Coaxials - Reality vs. Experience?

A coaxial application done right can give the best coherence and power dispersion in all directions.  You have the potential for the biggest sweet spot and sound stage with proper supporting equipment, positioning and amplification.  

Unfortunately getting coincident drivers right is only part of the recipe.  It has been ruined for me overall with the following errors-

1) Voicing.  Coax drivers will not make up for a voicing and frequency balance you do not like.

2) Driver size step.  using too big of a step between drivers (e.g. 8 or 10 inch woofer to a 1" tweeter) can cause issues that a coax setup will not make up for. 

3) House sound.  Some coax speakers sound artificial and metallic to my ears.  Again, a coax design cannot make up for a bad house sound. 

Altec Model 18, 604-8h alnico coaxial, mantaray horn, 9cu.ft. Cabinet.  By far the best of all the speakers I have owned.  Just amazing with good tube amp.  But very hard to find.  I’ve only see one other pair for sale in the last 10 years.

@prof “:The other thing with the Thiels is the insane imaging prowess.  There is a focus and precision and density to the imaging I have rarely heard before.”

I had the Thiel CS5 monsters, had to work at placement really hard to get imaging and even then it was finicky relative to slight changes in sitting position. Granted that model didn’t have coax drivers. Eventually gave up on them, too much work.

Regarding coaxial drivers, as a general statement to OP with my take, slanted baffle speakers get the time domain right in the vertical plane. coax drivers get them right In both horizontal and vertical. So my question is this : a stereo setup offers a center image as if there was a center channel. So with D’appolito driver setups sandwiching a tweeter between 2 equally spaced midranges, do you get a phantom centered midrange that seems to come from where the tweeter is? Is that faking a coaxial presentation?

@jacksky I think the prime benefit of the D'Appolito configuration is narrow vertical dispersion.  with wide horizontal, so it is very different than a coaxial with equal dispersion in either direction.

Because of the changing time alignments in a D'Appolito, he's gone away from low order filters and now recommends 4th order (combined electrical + acoustical) crossovers for best off-plane axis listening.

This is an interesting thread on coaxial speakers. It was nice to read the comments on the HSU CCB-8’s.

I upgrade my speakers every 15 years or so and this summer I replaced my L/C/R speakers with the HSU CCB-8’s. They sound great, providing exceptional detail with a very full soundstage.

Of course, I also wanted to replace the rear surrounds and originally thought about two more CCB-8’s but that seemed like overkill for surrounds. Instead, I purchased KEF Q-150’s for the rear surrounds. They are also a coaxial speaker and blend very well with the HSU’s. Picked them up at Crutchfield at $254 for the pair, which was a great price (they retail for $599 a pair, but they go on sale frequently now).

Our home theater, with new speakers in the 5.1 setup, has never sounded this good before. Very pleased. And while I’m sure that upgrading to any speakers in this general price range would have made a difference, I like to think that the coaxial speakers are punching above their weight class!