Mega D'Appolito Speakers - The Holy Grail?


The engineer, scientist and author Dr. Joseph D'Appolito has a speaker arrangement named after him, a vertical array of mid-Woofer, Tweeter and mid-woofer. There is more to it than this, as the good Dr. has written quite a bit about crossover design needed to achieve good results.

I'm not necessarily talking about a true D'Appolito speaker though. I'm rather thinking of large speakers which have a central tweeter in between increasingly larger drivers. MBL, Dunlavy, Von Schweikert, Legacy, Gryphon all have built some version of this idea.

What do you listeners think? Is the dynamic range, detail, transparency, distortion and imaging consistently better than other type of designs?

Best,

E

erik_squires
So many designs shine with proper implementation. As you know, Eric, for a D'Appolito, optimizing the MTM vertical off-axis response and achieving the best mid-mid comb filtering response are givens.  Here's why I like MTM - in theory: I prefer cone midrange drivers over cone midbass drivers, but I also want as much midrange cone surface area as I can reasonably get for "scale" (for lack of a better descriptor). Nice 6-8 inch dedicated midrange drivers exist, but beaming at crossover frequency and breakup at top end come into play much more than with most 4-5 inch mids. My "one of" MTMWW loudspeakers use a pair of 4 inch mids, with a 200 cm2 total surface area. I use an older "non cell" 1.2 inch Accuton tweeter between them, in part for the very short 82mm per side square face plate (sound nice, too). The larger diameter tweeter lets me cross at 2kHz, well below both midrange driver beaming and significant combing frequencies. The 1.2 inch may have a bit less sparkle at the very top compared to its 3/4 inch brother, but my aging ears probably couldn't tell. This particular MTM has the qualities you listed, and the midrange "presence" with the smaller cones makes a difference I believe. I haven't heard a WMTMW, but smaller woofers should generally sound better in upper bass/low midrange and still move as much air as a somewhat larger single driver. My previous speakers had a 15 inch woofer, and I prefer the 9 inch bottom WW woofers I now have. 

Unsound: Your comments absolutely apply. Driver synergy, crossover design, enclosure materials/construction are as/more important.
Now we are getting into the weeds of a slightly different topic. When I started this thread I was thinking more of the W M T M W type of design, or W W w m t m w WW like the mega speakers use. I borrowed the good Dr.’s name to kind of illustrate a design for which I have no better name for than "mega D’Appolito." Maybe I should have said "Multi way, vertically symmetrical around the tweeter."

But this is not a bad path either.

The original Focal-JmLab Utopia series had a couple of M T M W designs which kind of qualify too. I also very much liked the idea of having the mids tilted inwards a little to improve the phase alignment. Wilson also seems to like the idea and uses it in the Alex among other designs.

So you like lots of midrange surface area to improve dynamic range?

I like the Scanspeak 6.5" mid-woofers a LOT. They measure much better than on paper. Not sure if they ahve been improved since original, but they are much easier to deal with and cross over well around 2 kHz. Also love the rich warm sound.
Is the dynamic range, detail, transparency, distortion and imaging consistently better than other type of designs? 

No. 
The  OP's example speakers are all fairly unique not only to each other but to most speakers in general, and some cases carry (ied) some rather lofty prices compared to most typically bought speakers. I'm not at all surprised that commonality is somewhat limited. That said; I'm not sure that the outlined driver alignment alone would necessarily have provided overwhelming commonality in more typical speakers either.
Is the dynamic range, detail, transparency, distortion and imaging consistently better than other type of designs?

I would say not really so much,only tiny differences in presentation.


Kenny.