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Underpowering Speaker/sub Test (simple test)

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  • Underpowering Speaker/sub Test (simple test)

    Ok it made me too upset so i did a little test on my own today.

    SI Mag 12"
    SA70 Plate Amp 4 ohms: amp does 70 watts but i chose to give ~30ish watts to severely underpower it
    16awg speaker/conductor wire
    iPod video 60GB black
    ROE - 45HZ Track (looped)
    camera used was a JVC DV500 (for stationary video) & a Canon SD1000 for photos and 2nd clip
    1.5 sheet of Second Skin Damplifier (to stop rattling :P

    3hrs 6min 23sec and some
    speed up by 50k% to 22 seconds
    each frame is about 15seconds

    foam ball falls off for 30min, i didnt realize it, footage moves to fast to show it being placed back on, i can provide footage of my bro putting foam ball back on by request

    Foam ball just shows movement of sub







    captured in real time to hdd, real footage ended up being like 46gb, I should have cleared hdd some more to do longer testing


    just to monitor it that i am gettting video signa




    its on basket to stay elevated and not to block chamber vent for proper cooling




    This just shows proof that i did indeed try it
    Broadcast Your Audio System - CarAudioClips.com


    After: put back in my box at ~800 plays fine and dandy, no problems what so ever.
    Broadcast Your Audio System - CarAudioClips.com

    its fine


    Mythbusted!



    some might say that i put my sub at risk by underpowering , i was very confident, reason i did it.


    simple test i know, but that sums it up well
    screen name here use to be MegaloRESE15"

  • #2
    I just don't get what your test shows. Was the audio signal clipped?

    I ask because my understanding of under powering causing speaker harm occurs when one trys to use too small an amplifier and driving it into clipping to get the volume up to desired levels. Clipping changes the duty cycle of the speaker from that of a sine wave to something approaching a square wave (or from say 70% to near 100%). The damage caused is from overheating due to clipping, not absolute power levels.

    Comment


    • #3
      it's not really under powering it that makes you put the sub at risk; rather it's not having enough power and trying to increase the spl by increasing the gain on your amp. that's what is commonly to referred to as risking damage by under powering a sub. :-)
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      • #4
        Originally posted by lbridges View Post
        I just don't get what your test shows. Was the audio signal clipped?

        I ask because my understanding of under powering causing speaker harm occurs when one trys to use too small an amplifier and driving it into clipping to get the volume up to desired levels. Clipping changes the duty cycle of the speaker from that of a sine wave to something approaching a square wave (or from say 70% to near 100%). The damage caused is from overheating due to clipping, not absolute power levels.

        no the audio was not clipped. thats the point.

        underpowering a driver will not kill it. When you give a clipped signal thats when things start going "byebye"
        screen name here use to be MegaloRESE15"

        Comment


        • #5
          I have been professionally designing speaker enclosures for more than 15 years and I am constantly annoyed by the confusion that surrounds this topic. The problems with busting the myths that surround this are that you can not rely on either the rated power out put of the amplifier or the thermal limitations of the sub. In the real world both of these specifications are at the mercy of a number of variables. You can measure the out put of the amplifier in order to eliminate that variable but you must understand that the speaker has been rated by approximation. You can play it at RMS power indefinitely but any thing over that for an extended period of time may lead to enough heat to cause thermal melt down. A common misconception is that this only happens at the speakers max rating. Not true. That’s a fact.
          The next but not least significant element is the speakers suspension. Even if the speaker is underpowered and never reaches its thermal limitations it can still easily be damaged due to over excursion. Excursion is not a direct result of input power and dose not necessarily result in more output. Also a fact.
          And not even close to least, most manufacturers build subs with obese inefficient motors and then under rate the thermal limitations. Think about it if you where a manufacturer with millions on the line what would you do?
          The problem here is not the manufacturers approach, it’s the testing approach. Lets say that you feed a 500 watt sub 800 watts in a .25 cubic foot sealed enclosure for 10 hours and nothing happens. You haven’t proved anything. That sub might be able to take 850 watts for 9.5 hours before melting down. The point is that you don’t know if the sub is under rated, or over rated, or if your amplifiers particular design causes unexpected levels of heat in the clipping stage. You cant prove anything in a test like this with out accounting for every variable. And the day that I see some one with the resources and the time to write a 20 page report on the definitive answer to this topic I will have to point out that they have one hundred thousand amplifier/sub combos left to test not to mention the sub/enclosure combinations and that they have effectively proved nothing.
          If you want to be safe stick to the numbers and power your speakers with the RMS rating. If you want to push the edge of performance you take the risk of exceeding the thermal limitations of your speakers. If you have an education in speaker design you can predict and push the limitations to new levels and only blow something up once in a while. Its life deal with it!

          Comment


          • #6
            Question it has nothing to do with your testing

            But does this woofer always sound that way, I don't see the point in moving air and annoying noises, that does not complement the music to my ears, or was this also to make a point in your testing.

            Comment


            • #7
              Originally posted by ca55e5a View Post
              Question it has nothing to do with your testing

              But does this woofer always sound that way, I don't see the point in moving air and annoying noises, that does not complement the music to my ears, or was this also to make a point in your testing.
              noises you heard in 2nd clip were trunk rattles

              Originally posted by speakermakers View Post
              I have been professionally designing speaker enclosures for more than 15 years and I am constantly annoyed by the confusion that surrounds this topic. The problems with busting the myths that surround this are that you can not rely on either the rated power out put of the amplifier or the thermal limitations of the sub. In the real world both of these specifications are at the mercy of a number of variables. You can measure the out put of the amplifier in order to eliminate that variable but you must understand that the speaker has been rated by approximation. You can play it at RMS power indefinitely but any thing over that for an extended period of time may lead to enough heat to cause thermal melt down. A common misconception is that this only happens at the speakers max rating. Not true. That’s a fact.
              The next but not least significant element is the speakers suspension. Even if the speaker is underpowered and never reaches its thermal limitations it can still easily be damaged due to over excursion. Excursion is not a direct result of input power and dose not necessarily result in more output. Also a fact.
              And not even close to least, most manufacturers build subs with obese inefficient motors and then under rate the thermal limitations. Think about it if you where a manufacturer with millions on the line what would you do?
              The problem here is not the manufacturers approach, it’s the testing approach. Lets say that you feed a 500 watt sub 800 watts in a .25 cubic foot sealed enclosure for 10 hours and nothing happens. You haven’t proved anything. That sub might be able to take 850 watts for 9.5 hours before melting down. The point is that you don’t know if the sub is under rated, or over rated, or if your amplifiers particular design causes unexpected levels of heat in the clipping stage. You cant prove anything in a test like this with out accounting for every variable. And the day that I see some one with the resources and the time to write a 20 page report on the definitive answer to this topic I will have to point out that they have one hundred thousand amplifier/sub combos left to test not to mention the sub/enclosure combinations and that they have effectively proved nothing.
              If you want to be safe stick to the numbers and power your speakers with the RMS rating. If you want to push the edge of performance you take the risk of exceeding the thermal limitations of your speakers. If you have an education in speaker design you can predict and push the limitations to new levels and only blow something up once in a while. Its life deal with it!


              again in simpler words

              as long as the signal is clean and doesnt effect mechanical performance, like cooling, then it will not blow from underpowering.

              if the signal had been clipped it would drive the driver to its thermal limits a bit faster and then start to get "smelly"
              screen name here use to be MegaloRESE15"

              Comment


              • #8
                Not trying to be an *** here, but there is one even simpler way to think about it...

                Q: If a speaker could be killed with too little power, then everytime you turn your volume down then your speakers would run the risk of death?

                A: No.

                If you really want to discuss power delivery to a speaker I suggest doing some math and look at the difference between the power associated with a sine wave vs a square wave.

                The problem with too little power, is that a PERSON attempts to correct for this by getting more out of the amp in effect clipping the output. The difference in power of a sine wave (what manufacturers use to rate power) vs a square wave (clipped signal) is larger then you may think . It's all about duty cycle.
                System always under construction


                Comment


                • #9
                  Originally posted by durwood View Post
                  Not trying to be an *** here, but there is one even simpler way to think about it...

                  Q: If a speaker could be killed with too little power, then everytime you turn your volume down then your speakers would run the risk of death?

                  A: No.

                  If you really want to discuss power delivery to a speaker I suggest doing some math and look at the difference between the power associated with a sine wave vs a square wave.

                  The problem with too little power, is that a PERSON attempts to correct for this by getting more out of the amp in effect clipping the output. The difference in power of a sine wave (what manufacturers use to rate power) vs a square wave (clipped signal) is larger then you may think . It's all about duty cycle.
                  duwood you arent being rude at all
                  i have thought about all those things. But on another forum i was criticized and name called "idiot" for even mentioning that. they all thought i was high and mighty. when i was just pointing out the "obvious". argument was that can Underpowering a sub cause damage, answer is no, clipping will cause damage

                  so i took it to the next level. witht that Footage i did yesterday, I dont like to brag but it thought that video idea was brilliant. sorry enough with being all high and mighty now :

                  if you seriously want to know why i was upset in did that test heres the thread with the argument, the admin is childish IMO i tried to speak respectfully and factually(if thats a word as possible) in that thread /rant

                  http://www.stevemeadedesigns.com/boa...howtopic=11241
                  screen name here use to be MegaloRESE15"

                  Comment


                  • #10
                    By the way I failed to mention that I think that your test here was a nice scientific, common sense type approach that you executed very well. And you are absolutely right.

                    Comment


                    • #11
                      Originally posted by speakermakers View Post
                      By the way I failed to mention that I think that your test here was a nice scientific, common sense type approach that you executed very well. And you are absolutely right.
                      thank you.


                      I tried debating some more over there but some people just dont get it when it comes to a technical level. I described how a clipped signal becomes a square wave and the harmonics with it carry more power than a standard sine wave, which is the reason a driver will heat up quicker.

                      As long as you dont send a clipped signal to driver and you are within thermal limits, you should(will) be fine



                      actually here is a 45hz extremely clipped signal
                      http://media.putfile.com/45hz-clpped

                      If i had used the same track on the test i did(my particular exact setup) nothing would have happened...to the sub atleast.

                      The amp is capable of 70watts rms I was only giving 30watts to sub. even with the clipping lets say(to make it easier) that a square wave uses double the power than a sine wave. so for that 30watts and playing that track the amp would "try" to produce 60watts because of that particular signal. either way i am within the amp's limit(might have gotten warmer) and I am COMPLETELY within the Mag's(sub) thermal limit(i have gave this sub 1600+ watts before on music, but average 800watts daily)...i know watts isnt necessarily heat but you get the idea.


                      now had i used a more powerful amp like a 500+watt amp then i could see the mag get damaged some.

                      just goes to show that as long as you are within thermal limits of a driver it wont take damage...no matter how bad it sounds
                      screen name here use to be MegaloRESE15"

                      Comment


                      • #12
                        Originally posted by Megalomaniac View Post
                        if you seriously want to know why i was upset in did that test heres the thread with the argument, the admin is childish IMO i tried to speak respectfully and factually(if thats a word as possible) in that thread /rant

                        http://www.stevemeadedesigns.com/boa...howtopic=11241
                        geez, and he is a moderator over there? Yikes! Well in his case, there is so much more going on with enclosures. There are many reason you could blow up a subwoofer, too little power on it's own will not destroy a subwoofer. I know he says he had a properly designed box, but there are so many other factors.

                        A sub has a thermal power rating. That does not take into account mechanical limitations. Kipple testing can find those limitations. Also, never rely on a subwoofer box program to tell you power limitations. The only one I have seen that will show you if you exceed mechanical excusion limits of a subwoofer in a given box design (IF published specs are correct) is a program called "unibox".

                        Those guys that believe underpowering a sub can destroy it would be eaten alive at DIYMA. It sucks to see mis-info being passed around and its hard to convert people who believe so strongly in something when they don't understand all the limiting factors at work.
                        System always under construction


                        Comment


                        • #13
                          Originally posted by durwood View Post
                          geez, and he is a moderator over there? Yikes! Well in his case, there is so much more going on with enclosures. There are many reason you could blow up a subwoofer, too little power on it's own will not destroy a subwoofer. I know he says he had a properly designed box, but there are so many other factors.

                          A sub has a thermal power rating. That does not take into account mechanical limitations. Kipple testing can find those limitations. Also, never rely on a subwoofer box program to tell you power limitations. The only one I have seen that will show you if you exceed mechanical excusion limits of a subwoofer in a given box design (IF published specs are correct) is a program called "unibox".

                          Those guys that believe underpowering a sub can destroy it would be eaten alive at DIYMA. It sucks to see mis-info being passed around and its hard to convert people who believe so strongly in something when they don't understand all the limiting factors at work.
                          I agree. I dread be a mod over there now i got soo much hate from them. But whats funny is the guy(admin) didnt expect me to go out and test it out that made him furious...I got a pm from him you can see what he wrote first and how i responded. the guy backtracked way too much all of a sudden.





                          very rude admin
                          screen name here use to be MegaloRESE15"

                          Comment


                          • #14
                            this is funny..this arguement is still going on between people 15 years after the "mainstreaming" of the high excursion / over excusion proof sub.

                            i dealt with these kind of yoyo's 15 years ago....its getting like people arguing over supercharger or turbo....(never ending for no reason)

                            Megalo and Dur obviously know what they are talking about...

                            there is you true proof....underpowering will not blow a sub...otherwise you wouldn't be allowed to turn it down!!!!!!!!!!

                            also.... am I the onlu one noticing the rediculous exaggerations about peak vs rms???
                            or did they just start making amps so crappy they cant keep peek to double (ish)??

                            i have allways underpowered..why .....its cheaper.....i dont crank it even then....

                            I used to say you can blow any speaker with a 10 watt amp....
                            as long as you turn it up all the way.

                            same goe's for the inverse...you really can't blow any speaker with the matched wattage appropriotly setup and not turned up...a...la...
                            100 watt sub rms, 100 watt amp rms, 30% gain rms, 30 % volume rms, new alternator and battery.
                            well you can but it's awful hard to do..

                            he I torched a 1500 watt sub with 2 milli-watts before.....it was an electric start lighter!!
                            30,000 volts!!!! yaaaaa lol...
                            06 Altima..SER front bumper.
                            CAR PC.....soon to be true!!
                            Oshawa Canada!!

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