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Adapt a 6x9 mount to take 8" sub... good idea?

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  • Adapt a 6x9 mount to take 8" sub... good idea?

    My rear Fosgate 3 way 6x9's in my Buick century finally died. I have some nice Focal poly-glass components in the front doors, and never liked the "rear fill" from full range in the back.
    I am thinking about using MDF to fabricate an adapter to mount 2 8" subs to cutoff at 80hz.

    I will be driving them with this amp

    Any suggestions for a driver for this purpose?
    My projects
    https://picasaweb.google.com/112307725038877176664

  • #2
    Re: Adapt a 6x9 mount to take 8" sub... good idea?

    Tough crowd.
    My projects
    https://picasaweb.google.com/112307725038877176664

    Comment


    • #3
      Re: Adapt a 6x9 mount to take 8" sub... good idea?

      I think it's a good idea and shouldn't be too hard to pull off.

      I don't really know for sure which of PE's 8" drivers would work well in free air, but having pushed on the cone of these, they feel very stiffly suspended:

      http://www.parts-express.com/pe/show...number=264-854

      They might work well in a free air application, but it's just a guess. Really it's not a request that shows up here very often.

      Hopefully those with more experience with free-air implementations will chime in.

      TomZ
      Zarbo Audio Projects Youtube Channel: https://www.youtube.com/channel/UCEZ...aFQSTl6NdOwgxQ * 320-641 Amp Review Youtube: https://youtu.be/ugjfcI5p6m0 *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
      *Part 2 *Gluing multiple curved laminations of HDF

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      • #4
        Re: Adapt a 6x9 mount to take 8" sub... good idea?

        It should work fine, the W8-740P 8" has a low qts(.30) so would probably benefit from eq. Tang band has also made a couple 6x9 woofers for that application.
        http://www.parts-express.com/pe/show...number=264-837

        Are you planning to run these only as low as 80 hz or starting at 80 hz and below?

        Comment


        • #5
          Re: Adapt a 6x9 mount to take 8" sub... good idea?

          80hz low pass.

          I considered the Tangband 6x9 sub, but it looks like it would require modification anyway, since its not really oval, its rectangular, with rounded ends.
          My projects
          https://picasaweb.google.com/112307725038877176664

          Comment


          • #6
            Re: Adapt a 6x9 mount to take 8" sub... good idea?

            I did exactly what you are proposing in the rear deck of a 1996 chevy lumina a few years back. I used a pair of 8"ers that were similar in specification to the Dayton Classic 8" with 50W per channel. They sounded great! Not the deepest lows, but very satisfying.

            -David

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            • #7
              Re: Adapt a 6x9 mount to take 8" sub... good idea?

              I did the same thing, 8"ers in the rear deck. I removed the trunk springs running across the under side on the deck and replaced with struts from the floor. This allowed me to mount a baffle across the bottom of the rear deck to mount the subs below the OEM openings. Next I bought some Vifa woofers made for a large ported enclosure. Then I made aperiodic membrane above the drivers. Basically just 1/4" chicken wire with FG insulation sandwiched between it. You tune how much it damps the driver by how much FG is in the aperiodic membrane.
              A mains
              The Ventures
              Open Invit8tions
              RSR
              Sound Troopers
              Acorns
              442
              DGBG's
              The Monuments

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              • #8
                Re: Adapt a 6x9 mount to take 8" sub... good idea?

                I do have a Dayton SD215 laying around has an "extra" for my Triska project. Would this driver perform well in basically IB environment, (trunk)?
                My projects
                https://picasaweb.google.com/112307725038877176664

                Comment


                • #9
                  Re: Adapt a 6x9 mount to take 8" sub... good idea?

                  Another option which I've used in the past is a bandpass box ported through the rear deck. The port could extend out of the box up to the rear deck. Bandpass setup can provide added 'oomph' of desired frequencies while naturally rolling off higher after the bandpass.

                  Easily enough a 6x9 speaker grill could be placed over both openings for a finished look. A single 8 or 10" speaker in a properly designed bandpass box will provide some good and low bass for cheap. I know this isn't what you're attempting, but it may provide an alternative solution to your bass needs. Heck, even a few 6.5" subs would excel in this setup. Just a thought.

                  TomZ
                  Zarbo Audio Projects Youtube Channel: https://www.youtube.com/channel/UCEZ...aFQSTl6NdOwgxQ * 320-641 Amp Review Youtube: https://youtu.be/ugjfcI5p6m0 *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
                  *Part 2 *Gluing multiple curved laminations of HDF

                  Comment


                  • #10
                    Re: Adapt a 6x9 mount to take 8" sub... good idea?

                    It's not technically "free air" until you open the trunk :D I'm guessing anything with a stiff suspension would work fine. With the cabin gain factored in, it wouldn't have to be anything super low. Six of these might do the trick. Just build a long shallow box that mounts under the deck lid, leave enough room for the drivers to breath through the factory cutouts, and let em hang free, venting the rear into the trunk. The 12ohms impedance should be good for wiring them all in parallel to 2ohms, so you'll get the most power from that amp. It should also give you enough extra SPL to add a bit of eq if needed. And if you buy more than 4 the price drops to $10.88.
                    My modest builds:
                    Armadillo TM, A.K.A. Lil' Dillo
                    Tarkus/Armadillo build #2
                    Armadillo Center Channel
                    Au-Rock-O Sub
                    Tarkus
                    Staining MDF tutorial

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                    • #11
                      Re: Adapt a 6x9 mount to take 8" sub... good idea?

                      You could do a 10 or 12 through each opening and would be fine provided you had enough deck space to mount them.

                      8s IB wouldn't get you a lot of umph down low.

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                      • #12
                        Re: Adapt a 6x9 mount to take 8" sub... good idea?

                        The SD215 has similar parameters to the speakers I used, but with more xmax and a bit less sensitivity. I don't know if one will be suitable for your needs, but it couldn't hurt to try it out to get a feel for how it sounds. You can add a second one if the first works out.

                        -David

                        Comment


                        • #13
                          Re: Adapt a 6x9 mount to take 8" sub... good idea?

                          Originally posted by bolland83 View Post
                          It's not technically "free air" until you open the trunk :D I'm guessing anything with a stiff suspension would work fine. With the cabin gain factored in, it wouldn't have to be anything super low. Six of these might do the trick. Just build a long shallow box that mounts under the deck lid, leave enough room for the drivers to breath through the factory cutouts, and let em hang free, venting the rear into the trunk. The 12ohms impedance should be good for wiring them all in parallel to 2ohms, so you'll get the most power from that amp. It should also give you enough extra SPL to add a bit of eq if needed. And if you buy more than 4 the price drops to $10.88.
                          Very intriguing idea!

                          My amp is 2 ohm stable, so this should be interesting.
                          My projects
                          https://picasaweb.google.com/112307725038877176664

                          Comment


                          • #14
                            Re: Adapt a 6x9 mount to take 8" sub... good idea?

                            And a waste of money.

                            IB displacement is king. You limited to just buying at PE?

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                            • #15
                              Re: Adapt a 6x9 mount to take 8" sub... good idea?

                              For 70 bux I would get a new JBL G5 10" and hae a ton more displacement than those buyout 6s.

                              And I bet if you searched hard enough you could find a pair of said JBL 10s for a touch over $100.

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