Quote Originally Posted by Pat D
A typical two way has some limitations which may or may not be significant for you.. In order to achieve deep bass response, you need a largish driver in a good sized box. Largish drivers start beaming at lower frequencies than smallish ones, so to maintain even dispersion very far off axis, the tweeter must be crossed over fairly low. Alas, tweeters tend to be more delicate and can't handle so much power. Hence, the typical two way has a fairly small woofer, about 6 inches or so so that the tweeter can be crossed over moderately high, but give up deep bass response and power handling capacity. Now, this may not be that much of a limitation for many people, for most people listen at reasonable levels. The typical reasonably priced high quality speaker is a two way.
Actually, there's tons of tweeters available that have high power handling, the delicacy of a tweeter only presents itself if a poor crossover is employed, and low frequencies are sent there in abundance. The crossover point is a function of acoustic performance in the midrange, the size of the woofer really doesn't have a whole lot to do with this.
There are many drivers of varying sizes that have good off-axis response, again, for woofers, this is rarely an issue because of the wavelenghts of the frequencies woofers are responsible for.

The biggest problem you will run into with 3-way (or more complex) speaker systems is the smooth transition from one driver to the next, and matching the sensitivities of each driver. I don't like just plugging resistors into the circuits to decrease the volume of a driver as it seems to alter the tonality in doing so.

As for power output, there are some very good drivers with very high sensitivities that will play as loud or louder than three way drivers, not to mention those with high power handling capabilities. You have choice, but if you are going to increase cost by adding a 3rd driver, you can just as easily put that money into higher quality drivers in a 2 way.

I think it comes down to personal preference and cost considerations. I love the deep, tight, accurate bass a transmission line speaker presents, the best t-lines I've heard were all 2 ways. No need for a large woofer for the bass here, 5-1/2 inch units are fine. Totem has acheived impressive results with small woofers in using isobaric designs.

A good example of going the other way would be what Paradigm did with the Monitor 5's, replacing a bass reflex 2-way system with a passive radiator design...(not really a 3-way, but still). There's many ways to arrive at the same destination. I don't think it's as simple as saying a 2-way is better or worse than a 3-way, it would always come down to the speakers in question.