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Aura NS6-255 and Vifa BC25SC TM

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  • Aura NS6-255 and Vifa BC25SC TM

    Thanks to many patient gurus here who have helped me with many aspects of simulation and modeling. I found some cheap drivers, the Aura NS6-255-8A mid-woofer and the Vifa BC25SC06-04 tweeter. Since everyone seems to need to name their creations, I dub them AURBACS. Here is the first test box, about 14 liters, ported - Unibox predicted about a 63 Hz F3, which would make them good for HT surrounds. A crossover cobbled together from my junk box sounded pretty good, so the final design was a go.

    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

  • #2
    Re: Aura NS6-255 and Vifa BC25SC TM

    I really liked the basic sound of the drivers, but frankly, the bass was a disappointment. Not sure whether I had messed up the box tuning, but Unibox predicted a F3 of 43 Hz with a slightly larger box. That sounded more like it!

    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


    • #3
      Re: Aura NS6-255 and Vifa BC25SC TM

      Awesome.

      I am glad to see this project finalized. Your work on this build is much appreciated.

      Comment


      • #4
        Re: Aura NS6-255 and Vifa BC25SC TM

        you can import the frd file to unibox in the "active filter" section or w/e and get a better idea as to the bass response.

        रेतुर्न तो थे स्रोत
        return to the source
        leviathan system thread
        deadhorse thread
        shockwave build thread

        instagram :: greywarden_13

        in war, victory . . . in peace, vigilance . . . in death, sacrifice.

        Comment


        • #5
          Re: Aura NS6-255 and Vifa BC25SC TM

          The "final" box was constructed of 1/2 inch red oak faced plywood from Lowes. In retrospect, not a great choice, but I didn't want to drive 30 miles round trip to buy baltic birch. (Not to self, next time, make the drive!) Outside box dimensions are 16H x 11.5D x 9.5W, yielding a .84 ft ^3 inside volume. Since the box was a bit too big for 1/2 inch, I added several braces, and a lip of 3/4 inch ply to attach a removable 3/4 inch baffle. Port is 2 inch inside diameter PVC and 4 5/8 inch long. Unibox complained a bit about port air speed, but I knew that I was not going to play them very loud.
          Last edited by donradick; 04-25-2011, 06:45 PM. Reason: corrected port length

          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


          • #6
            Re: Aura NS6-255 and Vifa BC25SC TM

            Originally posted by greywarden View Post
            you can import the frd file to unibox in the "active filter" section or w/e and get a better idea as to the bass response.
            Sorry, Grey, I have NO idea what you are talking about!

            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


            • #7
              Re: Aura NS6-255 and Vifa BC25SC TM

              I'm sort of proud of this - the most clamps I've ever used.


              I used corner clamps and brad nails to secure the basic box. Not real satisfied - the pieces still shifted a bit, and the wood filler is still visible after finishing.

              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


              • #8
                Re: Aura NS6-255 and Vifa BC25SC TM

                Finished boxes came out all right - I'd decided that I wanted a black baffle with light sides and top. Used a 3/4 inch ply for the baffle, and (per LouC), hit it with sanding sealer, Krylon satin black, and Krylon satin clear. Sides were finished with a couple of coats of Deft satin.


                Here you can see the imperfect match of the brad nails with generic wood filler.


                My wife was SO kind, she said they were very beautiful, that she didn't know I could make something so perfect. (aaawww....)

                UPDATED BAFFLE PLACEMENT INFORMATION:

                One of these days, I should post a nice drawing. For now, this is what I built:
                Overall baffle dimensions: 9 1/2 W X 16 H
                NS6 woofer: centered left to right (4 3/4 inches), center of woofer is 9 inches from the bottom of the baffle.

                Vifa BC25 tweeter: 14 inches from bottom of the baffle to center of the tweeter, tweeter center is offset left of right of baffle center by 1 1/4 inches (mirrored offset per pair). Or you can think of it as the edge of the tweeter is about 5/8 down from the top, and about 1 7/8 in from the respective left or right baffle edge.

                Port is centered left to right on the pack, center of hole is about 4 5/8 down from the top of the box.
                Last edited by donradick; 03-07-2012, 02:44 AM. Reason: added drive placement on baffle.

                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


                • #9
                  Re: Aura NS6-255 and Vifa BC25SC TM

                  I learned a TON about simulation and modeling on this - thanks once again to Jeff Bagby, Wolf, and Paul Carmody. Here are the PCD screen shots with all the details. I went through many crossover revisions - finally settled on stock values as much as possible, and played with the resistors in the "legs" to get a decent frequency response and good phase matching. I found that as little as .1 ohm would really affect the null. I finally got a 50 dB null, and decided that was as good as it gets.

                  Null actually goes to 50 dB. I really don't notice the slight bobble around 1-4 K, and the bass does not sound like it drops - which is probably due to imperfect BSC modeling on my part.


                  Woofer crossover and low pass


                  Tweeter crossover and high pass


                  Filter transfer functions


                  System Impedance

                  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


                  • #10
                    Re: Aura NS6-255 and Vifa BC25SC TM

                    Crossover bill of materials (Parts Express) for a pair:


                    The final BOM should have:
                    Qty 2 1.20 mH 18 guage
                    Qty 2 .20 mH 20 gauge

                    A crossover schematic:


                    And a pic of the finished crossover:


                    (I paralleled a 1.0 and 1.2 to get .57 for R12)
                    Last edited by donradick; 09-26-2012, 11:31 PM. Reason: corrected BOM crossover

                    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


                    • #11
                      Re: Aura NS6-255 and Vifa BC25SC TM

                      Subjective eval -
                      Very good bass, clear and balanced mids, clear highs, with dynamite imaging both side to side and back to front. Well exceeded expectations for $100 a pair. I tried playing with the tweeter level several times, and never wanted more, but I felt highs were a bit recessed when I cut them down a bit.

                      I'd post measurements, but I'm having trouble getting reasonable results from my hardware at this time. The sims correlate well with what I am hearing.

                      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


                      • #12
                        Re: Aura NS6-255 and Vifa BC25SC TM

                        Nice work Don. its good to see that a build like this can be had for Just under a hundred bucks.

                        I like it so much that I'll be building me a pair in natural 5/8" baltic birch in the near future.

                        By the way my Karma Indignias are done. I'll post pics pretty soon.

                        Comment


                        • #13
                          Re: Aura NS6-255 and Vifa BC25SC TM

                          Nice design. I can finally see everything!

                          I actually ended up getting the parts I needed for nearly the same price from erse audio even having to run 6uf and 1.5uf caps in parallel for the 7.5uf component. The crossover parts ended up costing $47 per speaker including shipping and I used their Pulse-X caps. I ordered enough parts for 3 pairs of these.

                          My brother-in-law is building these as his first set of speakers. Prior to this, he's never used a table saw, a router, a dremel a soldering iron, or even seen a crossover diagram.

                          Boxes for this design are 19L, 8" wide x 16" tall x 14" deep. Should be a 5.75" port length for a 43hz F3 as you mentioned in our emails.

                          I'll get some pictures up of how we're doing as soon as I get a chance.
                          Modding the Lepai T-Amp

                          Comment


                          • #14
                            Re: Aura NS6-255 and Vifa BC25SC TM

                            Wow, Don, that's a nice design. The finish on your cabs looks great, and I like the contrast of the black baffle. Well done!

                            Comment


                            • #15
                              Re: Aura NS6-255 and Vifa BC25SC TM

                              Wow the GRS from Johnny and this one are $4 different on the BoM! Sounds like a "sound-off" to me! :D

                              I noticed that in the test box, the tweeter was centered, and in the final it's offset, is that going to affect the FR any?

                              रेतुर्न तो थे स्रोत
                              return to the source
                              leviathan system thread
                              deadhorse thread
                              shockwave build thread

                              instagram :: greywarden_13

                              in war, victory . . . in peace, vigilance . . . in death, sacrifice.

                              Comment

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