Is the 2.5 way speaker the ideal home speaker?

Time for what I hope is another fun thread. 

One type of speaker which is actually pretty common but which gets little press / attention here on audiogon is the 2.5 way. 

A 2.5 way speaker is almost a 3-way, but it isn't. It is a speaker with 3 drivers, but instead of a tweeter, midrange and woofer (TMW) it lacks a true midrange. The "midrange" is really a mid-woofer, that shares bass duties with the woofer. Often these two drivers are identical, though in the Focal Profile 918 the midwoofer and woofer were actually different drivers with the same nominal diameter (6"). 

The Monitor Audio 200 is a current example of the concept, but I am sure there are many others. It's also quite popular in kit form. One of the most high-end kits I know of is the Ophelia based on a ScanSpeak Be tweeter and 6" Revelator mid-woofers. I haven't heard them, but I am in eternal love with those mid-woofers. I believe the original plans come from the German speaker building magazine Klan Ton. 

However many other kits are also available

But regardless of kit, or store purchased, are you a 2.5 way fan? Why or why not? 



Showing 1 response by omniplanarhorn

Hi. Newbie here. I've been reading this thread with interest and wondered if it might be helpful to briefly summarize the basic rationale behind a 2.5-way design.

It's really a question of performance versus cost. Multiple woofers deliver more bass output than a single woofer. If those woofers are relatively small -- say, 6.5-inch or less -- they should also deliver reasonably good sound in the midrange. However, if they are all operating in unison up to the crossover point with the tweeter, there will be anomalies in the midrange stemming from the physical separation of the woofers. So only one woofer (usually the one closest to the tweeter) is allowed to operate that high; the other (there could be more than one, although I can't think of any examples) is rolled off at a much lower frequency.

A 3-way design should preferable, at least in theory, but it requires an additional type of driver and a more complex crossover network, and both of those increase the cost.