When using a subwoofer, does it make a difference if your mains are 2-way as opposed to 3-way speakers? Trying to discern if 2-way speakers can be just as effective as 3-way speakers.
Some thoughts;
Generally two way speakers must select a crossover in the midrange/high frequency area that makes it tougher for the bass/midrange driver (especially if this driver is >6.5") to produce both bass and midrange at the same time with low IM (Inter-modulation) distortion.
Many 2-ways will also use a ported design to help get more and lower bass.
A good thing to do for many 2-way designs is to xover the low-bass to a sub. This will help increase the mid-range clarity and reduce the IM distortion in many 2-ways.
I have done this with my 2-ways and an electronic crossover (separate component) so I get the benefits of the sub when listening to music as well as HT. My system
With a 3-way design woofer, mid-range and tweeter, the answer could be YES it matters, depending on how low they go, where you set the pre-pro crossover, and what slope the pre-pro crossover uses. There could be an overlap of bass from mains and sub causing "comb filtering" to occur. This could cancel out certain bass frequencies in the room just like room null points, depending on where you place your mains and sub.
This is why it's important to measure SPL response in-room at various bass frequencies including the crossover frequency.
A good rule of thumb is to set the crossover one octave above the -3dB low point of the mains (eg. with a -3dB of 40Hz for mains, crossover should be set to 80Hz).
BruceD
When using a subwoofer, a 2-way speaker is fine. 3-way is ok too, but it really won't make much difference because the bottom octave is taken care of by the subwoofer.