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Inherited a NHT SW10mkII sub

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  • Inherited a NHT SW10mkII sub

    Inherited a NHT SW10mkII today. A guy I do work for said it had a blown driver and had tossed it in the dumpster. Scratched it up some but I can fix that pretty easily. It looks to be about 1.25cf before driver volume. Plate amp is rated at 150w. Could I make a RSS265HF work or should I look for a different driver? The original driver had a steel frame, it would be nice to give it something a little better. Sent from my XT1710-02 using Tapatalk

  • #2
    The choice of a new woofer will be better if we know the exact box size and port dimensions (if any). Post those and we can make a much better recomendation. The RSS265HF is nice (I have one and use it everyday), but it's in a 2 cu. ft. ported box.
    -Bob
    -Bob

    The PEDS 2.1 mini system
    My A7 Project - another small desktop speaker
    The B3 Hybrid Dipole - thread incomplete and outdated

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    • #3
      Does that amp have any boost, or is it "flat"?

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      • #4
        I found a user's manual online:
        https://www.manualslib.com/manual/11...?page=8#manual
        ​It shows that it is indeed 1.25 cu ft. The vent diameter is not shown, but using the pictures on the cover, it looks like its maybe 2.5" in diameter, but there is no way to determine the length. It also has a "boundary EQ" switch which is some kind of selectable, switchable boost. Set that to 0db to start with.

        That said, I would recommend the RSS265HO rather than the HF version. The HO version will work very well in that 1.25 cu ft box with a 2.5"X15" port to tune it to 25 hz. Here is the response with an 80 hz low pass:
        Click image for larger version

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        ​So if you can extend the vent to 15" with an elbow, if needed, you could get a sub that's flat to below 30 and an F3 of 24Hz. That is great performance from a relatively small 1.25 cu ft box.
        -Bob

        The PEDS 2.1 mini system
        My A7 Project - another small desktop speaker
        The B3 Hybrid Dipole - thread incomplete and outdated

        Comment


        • #5
          The port is 3" in diameter,10 1/4" ling with long tapered round overs on both ends. I could use the plate and build a box to fit the hf driver. Not having heard them I don't know how much difference there is between the two. This will primarily be used for music.

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          • #6
            Its good that its a 3" vent because its easier to modify using regular plumbing fittings from your local big box store. The box "as is" is tuned to about 36 hz which is a bit high in my opinion but you might like it depending on your music preferences. Its gives you a 3 to 6 db peak around 40 with a lot of sub drivers. This is quite OK since that is what a lot of people like. It sells best because it is immediately impressive for home theater or rap/dubstep/techno music, but is maybe not optimally tuned for a wide variety of music. The 265HO is still at the top if the list, but will require a vent about twice as long as what is there to prevent the peak at 40 and get the response down into the 20s.

            ​The 265HF is designed for larger, home boxes. The 265HO was, I think, originally intended for car subs, so it was designed for smaller boxes that could fit more easily in a trunk. That's really the only difference. You give up a few hertz in LF extension, but get a much more compact build. If you want to use your existing box, get the HO version.

            ​From a quick model using a 100 hz low pass filter, here are the choices so far:
            ​Blue: 265HF in the existing box with existing port, peaks at 50 hz
            ​Green: 265HO in the existing box with existing port, small peak at 40 hz
            ​Red: 265HO in the existing box but with an extended 18" port, slight peak at just over 30 hz

            Click image for larger version

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            ​So try a 265HO without modifying the box and see how you like it. Use the Boundary EQ switch as needed. I am guessing that it is designed to boost or cut around 35 or 40 hz. If you still want more LF extension, then consider modifying the port to 18" to 22" long.


            ​-Bob






            -Bob

            The PEDS 2.1 mini system
            My A7 Project - another small desktop speaker
            The B3 Hybrid Dipole - thread incomplete and outdated

            Comment


            • #7
              I think that box is too small for that woofer (unless you go sealed w/boost, +5dB @ 37Hz looks pretty good).
              Also, a 10" sub (w/gobs of Xmax) really likes a 4"id port, although a 3" "Precision Port" should suffice. (2-1/2" should chuff like crazy)

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              • #8
                Hi Chris,
                The models above were run at 100 watts and if I remember, port velocities were under 25m/s and xmax was not a problem. You and I might do it a little different, but this is case where I didn't want the perfect to be the enemy of the good. Run the numbers. I was trying to use what was available in the most effective manner I could. A 6db peak at 40 hz sounds pretty good and there is an easy remedy to lengthen the port if the OP wants a better, flatter alignment.
                -Bob
                -Bob

                The PEDS 2.1 mini system
                My A7 Project - another small desktop speaker
                The B3 Hybrid Dipole - thread incomplete and outdated

                Comment


                • #9
                  Thanks for all of the input. I will probably try the ho with the extended port. I prefer a flatter sound over all. I believe the switch flattens the out put for music and gives it a little boost for movies. After I fix it I may even offer it back to the guy who gave it to me. He gives me plenty of work and his theater really needs a decent sub. Sent from my XT1710-02 using Tapatalk

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