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    I just picked up a great deal from PE. Celestion 18-190X 18" sub 4ohm. Just did it, no need, no reason..just didit! Question now is what do I do with it?
    I think a vented box is good but I have no idea on the vent size. 3.5 cuft is a small cab for an 18"! Any help appreciated! B52 folded horn seems to be the cab it was built for. Any plans?

    Gary
    Getting better!:D

  • #2
    A 6"id port 3" long yields an F3 near 50Hz I think.
    3 - 4"ports (each 6" long) would be equivalent, but w/lower port velocity.

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    • #3
      Where do I find a 6" wide port? Can a slot port work?.
      Thank you for your help. I want to make this for a DJ rig for small parties. Like to get good bass at reasonable volume.
      Getting better!:D

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      • #4
        Originally posted by garychelette View Post
        Can a slot port work?.


        A slot port is actually becoming preferred in some situations as I've read the boards and project outcomes over the last several years. Slots can eliminate chuff / noise / velocity better than typical ports (including flared), and can use internal walls as part of their design (an add further strength to the cabinet by breaking panels into smaller sections pushing resonance outside the woofer FR) and slots can help be alternatives when it's physically impossible to use a tube to reach super deep F3 where there's not enough room for the tubing.

        It's also been fun watching more folks becoming more open minded toward the use of passive radiators as the middle ground between sealed and ports over time.

        It's because they solve several issues as just outlined related to ports in general, especially difficult or complex internal cabinet design and construction considerations - they're just easier to implement and they can absolutely significantly extend bass response beyond sealed just by tuning with added mass.

        Options.
        Feel free to rip my assumptions apart when wrong, or fix if close.

        Passive Radiators:
        All PR(s) Vd must at-least double all woofer(s) Vd. Calc = Sd x Xmax to get Vd for all PR(s) and all woofer(s). If all PR(s) Vd at-least double all woofer(s) Vd they'll work.
        For woofer(s) with large Xmax vs Sd, all PR(s) with Xmax at-least double all woofer(s) Xmax will work.
        A PR max weight is said to be its Mms x3

        PR Systems - tight focus with key parameters.
        PR Speaker Design - thorough coverage.

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        • #5
          Originally posted by garychelette View Post
          Where do I find a 6" wide port? ...
          PVC Sch. 40 DWV pipe

          "Not a Speaker Designer - Not even on the Internet"
          “Pride is your greatest enemy, humility is your greatest friend.”
          "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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          • #6
            The B52 folded horn looks a bit like the CV EL36 cabinet. I modelled the driver in an EL36, and output looks pretty good for a horn, particularly if used in a stack of 4, which will get you down to 40 Hz. A Google search should bring up the schematics for an EL36.

            IMO your best use for this driver would be based on exactly what it is that you're trying to achieve.

            If small and loud, but nothing below 50 Hz, the suggested vented cabinet might work (but I'd go with an MLTL arrangement like my POC design (which just so happens to be a 48 Hz box - http://www.diysubwoofers.org/projects/other/POC6/) so midbass response doesn't suffer due to the use of a large vent).

            If you are Ok with a larger box to get down to 40 Hz, but don't might giving up a few dB in output, then a BP6 or TH might work.

            If you want both loud and low, then not much choice - big box like the EL36
            Brian Steele
            www.diysubwoofers.org

            Comment


            • #7
              I was able to come up with one or two TH alignments that get down to 40 Hz with this driver. Box size around 10 cu.ft. net, so they are a bit bigger, but hey, over 100 dB with 2.83V of input and capable of doing 40 Hz .

              I wouldn't attempt to build one of these things though before confirming the t/s parameters for that driver and measuring its "semi-inductance" parameters as well. There's an issue with the PE-quoted parameters as Sd is clearly too small for an 18" driver. Have you got a DATS or another means of taking those measurements?
              Brian Steele
              www.diysubwoofers.org

              Comment


              • #8
                Originally posted by Brian Steele View Post
                Sd is clearly too small for an 18" driver.
                Move the decimal point one digit to the right.

                www.billfitzmaurice.com
                www.billfitzmaurice.info/forum

                Comment


                • #9
                  Originally posted by billfitzmaurice View Post
                  Move the decimal point one digit to the right.
                  I thought so to, and used that in my sims. But at 1046.3 cm^2, it still seems a bit.. small for an 18" driver. It;'s usually closer to 1200 cm^2.
                  Brian Steele
                  www.diysubwoofers.org

                  Comment


                  • #10
                    Boy, if you can be satisfied w/50Hz (in 3.5cf), why go bigger?

                    Most of the time, slots get used when a "small" box (NOT 3.5cf) is trying to be tuned quite low (NOT in the 50s). In THIS case (a large box w/higher tuning) you have the opposite challenge. make the port too small (like a single 4") and you end up w/a length less than the thickness of the cab wall ! (Then, just keep upping the number of ports - or their diameters, until you get a length at least as long as your wall thickness.)

                    All you need here is a 2" long hunk of 6" id PVC plumbing pipe (possibly a bit longer - depending on where you loss pass it).
                    (Also, I found a "reasonable" value for Sd on a diff. site, of 1034 sq.cm. Still seems small-ish though.)

                    Comment


                    • #11
                      Originally posted by Brian Steele View Post
                      at 1046.3 cm^2, it still seems a bit.. small for an 18" driver.
                      When you run it the Mms comes out as it should, so it's got to be right.
                      www.billfitzmaurice.com
                      www.billfitzmaurice.info/forum

                      Comment


                      • #12
                        Originally posted by Chris Roemer View Post
                        Boy, if you can be satisfied w/50Hz (in 3.5cf), why go bigger?

                        Most of the time, slots get used when a "small" box (NOT 3.5cf) is trying to be tuned quite low (NOT in the 50s). In THIS case (a large box w/higher tuning) you have the opposite challenge. make the port too small (like a single 4") and you end up w/a length less than the thickness of the cab wall ! (Then, just keep upping the number of ports - or their diameters, until you get a length at least as long as your wall thickness.)

                        All you need here is a 2" long hunk of 6" id PVC plumbing pipe (possibly a bit longer - depending on where you loss pass it).
                        (Also, I found a "reasonable" value for Sd on a diff. site, of 1034 sq.cm. Still seems small-ish though.)
                        Thank you. It maybe that simple. A 3.5 CuFt w/ 6"id x 2" port
                        Gary
                        Getting better!:D

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