Thoughts on single driver speakers

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.

Eldartford makes a good point regarding cone breakup but, if properly managed, breakup also increases dispersion, resulting in much less midrange beaming. Most two ways also operate the low frequency drives in breakup mode in the mid and upper mid frequencies. Sometimes it is beneficial to trade phase response for improvements in other parameters, but it does mean that most single driver moving coil systems are not phase coherent. At least not if you define it by meaning that the driver can pass a clean square wave.

Nothing's perfect. I like my single-driver setup just fine. I've had alot of the "more normal" stuff, and the single-drivers sound better to me, especially when using a low power SET amp.