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Lab 15 Subwoofer Build - New Guy - Advise Appreciated

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  • #16
    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

    Originally posted by isaeagle4031 View Post
    My personal plan for them is a 5cube section of 24" sonotube tuned to about 28-30hz. 150-200hz LP. That is only about 20 internal. F3/6/10 of 27/23/20 no eq, no ssf.
    That's really not that big. I figure as long as I'm getting into the 20s with decent volume overhead, I should be happy.
    Would you use the woofer downfiring?

    I think I hear a difference - wow, it's amazing!" Ethan Winer: audio myths
    "As God is my witness I'll never be without a good pair of speakers!" Scarlett O'Hara

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    • #17
      Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

      Originally posted by donradick View Post
      That's really not that big. I figure as long as I'm getting into the 20s with decent volume overhead, I should be happy.
      Would you use the woofer downfiring?
      Nope front. With a 12" section of pvc loaded with a 10 above it.
      https://www.facebook.com/Mosaic-Audi...7373763888294/

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      • #18
        Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

        QVF - .51, 3.3cf, 34?

        For me, it goes to 8.2 cf, tuned to 26. F3 a smidge lower.

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        • #19
          Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

          Originally posted by donradick View Post
          Bill, I'd build one of your TTs and be done with it, but it's too big for my room.
          No matter, it will only take an eight or ten. I designed my T60 specifically for the LAB 15, and it works extremely well, as any owner will tell you. At 28 cu ft you won't see many of them out there, but interestingly most of those who do use them have at least four. :eek:

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          • #20
            Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

            Wow, Thank everyone for the time you've taken to help me understand my situation. I suspected there would be a mismatch but nothing like I'm discovering. Hum, ditch the Lab 15's or ditch the enclosures. Any additional ideas would be appreciated. Thanks Guys.

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            • #21
              Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

              Originally posted by doctormorbius View Post
              They should be fine for music, just not so much for home theater.
              I rechecked Unibox, and the Lab15 looks fine for music, which is def my concern.
              3 foot ^3 vented gives an F3 of 22, and it just barely exceeds xmax at 26 Hz and 106 dB.
              Last edited by donradick; 12-22-2014, 06:35 AM. Reason: removed sig

              I think I hear a difference - wow, it's amazing!" Ethan Winer: audio myths
              "As God is my witness I'll never be without a good pair of speakers!" Scarlett O'Hara

              High value, high quality RS150/TB28-537SH bookshelf - TARGAS NLA!
              SB13/Vifa BC25SC06 MTM DCR Galeons-SB13-MTM
              My Voxel min sub Yet-another-Voxel-build

              Tangband W6-sub

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              • #22
                Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

                TOM ! - your "spec sheet" you posted (which LOOKS like it's from 2014) is most likely NOT the set of specs most of these guys are giving you advice on. The "standard" Lab 15 driver (that PE sells and that I see today on the Eminence site) is rated at "6 ohms" (nominal) and is pretty "low Q" (with a Qts value of 0.35). YOUR specs (you attached) SEEM like they're for a nominal "4 ohm" driver and have a Qts value that's MUCH higher, at 0.51, and will require the MUCH LARGER box I was recommending.

                You might not have (or know anyone who has) a "Woofer Tester", or DATS, but you should be able to tell WHICH Q version of this driver you have (if, in fact, there ARE 2 versions). If the ones you bought off Ebay (or wherever) are the high Q version (like your posted specs), then a $3 Digital Multimeter (like from Harbor Freight) should read a DC resistance (through the voice coil - the driver's terminals) near 5 ohms (the spec is 4.9). The driver that's got a lower Q (and that should work fine in a 3 cf box) should read closer to 4 ohms (3.7 or 3.8 ohms).

                The lower Q ddriver (0.35 Qts - that's on PE's site) should reach 30Hz in a 3cf box using a pair of 4"id x 20" long port tubes.

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                • #23
                  Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

                  Originally posted by Chris Roemer View Post
                  TOM ! - your "spec sheet" you posted (which LOOKS like it's from 2014) is most likely NOT the set of specs most of these guys are giving you advice on. The "standard" Lab 15 driver (that PE sells and that I see today on the Eminence site) is rated at "6 ohms" (nominal) and is pretty "low Q" (with a Qts value of 0.35). YOUR specs (you attached) SEEM like they're for a nominal "4 ohm" driver and have a Qts value that's MUCH higher, at 0.51, and will require the MUCH LARGER box I was recommending.

                  You might not have (or know anyone who has) a "Woofer Tester", or DATS, but you should be able to tell WHICH Q version of this driver you have (if, in fact, there ARE 2 versions). If the ones you bought off Ebay (or wherever) are the high Q version (like your posted specs), then a $3 Digital Multimeter (like from Harbor Freight) should read a DC resistance (through the voice coil - the driver's terminals) near 5 ohms (the spec is 4.9). The driver that's got a lower Q (and that should work fine in a 3 cf box) should read closer to 4 ohms (3.7 or 3.8 ohms).

                  The lower Q ddriver (0.35 Qts - that's on PE's site) should reach 30Hz in a 3cf box using a pair of 4"id x 20" long port tubes.
                  There was a limited buy not too long ago for LAB15's that were not the typical spec. I imagine he has that model.

                  Later,
                  Wolf
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                  • #24
                    Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

                    Yep that's what he's got. I also have verified that the specs are correct. Mine measured within 2-3% on all.
                    https://www.facebook.com/Mosaic-Audi...7373763888294/

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                    • #25
                      Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

                      I did order the special run of 4 ohm lab 15 which have been described. If that is true, is it also true what Chris says about using the speaker in the 3 cf box using a pair of 20"x4" ports?

                      If so that would really be a life saver for me

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                      • #26
                        Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

                        In the 3 cube enclosure (gross) with a pair of 4"d x 20"l ports, is a tuning of 33hz with f3/6/10 of 38/31/25. On 500w, xmax is exceeded at about 25Hz.
                        https://www.facebook.com/Mosaic-Audi...7373763888294/

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                        • #27
                          Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

                          Originally posted by isaeagle4031 View Post
                          In the 3 cube enclosure (gross) with a pair of 4"d x 20"l ports, is a tuning of 33hz with f3/6/10 of 38/31/25. On 500w, xmax is exceeded at about 25Hz.
                          Yep, I just can't get around that xmax problem. :eek: -- so I took a another look at the problem, and found that if I could live with 106 dB, I'd stay within xmax.

                          Chuck, both you and Chris are showing F3 of 30 or more,
                          I'm getting F3 of 22 or so in 3 cf (doubled checked the driver parameters.)
                          Click image for larger version

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                          I think I hear a difference - wow, it's amazing!" Ethan Winer: audio myths
                          "As God is my witness I'll never be without a good pair of speakers!" Scarlett O'Hara

                          High value, high quality RS150/TB28-537SH bookshelf - TARGAS NLA!
                          SB13/Vifa BC25SC06 MTM DCR Galeons-SB13-MTM
                          My Voxel min sub Yet-another-Voxel-build

                          Tangband W6-sub

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                          • #28
                            Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

                            Don are you sure you have 3 cubes entered? The 109L Vb equates to 6.75 cubes doesn't it? So if I am reading that right, would equate to what I am getting in WBCD. In 6.71 cubes net with 2 4"x12" ports equates to a 26Hz Fb and f3/6/10 of 22/20/19.
                            https://www.facebook.com/Mosaic-Audi...7373763888294/

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                            • #29
                              Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

                              Originally posted by isaeagle4031 View Post
                              Don are you sure you have 3 cubes entered? The 109L Vb equates to 6.75 cubes doesn't it? So if I am reading that right, would equate to what I am getting in WBCD. In 6.71 cubes net with 2 4"x12" ports equates to a 26Hz Fb and f3/6/10 of 22/20/19.
                              sheesh <strikes forehead with hand> I was using <ahem> a different constant..... Thanks. Things don't look quite so rosy now!

                              I think I hear a difference - wow, it's amazing!" Ethan Winer: audio myths
                              "As God is my witness I'll never be without a good pair of speakers!" Scarlett O'Hara

                              High value, high quality RS150/TB28-537SH bookshelf - TARGAS NLA!
                              SB13/Vifa BC25SC06 MTM DCR Galeons-SB13-MTM
                              My Voxel min sub Yet-another-Voxel-build

                              Tangband W6-sub

                              Comment


                              • #30
                                Re: Lab 15 Subwoofer Build - New Guy - Advise Appreciated

                                Originally posted by donradick View Post
                                sheesh <strikes forehead with hand> I was using <ahem> a different constant..... Thanks. Things don't look quite so rosy now!
                                LOL. Got your back my friend
                                https://www.facebook.com/Mosaic-Audi...7373763888294/

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