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Codename B.O.T. - Omni Three Way Design

JasonPJasonP
edited April 2017 in DIY
Now that I have finalized the design (almost anyway) and got into the garage to start working, figure I'd post the details up here for kicks.

B.O.T. stands for Bucket Omni-directional Three-way. It uses a 5 gallon bucket for the bass bin, and seeks to radiate almost equally in all directions. The drivers I've chosen so far:

  • Woofer: Usher 8945A. I picked these up for a steal used, and have yet to try them in anything. From what I've heard of the Usher line though, I have high expectations. This driver uses the bucket for the bass bin, making it a vented 19L enclosure tuned to about 40hz.
  • Midrange: Vifa TC6FC02. Tiny neo driver, I measured these a while back and they are very low distortion. They sound quite nice too. There are two per speaker in this design, bipolar arrangement. While I've not down the xo work yet I imagine they'll be covering 800 to 5k.
  • Tweeter: This is the big question. It faces upward in the design, so excellent off-axis is a must. I am making a plate to be changed out, and I plan on first trying the SB19ST again. I wasn't sold on its sound in the Iron Driver challenge, but I'll give it another shot. Another possibility is the SB26STCN, which has stunning off-axis for a 26mm dome.
These are all smooth drivers, and because they will be acoustically centered/time aligned I expect a very minimal crossover network. Here is the concept:


= Howard Stark: "This is the key to the future. I'm limited by the technology of my time, but one day you'll figure this out."
Tagged:
kennykMzissersonjr@macTurn24thtrygreywarden

Comments

  • ani_101ani_101
    May I suggest sonotube instead of bucket??? 

    Very nice concept. I am yet to hear any omni
    kennyk
  • JasonPJasonP
    Plates machined and ready for the bass bin:





    The port pipes that support the mid/tweeter assembly are 1.5" PVC. Above you can see the two fittings installed into the top plate, just on either side of the mounting hole for the Usher. The whole design with be able to be broken down and moved and assembled with minimal tools. I'll be doing this at Dakota.
    kennyk4thtry
    = Howard Stark: "This is the key to the future. I'm limited by the technology of my time, but one day you'll figure this out."
  • JasonPJasonP
    Ani, you are correct in thinking that the bucket is kind of a stop-gap measure. I'm actually thinking about custom slats that link together to form a circle(ish) form for the bass bin. US Plastics is a large company based in Cleveland that just might be able to do something like that for me. I'm looking into it.
    kennyk
    = Howard Stark: "This is the key to the future. I'm limited by the technology of my time, but one day you'll figure this out."
  • kennykkennyk
    edited April 2017
    That TC6 is my love. You can use a tweeter at 5k up, so try a cheap planar.
    Maybe try the TB 13-1761s, https://www.parts-express.com/tang-band-13-1761s-1-2-silk-dome-tweeter-pair--264-841
    2 pair is CHEAP!
    ............. could you hum a few bars.
  • jhollanderjhollander
    Might want to try a diffuser or phase plug on top of the tweeter to improve dispersion
    Face
     John H, btw forum has decided I don't get emails
  • kennykkennyk
    a dipolar Beston, https://www.parts-express.com/beston-rt002a-dipolar-ribbon-tweeter-6-ohm--277-116
    or opposing tweeters would work.
    ............. could you hum a few bars.
  • MzissersonMzisserson
    Spatially averaged measurements will mean far more than any one given axis. Remember that! 
  • JasonPJasonP
    Good points everyone, thanks. I'm planning on playing with a cone shaped deflector above the tweeter.

    Good Lord, this hobby always has me buying something... found this Vifa tiny tweeter at... digikey? Who knew: https://www.digikey.com/product-detail/en/peerless-by-tymphany/OC16SC00-04/OC16SC00-04-ND/6211112 *ordered*
    = Howard Stark: "This is the key to the future. I'm limited by the technology of my time, but one day you'll figure this out."
  • jr@macjr@mac
    I would love to see that little guy in a small, elliptical waveguide. Maybe put it over this guy:

    http://www.tymphany.com/wp-content/themes/pathfinders/cache/pdfs/PLS-75F25AL02-08.pdf

    Or:

    http://www.tymphany.com/wp-content/themes/pathfinders/cache/pdfs/SLS-85S25CP04-04.pdf

    Hmmm... nice find, JP. Has my wheels turning for sure. We had spoken in the past about the cool drivers Tymphany has made available but not necessarily through traditional outlets frequented by DIY'ers. I always thought Digikey limited themselves to shitbox speakers for computer cases and industrial beeper applications - turns out they are a Tymphany distributor as well, how cool is that?

    Now we know where we can get that little Peerless woofer :) 

    I have a signature.
  • ani_101ani_101
    Got my fill of omnis at Axpona....
  • jhollanderjhollander
    I ordered from Digikey for my SLS-85 project.  I got approval to post the project at PE as Matt P? said they would be adding the drivers with another 100 Peerless part numbers...
    kennykJasonPScottS
     John H, btw forum has decided I don't get emails
  • JasonPJasonP
    Tiny Tymphany tweeters came. Appear well built, I'd wager they are built where the OX20 and OT19 are made.
    = Howard Stark: "This is the key to the future. I'm limited by the technology of my time, but one day you'll figure this out."
  • jhollanderjhollander
    Wow those are small.  What kind of sensitivity?
     John H, btw forum has decided I don't get emails
  • JasonPJasonP
    83db/watt, 86db/2.83V (4 ohm)
    Low, but not to low for most woofers these days. Specs claim 100W noise power 2.5k and up. Though I can't imagine how the little assembly could sink all that heat. 
    = Howard Stark: "This is the key to the future. I'm limited by the technology of my time, but one day you'll figure this out."
  • ani_101ani_101
    Whatever happened to this?
  • JasonPJasonP
    They are about 75% complete, but due to some snags in the modular construction I had doubts they could be ready for DDIY. I'll keep this thread updated as I move forward.
    = Howard Stark: "This is the key to the future. I'm limited by the technology of my time, but one day you'll figure this out."
  • 4thtry4thtry
    Nice little tweeter.  Thanks for sharing.  Will have to order a few for future experiments.
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