Differences between small vs. large mid driver

No driver over about 4" is capable of upper midrange frequencies without cone breakup. (Breakup means that different parts of the cone are vibrating differently instead of moving as a rigid piston). Cone breakup is not a complete disaster, but tends to produce irregular frequency response, often compensated (sort of) by components in the crossover network.

Wait a minute! a "Midrange" driver, by definition lives in a three-way system (at least). The 6 and 7 inch drivers in two-way systems are not midrange drivers, although they do need to pinch-hit for the missing driver. Even the best 7-inch drivers develop ripples in their response starting around 1500 Hz, and tweeter performance is compromised if you cross it over that low.

A midrange driver covers the range from about 600 Hz to 3000 Hz.

The midrange driver range that I suggested (600 to 3000) is based on what I have seen done in three way speakers. I think that Nighthawk agreed with me, and provided all the details.

If you suggest that a woofer is good to 2500Hz, what's wrong with using it to 600 Hz?

Trelja...The system you describe can cross over to the "Midrange" driver at 200 Hz because it is a 6.5 inch ubit, which I would not describe as a midrange driver. I would describe the system as a 8 inch subwoofer that can be crossed over at 200 Hz because it is so small, plus a two-way system. Not a bad idea. I have advocated running the subwoofer up to a higher than usual crossover frequency if it can hack it. Takes the heavy lifting out of the main system.

One reason to keep the woofer/midrange crossover higher than what you suggest is the electrical values of crossover network components necessary for subwoofer-like frequencies. Expensive, and bulky.

Trelja...I read Andy2 comment to be saying that expensive systems have midrange drivers (suitably small) whereas less expensive speakers are 2-way.

I think that a 6.5 inch driver will have some problems in the 1500 to 3000 Hz range. (Check Nighthawk). Good tweeters cannot be crossed over low enough to avoid this.

Agree that a 4-5 inch driver can go well below 200 Hz...the 5 inch woofers (and I use that term loosely) in my MTM Dynaudios put out surprisingly low tones, but not very loud. These drivers, with 3 inch voice coils, (almost as large as the moving cone) do make darned good midranges, and I used the Dynaudios that way in a biamped system for a few years. I now have MG1.6 Maggies doing what the Dynaudios used to do.

$200 is dead on for cost of the 200Hz crossover parts (I know because I bought three sets). That's a fair chunk of change for parts that the typical consumer will never see and doesn't appreciate.