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  • clipping amp kills woofer?

    Several places recently I have read it stated that an amp driven into clipping may damage or destroy a woofer or subwoofer, it being implied that an amp with greater current capacity at the same drive level would be fine.

    This does not make sense to me. I am aware of the spectrum shift that occurs with a clipped signal and the danger this poses to higher frequency drivers, but I think a clipped signal would drive less power into a woofer, because its impedance rises with frequency.

    Is there some woofer-killing amp instability that coincides with clipping that I am unaware of?

  • #2
    Re: clipping amp kills woofer?

    From past experience, most of the blown car woofers we sold were paired with gutless amps presumed to be throwing square waves (clipped signal) at their downstream partners. Those who had good big amps had a much lower percentage of problems. In home audio, the kids who bought 35 watt receivers damaged more stuff than those with good separates. In both instances there also might be a correlation between caring enough about your gear to turn it down at the first sign of distress and caring for your ears and doing the same thing
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    • #3
      Re: clipping amp kills woofer?

      When an ampl clips a signal, you are basically putting maximum DC voltage out which overheats the voice coils.

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      • #4
        Re: clipping amp kills woofer?

        Originally posted by Mr. Wizard View Post
        Is there some woofer-killing amp instability that coincides with clipping that I am unaware of?
        No. Clipping doesn't kill woofers, overpowering does.
        When an ampl clips a signal, you are basically putting maximum DC voltage out which overheats the voice coils
        Absolutely positively false. Read this:
        http://billfitzmaurice.info/forum/vi...hp?f=10&t=1886
        www.billfitzmaurice.com
        www.billfitzmaurice.info/forum

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        • #5
          Re: clipping amp kills woofer?

          Yes, severe clipping of a signal by an amplifier can cause the voice coil of a woofer to overheat. Some clipping is generally not a problem (except to your ears, of course).

          Here's a real nice explanation:
          http://www.bcae1.com/
          Go to page 29 called "Too little power."

          I like it when he says:
          "You should remember:
          1.Idiots blow speakers, not low power."

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          • #6
            Re: clipping amp kills woofer?

            It's simple really, an amp driven into clipping will deliver more than it's rated power.. sometimes a little more and sometimes a lot, and if that exceeds the power handling of the attached speakers and the system is operated this way long enough the speakers will be damaged. High frequency drivers may only survive seconds when being overpowered while woofers may take hours to destroy, but they all fail for the same reason.. from being overpowered.
            Paul O

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            • #7
              Re: clipping amp kills woofer?

              Originally posted by billfitzmaurice View Post
              Absolutely positively false. Read this:
              http://billfitzmaurice.info/forum/vi...hp?f=10&t=1886
              I stand corrected. Thanks for the information. It's funny how many times I have heard/read that myth.

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              • #8
                Re: clipping amp kills woofer?

                Originally posted by Mr. Wizard View Post
                Several places recently I have read it stated that an amp driven into clipping may damage or destroy a woofer or subwoofer, it being implied that an amp with greater current capacity at the same drive level would be fine.

                This does not make sense to me. I am aware of the spectrum shift that occurs with a clipped signal and the danger this poses to higher frequency drivers, but I think a clipped signal would drive less power into a woofer, because its impedance rises with frequency.

                Is there some woofer-killing amp instability that coincides with clipping that I am unaware of?
                If the amp is of lower design quality, under clipping conditions, it may be doing so unsymmetrically, imparting a DC component, not a large one, but perhaps enough to cause heating on top of the other harmonics being introduced.

                I find it unfathomable that a 100W amp could blow a 500W woofer, unless the amp failed to one rail, and even then . . .
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                • #9
                  Re: clipping amp kills woofer?

                  http://www.audiovisualdevices.com.au...ne/note128.pdf

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                  • #10
                    Re: clipping amp kills woofer?

                    Originally posted by superbrew View Post
                    I stand corrected. Thanks for the information. It's funny how many times I have heard/read that myth.
                    It more or less originated with this:
                    http://www.jblpro.com/pub/technote/lowpower.pdf

                    Unfortunately more than a few readers of the JBL document overlooked the key phrase high frequency components. So as with most myths it started off with basis in fact but with each retelling the facts became less and less important until they disappeared entirely.
                    www.billfitzmaurice.com
                    www.billfitzmaurice.info/forum

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                    • #11
                      Re: clipping amp kills woofer?

                      Originally posted by Mr. Wizard View Post
                      Several places recently I have read it stated that an amp driven into clipping may damage or destroy a woofer or subwoofer, it being implied that an amp with greater current capacity at the same drive level would be fine.
                      Close, but no cigar.
                      The truth is an amp driven into clipping will most likely destroy a TWEETER!

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                      • #12
                        Re: clipping amp kills woofer?

                        Thank you all. I have been away from Audio for seven years, and undoubtedly new discoveries have been made in that time, so I didn't want to dismiss the claims outright.

                        Pete, how much asymmetry are you talking about? I suppose there could be an over-excursion risk on vented designs if it is large enough.

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                        • #13
                          Originally posted by View Post
                          Re: clipping amp kills woofer?


                          Close, but no cigar.
                          The truth is an amp driven into clipping will most likely destroy a TWEETER!
                          most true in a passive filtered speaker. However, while mids, and especially woofers are more tolerant, sooner or later clipping WILL take them all down. Further a 50 watt amp can blow a 500W speaker faster than 5K watt amp.
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                          • #14
                            Originally posted by gp4Jesus View Post
                            . Further a 50 watt amp can blow a 500W speaker faster than 5K watt amp.
                            Sorry but that is preposterous.
                            Paul O

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                            • #15
                              Originally posted by marscoast View Post
                              Re: clipping amp kills woofer?

                              Yes, severe clipping of a signal by an amplifier can cause the voice coil of a woofer to overheat. Some clipping is generally not a problem (except to your ears, of course).

                              Here's a real nice explanation:
                              http://www.bcae1.com/
                              Go to page 29 called "Too little power."

                              I like it when he says:
                              "You should remember:
                              1.Idiots blow speakers, not low power."
                              ​Yup, that explanation sounds the best so far.

                              Direct link: http://www.bcae1.com/2ltlpwr.htm
                              Brian Steele
                              www.diysubwoofers.org

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