Yes, a horn with a higher directivity index has a higher direct to reflected ratio than a lower DI horn.
In post # 434, I responded both to Camplo's post 431, and your post 432 quoting a Reddit poster.
Reflections from a high DI horn from behind the listening position may sound more like the sound is coming from behind than the more diffuse reflections from a lower DI speaker system.
Depending on the listening position in relation to the rear wall, and toe in angle of "Alternative_Eye's" horns, it's possible that the high frequency rear reflections are actually louder than the sound heard from the speaker direction, which could sound "surreal".
This diagram depicts a listening position where the direct "beam" misses the listeners head, but the red reflected beams arrive from the rear wall:
The reflected high frequency sounds are perceived as coming from either side of the listeners head from behind, while the wider dispersion lower frequency content will appear to come from their location as recorded.
Even mono signals will appear to diverge in space in that position, "incredibly 3D", is an interesting effect, not a credible reproduction.
One technique for "mono reprocessed to stereo sound" uses alternate frequency boost and cuts left and right. Frequencies boosted on the right are cut on the left, frequencies cut on the right are boosted on the left, creating a perception of a wide and shifting image, rather than a center image between the two speakers.
Listening to that sort of record in the above scenario can create a sensation the sound is coming from anywhere other than the speakers.
A more normal image projection of the recorded sound stage can easily be achieved by focusing the horns at the listeners ears, or a bit in front of the listening position for wider coverage.
For a higher direct to reflected ratio (a more defined sound) the equilateral triangle apex should be closer to the speaker wall position than the rear wall.
Art
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Still can't get the explanation of a speaker's directivity index, at least not from tmuikku's post 6
https://www.diyaudio.com/community/threads/question-on-directivity-index-and-amplitude.396667
The directivity index is a way of specifying dispersion at a given frequency with a single number.
A higher DI is a more narrow dispersion pattern.
A DI of 0dB is an omnispherical dispersion pattern, a DI of 3 is the equivalent of 180 degree dispersion at -6dB.
Directivity Index DI = 10 log Q (dB)
If I got the math correct (not my strong point, check it if you want to be sure) the conversion should look like this:
The more narrow the beam width, the higher the DI.
At 20kHz, a DI ~25 would be about as high as would be seen in a beamy HF horn, while it's low end could approach 0.
Thanks for explaining this.
Yes, until stems along with the original three track masters were eventually used to create stereo mixes of songs and then complete albums https://www.hdtracks.com/?gclid=Cj0...aAlXMEALw_wcB#/album/5df1427d0bee25c09bc163fd , Capitol Records had marketed their "Duophonic" series of vinyl and CD albums using this or similar filtering technique.
Can't picture this; can you please sketch it for me?
Please check posts here from Monday on and share your thoughts.
https://www.audiosciencereview.com/...peakers-is-it-me-or.9633/page-45#post-2275792
https://www.audiosciencereview.com/...peakers-is-it-me-or.9633/page-45#post-2275792
The red lines depict the horn's center axis focus slightly in front of the listening position at the apex of an equilateral triangle:
That focus would widen the even coverage listening area while reducing the center "hot spot" high frequency level.
Art
I'm not understanding Marco's statement on this. But if I understand NicoB correctly, as all compression drivers have round exit holes, therefore he said:
A throat adapter is always required when transitioning from a round to a square or rectangular shape on a biradial horn. The wavefront cannot be overly compressed, so it's best to start with a 1.4"/1.5" throat rather than 2", ensuring the initial throat size remains manageable.
There is a common misunderstanding about throat adapters: they are always present in biradial designs, and they are not a problem. For example, the JBL 2450 is fundamentally a 1.5" driver, sometimes fitted with a 2" adapter. The proper match for this driver is a 1.5" horn, not a 2" one—this is exactly what I use in my designs.
When mounting a 2450 on a TH4001, you are effectively using a 1.5" driver with a 2" adapter, followed by a 1" round-to-rectangular adapter.
I believe it has been argued at this or other threads that a 1.4" throat diameter, 3" diaphragm driver will have better high end response https://www.usspeaker.com/radian 745neoBepb-1.htm while a 1.4" throat diameter, 4" diaphragm driver will have better low midrange response. https://www.usspeaker.com/radian 951Bepb-1.htm
-and/or a 2" throat diameter, 3" diaphragm driver will have better high end response https://www.usspeaker.com/radian 760neoBepb-1.htm while this 2" throat diameter, 4" diaphragm driver will have better low midrange response. https://www.usspeaker.com/radian 950Bepb-1.htm -all with respect to frequency, distortion, spectral decay, et al.
But at least from the standpoint of driver exit round hole / horn non-circular entrance hole com, why should there be any less geometrically imposed resonances or other abhorrent artifacts with 2" exit hole drivers (e.g. JBL 2450J) than 1.4" exit hole drivers (e.g. Radian 745NeoBe), since both will need adapters for use with most biradial and other horns non-circular horns?
In any case, it's nice that I discovered this 2" exit hole version in case it really turns out to be the best fit for the chosen horn.
https://www.usspeaker.com/radian 760neoBepb-1.htm
OTOH, assuming that an initially compressed wavefront is always problematic, NicoB seems to say that 2" exit hole drivers are disadvantageous: The wavefront cannot be overly compressed, so it's best to start with a 1.4"/1.5" throat rather than 2", ensuring the initial throat size remains manageable.