I've built speakers with fairly well-controlled dispersion patterns thanks to using horn drivers and super tweeters in my builds. While the actual dispersion pattern can be wider or narrower depending on frequency, the nominal HxV pattern is generally contained in the advertised range (of the horn).
For a small set of speakers that I listen to from fairly close range use the super tweeters with a 40x40 degree nominal dispersion pattern. Once adjusting the speakers to be angled inward, the result is audio that sounds like I'm wearing headphones without the discomfort of actually wearing headphones. I use these speakers with my computer for both music and playing games. With games, they are incredible because the controlled dispersion allows for "3D sound" to actually have precise positions in space.
For a larger set of speakers that I use with my home theater I went with a 90x90 radial flare horn (aka buttcheeks). This also sounds excellent with movies and music. My typical listening distance here is around 12-15 feet.
I want to build some additional speakers for the home theater and I'd like to hear some thoughts on what kind of dispersion patterns would make sense for the center channel and satellites from people who have had the opportunity to compare.
On one hand, I could go with a similar 90x90 or perhaps something with 120Hx60V for the L/R surrounds, with the idea being that the sounds coming out of these speakers are generally ancillary and enhance special effects. A wider dispersion would help hide the speaker, but at the same time, it may muddle the positional precision of the effects.
On the other hand, going to the other extreme and using a 40x40 super tweeter would enhance the positional precision, and for people sitting where the speakers are aimed, it would sound really good...but not so much for anyone not sitting in the sweet spot.
As for the center channel, I'm thinking that something matching the front L/R channels would work best, so 90x90 in my case...then again it may be better altogether to try to limit the angle of vertical dispersion and focus more on horizontal for all of the speakers.
Thoughts?
For a small set of speakers that I listen to from fairly close range use the super tweeters with a 40x40 degree nominal dispersion pattern. Once adjusting the speakers to be angled inward, the result is audio that sounds like I'm wearing headphones without the discomfort of actually wearing headphones. I use these speakers with my computer for both music and playing games. With games, they are incredible because the controlled dispersion allows for "3D sound" to actually have precise positions in space.
For a larger set of speakers that I use with my home theater I went with a 90x90 radial flare horn (aka buttcheeks). This also sounds excellent with movies and music. My typical listening distance here is around 12-15 feet.
I want to build some additional speakers for the home theater and I'd like to hear some thoughts on what kind of dispersion patterns would make sense for the center channel and satellites from people who have had the opportunity to compare.
On one hand, I could go with a similar 90x90 or perhaps something with 120Hx60V for the L/R surrounds, with the idea being that the sounds coming out of these speakers are generally ancillary and enhance special effects. A wider dispersion would help hide the speaker, but at the same time, it may muddle the positional precision of the effects.
On the other hand, going to the other extreme and using a 40x40 super tweeter would enhance the positional precision, and for people sitting where the speakers are aimed, it would sound really good...but not so much for anyone not sitting in the sweet spot.
As for the center channel, I'm thinking that something matching the front L/R channels would work best, so 90x90 in my case...then again it may be better altogether to try to limit the angle of vertical dispersion and focus more on horizontal for all of the speakers.
Thoughts?
My general thoughts are that the better treated the room, the wider a dispersion pattern you can have. Others have written papers on this, and for me it seems to work very well. In addition, movies are mixed for more acoustically damped rooms than music. That's why THX theaters (and others) have so much wall treatment.
Personally I use controlled dispersion tweeters (line source or narrow ring radiators) and modest room treatment for a modest living room. That's 5 2'x4' panels and a pair of soffit traps from GIK Acoustics, and a curtain across the ceiling, and windows. Together with DSP on the sub and center it's pretty awesome. The center is kind of poorly placed, so DSP tames the bass boom the other speakers don't have.
A big question left unanswered is where are you going to sit? Why disperse sound to the ceiling if no one is there?
It just adds to the reflected noise. For home movie listening I would estimate that horizontally wide (45 to 90 degree), but vertically narrow (20 degrees) horns would be good choices assuming you have a wide seating area, or plan to entertain guests who would be moving around.
Personally I use controlled dispersion tweeters (line source or narrow ring radiators) and modest room treatment for a modest living room. That's 5 2'x4' panels and a pair of soffit traps from GIK Acoustics, and a curtain across the ceiling, and windows. Together with DSP on the sub and center it's pretty awesome. The center is kind of poorly placed, so DSP tames the bass boom the other speakers don't have.
A big question left unanswered is where are you going to sit? Why disperse sound to the ceiling if no one is there?
It just adds to the reflected noise. For home movie listening I would estimate that horizontally wide (45 to 90 degree), but vertically narrow (20 degrees) horns would be good choices assuming you have a wide seating area, or plan to entertain guests who would be moving around.
I think this thread covers your question:
http://www.diyaudio.com/forums/multi-way/195124-what-ideal-directivity-pattern-stereo-speakers.html
http://www.diyaudio.com/forums/multi-way/195124-what-ideal-directivity-pattern-stereo-speakers.html
That's not a direction I'd like to go, and besides that, my AV receiver does an excellent job of compensating for room acoustics with its auto-setup program. It's more practical for me to tune speakers to work better in the room than it is for me to try to tune the room for speakers.
Speaker placement - optimal vs practical - is always a consideration. I have my center channel right below my TV. I used to have it above, but it was way off-axis up top. Moving right below the TV provided notable improvement.
A big question left unanswered is where are you going to sit? Why disperse sound to the ceiling if no one is there?
I don't want to overspecialize and end up with a system that only sounds good in small area. I was thinking along the same lines - stay wide on H and narrower on V. I don't think that 90x90 for the front L/R was a bad decision because I want well-dispersed sound and it sounds very good the way it is as it fills the room with sound without losing positional precision for sfx and stereo effect.
I haven't gotten around to building the rear surrounds or the center yet, and since they are more specific in their purpose as points of sound rather than general purpose like the front L/R, I was thinking that it may be better to focus their vertical output a bit more, but not too much.
As it stands now, considering these patterns:
- L/R Surround - 120 H x 90 V
Reasoning - wide horizontal with narrower vertical to allow flexibility of placement in room while maintaining precision for surround effects. Since they are almost exclusively for sound effects, there is no real need for a broad vertical dispersion...although too little vertical dispersion would require further seating distances so 70-90 degrees for vertical dispersion would work.
- Center - 90 H x 60 V
Reasoning - Mostly vocal range sound coming from this speaker, so I think it's more about tuning the crossover point than anything. Horizontal dispersion should be wide enough to have some overlap with the front L/R and that depends on where they're physically located. For me, 90 deg H, the same as the L/R, should be fine. For vertical I can go narrower because sitting distance is fairly far away, and its location is close to ear level.
Perhaps, but I'm not going to dig through 300 pages of replies to find out. What do you have against conversation?
The problem with going narrow in any dimension is that it takes a reaaly big horn or driver (in the dimension you're trying to narrow) to do it down to even upper mid frequencies. A 90x40 horn that holds horizontal pattern to 1kHz (about a 12" horn) will be unlikely to control vertical pattern below even 3kHz.
If you want to keep energy from the ceiling and floor below high frequencies, a tall ribbon or array is about the only way I know of, other than a horn that is much taller and deeper for vertical than for horizontal.
If you want to keep energy from the ceiling and floor below high frequencies, a tall ribbon or array is about the only way I know of, other than a horn that is much taller and deeper for vertical than for horizontal.
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I would turn that on its head. The more consistent and controlled the polar pattern with frequency, the less important room absorption is.
On one extreme you have an omni, which seem to do best in a reflective environment, on the other you have a laser beam horn which will not interact much with the room at all between horn and listener. In between you have a sort of continuum.
For ordinary speakers and ordinary rooms, Toole and olive have found that a gentle smooth narrowing of directivity with frequency seems to correlate best with listener perceptions of quality.
In an ordinary listening room, the old 8" 2 way with tweeter crossed at 3K is going to have a huge widening as the tweeter pulls in, and reflected sound is going to be colored with extra treble. You can't really make your room treatments into reflected response correctors, so correct the speaker, or absorb all reflections.
If you live in an anechoic chamber, the directivity can be anything and only the direct sound matters.
For surround speakers, you can get more even directivity by using the dipole's inherent figure 8.
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