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TB/SB, an active compact(ish) 3-way using the Tang Band W6-1139SIF

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  • TB/SB, an active compact(ish) 3-way using the Tang Band W6-1139SIF

    So here’s a project I’m about to wrap up. I wanted to build something around the Tang Band W6-1139SIF. Fun little driver, but anyone who has played with the models knows it needs a really long port.

    I decided to build a modestly priced and reasonably compact active 3-way around it. I already have the active gear, so it was just a question of materials.

    The bulk of the detail is available on my Flickr: https://flic.kr/s/aHskzTwXMV





    Here’s that little Tang Band driver:



    I used the free version of Sketchup to design the cabinets. All of the drawings and measurements are on the above Flickr album.

    It was a really helpful tool in this case as I really wanted to get into the smallest possible box incorporating the really long port that the TB driver needs.

    The resulting design is really efficient on space with the only unused volume being the tweeter box. I had thought of keeping that volume for the woofer and reducing the overall box size, but the size reduction wasn’t really worth the effort of the design changes.

    Here’s a taste of the design:







    The woofer portion of the cabinet is .375 ft3 tuned to 37Hz



    I opted for a slot port to deal with the length issues that come with this woofer. The dimensions I settled on are: .75” tall, 7.5” wide by 27.5” long.

    This fits nicely in the cabinet with one 90 degree turn and very little wasted space. The apsect ratio isn’t ideal, but this is a bit of an experiment…




    Port velocity (this is with 40 watts) stays under 12m/s





    Midrange duty is handled by a 4” SB Acoustics SB12MNRX25-4:



    The WinISD model shows a QTC of .723 in a .061 ft3 sealed box:




    Here are the internal dimensions of the midrange box:



    Tweeter is the respected SB Acoustics SB29RDC-C00-4:





    The cabinet is constructed from .75” Baltic Birch. Note that the drawing dimensions are for a full .75” thickness. In reality Baltic Birch isn’t quite .75”. I had to do a tiny bit of adjusting to keep everything in line, but no big deal.



    Starting to take shape:





    The baffles are 1.5” thick Beech butcher block and some Sapele for color. I ripped it all on the table saw, glued it up and planed it flat:







    I’ve taken to inlaying hardwood in the cabinet corners. They end up being much more resistant to bump damage and I think they look nicer, too. It’s minimal effort, so even when I think this is the build I don’t bother with them I end up doing it anyway:







    I cut the driver recess holes on the Bridgeport with a big Troyke rotarty table:







    I went back and forth on how to cut the skinny rectangular port hole in the front baffle. I decided on marking really accurate lines and hogging most of the wood out with a forstner bit. I'll use a long flush trim bit in the router table later.







    Given the amount of air the little TB driver moves and my less than ideal port dimensions (too rectangular) I rounded over all of the edges I could to avoid port noise:



    I had some leftover quarter round molding so I added some aero. Just like formula one, kid. No idea if this makes any difference, but I try to avoid sharp edges on port parts.




    That's kind of it for now. On to measuring and testing but my initial impression is favorable. There's a lot of low end coming out of these relatively small boxes. Not sure how flat they'll end up measuring and I expect to have some EQ work to do on the woofer, but I don't intend to mix or master with these. They'll likely live in the workshop. Fun project.

    I should have the MiniDSP files (I use a 4x10HD) available at some point if anyone is interested...

    Thanks for looking!


  • #2
    That is a great looking speaker.
    I have a few of those subs and want to buils something with them at some future point, but will have to be passive for me ;-)
    Great job.
    Andy.

    Comment


    • #3
      Do you have an impedance curve measurement for that bass driver in that slot-ported enclosure?
      Brian Steele
      www.diysubwoofers.org

      Comment


      • #4
        They came out really nice Mike.
        I love that speaker recess tool..... Um, I mean milling machine!
        They came out great.

        Once you get these dialed in, I'd love to hear about your thoughts on the slot port and if things worked out as you intended/what changes you may have considered making if you did it again.
        I love the effort, it's a great looking speaker!

        TomZ
        *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 *Cello's Speaker Project Page

        *Building the "Micro-B 2.1 Plate Amplifier -- Part 1 * Part 2 * Part 3 * Part 4 * * Part 5 'Review' * -- Assembly Instructions PDF

        Comment


        • #5
          WinISD will do a simmed Z-plot (unless you want to know how close he hit his tuning?).

          Comment


          • #6
            Originally posted by Brian Steele View Post
            Do you have an impedance curve measurement for that bass driver in that slot-ported enclosure?

            Hi Brian. I've read a bunch of your site over the years. Thanks for posting. My first thought on reading your question was "uh-oh..."

            Here's what I've got. Impedance is well below 2 ohms at the tuning frequency. Hmph...
            I played with a bunch of different variations on the box volume, port shape, length, etc and with the exception of a sealed box I consistently get real low impedance.

            For what it's worth (if anything) I'm driving with a Rotel RMB-1066



            Last edited by TrickyMike; 01-20-2018, 09:18 AM.

            Comment


            • #7
              If THAT's "WinISD", I'll wager that your T/S parms table has an "Re" value of (near) zero !
              Put in 3.6ohms and you'll prob'ly have a Z-min more like 4.5ohms.

              Comment


              • #8
                Thanks. Yeah, I saw .9 ohms and thought "Holy sh*t!"

                So, Chris, it looks like you were right about the Re value in the T/S parameters. Thanks again. It was 0.00. I changed it to 3.6ohms and here's what I've got:

                Last edited by TrickyMike; 01-20-2018, 02:16 PM.

                Comment


                • #9
                  VERY nice looking build, BTW.

                  Comment


                  • #10
                    Thanks guys!

                    Comment


                    • #11
                      Beautiful woodwork! Wish I had those skills!
                      Projects:

                      Breezy Monitors: http://techtalk.parts-express.com/fo...reezy-monitors
                      transcenD: http://techtalk.parts-express.com/fo...5035-transcend
                      Summits: http://techtalk.parts-express.com/sh...75-The-Summits
                      References: http://techtalk.parts-express.com/sh...-My-References
                      Vintage Style 2-way: http://techtalk.parts-express.com/sh...-vintage-2-way

                      Comment


                      • #12
                        Originally posted by TrickyMike View Post
                        Thanks. Yeah, I saw .9 ohms and thought "Holy sh*t!"

                        So, Chris, it looks like you were right about the Re value in the T/S parameters. Thanks again. It was 0.00. I changed it to 3.6ohms and here's what I've got:

                        ​That looks like a simulated impedance curve. What does the actual impedance curve look like? Have you measured it?
                        Brian Steele
                        www.diysubwoofers.org

                        Comment


                        • #13
                          Originally posted by Brian Steele View Post

                          ​That looks like a simulated impedance curve. What does the actual impedance curve look like? Have you measured it?
                          It is. Not yet.

                          Comment


                          • #14
                            Originally posted by Chris Roemer View Post
                            WinISD will do a simmed Z-plot (unless you want to know how close he hit his tuning?).
                            I was thinking more about potential noise issues and chuffing, but also how close the actual tuning/impedance ended up being compared to predicted.
                            As you know, I've had a failure or two with slot vents and obviously need to learn a bit more about how they work in real life. This vent is .75" high and quite long with lots of surface area so I'm curious how it came out.

                            TomZ
                            *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 *Cello's Speaker Project Page

                            *Building the "Micro-B 2.1 Plate Amplifier -- Part 1 * Part 2 * Part 3 * Part 4 * * Part 5 'Review' * -- Assembly Instructions PDF

                            Comment


                            • #15
                              Yeah, the port is a bit of an experiment, to be honest. I kind of just wanted to see what I could get away with. Jury's still out on that as I'm waiting on a Dayton DATS I ordered, but I can at least talk about port noise in the meantime.

                              I did get a little bit of chuffing before I rounded over the exit, but only with one reference track at full power (Yonce/Partition by Beyonce: https://www.youtube.com/watch?v=IsVE8zwld28 ). The noise was slight.

                              After I rounded the edges (3/4") I wasn't able to reproduce the chuffing. Maybe fixed? I dunno.
                              I'm unlikely to be listening to that type of track (the song has a distinct low frequency sweep... down to maybe 20-25Hz?) at full power.

                              I've had them in my office all week and haven't noticed any port noise at all.


                              Comment

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