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Project Code Name BILC

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  • Project Code Name BILC

    This will be my first personal project in a long time. I was planning to get started this summer and then my son was born 5 weeks early and kind of threw things off. I’m calling this project BILC, which stands for Because It Looks Cool. This design uses four, 4” bass drivers (Dayton Audio ND105-4) per side, one 4” midrange (Peerless 830870 HDS PPB), and one 1” tweeter (Tang Band 25-1744S) so it is going to be a tower of drivers! And who doesn’t think that looks cool?




    Why is it named BILC? Looking at this design rationally, There are a lot of things that tell you not to build this. While the ND105-4 can play down to 40 Hz, it still needs a decent size box (about 0.3 cu ft) to do so, which means for 4 of them we need about 1.2 cu ft. And while the four 4” drivers have almost the surface area of about a standard 8” woofer, the 8” woofer would work in about the same size box. Also, these aren’t necessarily cheap 4” woofers at a $23.29 ($93.16 per side) so looking at something like the Peerless by Tymphany 830869 8" Nomex Cone HDS Woofer at Parts Express, I could basically get the same size box, cheaper price, and most likely better distortion performance. So why did I choose to do this? BILC… and the one benefit a front firing 8” woofer can’t give you – a slim tower.


    While the pictures of the drivers show the tweeter at the top, I’ve changed my mind since taking the picture and starting to plan the cabinets. I’m now going with the mid on top in the layout so it will be a MTWWWW. The cabinet external dimensions will be 44” H x 6.5” W x 14” D. This gives me about 1.53 cu ft of total internal volume available to work with before bracing, drivers, and ports. I will be taking up around 0.2 cu ft for the midrange chamber leaving about 1.3 cu ft for the bass drivers after accounting for all the bracing, port and drivers.




    The bass enclosure will be tuned to 49 Hz, which produces and EBS alignment with an f3 of 42 Hz. I’ll be using a 3” PVC port to achieve this and keep port velocities under control up to about 50 watts of input power. One of the unique things about the ND105-4 is that while the xmax is pretty standard at 4 mm, the xmech 10 mm so there is still lots of excursion past the xmax limits. While driving something past xmax isn’t a goal, these will be used for bass only, and bass distortion is less audible than midrange distortion. This means there will likely be some useable output beyond xmax before they really start to become objectionable and also means you can really crank them without fear of damage. The woofers will be wired in a series parallel configuration so if the specs are accurate, even with full baffle step I should end up at a realistic 87 db @ 2.83 V. This is one additional benefit over going with something like the Peerless 8” I mentioned earlier. That driver after full baffle step would put me around 83 dB @ 2.83 V. Likewise, the Dayton RS225-4 would put me around 85 dB @ 2.83 V.




    Tweeter (NLA): https://www.parts-express.com/tang-band-25-1744s-1-ceramic-dome-tweeter--264-866
    Mid: https://www.parts-express.com/peerless-by-tymphany-830870-4-ppb-cone-hds-woofer--264-1070
    Woofer: https://www.parts-express.com/dayton-audio-nd105-4-4-aluminum-cone-midbass-neo-driver-4-ohm--290-212
    -Kerry

  • #2
    Hey Kerry,

    interesting project. The ND105 drivers are too good bass-wise to ignore. A couple of years ago I built a set of speakers with only two of them per side with a PR side-mounted and they produced enough bass to satisfy me. I suspect four per side will be twice as good!

    Being relieved of midrange duties brings a whole different dimension to what the ND105 can do. I suspect you're right... most of the bass 'flubbery' going on won't be too noticeable as long as it doesn't get too crazy. Clarity will come from the tweeter/mid. It will be interesting to see what you think of these compared to your 'Boom Sticks' which used the RS100 in a quad arrangement (I think.)

    Glad to see you're doing this 'for fun!'

    I'm working on a somewhat similar setup using 8 of the 8 ohm TCP115 4" drivers per cabinet. My figuring was that they were equal to about an average 10" woofer displacement-wise.
    Your solution sounds a bit more promising!

    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


    • #3
      Sounds like a great project! But I think it would be much more interesting if the tweeters weren't NLA. How about the XT25SC90-04 instead? I will even buy you one!

      Comment


      • #4
        Originally posted by ontariomaximus View Post
        Sounds like a great project! But I think it would be much more interesting if the tweeters weren't NLA. How about the XT25SC90-04 instead? I will even buy you one!
        Yeah, the tweeters weren't NLA at three years ago when I purchased them and started planning this project

        I actually have a pair of the XT25SC90-04 that I could do some measurements and testing with if you are wanting to try and replicate this one. You still need to come down for a listening session and you could repay me in some unique Canadian craft beer
        -Kerry

        Comment


        • #5
          Originally posted by tomzarbo View Post
          Hey Kerry,

          interesting project. The ND105 drivers are too good bass-wise to ignore. A couple of years ago I built a set of speakers with only two of them per side with a PR side-mounted and they produced enough bass to satisfy me. I suspect four per side will be twice as good!

          Being relieved of midrange duties brings a whole different dimension to what the ND105 can do. I suspect you're right... most of the bass 'flubbery' going on won't be too noticeable as long as it doesn't get too crazy. Clarity will come from the tweeter/mid. It will be interesting to see what you think of these compared to your 'Boom Sticks' which used the RS100 in a quad arrangement (I think.)

          Glad to see you're doing this 'for fun!'

          I'm working on a somewhat similar setup using 8 of the 8 ohm TCP115 4" drivers per cabinet. My figuring was that they were equal to about an average 10" woofer displacement-wise.
          Your solution sounds a bit more promising!

          TomZ
          It will be a completely different animal compared to those going to a true 3-way. The ND105 also has considerably more surface area at 51.5 cm^2 vs 35.3 cm^2 in the RS100 so they'll be a lot more surface area in the bass. However, the cabinets are going to be about twice as large volume wise and I suspect they will look less elegant once finished.
          -Kerry

          Comment


          • #6
            Looking forward to your build and what you do with the tweeter. I bought the tweeters just a little over a year ago and didn't notice they were NLA until last week. I haven't seen write-ups of designs using them but I have seen favorable comments on the forum so it seems that people have heard them.

            Comment


            • #7
              I made some progress on the cabinets as well. I got everything cut except for the midrange chamber pieces. I ran out of 3/4" plywood so I used some 1/2" I had for a couple of the braces. The center body is completely assembled. I plan to finish it first and then attach the sides and trim with a flush trim bit. The middle is going to be veneered and the sides are going to be painted and I don't want transition to look weird, which would happen if I put the sides on first.

              A 3 1/2" and 2" hole saw made quick work of cutting the braces.



              Both cabinets look like this now. Midrange pieces still not cut to actual size or glued in, just laid in place for an idea of what it will look like. I left more room in the bottom for the 3" port and the crossovers.
              -Kerry

              Comment


              • #8
                Those look great Kerry. I hope I get to hear them this coming year at a DIY GTG. How low do you anticipate you will need to cross all those woofers over to the mid due to the large ctc separation?
                Craig

                The lowest possible F3 box alignment is not always the best alignment.

                Designing and building speaker projects are like playing with adult Lego Blocks for me.

                Comment


                • #9
                  Originally posted by Navy Guy View Post

                  Yeah, the tweeters weren't NLA at three years ago when I purchased them and started planning this project

                  I actually have a pair of the XT25SC90-04 that I could do some measurements and testing with if you are wanting to try and replicate this one. You still need to come down for a listening session and you could repay me in some unique Canadian craft beer
                  I will be over in 2020 no question. Thanks

                  Comment


                  • #10
                    Originally posted by PWR RYD View Post
                    Those look great Kerry. I hope I get to hear them this coming year at a DIY GTG. How low do you anticipate you will need to cross all those woofers over to the mid due to the large ctc separation?
                    My plan was to cross as low as possible anyway since the Peerless will handle midrange better. There will be about 13 3/8” between the mid center and the center of the four woofers so nothing too different extreme and given the low frequency operation only the interference should be a significant issue. I’m looking to cross around 250 Hz if it’s feasible once I take measurements. I’m hoping I’ll have these done by InDIYana if you are coming again this year.
                    -Kerry

                    Comment


                    • #11
                      Nice idea, very cool design Kerry.

                      Comment

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