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In the Forum: Horn-Loaded Speakers
In the Thread: Vertical Axis Midbass Horn
Post Subject: It's AlivePosted by skushino on: 2/8/2016
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This project just woke from a long slumber.
I've been granted access to tools and people to move this forward. The tools are a large-scale CNC cutting machine and paint shop, used to fabricate volumes (large 3D shapes) attached to climbing walls at indoor climbing gyms. The people are the shop owner / operators. They're excited about re-purposing their activities to create a better music playback. The volumes are large enough to climb over and around, are very strong, and are finished in a coarse, durable, sandy epoxy paint texture for friction.
Would interested readers comment with any problems or topics of interest you see in the design? We plan to begin cutting soon. I'm less interested in debating the merits / demerits of a vertical horn. I think Bruce Edgar and Tune Audio have already confirmed proof of concept.
The horn design is a two-segment conical approximation of a four ft exponential horn. I didn't see the benefit of hyperbolic for a downward horn limited to 200 - 250 Hz on top. The range is expected to be around 60 - 200 Hz.
Details:
- Throat - 480 sq cm / 8.6 in square
- Mouth - 6250 sq cm / 31 in square
- Segment 1 length - 86 cm
- Segment 2 length - 40 cm
- Total horn length - 126 cm / 49.6 in
- Back chamber length - 11 in
- Est. back chamber volume - 31 L
- Est. gap of mouth above the floor ~ 7.5" (per Edgar. Legs will be height adjustable to tune response)
- Est. total height of horn ~ 162 cm / 64 in
Still unresolved:
- How to fasten the back chamber (18" diameter very heavy PVC pipe used in commercial building construction.) on to the horn throat.
- How to design a fastening system to attach the two conical segments together, but with the option to disassemble for convenience when moving.
- How thick should the horn walls be? Using 1 inch baltic birch but perhaps should double up? Nominal thickness would be 1.5"
- Stand design. Right now the plan is to separate the bass horn from the MF and HF horns.
- Bottom exhaust. Could keep it simple and fire straight down onto the floor. I think there are benefits to adding a very robust floor platform beneath the mouth, maybe with a reflector, similar to Bruce Edgar's Seismic Sub. I used to have the Seismic. It was large and ugly but the sound was surprisingly very good.
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