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High Efficiency Speaker Asylum Need speakers that can rock with just one watt? You found da place. |
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High Efficiency Speaker Asylum Need speakers that can rock with just one watt? You found da place. |
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In Reply to: RE: Ping tomservo regarding US patent US4845759A posted by Rafaro on January 11, 2023 at 15:02:52:
Hi
There is a way to make a horn that is very narrow in the vertical and wide in the horizontal as described above.
The way that is used is aimed over the front row, in fact if one chooses the right radiation angle down angle and height, one can make the spl near constant over a large area. The old thumb rule was "Aim at the back row", it's more scientific now but the same concept.
People talk about it have cylindrical radiation and so half the spl change vs distance compared to a point source.
So let's imagine a simple array of say 32 small sources. Each one has a frequency below which the baffle governs the radiation angle and up high, the radiation pattern will become narrow and complex as the radiator becomes "large" acoustically.
To be clear, for two sources to combine into a single new source. If you were to invert one of them, they largely cancel each other out), they have to be less than 1/4 wavelength apart for this coherent addition. There is a transition to two separate radiations by the time they are 1/2 wl apart (and radiate a figure 8 pattern, inverting one, changes the direction of the lobes)
Two equal but opposite sounds cancel each other but in phase, they add.
When your in front of the imaginary array what you get depends where you are, the vector sum of the sound from each of those sources and because they are all different distances, they don't "add" in the normal sense like close coupled subwoofers do they add and cancel depending on the frequency, angle and distances (a polar pattern of lobes and nulls, an interference pattern).
So lets say your far away from this source and it is X SPL, next to it is a point source producing the same SPL at X distance. As you walk closer, the point source increases in loudness following the inverse square law but as you get closer to the line, the more spread out in time a single sound event is and less addition of the sources there is. If you look at the envelope time curve, you can see that an impulsive event is stretched out according to the span off arrivals in time from the different sources.
In the critical listening sense, a true floor to ceiling line is impressive, the image is "a tall wall" So is the mono phantom like D Krall instead of standing in front of you.
If you remove the things the loudspeaker produces that give it an identify-able location in space with your eyes closed, it also will more disappear in the stereo image. That can produce a very powerful stereo image where your not aware of the loudspeakers if done at the right scale also for an audience.
So as the large line increases less rapidly as you get closer and closer to this requires a large sale of amplifiers and loudspeakers, the solution i came up with for work is a large full range constant directivity horn.
Skip all the self cancellation and time smear, use horn loading for efficiency and pattern control and often one box replaces a large array and sounds better.
The problems with large rooms is a greater challenge than the home or studio sized rooms and like large rooms, horizontal directivity is your friend keeping the direct sound where it belongs and lets you keep the speakers as wide apart as desired.
Tom
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Follow Ups
- RE: Ping tomservo regarding US patent US4845759A - tomservo 10:56:23 01/15/23 (1)
- RE: Ping tomservo regarding US patent US4845759A - Rafaro 12:50:37 01/29/23 (0)
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