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omni BT speaker design

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  • omni BT speaker design

    I could't find a design that met my list of requirements so I cobbled together a few design ideas into one.
    Inspired by:
    Duevel Planets
    the only one high-end audio horn-speakers with a perfect omnidirectional character, like the acoustical ideal of a point source, with a new quality of natural music reproduction.

    Heed Audio Enigma
    Heed Audio design and manufacture truly engaging hand crafted high-end audio equipments.

    The common application for a general BT portable speaker comes down to placement. Kitchen countertop, table, workbench, credenza, floor, outside table, outside chair, ground. In these locations, a forward firing drivers makes little sense as the sound is either directed at your stomach or ankles or something in-between. Also, considering that no one will be locking their heads in the sweet spot but rather walking around it or sitting to the side of it, the idea is to project sound into the listening space from it's compromised location. Imaging? What imaging? From your kitchen countertop to the left of your sink, between the microwave and the toaster? No. I say, diffused, pleasant, quasi-omnidirectional sound that will fill the space and be vaguely aimed towards the ears of the occupants -- indoors or outdoors. The best we can hope for is hearing some direct sound and less of reflections off the tabletop or ground.

    So I say lets just take the wonderfully elegant design of ISETTA
    angle it as HEED ENIGMA
    and diffuse the fullrange drivers as DUEVEL PLANETS.

    and that's about it. Nothing groundbreaking here. Very rough sketch:
    SB Acoustics SB10PGC21-4 for the pair of fullrangers
    Tang Band W5-1138SMF for the woofer + pair of Peerless passive radiators
    TPS3116D2 Class D 2.1 Bluetooth 5.0 Amplifier Board and batteries

    Internal Volume: 10L (6L for W5 + 4L for SB Acoustics full rangers)

    Any comments and critique would be appreciated.

  • #2
    I think the angled/wedge design and the diffusers might not pair ideally with each other, since part of the plan for the angle is to direct sound potentially toward a listener's head instead of their knees, but the diffusers would then directly block most of that upward+forward on-axis sound and redirect it toward the knees and far upward-backward.
    I think an angled design by itself should work well for very low placements, and I think the diffusers could work well for an upfiring driver when the speaker is positioned up high near chest/head level, but I don't think the two things will necessarily work well together.

    If possible (maybe with a mono build, or with a dual-woofer stereo build) using 1/2" or 3/4" tweeter/s for their naturally wide dispersion might work nicely without the diffusers.
    Something like an angled-cab MKboom with ~4L of space for each woofer would be the same 8L size while trading away ~10hz of bass depth in exchange for gaining ~4db extra sensitivity and headroom compared to the Isetta.

    I don't personally care much for the diffuser thing in general, so I have a bias there. Not for any concrete reason like "I've heard this and that build and didn't like how the diffuser sounded", but more like I'm paranoid of gimicks and snake-oil and while I'm certain some diffusers can work wonderfully, I'm also pretty sure there's no shortage of companies that'll tack on an interesting-looking or showy thingmabob just to try and push sales. So it's an irrational hatred. Plus I kind of imagine they might be a pain for something portable...easy to bump out of position or break, and gives the box a protruding larger footprint (if that makes sense).
    My first 2way build


    • #3
      My first impression is your after the "holy Grail" of sound in a boombox - solving long standing problems with speakers in their environment and intended use.

      Best suggestions are from LOUT. Add small tweeters to minimize high end directivity. If it were me, I tried to find/adapt/buy a mechanism that would allow you to dial in various angles for the box on a flat surface. Something recessed when not in use. Sliding, or, the simplest approach, 3" bolts under the front corners with blind nuts to screw them into. A flick of the wrist and you can dial in the box's upward angle.


      • #4
        What Mike said, a normal square boombox with a mechanism for tilting, or a boombox with a fixed middle subwoofer and rotatable ends with the full range speakers, allowing them to be pointed to the target.


        • #5
          Looks like a Soundblaster Roar 2, except all of the drivers fire straight up. The two high frequency drivers are small enough so that the rolloff at higher frequencies isn't too steep.
          Brian Steele


          • #6
            Originally posted by Brian Steele View Post
            Looks like a Soundblaster Roar 2, except all of the drivers fire straight up. The two high frequency drivers are small enough so that the rolloff at higher frequencies isn't too steep.
            oh thats what that thing is called lol, i had no idea but basically did up my own version of that, but failed with finding the right 2.1ch amp for that size that doesnt cook my smaller drivers. of course OP wont have that issue having 3" drivers and an actual sub.


            • #7
              All valid concerns about the dispersion of the full range driver. I'll make up a test box from foam board to test it.


              • #8
                Some photo updates on the prototypes.

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                It works. Very rough sound check. That W5 sub is powerful and needs a box with good mass to keep from jumping up and down. Maybe the ported 2" would be better than a pair of PRs? (each PR has a Mms of 48g!!)
                The Sb Acoustics full ranger sounds decent in the sealed, stuffed foamboard box but it would be difficult for me to predict how the sound would change in a 1/2" plywood box...
                The prototype is made to set a good angle for the speaker baffle and choose the offset axis (physical delay) between the W5 and full rangers.
                Attached Files


                • #9
                  After some listening and rough measurements, the FR boxes need some baffle step EQ.
                  1-1.2mH inductor and 5-10ohm resistor is in the ball park.

                  What type (air core/iron core) and what resistance (or gauge) inductor would be ok?
                  Wattage of resistor?