True high-end Speakers need a midrange
To be clear, I don’t mean expensive, I mean high performing.
I recently built a new center speaker for my home theater and as I was comparing/contrasting design alternatives between a variety of designs, everything from expensive DIY designs to Wilson, Legacy, ATC and Focal and others the thing that stood out the most was this:
I say this as a person who has had pretty good success with 2-way speakers and really admire 2-ways from Fritz and others, but when push came to shove, there was no way to make a 2-way with very high output AND low distortion AND excellent off-axis performance without a midrange driver.
You can push many tweeters down to 2kHz or even a tad below but it is very hard to find a tweeter that will do so with low distortion at high volume. On the other hand there are many 1" domes which will perform excellently when crossed over at 3 kHz or higher even when driven hard, things you don’t see from a frequency response plot, or really any measurements from Stereophile which never plots dynamic range charts. It’s not just about the frequency response and imaging, sometimes it is about doing all of that under pressure that matters.
Similar, complementary issues are true for the woofer in a 2-way design. First, good mid-woofers with good frequency responses through 2-4kHz are expensive, but as you push the crossover up 7" drivers and larger have to beam, right in the middle of the midrange. Instead of a wide open sound stage you can hear anywhere they restrict where you can sit.
In a large, full range speaker you can push your design for high output even further by going with a 5" midrange for instance. Not quite as wide as the 4" counterparts but lots of power handling and plenty of overlap with the tweeter and woofers.
