One last thing... the center channel needs WIDE dispersion to function effectively. Perhaps narrow vertically but wide horizontally is a must, though the terms are relative.
It seems I failed to convey my point clearly. I was responding to your post but not addressing you directly—I was simply discussing the argument that speaker dispersion width is crucial for even coverage across a couch. I believe it's one of the possible conditions but not a sufficient one.
Let me try to illustrate this. Let's take, for example, the RCF 950 horn (since we are discussing horns here). These have a constant directivity of 90x50, which can be considered neither narrow nor wide—making it a good example for our discussion.
If we position them parallel to each other, then when you sit at the far-right seat on the couch, you hear the direct sound from the right speaker, which is also physically closer. Meanwhile, the left speaker's sound reaches you at a significant off-axis angle (resulting in SPL drop), plus there is added distance and delay.
As a result, the listener mostly hears the right channel, with almost no stereo effects, and speech intelligibility may suffer if voices are not recorded exactly in the center (voice from left channel). Additionally, you perceive a significant amount of sidewall reflections from the same speaker.
Widely dispersed speakers will behave in a similar way. For speakers with inconsistent directivity, the situation can be even worse.
If the speakers are toed in, the situation changes. The listener hears the right channel at a significant angle, which lowers its SPL but maintains a normal tonal balance. The left channel, however, is directed straight at you, compensating for the volume loss due to distance.
The delay between channels remains, but the perceived volume and tonal balance of both channels stay more even. This allows the listener to perceive at least some spatial effects and maintain speech clarity, even if voices are not perfectly centered (for example, if dialogue is coming from the left). Reflections from the right speaker are reduced, while those from the left remain, preserving a sense of overall spatiality in the sound.
In this application, the horn's dispersion width affects room reflections more than stereo stability across the couch (although excessively narrow directivity can introduce limitations). Horns should ideally have constant directivity or a very gradual increase in DI towards the top end. Horns that are too narrow in the high frequencies may not perform well.
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Hi @olegtern
Sorry to make you type so much. Unfortunately I understand perfectly the theory and charts already. I really do. The problem has been that there has been a delta between what I've heard in practice and that. Maybe it's a matter of what we called controlled vs. narrow dispersion, but my in person, actual hearing experience has led me to believe a better center image is made by wide dispsersion speakers, which is why I specifically mentioned two brands to see if maybe that helped us get to the same terminology. The most narrow speakers I know of, ESL's have a terribly narrow sweet spot. Perhaps if we call Magico and Revel "controlled" dispersion then we can agree that controlled dispersion works very well, and excessively narrow does not.
Still, with plenty of room to the sides, these speakers with excellent, wide sweet spots do not need toe in.
That's not to say that room acoustics don't matter, they obviously do and wide dispersion in a reflective environment is bad, and significant toe-in can help.
I leave it to others to assert their own experiences in this area which may be different than mine.
In a theater delay times were critical, in a home not so much, so I agree in general that the changes in delay as you move L to R are not as critical as relative levels.
Best,
Erik
Sorry to make you type so much. Unfortunately I understand perfectly the theory and charts already. I really do. The problem has been that there has been a delta between what I've heard in practice and that. Maybe it's a matter of what we called controlled vs. narrow dispersion, but my in person, actual hearing experience has led me to believe a better center image is made by wide dispsersion speakers, which is why I specifically mentioned two brands to see if maybe that helped us get to the same terminology. The most narrow speakers I know of, ESL's have a terribly narrow sweet spot. Perhaps if we call Magico and Revel "controlled" dispersion then we can agree that controlled dispersion works very well, and excessively narrow does not.
Still, with plenty of room to the sides, these speakers with excellent, wide sweet spots do not need toe in.
That's not to say that room acoustics don't matter, they obviously do and wide dispersion in a reflective environment is bad, and significant toe-in can help.
I leave it to others to assert their own experiences in this area which may be different than mine.
In a theater delay times were critical, in a home not so much, so I agree in general that the changes in delay as you move L to R are not as critical as relative levels.
Best,
Erik
Sorry you had to read so much into what you already know 🙂
I still have one question. Have you listened to a movie without a center speaker in a home theater with Magico or Revel, sitting in front of one of the speakers (as in my example above) and did not experience problems with sound field and intelligibility of dialogues?
Hi @olegtern
Sorry for the lack of clarity in my original post.
Sorry, my experience with Magico and Revel was in how well they image in stereo as I move around the room, not in a HT per se.
In my current situation, at home with 3 front channels designed by myself, I have a weird situation where the processor double blind tests whether I can hear the center or not all all the time. 😆
Let me explain. I have an Anthem MRX receiver and it does not correctly apply surround processing. In the case of Netflix, 100% of their streams (that I've seen) are Dolby Digital encoded. However, some are 5.1 or Atmos and some are 2.0, especially the Korean supernatural dramas I'm addicted to, as well as many British things.
Every prior processor/recevier I had before allowed me to select ProLogic, regardless of the encoding (PCM or DD) giving me a strong center speaker signal. The latest Anthem WILL NOT. I've been through this with their very responsive tech support. The Anthem MRX series only apply ProLogic to 2-channel signals which are PCM encoded such as from Crunchyroll but if the audio is DD 2.0 it will NOT apply ProLogic, so no center (and no surrounds either). (BTW, the screen is wrong and shows Dolby Surround even when Dolby Surround is not actually on).
The point is, watching Netflix, I can't tell if the center is on or off UNLESS I'm lying down when it's obvious. Sitting in the center, switching video movies for an evening I absolutely cannot tell any improvement in dialogue quality. The only way I have of knowing is by literally touching the woofers.
Mind you, since I have control over all 3 speakers I carefully tuned L and R to neutral and the Center channel EQ curve is matched to that. If anything it is a little dry for music. In any event, the 3 channels are tightly matched to each other for EQ. In this case no, I really can't tell if the center is on or off.
I can imagine a situation where I have more musically euphonic speakers which just don't do that well for dialogue.
It may also help you to understand that I use a separate stereo amp for L and R. I first was alerted to this problem when I accidentally left the amp off and had NO sound coming out except via the subwoofer. That's when I became aware of the weirdness of Anthem receivers/Processors in the MRX generation.
Best,
Erik
Sorry for the lack of clarity in my original post.
Sorry, my experience with Magico and Revel was in how well they image in stereo as I move around the room, not in a HT per se.
In my current situation, at home with 3 front channels designed by myself, I have a weird situation where the processor double blind tests whether I can hear the center or not all all the time. 😆
Let me explain. I have an Anthem MRX receiver and it does not correctly apply surround processing. In the case of Netflix, 100% of their streams (that I've seen) are Dolby Digital encoded. However, some are 5.1 or Atmos and some are 2.0, especially the Korean supernatural dramas I'm addicted to, as well as many British things.
Every prior processor/recevier I had before allowed me to select ProLogic, regardless of the encoding (PCM or DD) giving me a strong center speaker signal. The latest Anthem WILL NOT. I've been through this with their very responsive tech support. The Anthem MRX series only apply ProLogic to 2-channel signals which are PCM encoded such as from Crunchyroll but if the audio is DD 2.0 it will NOT apply ProLogic, so no center (and no surrounds either). (BTW, the screen is wrong and shows Dolby Surround even when Dolby Surround is not actually on).
The point is, watching Netflix, I can't tell if the center is on or off UNLESS I'm lying down when it's obvious. Sitting in the center, switching video movies for an evening I absolutely cannot tell any improvement in dialogue quality. The only way I have of knowing is by literally touching the woofers.
Mind you, since I have control over all 3 speakers I carefully tuned L and R to neutral and the Center channel EQ curve is matched to that. If anything it is a little dry for music. In any event, the 3 channels are tightly matched to each other for EQ. In this case no, I really can't tell if the center is on or off.
I can imagine a situation where I have more musically euphonic speakers which just don't do that well for dialogue.
It may also help you to understand that I use a separate stereo amp for L and R. I first was alerted to this problem when I accidentally left the amp off and had NO sound coming out except via the subwoofer. That's when I became aware of the weirdness of Anthem receivers/Processors in the MRX generation.
Best,
Erik
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Not if speakers are or have been designed with those reflections in mind.
The narrower directivity is necessary to widen the listening area. Toe in is a part of the technique.
Not if the listening position is centered and narrow as would be in an environment purposed for critical music listening as is the case of the OP. Furthermore, a narrow horizontal or beam steered CC would enhance all multi channel algorithms.
From what I've read here, having both wide and deep sound stage and accurate imaging is rarely, or at least hard to achieve with a given horn design. Or can proper room measurement and treatment make it happen, depending on room size and how much early reflections can be reduced?
But would I come very close to that goal, and maybe get a good phantom center as well, with one of these horns?
https://audiohorn.net/x-shape-horn/
https://audiohorn.net/next-gen-bi-radial-horn/
IMHO, if you know you are going to be sitting between L and R the value of a center is greatly diminished, but I can see this not necessarily being the case for absolute best reproduction of mono recordings.
This hobby is all about exploration and experimentation though! Look forward to seeing what the OP builds and what he learns from it.
This hobby is all about exploration and experimentation though! Look forward to seeing what the OP builds and what he learns from it.
If we're deep diving here, and maybe it's already posted but what size screen are we talking or what's the spread between the L and R speakers?
Are you doing full multi way processing?
What is the overall width of your soundstage........to sidewalls etc
Will the acoustic centers of the drivers distance to the LP for the L and R speakers be the same as the distance of the center of the screen to the LP?
If not, does your processor have the ability to delay the audio?....THIS....IMO....is CRUCIAL to producing an effective phantom center.....the eyes will be the first sense to cue in that something is wrong
I'm not sure how "realistic" acoustic image depth is, but my experience is it is enhanced with appropriate levels of diffusion behind the L and R speakers and to the sides. Is it realistic? Is it illusory? I'm not sure but it sounds good.