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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.



hifisidejr@macS7910PWRRYDTurn26thplanetdynamoSilver1omoThumperTom4thtry

Comments

  • Love it. That is a great midrange driver. 
    GowahifisideNavyGuy
    I have a signature.
  • Love those Peerless HDS mids
    GowaNavyGuy
    Don, Donno, or "Hey you" all work for me, But never "Mr Johnson"
  • 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. 

    PWRRYD6thplanetrjj45WolfTurn2squamishdrocS7910ThumperTomR-Carpenter4thtry
  • Those look like they'll be tippy! 
    PWRRYD
  • On the tipsy subject; outriggers: square tubing, bar stock, or wood, aluminum or steel, threaded bolts or what for feet???  
    PWRRYD
  • Cool project! All those ND104s should move some air. I'm curious if you'll even need to pad down the mid at all.
    PWRRYD
  • Kornbread said:
    On the tipsy subject; outriggers: square tubing, bar stock, or wood, aluminum or steel, threaded bolts or what for feet???  
    I’m not 100% sure yet but I’m tossing around som ideas. Probably will be similar to my Juggernauts where I used aluminum glued to wood but will be painted mdf this time. 
  • Tom_S said:
    Cool project! All those ND104s should move some air. I'm curious if you'll even need to pad down the mid at all.
    Yeah, I’m actually nervous that because of the narrow baffle I might not have enough output from the mid to cross as low as I want. 

  • I really wanted to use that tweeter.  I hope I get a chance to hear these.
  • Hopefully Kerry and Dan will join us this year in Iowa.
  • PWRRYD said:
    Hopefully Kerry and Dan will join us this year in Iowa.
    Unfortunately I probably won't be able to make it to Iowa this year.
  • NavyGuy said:
    PWRRYD said:
    Hopefully Kerry and Dan will join us this year in Iowa.
    Unfortunately I probably won't be able to make it to Iowa this year.
    No excuses. Be there. 
    I have a signature.
  • Cool project.   Hope to  hear these someday. 
  • 4thtry said:
    Cool project.   Hope to  hear these someday. 
    Since you attend basically every event I'm sure you'll get a chance  =)
    PWRRYD4thtry
  • Unfortunately my son and wife were sick this weekend so I was dealing with one normal sized baby and one giant baby, which means that I wasn't able to get any additional work done on these. I'm hoping to route the baffles, get the ports in place, and get a decent amount of the veneer done by the end of this coming weekend. We'll see how it goes.
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