The midrange is the most important driver.

you should tweet your post

@erik_squires

In my main speakers the midrange unit is the most expensive one and the tweeter the cheapest, so the very reverse scenario of what you’re initially referring to. Among the traits of the mids driver one in particular may be a standout, namely how low it is able to extend and hereby meet the bass(-horn). Conversely the upper band of the (15") bass driver is vital, insofar in this case it extends to some 500Hz. Which brings us to the very important frequency range from what I can gather, with some arguing it may perhaps be the most important one, that of the upper bass to lower midrange. This area very much "grounds" or determines the overall sound with its proper energy and sheer ability to effortlessly move significant amounts of air (I’m not talking SPL’s here but rather energy and fullness, in a sense); so, if we maintain the premise of the importance of this frequency area in particular, and being that the lower mids to upper bass resides from somewhere between 150-200Hz and up to approximately 500Hz, the bass driver (and with my speakers its associating horn) and how it performs here is paramount. Given the cross-over though of ~500 Hz the performance of the midrange (plus horn) here is also a high priority, and that it reproduces this lower area of its band with ease and proper energy - not least also to uphold coherency (is there even a word like ’energy-coherence’?). To my mind the core midrange (and arguably upper midrange as well) is equally important, which brings us all the way up to some 4kHz, still within the band of the (in my case) midrange driver. I guess then from this one could deduce the tweeter to be the least important driver, and while I wouldn’t go that far I’m not really sympathetic with the notion of spending the most dough here. Perhaps this tendency, if it really is, could be symptomatic of the priority among many audiophiles to pursue "airiness" and extension here. Maybe the notion should be reversed that there’s really no less important driver, but that there are particularly audible pitfalls through the frequency spectrum (that also involves sheer radiation area and not least implementation) that calls for outright care and focus not to "fall into." Question is how much expenditure is an indicator through all of this, contrasted in a sense to care and implementation in finding and using the proper drivers? Just my $0.02.

Here is a sampler review in support of thie statement asserting the importance of a superior midrange performance:

http://stereotimes.com/speak121305.shtml

".... Immediate impressions are a clear and transparent portrayal with very high detail retrieval, fast and controlled transient response, and superb musical timing, both in articulating rhythms and tempi, and in placing instruments within the temporal flow and context of the performance. The RR125 is an outstanding mid/bass driver, sonically and musically right in line with the midrange performance of Rega’s amplifiers and phono cartridges. Get the midrange right and everything else will fall into place. Get it wrong, and all the king’s horses…"