I believe it's clear that we want a narrow vertical directivity in order to minimize detrimental ceiling and floor reflections. Ideally down to Schroeder. Horizontally, your mileage may vary depending on room, acoustics, usage and taste. But generally I believe a uniform horizontal directivity above Schroeder is beneficial, though some narrowing in the highs from a broad dispersion speaker doesn't matter much.
I believe so too but it has never been sufficiently tested in psychoacoustic studies, has it?
One of Keele's colleagues uses a full-length CBT as a center channel (full as opposed to half in the normal implementation, where the ground is used to virtually replicate the radiation of the physical array).
I also believe that you are mischaracterizing Bech's findings.
It's well know that vertical reflections only are negative. And a uniform directivity will lead to a room energy that's closer to the direct signal. But if you treat the room considerably, obviously things changes.
I'm well aware of the Monte's center speaker and he isn't a collegaue of Don FIY. But his brother was for a time.
That's a claim the scientific literature does not support in my opinion. Guess we have to agree to disagree.
I don't know that we can make that call about vertical directivity without measurements. Horizontally, looks fit for purpose to me:
Look, you can't be that dismissive. The language I'm using matches Bech's. Beyond that, acoustically, you're not even being accurate.
Your intuition is probably right. But I would reserve judgement until seeing data. The interference effects of that many drivers are not easy to predict.
My reading of Toole's summary of the research is that he concludes that research indicates we are more sensitive to horizontal suboptimalities, and less sensitive to vertical suboptimalities. A primary reason for this is the non-binaural nature of reflections off floors and ceilings.
Yes, it was a smart idea to let the floor-mounted (or ceiling-mounted) image become the second half of the full CBT source. It saves on space and halves the cost. BUT I don't think Keele was saying that halving it and floor-mounting it is essential to its performance as a CBT (which I think Bjorn claims a few posts above). A full-size CBT source, not attached to a room surface, will work just as well.
That's completely true, looking at the successful use of JBL's line of CBTs.
I've never met him in person. Thank you for your work. Keele has mentioned and simulated straight-line CBTs through delays, and JBL has a calculator and two such products: https://jblpro.com/en/product_families/cbt-series-passive-controlled-coverage-columns
I really wonder about this. If we were talking about regular speakers I would certainly agree. I think however the CBTs' more generally consistent soundfield will cause less issues. I would point to multichannel work by, IIRC, Rumsey, who showed that increasing channel count made flaws less detectable.
There are no researchers that show that very early reflections are beneficial, and which they are vertically in a normal small room. And no studies that show the vertical reflections are positive in any way. We only have studies that show they have a negtive impact on the sound quality.
Don is doing fine. But he at an age where he prioritize other things than audio now. He's a very social person and loves to talk and interact with people. That's his joy.
The horizontal dispersion is also very limited. So it will not work well as center much to the sides. And with such a placement, you end up with a potential severe floor bounce besides lots of high gain vertical reflections. Also much lower sensitive compared to a ground plane CBT.