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Ported and Sealed designs for Dayton RSS315 HF

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  • Ported and Sealed designs for Dayton RSS315 HF

    Hi eveyone,

    I think I am going to build both (not finished, just MDF to try them both out) and see which sounds better and works better with my room.

    I am "wasting" $40 on MDF for whichever one I don't use, but not a big deal, and will be interesting to hear the difference between them.

    For the sealed design, I have heard there are many tried and tested 2-3 cubic feet designs out there, and that what was recommended to me by many people. So I built an 18" cube, which will net out about 2.2 cubic feet after bracing, driver displacement, etc.

    Now for the ported design I'm looking for a bit of feedback here. I am told 4 cubes is pretty good for this driver, however, WinISD is telling me 5 cubes give me an F3 of 20 Hz, which would be awesome. The sub will be going into a nook in the room and will be completely out of sight (blocked by tv and stand) so I have freedom to have a large box.

    According to WinISD a 16" wide x 1.5" high x 28" long slot port gives me good air flow under 17 m/s. Cone excursion may be a problem under 20 Hz but the BASH500 i am using has a built in HPF at 18 Hz I believe, so hopefully that's fine.

    Just wanted to get feedback from the smart folks on this forum regarding the ported design. Theoretically or practically (i.e. if you have built ported with this driver before).

    Many thanks in advance!

    Spectre

  • #2
    Subbed - I'm following.
    Sausage With Meat Sause, Please

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    • #3
      I was not impressed with my 12" hf in the 2cf or 3cf cabinet sealed. If you want the 20hz stuff go ported.
      My Build Thread's
      Carrera's / Finalist TL's / Speedster TMM's / Speedster MTM Center / Overnight Sensation Surrounds

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      • #4
        It works in 4 ported, it works in 5 ported. There's a small difference in power handling, with the smaller box obviously handling a little more power around 30hz. And there's a very small difference in the F3. A 4 cube box will make it to about 20.7, the 5 cube something like 19.8. Not a difference that you're going to hear or feel. So decide whether you want to give up the extra floor space. A 5 cubic foot box isn't easy to hide in the room, but a 4 cube isn't a lot better, really.

        Assuming that the box tunings are about the same, the port(s) will be easier to fit in the 5 cubic foot box than the 4. So there's that.
        nothing can stop me now

        Comment


        • #5
          Originally posted by Dirk View Post
          It works in 4 ported, it works in 5 ported. There's a small difference in power handling, with the smaller box obviously handling a little more power around 30hz. And there's a very small difference in the F3. A 4 cube box will make it to about 20.7, the 5 cube something like 19.8. Not a difference that you're going to hear or feel. So decide whether you want to give up the extra floor space. A 5 cubic foot box isn't easy to hide in the room, but a 4 cube isn't a lot better, really.

          Assuming that the box tunings are about the same, the port(s) will be easier to fit in the 5 cubic foot box than the 4. So there's that.
          Thanks. It sounds like I'm splitting hairs here.

          The room is about 13x9 feet, however, there is a 6x3 nook in the back of the room (previous owner of the house had a computer desk there) so the sub will most likely go there. The room is also my mini man cave so I'm not bothered about a big sub being visible either if I decide to place it elsewhere.

          I'll probably just build the 5 cubes since the port is easier to fit.

          Another question I had was regarding driver and port orientation. If I build a rectangular box, is it okay if the driver is on the long side and the port on the shorter side? I've only ever seen subs with the port on either the same face as the driver or the opposite face. Does it make any difference for air flow?

          The reason I ask if because if I decide to place the sub behind the couch I want the driver facing the couch for a better tactile feel.

          Comment


          • #6
            The port can pretty much go on any face. If it opens near a wall, or the floor though, that will affect the tuning.
            Francis

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            • #7
              Another note about the port: slot ports benefit from flaring, or at least a roundover, just like tubular ports.
              Francis

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              • #8
                I wonder what placing the sub in the nook will do?

                Comment


                • #9
                  Originally posted by Spectre View Post
                  Hi eveyone,

                  I think I am going to build both (not finished, just MDF to try them both out) and see which sounds better and works better with my room.

                  I am "wasting" $40 on MDF for whichever one I don't use, but not a big deal, and will be interesting to hear the difference between them.

                  For the sealed design, I have heard there are many tried and tested 2-3 cubic feet designs out there, and that what was recommended to me by many people. So I built an 18" cube, which will net out about 2.2 cubic feet after bracing, driver displacement, etc.

                  Now for the ported design I'm looking for a bit of feedback here. I am told 4 cubes is pretty good for this driver, however, WinISD is telling me 5 cubes give me an F3 of 20 Hz, which would be awesome. The sub will be going into a nook in the room and will be completely out of sight (blocked by tv and stand) so I have freedom to have a large box.

                  According to WinISD a 16" wide x 1.5" high x 28" long slot port gives me good air flow under 17 m/s. Cone excursion may be a problem under 20 Hz but the BASH500 i am using has a built in HPF at 18 Hz I believe, so hopefully that's fine.

                  Just wanted to get feedback from the smart folks on this forum regarding the ported design. Theoretically or practically (i.e. if you have built ported with this driver before).

                  Many thanks in advance!

                  Spectre
                  So the equivalent round port would be about 5.5 dia?

                  Comment


                  • #10
                    Originally posted by Spectre View Post

                    Another question I had was regarding driver and port orientation. If I build a rectangular box, is it okay if the driver is on the long side and the port on the shorter side? I've only ever seen subs with the port on either the same face as the driver or the opposite face. Does it make any difference for air flow?
                    It does not matter. The only thing you need to do is make sure that there's plenty of "breathing room" on both ends of the port. The "rule of thumb" is clearance equal to the diameter. For example, if the port is 4", then there should be at least 4" of clearance between the port opening and the back wall. If it is near obstructions, then the obstruction serves as "more port wall" and extends the effective length of the port and you'll get a tuning lower than you would have otherwise intended.
                    nothing can stop me now

                    Comment


                    • #11
                      Regarding placing the sub in the nook, my last sub (that I sold) was a CSS SDX10 ported and it seemed to make everything louder and have more impact. I'm hoping it can do the same for this build but only one way to find out.

                      Originally posted by johngalt47 View Post

                      So the equivalent round port would be about 5.5” dia?
                      Not sure? I just put a rectangular port into winISD.


                      Okay so how does that work if my port is 16x1.5? Does that mean it needs to be 16" away from a wall? That's obviously not possible, but just wanted to understand.

                      Comment


                      • #12
                        Assuming the 4ohm version, are your T/S parms up to date? I could see WinISD liking 4-5 cubes w/the old specs (Q quite a bit higher, at 0.49), but w/the current specs (Qts = 0.39) Win picks a box quite a bit under that.

                        IMO, I never cared for THAT Bash's default boost, it's not much (+2dB?), but it's not "low", either. IIRC it's a lot closer to 40Hz than 20. I don't see the issues you do at high power. The driver's only rated at a thermal limit of 400 RMS - don't really see any problems down to 20Hz at 400w.

                        If I dial in an HP filter (to your mains) at 60Hz, and add +2dB of boost at 40, the closed box only runs down into the mid 30s, w/max output around 45Hz (not really very low, my 8" mains go that low . . . heck, my NanoNeos (4" woofers) probably go lower than that.

                        In 5cf (net !), w/your port (which SEEMs long to me), they play into the upper teens. Max output is still arund 40Hz, but at 20 it's only down -1dB.

                        My rec. using the new specs, 5cf gross, Fc near 60Hz, and +2.3dB @ 36Hz for the B500 boost, would be to make your slot 20" long (Fb = 23). The "bump" at 36Hz is minimized, and there's no excursion trouble @270w RMS down to the F3 at 21Hz (over 110dB).

                        Comment


                        • #13
                          Originally posted by Spectre View Post
                          Regarding placing the sub in the nook, my last sub (that I sold) was a CSS SDX10 ported and it seemed to make everything louder and have more impact. I'm hoping it can do the same for this build but only one way to find out.



                          Not sure? I just put a rectangular port into winISD.


                          Okay so how does that work if my port is 16x1.5? Does that mean it needs to be 16" away from a wall? That's obviously not possible, but just wanted to understand.

                          You'd be ok with ~6in from the rear wall. The port velocity will still be nearly identical to a cylindrical port of the same cross sectional area. I would probably shrink the aspect ratio to 9:1 ratio or lower if it were me.

                          Comment


                          • #14
                            Originally posted by Chris Roemer View Post
                            Assuming the 4ohm version, are your T/S parms up to date? I could see WinISD liking 4-5 cubes w/the old specs (Q quite a bit higher, at 0.49), but w/the current specs (Qts = 0.39) Win picks a box quite a bit under that.

                            IMO, I never cared for THAT Bash's default boost, it's not much (+2dB?), but it's not "low", either. IIRC it's a lot closer to 40Hz than 20. I don't see the issues you do at high power. The driver's only rated at a thermal limit of 400 RMS - don't really see any problems down to 20Hz at 400w.

                            If I dial in an HP filter (to your mains) at 60Hz, and add +2dB of boost at 40, the closed box only runs down into the mid 30s, w/max output around 45Hz (not really very low, my 8" mains go that low . . . heck, my NanoNeos (4" woofers) probably go lower than that.

                            In 5cf (net !), w/your port (which SEEMs long to me), they play into the upper teens. Max output is still arund 40Hz, but at 20 it's only down -1dB.

                            My rec. using the new specs, 5cf gross, Fc near 60Hz, and +2.3dB @ 36Hz for the B500 boost, would be to make your slot 20" long (Fb = 23). The "bump" at 36Hz is minimized, and there's no excursion trouble @270w RMS down to the F3 at 21Hz (over 110dB).

                            Hey there. I have the 8 ohm version. Long story, but I will eventually be getting another driver and will hook them both up to the BASH500 to get the total power out of the amp.

                            I made sure I input the TS parameters correctly again. After I add a butterworth HPF at 18 Hz and input signal of 300 W (which is the power I'd get at 8 ohms for now until I add the second driver), I get:

                            Sealed, 2.3 cubes with an F3 of 38 Hz
                            Ported, 4.95 cubes tuned to 20 Hz.

                            Cone excursion looks pretty good (see image). However, with the suggested 4" diameter x 14" length circular port, air velocity is really high.The best I can figure out is 11"x2" slot port, would have to be 26" long and would keep air flow at 17 m/s max (at 20 Hz). 17 is generally the goal to avoid noise right?

                            Let me know if I'm off with anything here. I hope the images help.














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                            • #15
                              That is correct as per the "rule of thumb" that is usually a pretty good estimate. Also keep in mind that using a slot port can significantly reduce required vent length if you use 3 enclosure walls as part of the port's 4 walls. The end correction factor ends up picking up A LOT of slack. One of my super old ported boxes for my JBL W10GTi is tuned to~32Hz when it "should" be tuned about 10 Hz or so higher, due to me using a slot port using 3 of the enclosure walls as the port's walls.

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