ESS AMT-1 Air motion transformers ?!

[srinath]

Oh hey I did an experiment this weekend, gutting a few horns.
The horn in a crappy speaker is a regular paper tweeter say its 2" OD and the dust cap is 1/2 inch OD, the horn starts out @ 2" and rapidly contracts to 1/2 inch in the "throat" and then it flares into its rectangle outlet. I suspect its a way to reduce dispersion from a near 180 degree to a 30-45 degree there by increasing its power.
In a high end speaker, its a compression driver (presumably built out of different material than paper but similar construction) that is coupled with a horn that is a little less drastic at the face that bolts to the driver.
I dunno how it would play out on my design with the side ways amt ... but I have seen enough to want to try. The 45 degree one will be my first choice. Easy to build. If it sounds awful, its easy to drop it and forget it.
Cool.
Srinath.

[badman]

Originally Posted by srinath

Oh hey I did an experiment this weekend, gutting a few horns.
The horn in a crappy speaker is a regular paper tweeter say its 2" OD and the dust cap is 1/2 inch OD, the horn starts out @ 2" and rapidly contracts to 1/2 inch in the "throat" and then it flares into its rectangle outlet. I suspect its a way to reduce dispersion from a near 180 degree to a 30-45 degree there by increasing its power.
In a high end speaker, its a compression driver (presumably built out of different material than paper but similar construction) that is coupled with a horn that is a little less drastic at the face that bolts to the driver.
I dunno how it would play out on my design with the side ways amt ... but I have seen enough to want to try. The 45 degree one will be my first choice. Easy to build. If it sounds awful, its easy to drop it and forget it.
Cool.
Srinath.

The contraction forms both a lowpass rolloff and maximizes dispersion over the operating band with diffraction. The construction of a compression driver is typically quite different, with the concave side of a dome firing into a phase plug, which then goes into a tubular expansion until the coupling to whatever horn is utilized. Turning the driver sideways, if that's what you're describing, will not work. Just as with the AMT it will have dipole cancellation.

[srinath]

The trick really is to get it to not occupy the same air space - ever.
Reflect it into the room with a 90 degree spread. I dunno, easy to experiment, I get steel plates from my friend and wend them in a V shape and plonk it there and move the heil into it. See how it works.
Cool.
Srinath.

[badman]

Originally Posted by srinath

The trick really is to get it to not occupy the same air space - ever.
Reflect it into the room with a 90 degree spread. I dunno, easy to experiment, I get steel plates from my friend and wend them in a V shape and plonk it there and move the heil into it. See how it works.
Cool.
Srinath.

You appear to be viewing the coverage cutoff defined by the horn walls as 100%. It doesn't work that way. Additionally, even if you COULD make parallel beams that were identical but out of phase and had no cancellation, you'd have one beam that was in-phase with the mid or woof, and one beam that was out of phase.

Summation like you're expecting only works over a limited range of frequencies, and that with a delay on one side of the transducer. Review tapped horns for a similar idea. If not for the pathlength on the rearwave, they'd not sum positively.

[srinath]

I hadn't counted the woofer's phase. Damn.
Cool.
Srinath.

[badman]

Some work on these... the render shows the intrusion of the rounded portion into the path. All told I should have done the whole thing with kerfs, it would have been easier. Too late now.

[badman]

oops missed attachment- it's hard to tell but the continuity between horn and heil is very good.

[badman]

I've split this off here:

Hornloading the Heil AMT1