Two Way Speakers: Is That All There Is?

[E-Stat]

Where did the midrange speakers go???

I see two very different factors at work:

1. Increased tweeter power handling

Tweeters were especially fragile in the 60s and 70s. Bozaks used multiple tweeters primarily for power handling. Another approach to prevent damage was to run the crossover to the tweeter at a high frequency to minimize their excursion at the lowest end. The ever popular JBL L-100 crossed over the 5" midrange to the tweeter at 6 khz! While that gave the tweeter better power handling, it resulted in peculiar imaging. The 5" cone was asked to produce 2.5" wavelengths at the top of its response. Naturally, it started beaming long before that transition and created an hour glass sort of image at a frequency range very sensitive to our hearing. The woofer and tweeter both had wide dispersion while the midrange was hard pressed to match the polar response.

Advents, for example, were originally designed for 20-50 watt amps. When folks drove them with Phase LInear 400s, they tended to smoke the tweeters. In the late seventies, along came ferro fluid cooled tweeters that could handle much more power.

Result? Today, most speakers crossover to tweeters around 2 kHz.

2. Fashion changed

Most folks today really don't want big "bookshelf" boxes in their living rooms. With the rise of HT, the trend has moved towards much narrower cabinets necessitating smaller woofers. Having a subwoofer or two isolated from the mains is considered more acceptable. Those smaller woofers can now easily meet the tweeters directly without the pinched image issue. So, for many speakers the midrange has been obviated because of these two factors. The "woofer" has in a sense become the midrange.

A very common configuration today is what I use in the HT system. You can see the details if you're interested by clicking my System link below. I use small two-and-a-half ways augmented by powered subs.