aud21

50 ways to make your speaker....

One way way

First there is a one way approach, when one full-range speaker is used. Or almost full-range, since there is no such thing....its all compromises in audio.
The advantage of this arrangement is no use of crossover, which is a big plus, no loss of power, no phase shifts, sound is coherent coming from one voice coil.
The disadvantages are limited frequency response on both or one end of frequency range, limited power handling, may require complicated and large enclosures to extend lower end.
Full-range speakers were historicaly first used on open baffle. Later in closed enclosures. Many variants of enclosures exist, their goal is to extend low frequencies. Some are more effective than others.

open baffle

bassreflex box

frontloaded horn

back-loaded horn enclosures

other back-loaded horn enclosures....somehow i don't see having one of these in my living room, simply because i don't believe it is possible to obtain serious bass from twinky 6" full-range, no matter what, the result is not worth the effort

transmission line

Another approach of one way speaker is the use of multiple fullrange drivers, like in line array or omni-directional speaker on next two pictures. There are some advantages, like increased power handling, pinpoint imaging for line array, spacious sound with large sweet spot for omni-directional speaker, but there are disadvantages too, like the comb effect in line array or too much early room reflections in omni-directional speaker. It all comes to personal preference.

Two way way

     These are the most common speakers. They come in two categories. First category is when woofer/midrange is paired with suitable tweeter. These vary from small bookshelf speakers up to big floorstanding speakers. Second category has full-range speaker accompanied with subwoofer.
     First category comes in numerous designes and configurations. Perhaps this is the most common form of the speaker.
The advantage of this speaker arrangement is that by using two speakers one can get much better extension on both ends of frequency range, specialized speakers for smaller frequency range have usualy flatter frequency response, decreased distortion and increased power handling.
    The disagvantage of this speaker arrangement is introduction of passive crossover, although biamplification with active crossover can be done too, there is still a crossover with its limitations and compromises. Another issue is the use of two speakers as two point sources for sound, which leads to phase shifts, differences in horizontal vs vertical frequency response and so on. This can be partly avoided by the use of coaxial drivers.
All the enclosure types in order to extend low frequency range as mention in one way speaker systems apply here as well.

some examples of two way speakers

another aproach with two woofer/midranges, still a two way system

other examples of two way speakers

two way speakers with horn drivers for midrange/tweeters

two way speakers utilizing coaxial drivers

two way with omnidirectional tweeter

two way line array

some two way omnidirectional speakers

Second and quite different approach to two way speakers is the use of full-range speaker supported with subwoofer. In this arrangement we have all the advantages of full-range speaker, no crossover in the most critical region of frequency spectra, plus a good bass extension. Various combinations of speaker enclosures can be used.

any of these two would be my choice

if you are very brave with waf or live alone, you can construct this industrial looking 2way system with full-range accompanied with subwoofer horn done with compression driver, bravoooo....

i am very fond of open baffle speakers, first picture are my speakers, full-range drivers on open baffle accompanied with subwoofer, second picture is dick olshers basszila, excellent design

Three way way

In three way speakers designers are solving some issues of two way speakers, for instance if you choose woofer/midrange, and you want excelent midrange performance, you have to sacrifice the bass, if you insist on excelent bass extension, you sacrifice the midrange, than you have to go lower with frequency for tweeter, which bring another issues, like tweeter's power handling, directivity, plus you get crossover point to a very sensitive area. So the solution might be three way speaker. Audiophiles like them, you select best midrange, mate it with best tweeter of similar efficiency, put these into small box on top of the big box with best woofer/subwoofer. Than you spent countless hours tweeking the crossover, after you spent fortune on crossover parts. Life's not easy, but live we must. Anyway, you can get pretty decent results here, but you will almost always hear the crossover. Power handling is great if thats what you want.