If I removed the rear chamber of an electrodynamic tweeter to enable dipole operation

[454Casull]

What would its radiation pattern look like? Would it behave like a cos(a) chart?

If not, would it be possible to build an electrodynamic dipole (i.e. cos(a) dispersion) cone/dome tweeter that rivals today's best?

[454Casull]

^

[454Casull]

Originally posted by 454Casull
What would its radiation pattern look like? Would it behave like a cos(a) chart?

If not, would it be possible to build an electrodynamic dipole (i.e. cos(a) dispersion) cone/dome tweeter that rivals today's best _monopole tweeters_?

[SY]

Roughly, but not exactly due to the differences in acoustic environment (e.g., radiation loading, diffraction) between front and back. These ARE short wavelengths we're talking about. If the front and back geometries and baffling are symmetrical, you'll get a closer approximation to dipolar.

[Cobra2]

AudioVector have done this a long time...

And they have a channel/port that extends from the back of the element to the rear.

It makes a difference, even on the ScanSpeak Revelators

Arne K

[454Casull]

Originally posted by SY
Roughly, but not exactly due to the differences in acoustic environment (e.g., radiation loading, diffraction) between front and back. These ARE short wavelengths we're talking about. If the front and back geometries and baffling are symmetrical, you'll get a closer approximation to dipolar.

http://www.scandic.com.hk/hexadym.htm

Do you estimate that up to (at least) 3-4kHz, a bare HEXADYM motor would be roughly dipolar?

[SY]

Without a scale, it's hard to tell, but it looks like the hole in the magnet might be a significant load at the frequencies you're talking about.

[Variac]

and it's horn loaded too! Maybe this will become the new fad-rip your tweeter apart and use it backwards. If you don't want dipole, then attach it to a small box filled with fiber.

Hmm , those Seas drivers are pretty pricey, but you only need one to try....

[GM]

Funny you should mention this, on another forum the other day we were discussing pros/cons of removing the end caps of compression drivers (the diaphragm is mostly hemispherical (convex) from the rear) and stuffing the 1" exit, which would either make it a small aperiodically backloaded conical horn if baffle mounted, or a dipole if free air or OB mounted.

GM

[454Casull]

Originally posted by 454Casull
...would it be possible to build an electrodynamic dipole (i.e. cos(a) dispersion) cone/dome tweeter that rivals today's best?

The reason I'm asking is because if this can be done, the effects of baffle diffraction would be much reduced (up until the tweeter starts firing into 2pi space, but then diffraction isn't a problem anyway) because of the cos(a) response - i.e. very little (to no) sound is radiated at 90 degrees off axis.