Yea, thanks for popping in Tracy, much appreciated!

 

>Yea, thanks for popping in Tracy, much appreciated!

anytime!

 

[updated:LAST EDITED ON 01-12-03 AT 03:32 PM (EST)]At this line:

>There is a difference between 'weak' watts and 'strong' watts.
>

I stopped reading. I don't know how you could ever have an EE and not have the slightest understanding of basic electrical theory RanDawg. Think about that statement for a second.... OK, now, for your homework. Are strong watts and weak watts anything like long inches and short inches? A watt is a watt, wether it comes from the tiny little amp powering the headphones of your walkman, or from a monstrous 5KW car amp, ALL WATTS ARE THE SAME BY DESIGN. A unit of measure CAN NOT CHANGE -*EVER*-. Think about it like this, say your going to build a 3ft by 3ft speaker box, and for the right panel you use a foot=9inchs and for the left one, you use a foot=13inches. See where the problem comes in? A unit of measure must ALWAYS have the same value, or it is useless. Simple as That.

Now for the topic of underpowering blows the speaker.

Low damping factor can not, and will not blow a sub. It will make distort more, but it will not overheat or cause the sub to go beyond its limits of excusion simply because the DF is low. Since your an EE, I have a project for you, it will cost less than $40, and probably wont take more than an hour of work. Build a small and simple amp that can only put out about 100 watts or so, and record a CD with a pure square wave for 1 track qand set it to repeat, and run the output of that CD to the input of your amp, turn the amp up FULL BLAST, as loud as it can go. Hell, clip the input stage too for good measure. Now hook that nice and clipped output to a speaker rated for about 500watts RMS or more in a .75cu ft sealed enclosure, and let it play. See how long it takes to blow the speaker. (hint: dont hold your breath)

 

I'm still waiting for his description of what the "stressed" output of an amp would look like, relative to clean, "unstressed" amp output.
(He's been arguing that clipping isn't a possibility the way he has his gains conservatively set)



I'd love to see him actually MEASURE what he is seeing - I don't understand why he hasn't already... if he has the equipment that he has.. if it were me arguing that some theory were possible, I would have done that before the thread got to page 3... but then again, I hate to look like a fool, I like to back up what I say.

It would be an easy one (After all, he has the culprit amp... And, he claims he has an oscilliscope in his teeming arsinal of test equipment!):
Just scope the output on his oscilliscope, with the amp running at the "stressed" condition he describes, using a nice, easy-to-see test tone anywhere below 80Hz...
And describe what he sees.

Simple 5 minute experiment...
Pull the meter out, set your scale, crank the volume, describe what you see.


If he describes that he sees signal irregularities (clearly describes, rather than trying to toss out big words and fast talk), I will even assist by replicating his test scenario, scope my own amp's outputs, attempting to confirm what he describes, to validate his results!

I happen to have a couple 200 watt amps - of not particularly fantastic quality (the cheaper Phase Linear line) - hooked up in the 'ol winterbeater right now...
An old truck, old battery, cheap amps, ...it would be an ideal set of conditions for reproducing what he is claiming, I must say...

But again, I need him to describe what the scoped output of a "stressed" amp would look like - to damage a subwoofer - so that I can look for that...

Just really looking for that description though, at this point...

After all, we can make a judgement on feasibility without testing.

 

>
>This is basic first year stuff.. and really very irrelevant!
>

I'm not sure everyone here will agree with that. This 'stuff' requires you to take the first derivative of a trigonometric function as the change in current with respect to time to represent EMF. And it is very relevant. The phase angle is changing direction, like you said, and the magnetic field is changing with it. All of them have a certain phase angle, and none are in phase with each other, except at resonance. I'll take it we all understand and accept these facts then?

>1) For one thing, the discussion was on cone MOTION lagging
>behind the current through the coil/resuting coil magnetic
>force, NOT on the current lagging behind the voltage, power
>lagging behind voltage, etc.

So are you saying current lagging voltage has nothing to do with anything? I'm not sure I agree with that. Didn't you bring up the proportionality of power? I have proven it is not proportional.

>
>2) I really really hope you aren't trying to argue that BACK
>EMF could contribute constructively with the motion of the
>voice coil and subwoofer!
>If you are, you should patent the worlds first perpetual
>motion machine!
>Just set a voice coil in motion and watch it pick up speed,
>right?
>Hahahaha... :+
>(hate to break it to you, but BACK EMF works AGAINST you!)

That is not the argument. The argument is that a cone can disconnect from the phase of the current. Further, I can theorize that it may not regain equilibrium until either amplitude is decreased or frequency is changed. If you don't believe this, set a few cinder blocks on your cone and send some power through it. This shows the cone does not have to move just because there is current trying to move it. And what will the result be? Heat.

>3) As for the power argument, and the phase angle being
>disjoint...
> Also irrelevant, as regardless, you aren't going to prove
>that you have MORE power at any point in the cycle...

Why not? Maybe I should leave it to you to prove to me that a sub cannot be damaged with less than rated power. After all, it is your goal to change the accepted notions.

>You can't end up with more power out of it than you put into
>it, right?

Less actually.

>"energy can neither be created nor destroyed"
>they teach that in 4th grade nowadays, don't they?

I don't know.

>I do see that these textbooks you are so proud of simply are
>first-year and/or high school level texts, eh?

Don't bet the farm on it.

 

>Please define what you mean by "stressed"

"stressed" is a condition in which an amp has little headroom to output more current and at any time may see that limit.

>If the amp is not clipping, as you say (and verified with an
>Oscilliscope, right?), how would the amp be "stressed"
>Quantify that...

I said it was very unlikely the amp was clipping. The gains were set with an oscilloscope some time before the day in question.

>Describe what elements of the amp would be "stressed", and
>how that would show up in the output from the amp (that's
>the most important part).

The transistors. It would still be a sine wave if not clipped.

>The phase angles are either perfectly "in phase", or else
>they are not.
>No doubting you (or really, the commonly known formulas) on
>that they will not be perfectly in phase..
>
>But when that happens, the result can be nothing other than
>there being LESS power than if all angles were perfectly in
>phase (which, I actually believe, is... impossible!)
>
>And the resulting power output would still be clean, still
>be a perfect sine wave out, if the input was a perfect sine
>wave out.. it just wouldn't have as much power.

That's what I'm saying.

>Phase angle of current vs. voltage vs. power is COMPLETELY
>not an issue. It cannot be constructive, only destructive..
>and by that the signal still remains perfectly well formed,
>couldn't be any more harmless on the subwoofer.

Yes, destructive.

 

>Since no reply in a few hours...
>
>This very chart from JL Audio themselves on the power
>recommendations for your subwoofer:
>http://www.jlaudio.com/subwoofers/RP_Chart.html
>is enough to prove your theory for failure wrong (barring a
>defective driver, if all other factors were correct as you
>say they were, and we say were not).
>
>Summing up the chart:
>Green = Maximizing woofer longetivity, minimizing SPL
>potential
>Yellow = good woofer longetivity, good SPL.. recommended
>compromise.
>Red = minimizing woofer longetivity, maximizes SPL
>potential.
>
>Look at your woofer, the 12W6:
>
>Note two things:
>1) The "green zone" extends down to 125 watts. Your 200
>watts was not running below JL's recommendations (remember,
>300 watts is a maximum RMS upper limit).
>2) Per JL's own descriptions [on the different color zones],
>the trend is that as the power decreases, woofer longetivity
>is increased (while SPL also decreases).

I have commented on this already, just yesterday. This doesn't prove anything.

 

>At this line:
>
>>There is a difference between 'weak' watts and 'strong' watts.
>>
>
>I stopped reading. I don't know how you could ever have an
>EE and not have the slightest understanding of basic
>electrical theory RanDawg.

I have an IE

>Think about that statement for a
>second.... OK, now, for your homework. Are strong watts
>and weak watts anything like long inches and short inches?
>A watt is a watt, wether it comes from the tiny little amp
>powering the headphones of your walkman, or from a monstrous
>5KW car amp, ALL WATTS ARE THE SAME BY DESIGN. A unit of
>measure CAN NOT CHANGE -*EVER*-. Think about it like this,
>say your going to build a 3ft by 3ft speaker box, and for
>the right panel you use a foot=9inchs and for the left one,
>you use a foot=13inches. See where the problem comes in? A
>unit of measure must ALWAYS have the same value, or it is
>useless. Simple as That.

It has to do with the amount of headroom above the 'watt' in question

>
>Now for the topic of underpowering blows the speaker.
>
>Low damping factor can not, and will not blow a sub. It
>will make distort more, but it will not overheat or cause
>the sub to go beyond its limits of excusion simply because
>the DF is low. Since your an EE, I have a project for you,
>it will cost less than $40, and probably wont take more than
>an hour of work. Build a small and simple amp that can only
>put out about 100 watts or so, and record a CD with a pure
>square wave for 1 track qand set it to repeat, and run the
>output of that CD to the input of your amp, turn the amp up
>FULL BLAST, as loud as it can go. Hell, clip the input
>stage too for good measure. Now hook that nice and clipped
>output to a speaker rated for about 500watts RMS or more in
>a .75cu ft sealed enclosure, and let it play. See how long
>it takes to blow the speaker. (hint: dont hold your breath)

The heavier the cone, the harder it is to control. The greater the power handling capabilities of the driver, the likelihood is, it will TAKE more power to properly drive it

 

>I'm still waiting for his description of what the "stressed"
>output of an amp would look like, relative to clean,
>"unstressed" amp output.
>(He's been arguing that clipping isn't a possibility the way
>he has his gains conservatively set)
>
>
>
>I'd love to see him actually MEASURE what he is seeing - I
>don't understand why he hasn't already... if he has the
>equipment that he has.. if it were me arguing that some
>theory were possible, I would have done that before the
>thread got to page 3... but then again, I hate to look like
>a fool, I like to back up what I say.
>
>It would be an easy one (After all, he has the culprit
>amp... And, he claims he has an oscilliscope in his teeming
>arsinal of test equipment!):
>Just scope the output on his oscilliscope, with the amp
>running at the "stressed" condition he describes, using a
>nice, easy-to-see test tone anywhere below 80Hz...
>And describe what he sees.
>
>Simple 5 minute experiment...
>Pull the meter out, set your scale, crank the volume,
>describe what you see.
>
>
>If he describes that he sees signal irregularities (clearly
>describes, rather than trying to toss out big words and fast
>talk), I will even assist by replicating his test scenario,
>scope my own amp's outputs, attempting to confirm what he
>describes, to validate his results!
>
>I happen to have a couple 200 watt amps - of not
>particularly fantastic quality (the cheaper Phase Linear
>line) - hooked up in the 'ol winterbeater right now...
>An old truck, old battery, cheap amps, ...it would be an
>ideal set of conditions for reproducing what he is claiming,
>I must say...
>
>But again, I need him to describe what the scoped output of
>a "stressed" amp would look like - to damage a subwoofer -
>so that I can look for that...
>
>Just really looking for that description though, at this
>point...
>
>After all, we can make a judgement on feasibility without
>testing.


Tell you what, scape up a couple cheap subs of equal quality. Put them in equal boxes. Hook one up to an amp that is overpower, and one that is underpower. Play a sinewave, your choice. Measure the spl so they are equal. Then gradually turn up the gains while keeping the spl equal between the two. Let me know which one blew first. Although this proves nothing, it is interesting no less.

 

> Okay, so basically just about everybody but RanDawg has
>accepted that underpowering a sub will not blow it.

Not quite everybody. There are a lot of "technically uninformed or totally ignorant" people in the world.

Most speaker damage is caused by amplifiers having too little power, not the speakers being fed too much. Make sure you have adequate power output for the size of room, for the efficiency of the speakers, and the intended volumes you wish to play. (Hi-Fi Corner (Edinburgh) Ltd)
http://www.hificorner.co.uk/homecinema.htm

The majority of speaker damage reported to manufactures today ,is caused by using under powered amplifiers , this is an expensive lesson for the owner as no speaker manufacturer will cover this cost under warranty . To avoid this always purchase an amplifier that will provide more power than you will need. Remember. a loudspeaker can require up to ten times the average power level for those instantaneous bursts of sonic power known as transients. If the amplifier has enough reserve power, transients will be clear and crisp. If not, the transients will be muddy or dull. When an amplifier runs out of undistorted power, it is forced to exceed its design capabilities, producing dangerous power levels rich in high frequency distortion. (Cinepro Productions)
http://members.iinet.net.au/~colinf/

When an audio system is called upon to deliver an instantaneous bass peak the vehicle’s electrical system is, often times, taxed to the limit. This means that the system voltage drops substantially to a point that the amplifiers are unable to produce their rated output power. This is referred to as clipping. When an amplifier clips it will cause distortion and can cause speaker damage. (Stinger® Electronics)
http://stingerelectronics.com/sting_products/Sting%20Cap%20Own.pdf

Actually amp/speaker matching is a little more complex than that, but as long as you ensure the amp you choose is at least as powerful as the speakers' minimum input rating, you won't go far wrong. Too little amp power can cause distortions and, in extremis, speaker damage, whereas using an amp more powerful than the speakers' maximum recommended input wattage is unlikely to cause problems. (What Hi-Fi? Sound and Vision - The World's No1 HI-FI and Home Entertainment Buying Guide.)
http://www.whathifi.com/newsMainTemplate.asp?storyID=40&newssectionID=3

Clipping distortion is the most common source of speaker damage. (Infinity Car Audio)
http://www.infinitysystems.com/caraudio/Techownerinfo/glossary.asp?Char=C

Most speaker damage is caused by amplifiers with too little power. Damage caused by operating the speakers at distorted volume levels is not covered by the warranty. (Bogen Communtications, Inc)
http://www.bogen.com/pdf/54-2038-01R3.pdf

It is very easy to do speaker damage by using an amplifier with insufficient power. The lack of headroom or reserve power may cause the smaller amp to clip, sending a distorted signal to the speaker, resulting in blown woofers or tweeters. (Mike Starnes of Mobile Beat Magazine)
http://www.mobilebeat.com/archives.asp?art=128

Ironically, you are more likely to damage a speaker when using a low-power receiver than a high power one. (Polk Audio)
http://www.polkaudio.com/home/faqad/q.php?article=whybreak

Put simply, any amplifier can damage any speaker, irrespective of power figures. Ideally, an amplifier should be as powerful as possible, and controlled by a sensible user! (Dr. Hi Fi Pty Ltd -- Robin Gandevia is a member of The Electronic and Technicians Institute of Australia (MTETIA). In 1986 he gave the address to the Institute's National Convention on the servicing of hi fi equipment, and has also given lectures on related subjects to the NSW division. He is also a member of The Institute of Sound and Communication Engineers (MInstSCE Eng.), based in England with representatives throughout the world. Dr. Hi Fi Pty Ltd is also a member of The Electronic Services Association (TESA) in Australia.)
http://www.drhifi.com.au/service.htm#Speakers

A speaker with a 100 watt power handling rating can be safely operated when connected to a 500 watt amplifier. The truth is that amplifier power almost never destroys a speaker. In far more cases, it is a lack of power that causes damage. (Joel P. Antonini -- AudioVideo101, The Audio/Video Knowledge Center.)
http://www.audiovideo101.com/learn/articles/speakers/speakers22.asp

As you use up amplifier headroom, the sense of detail in the reproduced sound will disappear. Then you may hear distortion on signal peaks - the distortion is generally easier to hear at higher frequencies, but is much more common at low (bass) frequencies. This means the amp is running short of power to send to the speakers. Allowing this state to continue will reach the third stage of failure, overt distortion followed by voice coil burnout. Many people have an amazingly high tolerance for distortion and just do not notice a problem until it is too late. Most failures resulting from improper operation can be traced to over or under powering the loudspeakers. (THIS INFORMATION WAS DIRECTLY OBTAINED FROM SOUNDTECH)
http://www.allkaraoke.com/watts%20vs.%20decibels.htm

Under powering a speaker is actually a more common reason for speakers to fail then would be expected. An under powered amp struggles to provide a speaker with the power it needs. In most cases the amp is driven in to distortion. (Stephen Ballast - Owner/Engineer BladeAudio)
http://members.tripod.com/~BladeAudio/training-2.html?#limitations

Many people think that you blow speakers because of too much power. In reality, speakers blow due to distortion, which is caused by too little power being availabe for a desired volume level. (Import Lounge - http://www.importlounge.com/pages/members.html)
http://www.importlounge.com/pages/modsICE.html

There is a fallacy that a heavy cone will produce better bass. WRONG! There is also the fallacy that a stiff cone suspension means higher power handling. WRONG AGAIN! The truth is that if the cone is heavy, it will not react quickly to the input signal. Hence without the application of considerable wattage, the signal will be gone from the line before the cone can move and thereby causing an undesirable noise, kind of a flopping honk sound. Not to mention the other restrictions placed on a speaker with a heavy cone. The same thing can happen with a suspension that is too stiff. (Thomas P. Colvin -- Musicians Hotline)
http://www.musicianshotline.com/archive/tech/reconing.htm

Nancy loved music and her stereo system. She could listen anytime she wanted to any music she wanted by slipping a small silvery disk into her CD player and pressing a few buttons. Then one day her wonderful 75 watts per channel amplifier died. Shopping for a replacement, she discovered prices had risen. But the salesman said not to worry -- quality had gone up. He told Nancy that she hadn't really used all 75 watts in her old amplifier and only needed that much power because her older amplifier didn't perform well near full power. He said that she could buy a 40 watt per channel amplifier and play it at the volume she usually used because the newer amplifiers performed very well even close to full power. Nancy bought the recommended amplifier, went home, hooked it up to her system, put her favorite CD on, adjusted the volume to her usual listening level, sat back in her favorite chair ... and one of her speakers blew out. ... Why? (Frank Wattenberg, Department of Mathematics, Montana State University, Bozeman, MT 59717)
http://www.math.montana.edu/frankw/ccp/multiworld/virtual/FourTran/nancy/learn.htm
http://www.math.montana.edu/frankw/ccp/multiworld/virtual/FourSer/learn.htm

Yep, 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. (Yorkville Sound Inc. WorldWide)
http://www.yorkville.com/pdf/other/pabasics.pdf

Another misconception: speakers blow because they can't handle power. Again, not true. They blow because the power sent to them is of an inferior quality. (Edmunds.com -- Editor-in-Chief Karl Brauer)
http://www.edmunds.com/ownership/techcenter/articles/44841/article.html

I have heard it so many times: "why did my speakers blow?!? They can handle 600 Watts and I was only running a 200 Watt amp on them!!" What that person failed to realize was that by badly mismatching his amp and speakers, he ended up pushing the power amp so hard that it was constantly clipping. (Dr.Sound - Carvin Corp)
http://www.carvin.com/doctorsound/

Fiction: as long as the power rating of your speakers is higher than your amp's power rating you won't have to worry about blowing out your speakers. "My speakers are rated to handled 100 watts, and my amp only puts out 50 watts. Why did the speakers blow?" (Matt Hennessy (BS. EE, Member IEEE, AES))
http://www.electrosound.com/articles/distortion.html

Top 10 car audio myths: "You can't blow a 300W sub with a 50W amp" This has to be one of the most frustrating of the car audio myths for dealers and manufacturers alike. An angry customer walks through the door of the dealer dragging his recently purchased Behemoth 2 kW subwoofer that's just cost him two weeks' wages. He slams it onto the counter demanding a free replacement on the grounds that it was faulty. (Total Car Audio Dec/Jan 01)
http://www.caraudiodirect.com/magazine/tca/myths.html

Now that we have a realistic power test all you need to do is determine the power rating of the loudspeaker, buy an amplifier with the exact same power rating and enjoy perfection right? WRONG! If it were only that easy, everything would work perfectly and people who re-cone speakers would be in the bread line. The amplifier must be capable of delivering more power than the long-term average power rating of the speaker. (Audio Video Broadcasting - Studio Systems Magazine May/June 1999)
http://www.studio-systems.com/audiofeatures/mayjune99/soundrespeakers3.htm

Oddly enough, the most common problem with matching speakers and amps is using an amp that is too weak to power the speaker. (CarAudioGalaxy)
http://www.caraudiogalaxy.com/caraudio_rmspower.htm

Contrary to popular belief, not having enough power can be more damaging to a speaker than having too much power. (Crutchfield)
http://www.crutchfield.com/S-h9PZf3vjdml/tech/kb303.html

Danger: Low Power
http://www.jblpro.com/pub/technote/lowpower.pdf

Q: How much power should I send to my speakers?
A: Always remember that underpowering a speaker will destroy it much faster that overpowering. When there is not enough power to satisfy the speaker's needs, the amp will try to out-do itself and start to send distorted information to the driver.
http://www.blaupunktusa.com/speakers/speakers_faqs.html

Another major cause of speaker damage: using a low-power head unit with high-end speakers.
http://www.napsnet.com/auto/54366.html

Always keep in mind that low wattage amplifiers are the normal cause of speaker damage. (Colquhoun Audio Laboratories)
http://www.axiomaudio.com/faqs.html

An important factor to consider with any speaker system is the potential for speaker damage. Even though your SS-150THXs have high power handling ability, they still can be damaged by relatively low powered amplifiers. (Miller & Kreisel Sound Corporation)
http://www.sanoconsulting.pl/pdfy/Ss150.pdf



All these people have emails and can be contacted if you don't agree.

 

great info randawg, my faith in my opinion is restored.

 

>> Okay, so basically just about everybody but RanDawg has
>>accepted that underpowering a sub will not blow it.
>
>Not quite everybody. There are a lot of "technically
>uninformed or totally ignorant" people in the world.
>
>Most speaker damage is caused by amplifiers having too
>little power, not the speakers being fed too much. Make sure
>you have adequate power output for the size of room, for the
>efficiency of the speakers, and the intended volumes you
>wish to play. (Hi-Fi Corner (Edinburgh) Ltd)
>http://www.hificorner.co.uk/homecinema.htm


This is solid advice. The key is the last portion about the intended volumes. I can't disagree with that at all. As has been said, lower power will just not play as loud. If you try to play it at louder volumes, it will clip which is potentially harmful. It is harmful because clipped signals HAVE MORE POWER! So underpowering is not an issue and this does not back up your argument about the sub being out of control.

>
>The majority of speaker damage reported to manufactures
>today ,is caused by using under powered amplifiers , this is
>an expensive lesson for the owner as no speaker manufacturer
>will cover this cost under warranty . To avoid this always
>purchase an amplifier that will provide more power than you
>will need. Remember. a loudspeaker can require up to ten
>times the average power level for those instantaneous bursts
>of sonic power known as transients. If the amplifier has
>enough reserve power, transients will be clear and crisp. If
>not, the transients will be muddy or dull. When an amplifier
>runs out of undistorted power, it is forced to exceed its
>design capabilities, producing dangerous power levels rich
>in high frequency distortion. (Cinepro Productions)
>http://members.iinet.net.au/~colinf/

Another great example of clipping, which your system cannot possibly have been doing, right?

So, let's see, clipping=higher power....next....


>
>When an audio system is called upon to deliver an
>instantaneous bass peak the vehicle’s electrical system is,
>often times, taxed to the limit. This means that the system
>voltage drops substantially to a point that the amplifiers
>are unable to produce their rated output power. This is
>referred to as clipping. When an amplifier clips it will
>cause distortion and can cause speaker damage. (Stinger®
>Electronics)
>http://stingerelectronics.com/sting_products/Sting%20Cap%20Own.pdf


Clipping=higher than rated power=overpowering....next

>
>Actually amp/speaker matching is a little more complex than
>that, but as long as you ensure the amp you choose is at
>least as powerful as the speakers' minimum input rating, you
>won't go far wrong. Too little amp power can cause
>distortions and, in extremis, speaker damage, whereas using
>an amp more powerful than the speakers' maximum recommended
>input wattage is unlikely to cause problems. (What Hi-Fi?
>Sound and Vision - The World's No1 HI-FI and Home
>Entertainment Buying Guide.)
>http://www.whathifi.com/newsMainTemplate.asp?storyID=40&newssectionID=3

clipping again

>
>Clipping distortion is the most common source of speaker
>damage. (Infinity Car Audio)
>http://www.infinitysystems.com/caraudio/Techownerinfo/glossary.asp?Char=C
>

Clipping again. Still haven't seen any mention of the speaker flailing wildly about like a cubs fan attacking a first base coach....

>Most speaker damage is caused by amplifiers with too little
>power. Damage caused by operating the speakers at distorted
>volume levels is not covered by the warranty. (Bogen
>Communtications, Inc)
>http://www.bogen.com/pdf/54-2038-01R3.pdf
>

Again, misuse of the amplifier by clipping it. Clipping provides more power which results in OVERPOWERING....This is getting redundant...

>It is very easy to do speaker damage by using an amplifier
>with insufficient power. The lack of headroom or reserve
>power may cause the smaller amp to clip, sending a distorted
>signal to the speaker, resulting in blown woofers or
>tweeters. (Mike Starnes of Mobile Beat Magazine)
>http://www.mobilebeat.com/archives.asp?art=128
>

Clipping....

>Ironically, you are more likely to damage a speaker when
>using a low-power receiver than a high power one. (Polk
>Audio)
>http://www.polkaudio.com/home/faqad/q.php?article=whybreak

clipping....

>
>Put simply, any amplifier can damage any speaker,
>irrespective of power figures. Ideally, an amplifier should
>be as powerful as possible, and controlled by a sensible
>user! (Dr. Hi Fi Pty Ltd -- Robin Gandevia is a member of
>The Electronic and Technicians Institute of Australia
>(MTETIA). In 1986 he gave the address to the Institute's
>National Convention on the servicing of hi fi equipment, and
>has also given lectures on related subjects to the NSW
>division. He is also a member of The Institute of Sound and
>Communication Engineers (MInstSCE Eng.), based in England
>with representatives throughout the world. Dr. Hi Fi Pty Ltd
>is also a member of The Electronic Services Association
>(TESA) in Australia.)
>http://www.drhifi.com.au/service.htm#Speakers

No one is arguing that a more powerful amp is a bad thing. The only way to get headroom in car audio is to add power. But if that 10000w amp is only using 200w, it will sound the same as the 200w using 200w. Again the key here is the sensible user comment.

>
>A speaker with a 100 watt power handling rating can be
>safely operated when connected to a 500 watt amplifier. The
>truth is that amplifier power almost never destroys a
>speaker. In far more cases, it is a lack of power that
>causes damage. (Joel P. Antonini -- AudioVideo101, The
>Audio/Video Knowledge Center.)
>http://www.audiovideo101.com/learn/articles/speakers/speakers22.asp

Clipping...

>
>As you use up amplifier headroom, the sense of detail in the
>reproduced sound will disappear. Then you may hear
>distortion on signal peaks - the distortion is generally
>easier to hear at higher frequencies, but is much more
>common at low (bass) frequencies. This means the amp is
>running short of power to send to the speakers. Allowing
>this state to continue will reach the third stage of
>failure, overt distortion followed by voice coil burnout.
>Many people have an amazingly high tolerance for distortion
>and just do not notice a problem until it is too late. Most
>failures resulting from improper operation can be traced to
>over or under powering the loudspeakers. (THIS INFORMATION
>WAS DIRECTLY OBTAINED FROM SOUNDTECH)
>http://www.allkaraoke.com/watts%20vs.%20decibels.htm

clipping


>
>Under powering a speaker is actually a more common reason
>for speakers to fail then would be expected. An under
>powered amp struggles to provide a speaker with the power it
>needs. In most cases the amp is driven in to distortion.
>(Stephen Ballast - Owner/Engineer BladeAudio)
>http://members.tripod.com/~BladeAudio/training-2.html?#limitations

clipping

>
>Many people think that you blow speakers because of too much
>power. In reality, speakers blow due to distortion, which is
>caused by too little power being availabe for a desired
>volume level. (Import Lounge -
>http://www.importlounge.com/pages/members.html)
>http://www.importlounge.com/pages/modsICE.html

clipping

>
>There is a fallacy that a heavy cone will produce better
>bass. WRONG!

Assuming the same motor/suspension, it will only produce deeper bass, not necessarily better.


>There is also the fallacy that a stiff cone
>suspension means higher power handling. WRONG AGAIN! The
>truth is that if the cone is heavy, it will not react
>quickly to the input signal.

Absolutely false. Mms has virtually nothing to do with how fast it will react to an input signal. It would be hard to give this link any credibility after that comment.


Hence without the application
>of considerable wattage, the signal will be gone from the
>line before the cone can move and thereby causing an
>undesirable noise, kind of a flopping honk sound. Not to
>mention the other restrictions placed on a speaker with a
>heavy cone. The same thing can happen with a suspension that
>is too stiff. (Thomas P. Colvin -- Musicians Hotline)
>http://www.musicianshotline.com/archive/tech/reconing.htm
>



>Nancy loved music and her stereo system. She could listen
>anytime she wanted to any music she wanted by slipping a
>small silvery disk into her CD player and pressing a few
>buttons. Then one day her wonderful 75 watts per channel
>amplifier died. Shopping for a replacement, she discovered
>prices had risen. But the salesman said not to worry --
>quality had gone up. He told Nancy that she hadn't really
>used all 75 watts in her old amplifier and only needed that
>much power because her older amplifier didn't perform well
>near full power. He said that she could buy a 40 watt per
>channel amplifier and play it at the volume she usually used
>because the newer amplifiers performed very well even close
>to full power. Nancy bought the recommended amplifier, went
>home, hooked it up to her system, put her favorite CD on,
>adjusted the volume to her usual listening level, sat back
>in her favorite chair ... and one of her speakers blew out.
>... Why? (Frank Wattenberg, Department of Mathematics,
>Montana State University, Bozeman, MT 59717)
>http://www.math.montana.edu/frankw/ccp/multiworld/virtual/FourTran/nancy/learn.htm
>http://www.math.montana.edu/frankw/ccp/multiworld/virtual/FourSer/learn.htm

Maybe I can get his colleague to respond to this. But he may get too wordy, we will see what his reaction is. Back on topic, the amplifier clipped, but it didn't mention what part of the speaker broke, was it a woofer, mid or tweet? Clipping is hell on tweeters.

>
>Yep, 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. (Yorkville Sound Inc. WorldWide)
>http://www.yorkville.com/pdf/other/pabasics.pdf

Underpowering isn't the correct terminology. They used a smaller amplifier, drove it into clipping which will produce more power and OVERPOWER the speaker application.

>
>Another misconception: speakers blow because they can't
>handle power. Again, not true. They blow because the power
>sent to them is of an inferior quality. (Edmunds.com --
>Editor-in-Chief Karl Brauer)
>http://www.edmunds.com/ownership/techcenter/articles/44841/article.html



>
>I have heard it so many times: "why did my speakers blow?!?
>They can handle 600 Watts and I was only running a 200 Watt
>amp on them!!" What that person failed to realize was that
>by badly mismatching his amp and speakers, he ended up
>pushing the power amp so hard that it was constantly
>clipping. (Dr.Sound - Carvin Corp)
>http://www.carvin.com/doctorsound/
>

In this scenario, the 200w amp wouldn't ever touch the 600w speaker, unless of course, it was driven into clipping and the tweeters couldn't handle it.

>Fiction: as long as the power rating of your speakers is
>higher than your amp's power rating you won't have to worry
>about blowing out your speakers. "My speakers are rated to
>handled 100 watts, and my amp only puts out 50 watts. Why
>did the speakers blow?" (Matt Hennessy (BS. EE, Member
>IEEE, AES))
>http://www.electrosound.com/articles/distortion.html

Clipping=overpowering

>
>Top 10 car audio myths: "You can't blow a 300W sub with a
>50W amp" This has to be one of the most frustrating of the
>car audio myths for dealers and manufacturers alike. An
>angry customer walks through the door of the dealer dragging
>his recently purchased Behemoth 2 kW subwoofer that's just
>cost him two weeks' wages. He slams it onto the counter
>demanding a free replacement on the grounds that it was
>faulty. (Total Car Audio Dec/Jan 01)
>http://www.caraudiodirect.com/magazine/tca/myths.html

The strange thing is the prevailing myth is that you can get it to blow, which is untrue.

>
>Now that we have a realistic power test all you need to do
>is determine the power rating of the loudspeaker, buy an
>amplifier with the exact same power rating and enjoy
>perfection right? WRONG! If it were only that easy,
>everything would work perfectly and people who re-cone
>speakers would be in the bread line. The amplifier must be
>capable of delivering more power than the long-term average
>power rating of the speaker. (Audio Video Broadcasting -
>Studio Systems Magazine May/June 1999)
>http://www.studio-systems.com/audiofeatures/mayjune99/soundrespeakers3.htm

BS once again.


>
>Oddly enough, the most common problem with matching speakers
>and amps is using an amp that is too weak to power the
>speaker. (CarAudioGalaxy)
>http://www.caraudiogalaxy.com/caraudio_rmspower.htm
>
>Contrary to popular belief, not having enough power can be
>more damaging to a speaker than having too much power.
>(Crutchfield)
>http://www.crutchfield.com/S-h9PZf3vjdml/tech/kb303.html

clipping

>
>Danger: Low Power
>http://www.jblpro.com/pub/technote/lowpower.pdf
>
>Q: How much power should I send to my speakers?
>A: Always remember that underpowering a speaker will destroy
>it much faster that overpowering. When there is not enough
>power to satisfy the speaker's needs, the amp will try to
>out-do itself and start to send distorted information to the
>driver.
>http://www.blaupunktusa.com/speakers/speakers_faqs.html

They misworded the answer, obviously. The speaker has no needs, but the application might. So, if they are trying to reach 120 dB and only have a 5w amp on tap, they are fighting a battle that will result in clipping and clipping causes an amp to produce more power which results in overpowering.

>
>Another major cause of speaker damage: using a low-power
>head unit with high-end speakers.
>http://www.napsnet.com/auto/54366.html


>
>Always keep in mind that low wattage amplifiers are the
>normal cause of speaker damage. (Colquhoun Audio
>Laboratories)
>http://www.axiomaudio.com/faqs.html

No, low wattage amps are not the cause of speaker damage. Ignorant users causing the amp to clip and therefore sending more power to the drivers is the cause of speaker damage.

>
>An important factor to consider with any speaker system is
>the potential for speaker damage. Even though your
>SS-150THXs have high power handling ability, they still can
>be damaged by relatively low powered amplifiers. (Miller &
>Kreisel Sound Corporation)
>http://www.sanoconsulting.pl/pdfy/Ss150.pdf

They clearly say that clipping is the cause.

>
>
>
>All these people have emails and can be contacted if you
>don't agree.

And I created an email address for you. Just go ahead and change the password and let me know. Why would you bother researching all of this but refuse to look at one more?

Also, make up your mind. Is it clipping that destroys speakers, or is it cones floundering about out of control like me skiing?

All of your links seem to agree that clipping is the cause.

State your ground or concede.

 

rbrendel,

Randawg is saying that underpowering causes a woofer to lose control. All of the links indicate that clipping is the cause. We have established numerous times that clipping results in square waves which have up to 2x the power of a sine wave. 2x the power results in too much power. In the case of speaker with multiple elements including a tweeter, clipping is even more dangerous. In either case, the amplifier is providing TOO MUCH power for the drivers to handle. This is OVERPOWERING.

We even got Tracy from Kicker to post, which is what you asked for, and you are still going to follow randawg? The industry is against him and his explanation.

 

Doesn't matter anymore. I was trying to illustrate another possibility, but since I cannot say 100% sure if I was clipping, even though I had set all my gains properly and had not clipped previously, I suppose I cannot rule this out after all. Which furthers my stance that one should always buy a more powerful amp because, even though your gains may be set properly, you just can never say for sure if you were clipping. Therefore, it is better to err on the big side.

Nevertheless, Richard Clark has stated, "it is another one of those voodoo beliefs that will always haunt the audio world that underpowering a speaker has any negative effects EXCEPT for the simple fact that if the speaker is underpowered it will not play as loud". **I have listed several respected people that take issue with that.**

In the very beginning, I had stated, "remember, your amp should always be able to put out more than your drivers are rated at, never the other way around."

Then Tempe said, "And why do you recommend AGAINST an amp that is rated for less than what the sub is rated for?"

I said, "Well, its not a hard n fast rule, but basically, an amp should be able to put out more watts than the sub can take."

This is what started it all, the issue of whether or not to recommend an amp have more power than the driver is rated. I maintain it is. Maybe I'm not the guy who can prove it (with or without clipping), but I don't care. I am very satisfied with my beliefs on the subject.

If you want proof, contact Thomas P. Colvin who said, "There is a fallacy that a heavy cone will produce better bass. WRONG! There is also the fallacy that a stiff cone suspension means higher power handling. WRONG AGAIN! The truth is that if the cone is heavy, it will not react quickly to the input signal. Hence without the application of considerable wattage, the signal will be gone from the line before the cone can move and thereby causing an undesirable noise, kind of a flopping honk sound. Not to mention the other restrictions placed on a speaker with a heavy cone. The same thing can happen with a suspension that is too stiff." (Thomas P. Colvin -- Musicians Hotline)
http://www.musicianshotline.com/archive/tech/reconing.htm

Until you disprove this, I only need to keep requoting it at the question of, "how can a sub be blown with clean power?"

geolemon said, "a bit of clipping is actually quite common and relatively harmless."

geolemon said, "Small amounts of clipping won't even hurt too much"

geolemon said, "In fact, even if you do have it set to clip a bit, that won't hurt anything."

MFCT said, "Nope. Clipping will not harm speakers. Its a myth. Pushed into the mainstream back in the early 70's by JBL and followed blindly decades to come."

geolemon said, "GIVEN the amp is not clipping (user error).." **Not necessarily user error, it is surely possible to set gains properly and still not be 100% sure you are not clipping. But, had you bought a more powerful amp, you could be more sure.**

Richard Clark said, "clipping is not the key to anything"

David Navone said, "Not only do we recommend "clipping" the amp, we recommend that it be super clipped"

David Navone said, "Clipping doesn't damage speakers"

geolemon said, "Clipping does not destroy speakers.... and clipping extremely underpowered speakers does abosolutely nothing."

RanDawg said, "Didn't someone here say no amount of clipping will damage a sub? I know of several posts that say minimal clipping is fine. Therefore, clipping has nothing to do with anything in this case. It is merely to prove or disprove that an amp of lower rated power than a sub has the ability to blow it."

RanDawg said, "I then play around with various gain settings at various frequencies and recording levels until I am satisfied I will not clip under most circumstances and yet still have headroom for poorly recorded music."


Needless to say, I'm very satisfied with my recommendations to others about amp selection.

 

So, suddenly we deliver a slew of posts that amount to stating:

"Clipping can cause dangerous overpower situations that can cause a speaker to thermally fail of gone unchecked for a period of time"


I believe that pretty much everyone on this thread...
Everyone that I quoted...
Everyone that you quoted...
Everyone except you, apparently...

Everyone [else] would agree that:
ONE))) You can create an over-powered situation with an smaller amp that is not meant to reach high power levels by dramatically clipping it.

If you damage a sub this way, it is not "because the speaker was running on an amp that was too small for it".
It would be because you overpowered it by clipping it.
If you clipped a larger amp similarly, the subwoofer would have died even faster.
If you had a small enough amp, and clipped that tiny amp extremely, you would not reach the RMS levels of the sub even still, and the sub would be fine.

Therefore, this statement does not prove "too little power blows subs".
This statement simply indicates that "clipping can (not will) damage subs", and still proves that smaller is safer, clipping or not...
Just that if you are clipping heavily, even SMALLER is safer.
Definitely doesn't prove that "I blew a sub BECAUSE the amp was too small".

TWO))) You can design an enclosure that is excessively large, and/or excessively high-tuned (if it is ported), such that the subwoofer's mechanical limits are reached much easier below a certain frequency range. Below those limits, it is possible to bottom some subwoofers out and damage them with relatively small amounts of power at those frequencies.

This is user error, in one of two forms:
1) I built an enclosure that was not appropriate for the music that I play through it.
2) I knew I built an enclosure that had inherent limits and frequency vulnerabilities, but I despite that I played the music that the system could not handle much power on.

Once again, if you played the same material that caused the bottoming out with at a higher power level, you would have caused an even greater collision and greater damage.
Conversely, if you had a small enough amp, even at those frequencies that the subwoofer system was vulnerable at, you would not overcome the suspension's own resistance against movement from the 'at rest' position, and you wouldn't bottom it out even at those frequencies.

Therefore, this again does not indicate that "too little power blows subs".
Even in this situation, more power would have been worse... and too little power could have saved the subwoofer.


Where have you shown ANYTHING that correlates woofer failure to "HAVING TOO LITTLE POWER"?

All you have done is correlate:
1) possible woofer failures to high levels of clipping (clipping enough to cause an increase in averaged voltage, and therefore power)
...you claim the amp was not clipping at all, and was verified VERY recently prior to that with an actual oscilliscope...
2) possible woofer failures to a possible incorrect combination of subwoofer / enclosure / musical material being played.

You were so confident that you understood the ins and outs of how having "too little power" alone can kill a subwoofer...
...without clipping...
...in a good enclosure...
...without abusive tones...
Yet you fail to provide any explanation of how this can happen?

Surely, with your level of grip on the topic at hand... you can describe what the scoped output of a sine wave input would look like from that amp as you "stressed" the amp?
If it was still a pure sine wave output, and the RMS was below the RMS of the subwoofer, how is that not the same as just regular clean power coming from the amp under acceptible conditions?
Describe what is different, compared to clean, "non-harmful" power!

I am seriously snickering inside thinking that you might be implying that some sort of a phase shift might be causing harm to the woofer...
As if the woofer were anticipating the signal to arrive at a certain time, and will destruct if the signal were a little "late"...
Seriously though, it's about the only concept we haven't visited yet..

OH PLEASE let's go there...
(Not like PHASING isn't one of my favorite topics of all time or something! ...you have visited my website, haven't you?)