Thoughts on single driver speakers

"Single driver" speakers are rarely full-range: it's (as yet) impossible for a single transducer to reproduce 20-20kHz. HOWEVER, the reference to "single" driver is in the use of one drive unit reproducing all or most of the ear-critical region, i.e. ~100 - ~10kHz (or 300-6kHz). The sound benefits greatly, as Ultrakaz notes above: you only have one source for the bulk of music's frequency content. And, therefore, you do not need a crossover in that area, AND the result is very versatile as, when you DO use a-over it can be behind the amp (line-level) - OR at frequencies where our ear is less sensitive to distortion effects (150Hz, etc).

On the down side, there are small peaks in the amplitude response as you go up in frequency (that can be addressed with appropriate filters, if need be), good wide-range drivers are expensive, accompanying super-tweets and woofs/ subwoofs MUST be commensurate (i.e. very good quality).

Good "single driver" designs are very high-end, both regarding reproduction & price.

Using ss is not a problem IMO -- I'm happy with it (I also use SET).
Cheers

The ones I heard briefly at shows sounded bad to my ears. If the composer called for thunder, by jove the speakers should put out thunder. They all sounded to me like listening to a table radio, a good table radio mind you, but a table radio nonethelss. Unfair to judge anything on a short listen in poor conditions such as shows, but nothing twigged me into wanting to hear more. A cult item if ever there was one.

I tried the single driver route. My experience was that I heard some of the benefits and I also heard the problems. They can sound very clear and coherent and,most importantly, involving. I couldn't, however, get over the obvious reduction in bass output and some of the unusual tonal balance problems. Maybe with much more expensive drivers, like Gregm suggests, the strengths would be greater and the problems less obvious. I used $280 Fostex drivers. If you were to buy a subwoofer,add a supertweeter and use filters for the frequency response irregularities, it could be made to work. It's a mixed bag of strengths and problems. Can be made to sound glorious,see the TNT article on the use of Lowther drivers with success.

Now, here's a twist on single driver speakers. My Acoustat 2+2s are a full range electrostatic going down to 28 Hz. All panels are full range, so no crossover distortion. They are very fast speakers and at almost eight feet tall they have a terrific stage. I'm driving mine with a Bryston 4BST.

"Full Range" cone drivers are not really "single" drivers. "Cone breakup" occurs, so that different parts of the cone are radiating different frequencies. Design of such a driver is more of an art than a science. The breakup characteristics of the cone constitute a crossover network...a mechanical one rather than an electrical one, and much harder to design.

The only real advantage (IMHO) of full range drivers is that the high and low frequency transducers are colocated. However, this is also true of a coaxial speaker, where the tweeter is mounted where the cone dust cap normally is located.

There are some applications, eg: speech, where high and low frequency response is unnecessary, and, for these, a good full range speaker is ideal.