation of
harmonics. These harmonics are also known by another name. This is what we call distortion. The more
an amplifier is over-driven, the more the signal is clipped and the more distortion is generated. No matter
how much an amplifier is clipped, it will never produce a perfect square wave because the generation of a
pure square wave requires infinite bandwidth. In fact perfect square waves only exist in theory because
there is no circuit with the bandwidth necessary to pass one -however, for all practical purposes some of
them come pretty close.

For the interests relating to loudspeaker power capacity, it is only necessary that we concern ourselves
with the very basics of square waves. We have already seen the frequency content of a square wave.
When a square wave is compared to a sine wave of the same peak amplitude, the square wave will have
twice the energy of the sine wave. This is because there is more area under the curve but not all of that
extra energy is from the harmonics. If we examine the actual power contained in the individual
frequencies that make up the square wave we can see this more clearly.

Figure 9 shows the relative power content of a square wave. The power levels relative to the fundamental
decrease with each ascending harmonic. If we add the total energy of the fundamental sine wave with the
harmonics we will get a total of 100% of the energy. What is important when we are considering the
heating effect on a speaker is that the fundamental frequency of a square wave, which is a sine wave, will
contain 2 dB more energy than a sine wave with the same peak voltage as the square wave. Put another
way, the fundamental of a square wave has a higher peak (27% more voltage, 62% more power) than the
square wave itself.

Maybe the phrase has you confused. Underpowering, maybe if we said low powered distortion?

Distortion kills speakers. I don't care if it is at 5watts or 200watts. Distortions kills.

Why would companies like Polk put polyswitches in speakers. It isn't for there inherent audio qualities. It is to protect the speaker from thermal loads. The same loads that underpowered amps pushed to distortion can produce.

steveinaz

Trust us man, we've been doing this for a few days. I have personally torched tweeters with a Pioneer A-9 integrated, this was back in the very early 80's. The amp was rated at 90 watts/rms, the speakers at 200 watts/rms. Over drove the Pioneer into clipping, goodnight tweeters.

Again, if you don't drive your amp to crazy levels, you'll likely never clip the output--so you won't have a problem; but if you like to get on tha gas every now and then, it's better to have a big amp, with lots of "headroom" for clean peak output.

tommyt21

Found this on the net. Seems easy to understand

Under Powering:
Yes, you read it right - under powering can blow speakers. In fact, it is a very common cause for speakers failing. This is a little bit difficult for people to understand, however, we will attempt to present a brief explanation here. Speaker science is very complicated (very few people in the world understand it fully), so we cannot hope to give a very thorough explanation in just a few lines in this booklet.

When a speaker receives power from your amplifier it converts most of the power into sound by moving back and forth and causing the air to vibrate. However, it is not 100% efficient and some of the energy is converted into heat. The higher the power, the higher the heat. When a speaker is given a signal that is clipped, it actually receives far more continuous power than it would when it is given a clean (not distorted) signal. This is converted into more heat than the speaker was designed to handle and the coil literally burns. It can, in extreme situations, actually catch on fire (remember, the cone is made of paper)!

So, you can use a power amplifier that puts out considerably less power than the speaker is rated for, and yet, because it is being run into clipping, the speaker will blow. The harder the amplifier is clipped (the louder the distortion), the greater the chance of this happening. Tweeters are particularly sensitive to clipping because a clipped signal generally has lots of extra high harmonics (high frequencies) and tweeters are normally able to handle only small amounts of power. However, woofers can be blown due to clipping as well. It's not the under powering that causes the problem, it's the distortion that often occurs as a result of under powering that is the culprit.

ravaneli

Joe, the author carefully explains why distortion/clipping = extra power and the power is the actual danger. It is physically impossible to create a thermal problem without enough power. If you don't care that is one thing, but to claim that low powered distortion can kill a speaker is not true according to the source. The only way to determine if distortion can kill a speaker, is to REDUCE IT TO POWER FIRST and then compare to the power handling of the speaker.

Also the author several times noted that to the speaker it makes no difference whether the signal is clipped or normal. Did you notice that?

'The speaker doesn't care if the music is distorted or not. To a
speaker it is all just a combination of sine waves. A speaker cannot tell the difference between noise,
distortion, or music. It doesn't care what kind of music it is or any thing else about it except how much
energy is contained in the signal.'

Tommy, your first bolded text is exact repetition of my own argument that distortion needs to be reduced to power before effect can be determined.

Your second bold seems out of context because the rest of the text is not there. The author seems to understand that the reason distortion can be dangerous is because it carries higher power than normal signal.
Also, good to source your quotes. Quoting random people on forums doesn't have much weight, it is pretty much like quoting H9 and shoving it in my face as actual evidence lol

Also I tilt my hat to mr Dennis Gardner for having the balls to disagree with the posse. He brought independently a very good example that happens to coincide with my source before I posted it.

BlueFox

tommyt21 wrote: »

Found this on the net. Seems easy to understand

Seems reasonable. However, it generally is good practice to provide a link to the actual article so that others can both read the entire article, and verify it is not made up.

tommyt21

The snip it came from DirectProAudio. http://www.yorkvilleproducts.com/pa_basics/speaker_damage.cfm

nwohlford

tommyt21 wrote: »

Tweeters are particularly sensitive to clipping because a clipped signal generally has lots of extra high harmonics (high frequencies) and tweeters are normally able to handle only small amounts of power.

The key is in Tommyt21's post above. Destroying a speaker (usually a tweeter) will take some power but often less than you would think if the amp is clipping. The problem is not distortion in and of itself but the excessive high frequencies present in a clipped signal. You could easily blow a tweeter with an undistorted high frequency tone played at fairly normal levels.

cnh

nwohlford wrote: »

The key is in Tommyt21's post above. Destroying a speaker (usually a tweeter) will take some power but often less than you would think if the amp is clipping. The problem is not distortion in and of itself but the excessive high frequencies present in a clipped signal. You could easily blow a tweeter with an undistorted high frequency tone played at fairly normal levels.

Agreed. Want empirical proof of this? Peruse the "reviews" sections on discontinued speakers and look for all the "audio challenged" folks who blew their tweeters--they often provide "clues" to just how they managed to clip their shoddy receivers.

cnh

steveinaz

Horse....

Water....

Nothin. Oh well. Enjoy.

heiney9

I thought you were done on this subject Ravineli :rolleyes:

You are mistaken, simple as that.

H9

tonyb

While low powered distortion won't kill speakers, think tube amps, that was never the discusion. It's when you crank up the volume with distortion and clipping.
Regardless, we can argue internet articles all day, but the best teacher in the world is called experience. When 95% of those with experience say distortion can kill speakers, you can take that to the bank.

Drenis

tonyb wrote: »

When 95% of those with experience say distortion can kill speakers, you can take that to the bank.

When 95% of "audiophiles" say Monster Cable is the end all, do we believe that?

I only post to point out that you can't ALWAYS take for granted what you read AND hear.

the best teacher in the world is called experience.

Nail. Head. Hammer.

tonyb

Drenis wrote: »

When 95% of "audiophiles" say Monster Cable is the end all, do we believe that? .

LOL...yeah man, that day will never come...thank God.

ravaneli

nwohlford wrote: »

The key is in Tommyt21's post above. Destroying a speaker (usually a tweeter) will take some power but often less than you would think if the amp is clipping. The problem is not distortion in and of itself but the excessive high frequencies present in a clipped signal. You could easily blow a tweeter with an undistorted high frequency tone played at fairly normal levels.

You don't bother reading my source though, do you, the author explained in detail why this is not true.

pitdogg2

tonyb wrote: »

Regardless, we can argue internet articles all day, but the best teacher in the world is called experience. When 95% of those with experience say distortion can kill speakers, you can take that to the bank.

100% agreed^^^^^^I'm one of those who has learned through experience

When 99% of "Best Buy's" say Rocketfish is the best you can buy, do we believe that?

not at all...... But when they advertize it that way 85% do.....

heiney9

I think it's quite hilarious that the article Ravineli linked to actually states the exact same things we have been saying all along. The article actually negates his POV and he doesn't even realize it. It's obvious he doesn't have the comprehension of the principles otherwise he never would have posted the link which confirms what all of the rest of us have been saying all along.

Read the section: "What Really Matters" on bottom of page 5. That in a nutshell is the essence of underpowering a speaker, or look at it another way, overpowering you amp (which is a result of the load......the load being the speaker which varies from speaker to speaker as well as with frequency)

H9

pitdogg2

And he keeps telling US we didn't read his link....post #10 says it all. enjoy Ravioli

Joe08867

Raveneli we did read the article. And we understood it. You are the one that doesn't seem to get it.

steveinaz

I don't put alot of effort into someone who refuses to listen.

heiney9

steveinaz wrote: »

I don't put alot of effort into someone who refuses to listen.

I have exceeded my desire to put anymore effort into this subject with this person. Good luck Ravineli.

H9

ravaneli

Lol, you were telling me that all along, good one! : )

H9, i hope you no longer believe that 5W of clipped signal can damage a pair of LSi 15s.. And the dude who advised that guy to pass on that great deal - that was a not cool and you never took that back.

By the way, it was a little out of style for all the people with the insults to jump on me like a pack of wolves on a three legged deer. I never called anyone such names, next time have some class, will you. Or wait until I come to some meet and tell me in my face if you will : )

steveinaz

"I said GOOD DAY SIR!"....LOL

nwohlford

ravaneli wrote: »

You don't bother reading my source though, do you, the author explained in detail why this is not true.

I did read it, but I think the example was not exactly what we are talking about here (I believe the article was written for car audio). The article mentions a 200 W, 50 Hz square wave would not destroy a tweeter that could withstand 10 Watts, but given the numbers in the article, a 50 Watt, 300 Hz square wave could destroy a tweeter that could only take 10 Watts.

With an actually AVR pushing 4 ohms speakers, I am not sure how likely this is to happen, but we can all of think of movies that have very loud sounds that are not low frequencies. Of course this just means that you have to be careful with the volume setting and account for that you will clip at a lower volume setting on the AVR with 4 ohm speakers than with 8 ohm speakers. (Of course, the issue of heat build up in the AVR is another issue to be considered.) My guess is that most mid to higher end AVR would do fine with most 4 ohms speakers as long as you keep the volume reasonably low, but most of us would rather not chance it. (You will also get more clipping in general which will in likely make things sound worse but not damage the speakers.)

Dennis Gardner

What noone has mentioned when blowing tweeters on speakers rated for 200 watts is that the tweeters alone are rarely rated for more than 30 watts or so. With this considered, the harmonics produced by a 5 watt amp could peak above the limits of a tweeter at frequencies that destroy it. I know that this is why protection circuits are built in and many times this is enough....... but we most likely would never even hear it happen if it was above 18k or so. Tweeters taking 50watts of power @ 25k for long enough will fry.

Ask any DJ pushing the limits at the end of a long night when he loses horns......I replace horns all the time in my business on speakers rated for 500 watt continous/1000 watt program/ 2000 watt peak. All blown by amps rated in the 200- 500 watt range.

tonyb

ravaneli wrote: »

And the dude who advised that guy to pass on that great deal

Oh yeah baby, that would be me. Given the info up to that point of that response, I still stand by it. If you cared to keep reading however, more info came out later in the thread and the owners willingness to let him bring his own gear over to hook up was key.

Your constantly complaining about others jumping on you when you do the same thing, usually first, drawing the attention your way. Could be thats why your response was deleted by the mods....maybe ? Oh well, it is what it is. Have a good night Ravaneli.

dudeinaroom

DISTORTION KILLS SPEAKERS

You are taking about a single frequency sine wave, not a multiple frequency jagged waved audio signal. Audio is never a perfect sine wave unless you are listening to test tones. In a nut shell speakers are made for alternating currents that peak quick and drops off, when you add distortion the signal stays at the peak of the signal(clipped part) longer than it should be which heat the voice coils and can cause failure. I have personally killed 500 watt subs with a 200 watt amp that was overdriven. And on the flip side I have used a 100 watt amp on 4" 10 watt speakers for a few years with out a problem (even at loud listening levels). As a rule of thumb, if not just plain common sense, watch the volume, be mindful of distortion, and if it doesn't sound right(this is harder to do with metal) turn it down. The whole monster cable thin above makes no sense, that is an opinion some one would make, distortion is some thing everyone can hear and has nothing to do with opinions. Do a good long search on the net and you will see people here are not just blowing smoke. LSIs should not be powered by a receiver, unless it is uber highend, and if it was me, I'd make sure it could handle a 2 ohm load. Crap I won't even run my SDA's off of a receiver. I have a Denon that is rated to handle a 4 ohm load, and is common ground but yet I will NOT hook the SDAs up to it. I have already killed one Denon with the SDAs so now they will only be hooked up to external amplification.

nooshinjohn

ravaneli wrote: »

Lol, you were telling me that all along, good one! : )

H9, i hope you no longer believe that 5W of clipped signal can damage a pair of LSi 15s.. And the dude who advised that guy to pass on that great deal - that was a not cool and you never took that back.

By the way, it was a little out of style for all the people with the insults to jump on me like a pack of wolves on a three legged deer. I never called anyone such names, next time have some class, will you. Or wait until I come to some meet and tell me in my face if you will : )

It's not the watts that kills(most of the time) but distorted signal that kills. I have run a pair of LSi-15's FAR above their handling and melted the crossover without any damage whatsoever to the drivers. I don't recommemend doing that to anyone, but it is proof positive for me that high quality/ high power does not kill drivers. Clipping kills drivers, and clipping is caused by overdriving an amp. Yes, 5 watts of clipped power can kill a tweeter. Once the amp is in clipping, watts become DISTORTION, and it is that distortion that kills the tweeter. Further, who would be insane enough to think that a FIVE WATT amp is enough juice to get them to make a sound to begin with??? (besides H9:cheesygrin:) Your argument makes ZERO sense.

As far as the three-legged deer comment goes, I don't think a wolf worthy of any respect would waste his time on such prey. They like the challenge, and your arguement, just like a three-legged deer, is not worthy is further comment. You can accept the facts or not. Being ignorant of them is up to you.

heiney9

I don't believe I ever said anywhere a 5 watt amp should be used to power LSi's. Why two people have made comments regarding that, I don't know.

H9

nooshinjohn

Just joking Brock...

I know you never said anything like that. I was using the absurd to illustrate the absurd, and put that **** eatin' grin and a wink behind it so everyone would know I wasn't being serious.:redface::cool:

heiney9

Ok, gotcha