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Single driver speakers without the pitfalls?

In researching SET amps, I have learned a lot more about the sort of high efficiency speakers that they are typically paired with, including single driver models like Omega, Blumenstein, Teresonic, etc.
The advantages of these designs are well acknowledged: coherence, imaging, high-efficiency and so forth.
At the same time, there seem to be equally well acknowledged drawbacks to these designs: Limited bass response, rolled off highs, and a harshness or "shout" in the upper midrange.
Some designers, like Tekton and Zu, seem to take the approach of getting the best of all worlds by joining a wide range driver to a tweeter of some sort. (To some extent, my Reference 3AM De Capo monitors take this approach.)
What I'm curious to learn is whether you think there are any single driver, full range systems that transcend the above limitations.
Eager to hear your thoughts.
rebbi
mapman's avatar
mapman
21,851 posts
 
Take a look at This primer on how speakers work. It helps me to actually visualize why conventional full range pistonic drivers might not be such a great idea from a distortion perspective. Bending wave Walsh drivers are much better suited IMHO.

Its truly incredible that speakers work as well as they do. Turntables too. Both have the laws of physics surrounding mass and inertia working against them. Not so much a concern with digital, amps, etc. Different physics at work there revolving solely around electricity (no moving parts) that are probably easier to overcome with technology over time in general.
rebbi OP
1,326 posts
 
Shakey,
I'm not really in the market for a single driver speaker; too many limitations and negatives. But I think that the wide-range + tweeter approach is a good one. That's essentially what my De Capo's and the various Tekton models seem to so. You get that coherence with the crossover out of the midrange's way, but you're not asking the main driver to do more than it can physically accomplish in the high end.
seikosha
218 posts
 
This thread led me to a question that may or may not have an easy answer. Under which scenario is a driver (lets say 7inch) being asked to do more:

1.) Run from about 45 to 5,000 hz
2.) Run from about 65 to 14,000 hz

I'm not sure what taxes a driver more: trying to produce a 45 and 5k hz signal at the same time or a 65 and 14k signal.

Probably not an easy answer for this but if anyone has any ideas, I'd be curious.
atmasphere's avatar
atmasphere
11,590 posts
 
Getting a small driver to do bass is hard. Its a matter of excursion.

Getting it to do the highs is an entirely different problem! You get cancellation in the cone, which is why many single-driver speakers have a device called a phase plug the helps prevent cancellation.

Then you often get comb-filtering effects in the cabinet, which is why the midrange can get harsh (and also why many people prefer open back setups, or else really expensive cabinetry that solves the comb filtering issue...).

So you are right. Not an easy simple answer.
mapman's avatar
mapman
21,851 posts
 
One of teh reasons I like the OHM Walsh CLS speakers so much is that the driver is above the cabinet firing vertically for the low end and wave bending to emit sound horizontally at the higher frequencies. The Walsh operating principle seem to distribute the work along the cone better. I have never heard any OHM CLS driver speaker exhibit any signs of stress or breakup EVER, even operating at high volume outdoors (off a suitable amp). And the sound is always most coherent, as advertised.

Cabinets only come in to play to provide volume needed for bass response and can be easily refurbed and refitted as needed to avoid expensive new cabinets unless desired.

Its a fantastic design with minimal tradeoffs. It does take some getting used to though, more like listening to live music than speakers.
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