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AUDIO FORUMS >> General Discussion and Support >> Constant Directivity Geometry Speakers
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Message started by beowulf on 12/18/14 at 18:13:34

Title: Constant Directivity Geometry Speakers
Post by beowulf on 12/18/14 at 18:13:34

Was just reading about this speaker design and sounds impressive. Supposedly good designs stay within ± 1.5 dB over the whole frequency range providing a very big sweet spot rather than the beaming that a conventional horn can produce.

Both THÖRESS and HAIGNER Audio produce this type of speaker. The Haigner Rho is reasonably priced I have seen them on the used market for under $3K.

I've never heard one though ... anybody out there know of this tech and what the pros and cons are?

Title: Re: Constant Directivity Geometry Speakers
Post by ski bum on 12/19/14 at 04:36:44

Just to be clear on the terms, "constant directivity" refers to similar response at different angles off axis, and we should throw in "controlled directivity" which refers to diminished intensity off axis. This is the sort of pattern controlled by horns/waveguides (like the Thoress), or the result of a large driver playing frequencies of wavelength less than the diameter of the driver (like the Haigner). So both speakers you linked to would be beamy. The Thoress looks like it has a fighting chance of producing smooth polars (constant directivity), but the Haigner looks like a hopeless case (no way the dispersion of the woof and tweet could possibly match at crossover frequencies, making it a fail in terms of constant directivity).

Also, it's a misconception that narrow dispersion speakers don't provide a big sweet spot. They can if you set them up correctly, as described in the following link:

http://libinst.com/PublicArticles/Setup%20of%20WG%20Speakers.pdf

Title: Re: Constant Directivity Geometry Speakers
Post by beowulf on 12/19/14 at 22:26:18

Interesting link, thanks for posting that ski bum.

As far as the Haigner, I can see your point as it doesnt seem to look like it woud mate well. But the super tweet on the Thoress design is pointing upward and the main driver covers most of the mid and to extent upper range. The sub fires forward and handles the lower end, what would give you the impression that this speaker would be beamy as well? It seems almost like a widebander in a sense with a non-directional super tweet and subwoofer integrated.

Title: Re: Constant Directivity Geometry Speakers
Post by ski bum on 12/19/14 at 23:47:34

Regarding the Haigner, just because there is a directivity mismatch at 6 khz does not mean the speaker sounds bad. The designer discussed the method to his madness in the 6moons Tech Talk article (link on the product page, which includes some decent discussion on his take on CD speaker design too, check it out). He also, not coincidentally, suggests cross-fire orientation as described in the link I posted.

As far as the Thoress, I didn't realize the tweet was upward firing, but like the Haigner, it would exhibit controlled directivity at least from the midrange horn. The woof's pattern probably matches the mid at the crossover point (well, who knows, but it really should!). So kind of like the Haigner, controlled directivity over certain frequencies including the mids/lower treble, with the upper harmonics sprayed around more liberally.