David, in my many attempts at designing and building audiophile speakers, I have achieved modest results, but always at least listenable.
After attempts at 2-way, 3-way, 4-way, 5-way, horn loaded multi-driver, and now single-driver, my feeling is that simple can be best in an overall sense.
Sure, the single driver will not be as "flat" over the entire range, may/will lack some deeper bass response, and have some other faults in areas of the audio range that would not seem to comport well with the expected +/- 1.5db(20-20kHz), or incredibly low distortion levels measured in an anechoic chamber,etc.
However, it does have "simplicity"(less complexity), and has alot of speed, efficiency, point-source radiation, transparency and openness, and is very natural sounding. Most other speakers that I compare to mine have a "congested" and "stifled" sound, in comparison.
During my older days of multi-driver speakers, it was always a conundrum trying to get everything to match together perfectly, because they simply are not going to match together perfectly. So, you build in filter networks, Zener networks, try to decide on the slope/vs seam vs phase problems, padding, etc, etc, in an attempt to get the "expected" results of flat response and wide range. The end result is that you basically get something that measures well, but has a low efficiency and is "all clogged up" sounding. Just like alot of speakers on the market sound today.
So, I went to the route which had a much "simpler" design, and accepted the basic "warts" of the drivers I selected, and maximized the cabinet design I chose. The result was much more open, transparent, fast, and had a very pleasing natural sound that exceeded all my previous DIY attempts, and exceeded many commercial designs too, for "listenability". It has been my experience that this was preferable to a "perfect" response curve that sacrificed things that are not measured(but are heard), in the attempt to achieve a "perfect" response curve. I am not after a "perfect" response curve. I'm after a good natural open musical sound. Actually, it is this apparent "disconnect" from typical audiophile practice, that led me to the best sound I've ever had.
There is a "merry go round" of speakers that are all iterations of the same basic thing(good measuring, low efficiency, multi-driver, full-frequency range, passive crossover), in all the showrooms today. This is the "norm". If you want to get off the "merry go round", then you have to look "out of the norm". That's what I did. Many people think I'm nuts. How could a 2 watt amp and a pair of single driver speakers possibly meet all the strict audiophile criteria? The answer is "they don't". They meet musical criteria instead.
It depends what you're after. If you're after a bunch of spec sheets that tell you your speakers are perfect, then fine and dandy. If you come to the realization that all of your speaker's spec sheets over the last 20 years told you that they all were "perfect", and you are still looking for better speakers, then you need to start looking where "perfect" isn't the criteria, but music is. This is the epiphany point. When music finally triumphs over the need/desire for specs.
Now specs are fine for what they are, but they aren't going to tell you how things sound. They don't have a spec for "natural tone" or "open, transparent sound", or "that musically right sound". They just don't have those specs. That's what reviewers speak about, after they've heard another 3-way "perfect" speaker, and try to make it sound like something buyable to the readers. Also, specs are helpful in matching the speaker to the amp, so that you don't get into trouble with impedances or efficiency, and that is a good thing. But that's all they are really good for.
I'm not saying that everybody should go out and get a SET amp and single driver speakers. But, I am saying that applying complexity to designs to try to meet "specs", chokes off the music in many/most cases. And this is the way most commercial speakers today are designed and made.
Speaking personally, I have eschewed "perfect" specs for a deeper window into the music, at the expense of a totally flat response curve, and even a loss of some of the lowest frequencies in the spectrum. And, believe it or not, I am happier as a result, because my system sounds more like "real music" because of it.
And so, to sum up, you have to know where you want to go, before you can get there. If you pick the right destination, then your path will be productive. If you don't, then you will be going in circles, just like many of us have for years.
