What matters most in speaker design?

I was thinking about speakers that use relativly cheap
drivers, but are executed in a genius enclosure with a good (but not exotic)
crossover - and they sound absolutely amazing.

Unless the manufacturer starts with high quality drivers then they won't ever be
accurate even though distortion and coloration can sound pleasant for some
provided the design is cool looking and has a nice finish. Distortion is
cumulative. Of course the drivers also need to be matched appropriately and the
woofer to the cabinet - so there are still many ways to mess things up even
when starting with good drivers.

I have a friend who designs speakers. I'd describe him as brillant - his dad is a department head at UVA. My friend has advanced degrees and has written at least one very thick book on signal processing.

I watched him build some speakers a few years ago. Very thick cabinet, the finest drivers, a lot of labor. I watched him work for months and months on the cabinet and later the crossover. He approached the cabinet design and x-over design from several angles eventually using some commercially available software for the x-over. He ended up with a perfectly flat frequency response and speakers that didn't sound too good.

Next he found someone with a lot of experience designing crossovers and worked with him for a few more months. They sounded better and eventually they got it to sound very good. He told me at one time he was thinking about adding some foam or rubber around the tweeter to take the edginess off the highs.

He took his speakers to a DIY show. I went as well. Basically he didn't win with the basic gist of it being the speakers weren't lively or forward enough. I didn't get it then but now I figure he'd built the kind of speakers you could actually sit down and listen to for a good, long while. They just didn't pass the "sip" test. The "sip" test is the first few minutes with the "boom and sparkle" jumping out at you.

Two important points I got out of this experience. First, all the parts he used were among the finest available and used in some very expensive speakers. But the drivers and crossover parts didn't cost much relatively speaking. Lesson 1: you pay as much or more for the design of the speakers as for the materials.
Lesson 2: A flat frequency response is no indicator of how good a speaker sounds.

None of the above.

While all those factors are important, they are secondary. The first consideration is the design concept. That must be thoroughly worked out and clearly defined before starting on the driver selection, crossover, or mounting/cabinet. How can a great result come out of a flawed approach? (Wireless200's story is a case in point.)

Hi Wireless,

Horn harshness really doesn't have anything to do with what's happening in the top 1/2 octave; it happens much lower down. It isn't necessarily caused by something that shows up in the frequency response curve either, but that's another topic.

I can't speak for Klipsch, but the tweeter I use has a mylar diaphragm and those tend to not go as high as titanium or other metallic diaphragms, but they often sound smoother. So indirectly the 17.5 kHz top end I claim is related to smoothness, but not because I think higher extension is undesirable; I just think that other factors matter more.

Duke

Lesson 2: A flat frequency response is no indicator of how good a speaker sounds.

True in that it will not sort out the wheat from the chaff but flat frequency response is a fundamental minimum requirement for accurate reproduction.