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  • Subwoofer reaching its xmax

    Ive built a vented box for my subwoofer, its a Dayton audio rss315hf-4, being powered with a no boost 300w amp, the box itself is 77L, tuned for 23.7hz/-3dbx, and has a 36×3.3×79cm vent. The project turned out very well, since the subwoofer is able to deliver punchy and deep bass. Only one thing about the final product is bothering me, the subwoofer will, sometimes, pop when there is an explosion or something, I'm pretty sure this is made because the sub is trespassing its xmax and therefore the voice coil is touching the magnet's end. Does anyone know how to fix this?
    thank's in advance

  • #2
    Probably need a high pass filter. Below resonance a bass reflex port is just a hole in the box. The cone motion is uncontrolled.
    Francis

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    • #3
      (turn it down a bit?)

      At 300w RMS that driver should stay below Xmax until the freq. drops down to 19Hz or below. MOST "plate amps" will have a high-pass filter somewhere in the 20-30Hz range to help reduce/prevent this type of issue.

      Are you running this amp flat out (we're talkin' 110dB here)?
      More likely the amp clipping? (Or some mech. issue w/the driver - like V.C. lead "slapping"?)

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      • #4
        I experienced a similar issue some time ago with a 10" driver in a vented box. I suspected that the "pop" was caused by the spider not exercising enough control over the motion of the cone and voice-coil former, allowing it to hit the back plate of the magnet. The only "solution" was to use it in a 4th order BP alignment instead - the small sealed volume and higher Fb provided more control over the speaker's cone.

        I'd be actually surprised if the RSS HF subs' design allows this to happen however. Still, I'd be tempted to just try that driver in the suggested sealed box to see if the popping issue still happens.
        Brian Steele
        www.diysubwoofers.org

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        • #5
          Originally posted by Chris Roemer View Post
          (turn it down a bit?)

          At 300w RMS that driver should stay below Xmax until the freq. drops down to 19Hz or below. MOST "plate amps" will have a high-pass filter somewhere in the 20-30Hz range to help reduce/prevent this type of issue.

          Are you running this amp flat out (we're talkin' 110dB here)?
          More likely the amp clipping? (Or some mech. issue w/the driver - like V.C. lead "slapping"?)
          Well, according to what I read online, the young sd300 plate amp has a hpf in 30hz.
          I often turn it down too, then the problem disappears, I'm wondering if there's a way of fixing it without loosing SPL.
          I'm not sure what you mean by running it flat out, could you explain?

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          • #6
            Originally posted by Brian Steele View Post
            I experienced a similar issue some time ago with a 10" driver in a vented box. I suspected that the "pop" was caused by the spider not exercising enough control over the motion of the cone and voice-coil former, allowing it to hit the back plate of the magnet. The only "solution" was to use it in a 4th order BP alignment instead - the small sealed volume and higher Fb provided more control over the speaker's cone.

            I'd be actually surprised if the RSS HF subs' design allows this to happen however. Still, I'd be tempted to just try that driver in the suggested sealed box to see if the popping issue still happens.
            It sure is strange, unfortunately mdf wood is very expensive where I live, specially because i haven't got a buzz saw, so I need to order it cut. I'm afraid I'm stuck with my current design.

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            • #7
              I'm also considering the possibility that this is caused by a distorted signal coming from the movie source. I find very strange that I can play something very heavy, such as bass i lover you, at max volume, without experiencing this pop, while a simple explosion does it. Could that be it?

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              • #8
                Originally posted by Subnoob2002 View Post
                I'm also considering the possibility that this is caused by a distorted signal coming from the movie source. I find very strange that I can play something very heavy, such as bass i lover you, at max volume, without experiencing this pop, while a simple explosion does it. Could that be it?
                I don't think that distorted signal may be a reason for it..Try using it in 4th order BPF as someone suggested above.4th order BPF will make it very much clear and also distortion free mybkexperience
                Last edited by Jerry250; 03-13-2019, 02:41 AM.

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                • #9
                  My suggestion would be to incorporate eq into your application, however you can, get it done. Then you can ring out your system with a test tone, at desired volume, looking for the frequencies that over exert your woofer. You might end up moving the high pass filter higher, you might end up with a high/low pass shelf to reduce everything lower then 35hz, you may end up with a -3db dip at at 30hz, etc etc but either way you will be able to customize your subs response to taste without loosing gain in a total sense. A minidsp is the first option that comes to mind but if you can find another way to implement an eq betwwen the source signal and the subs amp....problem fixed.
                  Last edited by camplo; 03-12-2019, 01:32 PM.

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                  • #10
                    Dynamic EQ would be a better solution for that approach, if MiniDSP offers that ability.
                    Brian Steele
                    www.diysubwoofers.org

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                    • #11
                      To say Dynamic EQ is a better solution but not to offer a product that actually uses dynamic eq, makes no sense. And yes Dynamic eq is a , slightly, better, solution, but the only way, I personally, would know how to get such, into a signal chain, is by literally, buying a hardware dynamic eq, which no one is going to do for this issue, cheapest one I see on ebay is 2 grand......or using the software that allows you to run vst plugins at system level, on a computer, to which, TDR nova's free version would be about perfect. Thats leaning on the idea that he is using a computer for the signal source. It would add latency to the signal but maybe not too much to care.

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