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Underpowering can damage a speaker?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=84110
Printed Date: March 29, 2024 at 9:13 AM


Topic: Underpowering can damage a speaker?

Posted By: master5
Subject: Underpowering can damage a speaker?
Date Posted: October 14, 2006 at 1:51 AM

There is alot of debate on this topic. Many believe there is no way to "blow" a sub by underpowering. Others strongly believe by experience that underpowering is the main cause for blown subs as well as other type speakers. Well both are right.....and wrong? how can this be?

It mainly depends on how you view the "cause and effect" and certain technical aspects. Other considerations include the type of amp, quality of the speaker (this doesn't apply just to subs), and how hard [over driving] the listener operates the system.

Now those like myself that think "underpowering" causes problems are not trying to imply that this is the only way to damage a sub. There are thermal and mechanical limits with any speaker and that of course is always a consideration.

Some "blow by underpowering" theorists believe that clipping is the cause of the damage. Some "impossible to blow by underpowering" theorists believe that there is no reason an amp should clip regardless of power and/or that clipping won't damage a speaker. Some simply blame it on the user stating that they are playing the system too loud...which can be the case but "too loud" is another subjective issue, ie: maybe the listener is hard of hearing.

As for the technical aspects regarding clipping you can find a ton of info about that here, other sites or any textbook that deals with A/C- D/C and audio. A clean sine wave viewed on an o-scope or on paper will be curved at the tops and bottoms. This picture of a sine wave, or audio signal contains the following info: Amplitude (power, this is where you see the clipped signal although other properties are involved), Frequency (cycles per second expressed in hertz or hz), period (time) and wavelength (size of the sound wave).

If you are looking at the sinewave from an amp that is clipping the top and bottom curves will appear flat, or cut off. Basically the amp can't produce any more "clean" signal at this point - Some engineers state that the output at that point is DC, or that a portion of it is. All transducers (speakers) don't really take well to DC, not a big fan. When an amp is clipping even though its clean output hit a "ceiling" (won't play the speakers any louder no matter how much more you crank the volume control) the amp is putting out more then its "peak" rated power. Many engineers claim up to 50% higher, some believe even higher and some say "nonsense". Again, confusion so who do we believe? 

Heres my take on it (or opinion if you wish). If the amplifier had enough "clean" power to begin with no clipping would occur. Regardless, whichever theory you side with we are trying to prevent toasting a woofer. Been there, done that.

Many audio engineers tell us that a high powered, quality amplifier won't clip, or at least is very difficult to clip and that you can safely run more rms power to the speaker then it is rated for. I completely agree with this, but within reason.

For example say we have a 50watt RMS amp. If we replace it with a 100watt RMS amp we can expect an increase of 3db output from the speaker. (note that for every doubling of power, or # of speakers you can expect a 3db gain) We need a gain of 10db to be twice as loud. So just to make a 50watt rms speaker play twice as loud we would need to run over 400watts rms to it. Now that may be a bit [sarcasm] overkill in the headroom department but I would see no major crisis in doing this. The potential is there to blow speakers but it would sound so horrendous before they ruptured that even the most ignorant of the ignorant would want to turn it down, unless they are purposely trying to destroy equipment. Start getting greedy and apply 500w - 1000w to that same speaker and you can too easily exceeded it's thermo/mechanical ability. The speaker may not nessecarily blow from clipping in this fashion but can basically self destruct. Been there, done that as well. You will release the "voice coil smoke".

Think of it this way. The speed limit is 65 mph on the highways where I live. But I would not really buy a car that has a top speed of just 65 mph. I want a little "headroom". Now in comparing this to an amp would be why lowering the gain control (assuming it was set properly to begin with) will help, but is in a way it's just a band-aid. The same analogy applied to the car would be that I put an egg under the gas pedel so I can't speed or floor it. It will work, yes, but not always leave a very satisfied customer. (plus I would crack the egg and have a mess..I'd like more power... please)

In my day to day system installs, I find that most of my customers like it LOUD !!!! They trust me to deliver what they want. Afterall, they are paying good money (master installers don't come cheap). Now if a customer has 2 woofers that are rated @ 1000w rms each but want me to install an off-brand flea market amp that says 2000 watts on its casing they assume this will work for them. Well it will amplify and produce audio. The problem in this case is the specs are an outright lie, or at the very least peak @ high distortion levels. And by "distortion" I don't mean the good harmonic kind like with heavy metal guitar. I mean any unwanted audio, or "change in waveform" which is the literal definition of distortion when it occurs with electronics. Hmmm..change in waveform..can this mean clipping?

Now on to reality, perhaps this amp can deliver 100w rms of clean power. Everything I have ever been told about audio would lead me to think this will cause clipping. The amp will send too much "dirty" power to the woofer(s) and cause destruction as the user attempts to enjoy the "2000 watts" of power, which is what they are expecting since the amp is labled so and the woofers are rated to safely handle it.

So, from that example you can see "cause and effect". The fact that the amp is not powerful enough can send  it into clipping, which in turn will send too much "dirty" power (possibly DC) to the woofers. Sooner or later this will cause a problem. If the amplifier had sufficient rms power to begin with the woofers will..... and DO, last for years. Once again, been there, done that, over and over again...oh what a life.

CAUSE:  The amplifier didn't have enough clean power.

EFFECT: Blown woofer(s)

Another factor was the user, agreed. The user likes it really loud. This problem would not occur at moderate listening levels-

CAUSE: User cranked the wiz out of it because they like it loud

EFFECT: Blown woofer(s)

And we haven't even talked about transient response, damping, voltage issues and a host of other goodies. And we won't talk about that here to avoid information overload....we don't want to "clip" our brains :)

My feelings about this is to simply use an amp with at least  the rms power rating of the speakers (if you can find anything with an accurate or honest spec...good luck), or go higher, within reason. Of course if the end user is not a bass head you can certainly get away with less power. The key is you can't be general in this industry, there are too many factors to take into consideration, especially when dealing with car audio where 2 ohm loads are commonplace, and loads as low as 1ohm and less are sometimes utilized. (this is rarely the case with home audio so I don't pay alot of creed to home audio or musical instrument specialists when dealing with mobile electronics as too many variables exist and the same physics don't always apply, in what other industry do they have off the chart mega wattage and insane spl levels with 12 volts???).

With all this said I hope some clarity can come out of this topic without there being any fights or name calling.

Yes, I might be pathetic and have no life (well, this industry is my life) but the things I sometimes hear regarding this topic bug the crap out of me.

Note that some info here is just my opinion but it is based on books, schooling, seminars, experience and actual events I see all too often. Other info is from professional sources and engineers in the industry.

Replacing speakers until I upgrade the customer to the proper amp,,,, and only then the speakers blow no more. That in itself is enough proof for me and regardless of what anyone believes is causing the problem....I found a solution that WORKS!  MORE RMS POWER!!  My credentials should be apparent.

Thanks for listening everyone. Any feedback, positive or negative is welcome, just no name calling please.



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Replies:

Posted By: Steven Kephart
Date Posted: October 14, 2006 at 2:15 AM
Read my too little power sticky to get the details on this. But to make some points:

1.It is impossible to blow a speaker with too little power. If damage occurs it is because too much power was applied (ignoring direct damage from say a knife to a surround, etc.)

2.There is no DC in clipping. Put an amplifier on a scope and actually watch what happens when pushed to clipping and you will see what I mean.

3. I have never heard any engineer say it is impossible or even hard to send an amplifier into clipping. I used to do it all the time when I worked in the warranty department of Adire Audio. I have repaired quite a few speakers that were damaged from the user running their amplifier into clipping.

Here's a link to another great technical paper on this topic: https://www.bcae1.com/2ltlpwr.htm




Posted By: master5
Date Posted: October 14, 2006 at 3:19 AM

I will check the technical paper you suggest but, I bet for every paper on this topic you could find 10 that contradict it.

In college my electronics professor actually was a student of einstein before he died.  A bit old (real old)school and arrogent but seemed to know his stuff.

When I was training coordinator at a tech school the man I replaced and who wrote the original curriculum was an army engineer. The instructor under me was a fresh audio engineering school graduate so these is some pretty good credentials and I learned alot from them but I guess anyone can be wrong or misunderstand, it happens to me enough.

I had to read the loudspeaker cookbook and memorize alot of info to pass the mecp master (I scored a 98% in electronics so I must be somewhat on the right track.) Unless all these kids that are killing subs and then when I finally get them to replace the amp to a much more powerful one and the woofs don't take a dump again..whats with that? Are the higher power amps rating too conservativly or the lower power amps way exagerating. are they all lying?

I will keep an open mind to anything but I also have to stick with what works for me.

Much appreciate the feedback, thanks



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Posted By: master5
Date Posted: October 14, 2006 at 3:33 AM

Oh I was told by an engineer that  high powered amplifiers won't clip, that it only occurs at with low power amps being driven into saturation.. If I find any info on that to verify I will post a link, this was told to me at a seminar. But you can probably find it on a search. Thats why I stated "high power, quality amps don't clip" but not to say it's impossible thats wrong, just what I was told by a source I trust.

You also state you easily clipped amps and  repaired quite a few speakers damaged by clipping. Do you think an amp with more RMS clean power would have prevented the clipping, hence no damage?  Or is it that high RMS powered amps clip easier? If thats the case everything I was ever taught is backwards and hence I have been teaching wrong. Hope thats not the case.

Let me know what you think. Thanks again



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Posted By: master5
Date Posted: October 14, 2006 at 3:59 AM

Ok I read the article. It seems like he is saying the same thing I am for the most part but using different concepts and verbage, such as Bul$&^t. ,lol, well you get the point. for the most part I agree with him, on other issues my personal real world experience contradicts him somewhat. 

He states that you can not underpower a woofer since thats like if you turned the volume down all woofers would blow. That is ridiculous and I don't think anyone thinks that and the anaolgy holds no wieght against what I have been saying.  But then he consistantly states thoughout the writing that supplying clean power is good for the speaker and using an amp with not enough power for the speakers rating will cause clipping and damage the speaker.

I don't know this persons credentials or where he attended school but regardless I understand everything technical in the writing and have been through most of it back in the day and think we more or less agree, but view certain aspects differently.

If you read through my entire post I think you will see what I mean. my anaolgies and experience make more sense then some of these "tech heads" trying to make a point, basing everything on charts and graphs but have never installed as much as an air freshner into a car.

Thanks again.



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Posted By: geepherder
Date Posted: October 14, 2006 at 6:31 AM
Any amplifier can be driven into clipping if it's fed too strong a signal.

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My ex once told me I have a perfect face for radio.




Posted By: stevdart
Date Posted: October 14, 2006 at 7:32 AM

This subject "underpowering causes speaker damage" is debated only because of a general disagreement in the interpretation of the meaning of that phrase.

"Underpowering" should be understood to mean that the speaker in question is receiving less power than it is thermally rated for.  With this basic understanding of the use of the word, anyone with a little bit of knowledge in the matter will understand that this is entirely untrue.

The matter only becomes debatable when the term "underpowering" is referring to the mismatch of audio gear to the end user's expectations.  If the user is expecting his system to get louder than it actually can get, his system is not meeting up with his expectations.  If he is a fool with a volume knob, he is likely to abuse the system and cause damage.

In the audio profession, dealers and installers see this occurrence.  The consumer wants "loud but cheap", buys below his expectations, and ends up damaging speakers and consequently complaining about it.  In order to head off this well-known possibility, the dealer wants to set the user up with a system that will meet his expectations to begin with.  While it is impossible to educate the user in all the details of "how and why", it becomes the most reasonable course of action to just inform him that "too little power will blow his investment".  It is not actually a lie, but a truth based on the reality of the end result but not in the reality of how that end result occurred.

Those who have an education in audio electronics know that a 10 watt amplifier will not damage a speaker rated at 200 watts unless it is used incorrectly.  A 100 watt amplifier will not damage a speaker rated at 1000 watts.  It is the usage of such systems that cause problems, and ultimately begins with the initial buy and setup.  When a dealer has 5 out of 10 users coming back with complaints that their speaker blew, it is understandably justified to try to head off this known problem by declaring, from the onset, that "underpowering causes speaker damage."  It is a reality-based "known" based on the interpretation of the concept of "underpowering".



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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: haemphyst
Date Posted: October 14, 2006 at 10:20 AM
master5, you seem like a smart guy... really.

What about "underpowering a speaker can never thermally damage a speaker" don't you understand?

If you had read those articles, (as you claim) and you REALLY understood them, (as you claim) you would (or should) realize that IF you take a 1000 watt woofer, and play ABSOLUTE square waves (i.e. perfectly clipped, and 100% distortion) from a 100 watt amplifier into it, it CAN'T EVER thermally overload that woofer, the margin is too great. With the voltage rails in a 100 watt amplifer, there is NO WAY to ever produce enough thermal energy to destroy a 1000 watt voice coil. At BEST it could produce 200 watts - an extremely far cry from 1000 watts, I believe a 5:1 ratio, or a 500% safety margin. Now, if you do nothing but replace the 100 watt amplifier with a 250 watt amplifer, and re-setup the test. Will it blow? No, for the same reasons (but this time with a 2:1 margin). Now use a 500 watt amplifier, and do the same thing. Will it blow? Hmmm, possibly, but I think the margin will still be in the favor of the woofer (for a shorter period of time, possibly) as a decent 1000 watt woofer will actually take 1000 watts (and possibly more) on a very continuous basis. Here we are looking square on a 1:1 ratio. Rated input power to the woofer.

Repeat this experiment one more time, but this time with a 750 watt amplifier, and yeah, I guarantee you're gonna blow that woofer in short order, thus "proving" your "low power blows woofers" theory. Why? Because a 750 watt amplifier could probably easily produce over 1000 watts, in a severly clipped, over-driven, saturated (whatever the word you want to choose) situation.

I am NOT even touching on the physical mismatches in a mis-aligned vented enclosure, where it is certainly possible to destroy a woofer with what one might describe as a "drastically underpowered" amplifier, but this is NOT thermal damage as described above. It is mechanical damage in this case.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: DYohn
Date Posted: October 14, 2006 at 10:26 AM

Again, where's the "head against the wall" icon?

IMO the only people who preach the "underpower" myth are those trying to sell high-power amplifiers to unsuspecting car audio buyers.

It is ALL ABOUT APPLICATION.  You may use ANY amplifier with ANY loudspeaker as long as you understand how to set it up and how to use it.  Period.

And master5, your points are similar to many made by folks over at places like Rane or Harmon, but you have missed the point that it is never "distortion" that blows loudspeakers, it is always thermal energy, or "power."  The source of the power and how the user controls it is the key.  Power hidden inside a clipped or distorted signal is simply harder to control.  And please, you keep harping on your "credentials" as some sort of justification for your posts.  No need for this, as many of the posters here are not only experts in their fields but have "credentials" as well.  Check profiles sometime.  People who post accurate information become self-evident.  posted_image



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Posted By: kicker guy
Date Posted: October 14, 2006 at 10:37 AM
I will say that it is impossible.... I have 2 L7s in my car right now... and well my amp took a crap cuz well its old and I beat the crap out of it... now because I was lacking bank for the time I had to put a 200 watt amp on them cus its what i had laying around.... and they haven't blown yet and I really really don't see how a 200 watt amp is gonna kill those subs EVER...




Posted By: master5
Date Posted: October 14, 2006 at 1:15 PM

What about "underpowering a speaker can never thermally damage a speaker" don't you understand?

I don't recall using the term "thermally" in that context to my defense because I do understand that.  Regardless, the issue here seems to be that I understand EXACTLY what most of you are saying, and most of you don't seem to understand ANYTHING that I am saying. Or flat out refusing. A shame really.

I also understand that turning down the volume will help with the issue we are discussing. But turning down the volume, or lowering a gain may not satisfy everyone. However, I do see many of your points in this regard.

What I don't understand is why when this problem of underpowering (or using an amp without enough power if you prefer) occurs and causes a speaker to blow how blaming this "phenomina" on the customer or the salesperson changes the facts. What is the difference who gets the blame? If this happens in the real world people should know. In the some token it is either the salespersons fault or the end user because they might not have been educated in this field, or they are utilizing equipment with specs that are dead wrong, mistated or misunderstood.

I don't believe every person who enjoys a really loud system in thier car is an "idiot" "moron" "bafoon" or such. They are just a person who likes it loud. It is left up to me to do deliver that. So I suggest the proper amp to drive thier subs loud and not to use the "dirty" amp.

Also, I take some insult to anyone (and I see this by a few) that thinks the ONLY reason salemen tell customers this is to sell a larger amp. I don't see why they would do this if they believed too much power was causing speakers to blow like crazy. They would lose in the long run by constantly changing out blown speakers and having unsatisfied customers. This in no way is good for business and any shop that gives improper reccomendations for the SOLE purpose of upselling should be shut down and probably will be.

I only make suggestions to my customers that will make them happy and if that means turning down a gain, or turning down the job completely thats what is done. But the bottom line is I want a customer to return to my shop for more upgrades, not problems. I also lose money when I am replacing stuff under warranty so it makes sense to "do it right the first time"

I base alot of what I post on daily experiences, not "test tones" and laboratories, my lab is the install bay. I do understand the "less is more" as a philosophy works in some cases but what I can't understand is that "underpowering IS overpowering" is too difficult for anyone but me to understand regarding this post.

I have recieved private im's that agree with me but I guess they have been through this and are hiding, lol. ;  )   

I enjoy debate so I won't hide. I just hope to share at least as much as I learn.

Thanks for responding crew and don't think I don't see your sides or understand the technicals because I do.



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Posted By: Steven Kephart
Date Posted: October 14, 2006 at 6:45 PM
Even if damage occurs mechanically, it's still due to overpowering the sub. I hope that installers know that a larger enclosure will require less power to run a sub to it's mechanical limits. Thus, mechanical power handling is a function of the enclosure size.




Posted By: haemphyst
Date Posted: October 15, 2006 at 12:09 AM
DYohn] wrote:

gain, where's the "head against the wall" icon?

Can't you do something with that, Dave? As an admin, I'd think you could add an icon like that...

Getting really tired of typing all this stuff over and over. Gonna make canned responses for all of these common question and answer sessions...

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: master5
Date Posted: October 15, 2006 at 12:11 AM

I totally agree Steven and nouse. Very glad there are no fights as I'd rather hear everyone elses point of view as well and perhaps learn something new.

I understand about how and why  enclosure size and type affect power handling as well as output. Enclosure design 101. But I appreciate the input and perhaps others will learn something.

I think it is a very fine line between where some of us disagree and only on a few points.

There is however no point in going on and on, back and forth about what clipping is, what causes it, what it does etc. because I consistantly am told different things to the point where I don't know what or who to believe or if I even care anymore   : )

I take responsibilty of any info I post that is wrong and hope I don't mislead anyone. But I would like to clarify my understanding of the topic and explain a little better where I am coming from.

A few facts I would think we can all agree on. Every speaker and amp is different. Test procedures can differ. I would think it could be difficult at times to predict real world outcomes unless something is tested over and over again, and then to test again and again with different parameters over great lengths of time. Kinda like what I do in my "lab", the install bay ,installing 100's of systems a year and seeing things almost every day that make me go, hmmm. We also can agree I would hope on the difference between "peak" and "rms" (or clean if you wish) power.

An example using one of my cars I call the "beater":  It is a 1989 Pontiac and it still has the original factory 6x9's on the rear deck. Take into account that is 17 years of the brutal, scorching south Florida sun beating down on them as the car has never been garaged. I have been running a  RF 75watt rms per channel amp (4 ch) to those and the pionner 4 x 6's in the dash for over 2 years now. (crossed over properly of course, that should always go without saying on anything I post). They still sound great and believe me, I am a rocker and I push them hard. Who could have predicted those old 6x9's (or 4x6's for that matter) could do that???  and I see no signs of them dying. I have a clean signal with the input gain at about 3/4 and using a Clarion deck.

For bass I have a 100watt rms amp running a RF p1 10'' bridged to it @ 2ohm in a ported enclosure I built. Before that I was running a JL 10w6. Granted it was old, but one day I heard a horrible noise in the trunk and then no bass. I toasted it. But the p1 is still going strong for well over a year. This is an example of a real world system, not a test bench or ultra, ultra high end equipment that has much tighter tolerences and therefore reliable specs. But understand, the w6 was an amazing speaker, the p1 in its wildest dreams will never sound near as good as that did.

Now about the underpowering,overpowering debate.I will be the first to admit I am wrong, I will admit defeat and concede if someone can help explain how I am wrong in my thinking.

This is how my mind works:

First the statements..."you can not blow a sub by underpowering it".......BUT.........

a sub can blow if you use it with an amp that sends a clipped signal to it.

Ok, I will agree with that, be it "wordplay" or whatever, I want everyone to know I agree with that.

An amp will clip if....(ok this may be the shakey ground but I will say it anyhow)...  you drive it too hard. (too much gain, volume whatever you want to call it)

Ok, can we all agree on that? If not post why and in a way I can grasp, pretend I am the retard you think I am..lol

And last for this topic......sending a clipped signal to speaker can(or will) blow the speaker.

Hope we all got that. The following is where I think many of us have different philosophies. This is where the charts and graphs don't count. This is more about the way we all as individuals view things differently, but, perhaps some or all of you will get it.

First off I get the feeling that some people have something seriously against those who like our music loud...really loud. I also feel many of you would think I can solve the problem of a customer that might be repeatedly blowing woofers due to clipping by asking them to turn down the volume and learn to like it. Now realize if my customer wants thier system to play louder then the physical abilities of the equipment I do not think they would be very happy if I told them..."why don't you just turn it down you dunce". I also know they would not be very happy campers if I turned down thier gain and filled the hole with hot glue so they could never raise it. Yes, it would prevent thier speakers from blowing, but it is not a permenent fix...not for this type of customer. Also keep in mind that this customer is using an amp with an RMS rating well below that of the the speakers RMS rating.

Now I agree with this...Keeping the volume down below distortion levels because if the speaker blows, it is the users fault, not the amplifier... But....

If I install an amp that has more usable, clean power, that is matched closer to the speakers rating (although I believe in headroom and that going over the speakers rating is fine... within reason, but for this discussion I will say "close to")..then the user will  be able to achive a louder system before clipping it.

Now when someone approaches me with this dilema I have 4 options-

1) Break the customers hands so they can't turn the volume up

2)lower the gain in an attempt to prevent the customer from overdriving the amp/speakers

3)convince the customer to try different woofers/enclosure

3) use an amp that has enough clean power to meet thier needs

It took alot of writing to get this point across but this is in a nutshell the only point I was trying to make. Not fight about o-scopes and sinewaves and magical things blowing speakers. So in closing although the statement "underpowering a speaker will blow it" is technically wrong, an amplifier can be driven into clipping which can damage a speaker. Using an amp that has more usable, clean power that is closer to the speakers rating is ONE way to pervent the clipping, therefore saving the speaker(s). I just said basically the same thing I always believed, but in a different way so I should hope this clears everything up. Please post anything on the topic if you have something to add.

I hope now you see where I am coming from but if some of us still never come to an agreement, we will just have to live with the fact that we agree to disagree.

Thank you all again for helping with this and debating.



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Posted By: master5
Date Posted: October 15, 2006 at 12:19 AM
Perhaps haemphyst is right. When someone new here wants to debate a topic that has been dealt with in the past... simply "paste" canned answers. The problem is who has the correct answer and who decides it is right? Oh wait...can you say..... "debating"

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Posted By: DYohn
Date Posted: October 15, 2006 at 10:54 AM

Master5, here is "what is right."

1)  Loudspeaker voice coils are damaged by heat or by mechanical stresses.  Heat is caused by excessive current flow (overpower) or by loss of cooling.  Mechanical damage can be caused any number of ways including stabbing the motor with a screwdriver, but the most common cause is through over-excursion.  Over-excursion can be caused from improper enclosure alignments or overpower.

2)  When I talk about over- or under-powering a speaker system I am not talking about the often incorrect ratings on equipment.  I am talking about providing too many amps at too high a voltage to the loudspeaker.

3)  An amplifier can produce much more power than its rating.  Indeed, when being clipped many amplifiers can generate 1.5 to 3 times their unclipped rating.

4)  The idea of "under-powering" a speaker causing damage is the result of believing amplifier and loudspeaker ratings.  If a loudspeaker is rated at 100 watts and an amplifier is rated at 75 watts (and let's for a moment assume these are accurate ratings) the uninformed user may think that's cool, this amp can never damage this loudspeaker.  But if the amplifier is over-driven, it may produce over 200 watts into the loudspeaker voice coil, which may indeed fry it.  Thus, the user thinks "Damn I under-powered my loudspeaker and it fried!" when in reality they over-powered it due to improper usage of the amp.  Using amplifiers with headroom, or that can produce enough power to drive the load without clipping, is the proper approach to prevent this and often means choosing a larger amplifier and setting it up correctly.  But if the guy with the 75 watt amp had not driven it into clipping, the loudspeaker would have been happy with the 75 watts all day long.  And by the way none of these discussions have anything to do with "how loud" a user wants to play a system.  That is a spurious argument.

5)  Distortion will not damage a loudspeaker all by itself.  If it did, all guitar players would blow their cabinets every time they played a note.  Distortion is another way to cause an amplifier to produce more than its rated power, as the peaks caused by gross distortion can contain as much power as a clipped signal.  Thus, if a person blows a speaker with distortion, they have over-powered it.

This is as plain as I can put it.



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Posted By: kicker guy
Date Posted: October 15, 2006 at 4:36 PM
*claps* that is the best discription about this subject... very good DYohn! posted_image




Posted By: forbidden
Date Posted: October 15, 2006 at 7:18 PM
There are other hidden factors at work inside the speaker as well that pertain to heat,.Perhaps we should also discuss this, thought on that part of the equation guys and add this to the sticky?

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Top Secret, I can tell you but then my wife will kill me.




Posted By: master5
Date Posted: October 15, 2006 at 10:45 PM

Ok DYohn, if I understand what you are saying is that myself and others are basing this underpower theory on faulty specifications. (ratings). To my defense I was very specific that the examples I was using were RMS ratings and have also stated in previous posts on the topic that this happens when the user thinks they have enough power because the amps rating they see is a "peak" rating, and the speakers are an RMS rating, but they are not informed enough to know the difference.

Basically they have decent (at least I believe so, now i'm not so sure)high rms power rated subs in a properly sealed or ported enclosure, but a crappy amp. This is why in those cases I recomend to upgrade the amp. Not because I am just trying to sell the most expensive amp or make more profit (not saying others don't do that, just that I don't) but trying to help them two fold. 1) to stop blowing subs and ,2) let them have more spl, volume, play it louder etc. If this is not what they wanted in the first place, simply turning the gain down would suffice. Now I fully understand everything you posted, it was an excellent learning tool for me and others. But I am still left a little in the dark.

What do you suggest I tell the customer in this instance? Should I tell them that the problem is that thier amp is too powerful and sell them a better quality, but lower power amp? But in the same token I have to explain to them why thier "KenPo" amp that says 1000watts on it is putting too much power to thier woofers and blowing them so here...let me sell you this 200watt amp. Would that allow them to play it a little louder without clipping or is the only option to change the subs/enclosure to remedy this? (In my experience regardless it seems when I sell them an amp with an RMS rating comprable to that of the sub, it remedies the problem and plays louder, hence adding to my confusion regarding the conflicting posts)

I hope I haven't come off as too pigheaded in regards to this topic. Please everyone realize that this is what I was told by people I trusted, people with credentials. Even some of my teachers as well as teachers I worked with. Part of my curriculum was to explain this to my students so now I feel like I was teaching the wrong information dealing with this topic. But at least 95% of my students passed mecp on the first try, however the basic exam does not really deal with this topic per say, more about tools,components and safety. The masters covers some of this and I scored 98% on the electronics section but not as well on the others so apparently I do need more education.

For years all the "pros" I know always told me not to "underpower" speakers or thay can blow easier then overpowering. Of course this made no sense at first but it seemed after a while that the only people who didn't know this were the ones lacking knowledge. Now from what some are telling me here is that the complete opposite is true. So understand my reluctance do be "swayed". The funny thing is this would make more sense to me but for  the fact that I find it difficult dispute what I deal with on a regular basis. So if my theory is wrong, then what I stated in an earler posting is true. That alot of specs out there are outright lies. Who knows what to believe anymore?

I do thank everyone for trying to help me understand this without belittling me (well somewhat, I am trying sooo hard to be extra nice). But as one of my "signatures" says, the more I learn ,the less I realize I know.



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Posted By: master5
Date Posted: October 16, 2006 at 2:32 AM

Ok, I know this seems like beating a dead horse to you and I apologize for that. I just want to ask a few more things and I promise, no more long post replies on this topic ever again, at least not by me.

You mentioned distortion, Now I play electric guitar in a rock band as use alot of loud distortion, I am also tuned a step and a half down from conventional tuning to C#, adding quite a bit of bottom end. As far as achieving distortion I know that effects products produce this, and some players overdrive the preamp signal to accomplish this. I have done it both ways but prefer a floor pedal (the good ol' fuzz box).

Now this distortion effect is something I desire. The literal definition of distortion is any UNWANTED audio or change in wave form. Is it fair to compare a sound I desire to something defined as "unwanted"? I am just asking, not really trying to make a point.

Also the distortion as you described will not blow a speaker or as you say the speakers in my guitar cabinet would keep blowing if distortion was bad for them. (actually I have blown many but I know it was my fault). Fair enough. And you also state this is not clipping or that clipping is not distortion. So can I take from that statement that distortion can NEVER toast a speaker? And is the "desired" warm distorted tone, note, chord etc. I create and send to the amps input literally the same kind of  distortion that is created by the amp (output) (a byproduct of amplification) for whatever reason (be it a bad speaker, a bad amp, or simply cranking the dickkins out of the volume until it sounds horrendous)? Or do amplifiers never produce thier own distortion on the output side? Oops. ignore that one , we know it does because it is part of the specs (thd in %). Is this spec only there to help predict tonal or harmonic sound characteristics or is it in any way a danger to a speaker? Or, am I totally off track?

Once again, I am asking this as real questions, not sarcasm or trying to prove a point.

I also want you and everyone to know I have been giving thought to every post reply and re read them a few times. I want what you are are saying to sink in. I also want to be able to teach this to other people so I need to fully understand it, not just repeat stuff I read verbatum.

I think I get the point that you could operate basically any sub with an amp of lesser rated power without damaging it,  I never doubted that as it is proposterous (spelling?) as a matter of fact most of the replys state it is "impossible" to blow one this way. But how can I use the word "impossible" when it is also stated that "unless you drive it so hard it produces large amounts of power and clips? I think thats what I am understanding most of you mean. So with that you can't really say "impossible" but you can say it can happen. Am I right?

I hope you understand my confusion with this and that not only am I trying understand the facts, I WANT to be on the side that is right about this. Please help me!!

I could set up tests using different amps, subs, enclosure types and take spl readings, power in/out readings and then see over time the results. But I think what would happen is at reasonable listening levels the subs and amps will play fine, theroetically forever until something naturally wears out. But lets say (extremes) I put a 20 watt amp (I actually have some of those from back in the day when many decks came without internal amps) to a 500w rms sub. Is it my understanding that this can NEVER blow the sub, or is it theoretically possible that it can?

And if I put a 500 watt rms amp on the same sub, it would play louder and not blow,( at moderate to high levels) but I could still blow it if I play it too loud for too long or (clip) the signal.

And if I use a 750watt rms amp, can I expect (in theory) to be able to get more volume without damage, or will the sub be destroyed if I try over time, regardless of volume level/enclosure quailty? And if the speaker is destroyed from this is it from clipping, or would it be difficult to clip an amp that has a higher rms power rating then the speaker? Can anything other then clipping (or taking a hammer to it)destroy a speaker or am I totally on the wrong track here too?

Or does it come down to the sub/enclosure combination alone as the main factor that affects powerhandling?

Keep in mind these questions are theoretical so lets assume all the specs are very accurate.

Does anyone have the patience to answer the above questions on by one,? It would really make me a happy camper to put closure to this topic, as I am more then sure ya'll feel the same way.

I think if these questions are answered I can finally be satisfied and go back to helping people figure out why thier remote starter doesn't work.

I really appreciate all responses so far and any in the future. Thanks a bunch.



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Posted By: haemphyst
Date Posted: October 16, 2006 at 8:14 AM
master5 wrote:

You mentioned distortion, Now I play electric guitar in a rock band as use alot of loud distortion, I am also tuned a step and a half down from conventional tuning to C#, adding quite a bit of bottom end. As far as achieving distortion I know that effects products produce this, and some players overdrive the preamp signal to accomplish this. I have done it both ways but prefer a floor pedal (the good ol' fuzz box).

This type of distortion will NOT destroy a speaker, in and of itself. As long as the mechanical and electrical power handling capabilities of the speaker are not exceeded, the speaker can take 100% distortion all day long, and it will never be damaged! As DYohn mentioned earlier though, added distortion, whether desired or undesired, will hide possible overpowering situations, so additional care is required in the matchiing of amplifier to driver.

master5 wrote:

Now this distortion effect is something I desire. The literal definition of distortion is any UNWANTED audio or change in wave form. Is it fair to compare a sound I desire to something defined as "unwanted"? I am just asking, not really trying to make a point.

I would have to disagree about your defnition of distortion... Distortion would be ANY deviation from "faithful reproduction", whether desired or otherwise. Even if you ADD it, it is still a destruction of the original sine wave actually produced by the plucking of the guitar string.

master5 wrote:

Also the distortion as you described will not blow a speaker or as you say the speakers in my guitar cabinet would keep blowing if distortion was bad for them. (actually I have blown many but I know it was my fault). Fair enough. And you also state this is not clipping or that clipping is not distortion. So can I take from that statement that distortion can NEVER toast a speaker? And is the "desired" warm distorted tone, note, chord etc. I create and send to the amps input literally the same kind of distortion that is created by the amp (output) (a byproduct of amplification) for whatever reason (be it a bad speaker, a bad amp, or simply cranking the dickkins out of the volume until it sounds horrendous)? Or do amplifiers never produce thier own distortion on the output side? Oops. ignore that one , we know it does because it is part of the specs (thd in %). Is this spec only there to help predict tonal or harmonic sound characteristics or is it in any way a danger to a speaker? Or, am I totally off track?

I cannot tell you what distortion is placed ON the signal by (for example) the fuzz box. If it is actually clipped off, then I believe this could possibly damage a loudspeaker, simply by virtue of the CONTINUOUS power increasing, due to the rules applied by Ohm's Law. Again, if this continuous power increases to the point of exceeding the capacity of the driver, then it will of course, damage the driver, eventually. Other forms of distortion, however, and again, as long as the continuous power rating of the driver is NEVER exceeded, can not, in and of themselves, damage the driver. The distortion rating of an amplifier is simply there to inform the user how much the input waveform will be damaged by this particular stage of the signal chain.

master5 wrote:

I think I get the point that you could operate basically any sub with an amp of lesser rated power without damaging it, I never doubted that as it is proposterous (spelling?) as a matter of fact most of the replys state it is "impossible" to blow one this way. But how can I use the word "impossible" when it is also stated that "unless you drive it so hard it produces large amounts of power and clips? I think thats what I am understanding most of you mean. So with that you can't really say "impossible" but you can say it can happen. Am I right?

If you read my examples from my previous post again, I gave you possible options at different "rated" power capacities... Read on further...

master5 wrote:

I could set up tests using different amps, subs, enclosure types and take spl readings, power in/out readings and then see over time the results. But I think what would happen is at reasonable listening levels the subs and amps will play fine, theroetically forever until something naturally wears out. But lets say (extremes) I put a 20 watt amp (I actually have some of those from back in the day when many decks came without internal amps) to a 500w rms sub. Is it my understanding that this can NEVER blow the sub, or is it theoretically possible that it can?

An honestly rated 20 watt amp couldn't blow a 500 watt woofer... it simply can't. Even at 3 times it's rated output capability, at 100% clipped output (actually, mathematically 2X the rated power i.e. 1.414 times the RMS voltage X 1.414 times the RMS current = 1.999 times the RMS power of the real world honestly rated 20 watts, so 40 watts) 40 watts could NEVER EVER electrically damage a 500 watt woofer. Again, it simply can't happen! There isn't enough power.

master5 wrote:

And if I put a 500 watt rms amp on the same sub, it would play louder and not blow,( at moderate to high levels) but I could still blow it if I play it too loud for too long or (clip) the signal.

Yes, for the same reasons above.

master5 wrote:

And if I use a 750watt rms amp, can I expect (in theory) to be able to get more volume without damage, or will the sub be destroyed if I try over time, regardless of volume level/enclosure quailty? And if the speaker is destroyed from this is it from clipping, or would it be difficult to clip an amp that has a higher rms power rating then the speaker? Can anything other then clipping (or taking a hammer to it)destroy a speaker or am I totally on the wrong track here too?

You will likely hear mechanical stresses before you damage the driver - i.e. "banging against the stops", especially in a vented enclosure, and even worse complaining in a poorly tuned vented enclosure. A sealed enclosure will not likely complain loud enough to alert the user, so electrical destruction will happen, especially if the user likes it loud.

master5 wrote:

Or does it come down to the sub/enclosure combination alone as the main factor that affects powerhandling?

Mechanical power handling, yes. Electrical power handling is not affected by the enclosure.

master5 wrote:

Does anyone have the patience to answer the above questions on by one,? It would really make me a happy camper to put closure to this topic, as I am more then sure ya'll feel the same way.

I hope I have shed some more light on this for you, master5.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: DYohn
Date Posted: October 16, 2006 at 8:46 AM

I have already said everything I need to say on this topic.  Read my posts.  If you don't understand, I honestly suggest a class or two at your local community college in the Physics or Engineering Dept.  See if they offer Electro-Acoustics; even basic electricity may help you understand the mechanics of energy through a coil and motor theory.

Cheers.



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Posted By: master5
Date Posted: October 16, 2006 at 1:22 PM

Ok, I promised no more long posts on this topic If I got some answers and my expectations were met.  I will live up to my promise. Thank you. I probably should have paid more attention in physics class and do believe I could use a brush up. However, my definition of distortion was quoted directly from the dictionary so blame them.

Now with all this said it is still difficult for me to change the ways I have been doing things for over 15 years with success but at least I now have some technical evidence on why so many customers are blowing thier speakers (not on systems I sell mind you, just walk-ins) rather then the oversimplified reason of "you are underpowering the speakers". I guess I just wasn't looking at this problem the same way due to what I have been taught in the past.

Again, I thank you all so much for sharing your time and knowledge, I will be more careful what I post regarding technical matters that I have forgotten, or perhaps wasn't taught  properly. (is "taught" even a word or used properly in this context?)    ...You don't have to answer that. ...



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Posted By: Steven Kephart
Date Posted: October 17, 2006 at 2:37 AM
Ok, time to beat a dead horse a little more. I came across a great discussion on this topic over at Car Sound that provides an even more technical look at this topic. It includes people like Manville Smith of JL Audio, Mark Eldridge of JL Audio and multi IASCA world champion, and Andy Wehmeyer of Harman Kardon. Here's the link: https://www.audiogroupforum.com/csforum/showthread.php?t=4332&highlight=clipping+blown




Posted By: DYohn
Date Posted: October 17, 2006 at 8:25 AM
Thanks for the link!  Recommended reading, and I think I'll add it to the sticky thread.

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Posted By: master5
Date Posted: October 17, 2006 at 1:31 PM

Thanks Steven, I will certainly check those links !!

Several years ago I had a shop in Pomano Beach FL.  Speaker Warehouse from what I understand was Manville Smiths place in Hollywood Fl., not too far from where my shop was and was basically competiton. But JL blew everyone away at the time, My Fosgate couldn't touch it. I eventually became a JL audio and Precision Power dealer  (Those old Art series amps were sweet). This is all going back 10- 15 years ago but as I can remember the JL seminars were some of the most informative ever !

Thanks again everyone.



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Posted By: Flakman
Date Posted: October 18, 2006 at 2:36 PM
WOW...that was a good read. Thanks again Steven.

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The Flakman
I feel strange. I have deja vu and amnesia at the same time.

John | Manteca, CA




Posted By: master5
Date Posted: October 18, 2006 at 11:29 PM

Ok went there. I must say Steven that was harder to put down the the last few good novels I have read. It made me feel like an imbecile and a genius all at the same time. And I almost sharted in my drawers some of those replys were so funny. Nice to see geeks with a sense of humor.

Some of those guys were quite impressive, especially Manville. When he started getting into "crest factor" I felt like a little kid in school again. He is the shizznit. Always was in my book.

I especially enjoyed when Manville posted...."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). "

That statement basically sums up where my "confusion" was coming from. You all helped me understand the defect in my thinking on this topic and for that I once again thank you all.

It is amazing how really simple a speaker is but all these great minds that know T/S parameters like it's fingerpainting to them can have so much to debate about it.

What an industry, you gotta love it,,,thanks again peeps.



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Posted By: Steven Kephart
Date Posted: October 19, 2006 at 2:11 AM
I think the greatest mistake any of us can make is to think we know all there is about this subject. Working at Adire was a very humbling experience for me as I got to glimpse at how technical it truely can get. Ever heard of an imaginary frequency? posted_image

Anyway, many times we project previous knowledge on something and form conclusions without fully knowing the whole truth about the subject. Sometimes the simple conclusions we come to could be a false. I've even seen a very prominent car audio figure guilty of this durring a debate over whether Mms effects transient response. He proposed an analogy of a go-cart to prove his position, stating the extra weight will slow it down. However he forgot that speakers don't just move one direction, they also come back, and that the extra weight doesn't slow the response down, but just limits the total distance (mass effects efficiency, not the response time).





Posted By: master5
Date Posted: October 19, 2006 at 2:29 AM

Yep, I think it has been more difficult to change my way of thinking on certain subject matter then the learning of the matter itself. But a little pride hurting aside, it doesn't seem all that bad to be humbled.

As far as "imaginary frequency" I have no knowledge on the subject whatsoever. But I think many of my customers hear them..lol

Well if I can stay out of trouble and don't get suspended (I will try) I hope to keep learning and contributing. It is addictive but there are much worse things to be addicted to. But it's sign off time, got a meeting tomorrow for a job doing full blown custom marine electronics, and I got that meeting from a post I found on this site. :).

If anything that's more than worth the price of admission.

Good Night



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Posted By: audiocableguy
Date Posted: October 19, 2006 at 11:48 PM
https://www.jblpro.com/pub/technote/lowpower.pdf




Posted By: master5
Date Posted: October 20, 2006 at 12:32 AM

I found that interesting audiocableguy. Thank you.

Everything so far I have gathered here has been very informative, but at the same time there still seems to be dispute with certain and specific aspects, or like with myself, it was the way I  was understanding (or my lack thereof) what I have been consistantly told in the past. It is a somewhat dissapointing feeling to find out some of the "educators" and leaders in my industry (some I even worked with for extended periods) can be so wrong, or at the very least the coming to the conclusion that thier teaching technique was not so effective.

I am alot less confused now but I still don't feel competent enough with the physics aspect to ever have a serious debate with experts on the particular topic of "amplifier power causing damage" and its subject matter. However, I have aquired enough info here to deal with anyone at or below my level, perhaps teach the basics effectivly and educate the customers who tend to blow stuff up.

I always realized that there are differences in the way a tweeter deals with power as opposed to a sub, and the JBL paper you linked helps explain it well,at least in my opinion.

My best results regardless have been from trial and error in the real world. I have learned (and this is tough) to ignore the specs (well at least when dealing with low to mid end components) and use what pleases the customer, keeping reliability has a main factor when designing the system or upgrading a component. This is not always easy when you have no faith in the reliability or honesty of specifications but being in this busniess for a long time you pick up "patterns" which helps decide the best product for the end user (consumer, I hate that word..lol)

As far as what "sounds" better I gave up on the argument years ago. WAY too subjective.

Thanks again.



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Posted By: master5
Date Posted: October 20, 2006 at 12:47 AM

***Side note.  Some of you should check out that JBL link. It looks like I wrote it...lol

well at least what I would have wrote a few days ago.

Peace everyone.



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