Underpowering can damage a speaker?

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.

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.

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.

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.

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.