Inverted mounted driver polar-response

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ripblade

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Joined 2007
Ken Newton said:
That’s what the patent looks to indicate to my eyes. It appears to be a multi-faceted Linaeum type tweeter. Which seem to be generically known as ‘Rubanoid’ tweeters. Whatever a Rubanoid is.
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Ruban is French for ribbon, so you could call it Ribbonoid.

The patent sketches don't look anything like the photos to me, more of a tapered tube than a quad of ribbonoids aligned 90° apart. The woofers are quite different too, with the spiders midpoint in the basket and a good portion of the VC exposed. I think the last bit would be essential to good HF response
 
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Ken Newton

Ken Newton

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Joined 2003
ripblade said:
A driver with a small magnet and cast basket with narrow spokes would be better suited but also be a strange, rare beast. Even if one could be found, dispersion would be limited to midrange along the horizontal axis dictating the need for a tweeter. Old school is to use a reflector with a normally configured driver. My own experiments along these lines lead me to conclude that vertical dispersion is just as desirable in an omni, at least for a stage height that matches the width and depth.
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ripblade,

I’m curious about the details of that Nerf football reflector you’re cleverly using. I can see how the ovoid shape could be advantageous for dispersing the sound horizontally, and vertically throughout the listening room. Since Nerf footballs are, however, made of a foam-rubber like material doesn’t that greatly reduce its effectiveness as a sound reflector? it looks in the photos that you may have coated the surface of one side with some substance, possibly to harden that surface?
 
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ripblade

Member
Joined 2007
Ken Newton said:
Since Nerf footballs are, however, made of a foam-rubber like material doesn’t that greatly reduce its effectiveness as a sound reflector? it looks in the photos that you may have coated the surface of one side with some substance, possibly to harden that surface?
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No coating, the two sides are different colours but the same texture. The foam is closed cell and the surface ia actually quite smooth, I suppose for cleaning purposes as these are children's toys and need to be washable. The foam was a bit of a concern initially, but now I think the soft, low density is an advantage as it prevents the possibility of the reflector developing sympathetic resonances (ringing) that could colour the sound as the walls of a horn might do. Overall, I think it's pretty benign in that aspect. I just wish it looked better lol.
 
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Boden

Member
Joined 2010
A bit late in the game, plus I did not read all the posts, but a first step toward improvement with a horizontally mounted driver would be to rebuild the driver in such a way the magnet is inside the cone instead of outside. Plus: frame inside. The magnet assembly then no longer obstructs radiation. This is the technique Bloomline, as shown by Wout31 in his first post in this thread, applies with rebuilt KEF Uni Q drivers. I vaguely recall Steve Deckert doing something similar. Whether it really works I do no know: never seen proper measurements of such set ups.
 
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ripblade

Member
Joined 2007
Ken Newton said:
Is it safe to assume that you don’t find the football’s foam material to substantially absorb, or otherwise roll-off the treble of the reflected energy to an unsatisfactory degree? I have been presuming that a hard surfaced reflector would be required.
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It's not like acoustic foam, porous and all that, but I suppose a polished metal reflector would be more efficient.
 
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Ken Newton

Ken Newton

Member
Joined 2003
Boden said:
A bit late in the game, plus I did not read all the posts, but a first step toward improvement with a horizontally mounted driver would be to rebuild the driver in such a way the magnet is inside the cone instead of outside. Plus: frame inside. The magnet assembly then no longer obstructs radiation. This is the technique Bloomline, as shown by Wout31 in his first post in this thread, applies with rebuilt KEF Uni Q drivers. I vaguely recall Steve Deckert doing something similar. Whether it really works I do no know: never seen proper measurements of such set ups.
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Here is Deckert’s omni speaker which I believe you are referring to.

https://www.decware.com/newsite/ERR.html
 
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ChrisABC

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Joined 2017
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