The Buttcheek Dipole

[Richard Ellis]

Has anybody done a dipole using two 12" sections of PVC piping..........put a 4-5" FR on a long length of board. Five feet tall filled with sand.
I know the waveform expansion will be all wrong, maybe at one frequency, but..........????
Anybody try something like this?


__________________________________________________ _________Rick.......

[motosapien]

I guess no one is touching that.............

[454Casull]

What's the point?

[Godzilla]

>>> What's the point?

Looking at the illustration, at the very least it could be a way to mount the driver and act as a stand without having to build a base. Also it could provide some kind of driver loading and increase efficiency? I think you can go smaller than 12" round too... maybe 6"... i think it's an interesting idea.

[Richard Ellis]

Yes, the idea is to 'horn' load the driver as a dipole......but the expansion of the horn is going to be off to say the least. The broader (slower) horn off axis in the vertical plane would load at lower frequencies.........I'm just curious how the waveguide numbers would work.

__________________________________________________ ____Rick...........

[planet10]

The idea is not unfamiliar with similar. In my execution i was going to cut it in half and sit as a big round-over on my ESL baffle.

They could be used whole, i don't know about the driver mounted in a "cave". You might get some waveguide action, i don't think you'll get any horn loading.

dave

[Rudolf]

Originally Posted by Richard Ellis

Anybody try something like this?

Earl Geddes was at least suggesting it, but as a complete torus around the driver. That would combine the openness of the dipole with some waveguiding of the torus.
Your proposal is somehow half-hearted compared to that.

[ra7]

As an approximation, one can imagine the high frequencies will see some benefit of waveguide loading. But there will be little improvement in the dipole pattern in the bass frequencies and the difference in efficiency between bass and highs will be even more. In other words, a tilted response towards the highs.

Just a thought!

[454Casull]

It won't be much of a dipole. Effective loading requires mouth size, and the more size you have, the less likely it's going to behave as a dipole... It's pretty much a bad catch-22 that's unresolvable. However, if you're looking for a directional bipole, this would work quite well (keeping in mind that the motor will highpass your response).

(speaking from estimates rather than actual crunched numbers)

[oublie]

I tested it for a while with an open baffle line array. Not quite as large butt cheeks as yours though I used the cardboard rolls that carpet comes on mated to a 12 cm wide baffle board. There is no real benefit to it apart from the visual appeal as you really just curving a wider baffle so if you can live with a wider baffle or u baffle just do that.