Plato -
The low-frequency resonance phenomenon you mention can indeed produce a very significant response peak if it isn't adequately addressed.
Roger West of Sound Lab uses a patented technique called "distributed resonance", wherein he divides up each of the seven vertical facets into 12 cells. Each cell is the same width, but of a different height - hence each has a different drum-head resonance. By carefully staggering these resonances, not only is the overall response smoothed but it's extended a bit lower than it normally would go. The result is excellent pitch definition in the bottom octaves (one customer, a concert violinist, told me that the Sound Labs were the only speaker he'd ever heard properly reproduce both cello and double-bass).
Martin-Logan also used a version of distributed resonance on the CLS - that's the purpose of those divisions you see on the panel.
The concentric rings of the Quads probably also distributes the drumhead resonances a bit, though not as precisely as the Sound Lab technique does. To my ears, the bass of the 989 is less coherent than the bass of the smaller 988 - perhaps the additional bass radiating area of the 989 suffers from low-frequency diaphragm resonances?
If I'm not mistaken, Magnepan tunes their panels so that the resonant peak occurs below the normal dipole roll-off frequency, and thereby extends the bass deeper than it normally would have gone.
Obviously, hybrids don't have to worry about low-frequency diaphragm drumhead resonances, but they do have box colorations and radiation pattern incongruities to deal with. My vote is for full-range panels, where practical.
Esoxhntr, congrats on being a CLS owner! In my opinion, that's the most physically beautiful loudspeaker ever made. And they sound wonderful as well. The CLS was my favorite Martin Logan speaker, and I sure was sad to see it go. I spend some time talking with Gale Sanders a couple of nights ago, and tried to convince him to bring back something along the lines of the CLS.
Duke
The low-frequency resonance phenomenon you mention can indeed produce a very significant response peak if it isn't adequately addressed.
Roger West of Sound Lab uses a patented technique called "distributed resonance", wherein he divides up each of the seven vertical facets into 12 cells. Each cell is the same width, but of a different height - hence each has a different drum-head resonance. By carefully staggering these resonances, not only is the overall response smoothed but it's extended a bit lower than it normally would go. The result is excellent pitch definition in the bottom octaves (one customer, a concert violinist, told me that the Sound Labs were the only speaker he'd ever heard properly reproduce both cello and double-bass).
Martin-Logan also used a version of distributed resonance on the CLS - that's the purpose of those divisions you see on the panel.
The concentric rings of the Quads probably also distributes the drumhead resonances a bit, though not as precisely as the Sound Lab technique does. To my ears, the bass of the 989 is less coherent than the bass of the smaller 988 - perhaps the additional bass radiating area of the 989 suffers from low-frequency diaphragm resonances?
If I'm not mistaken, Magnepan tunes their panels so that the resonant peak occurs below the normal dipole roll-off frequency, and thereby extends the bass deeper than it normally would have gone.
Obviously, hybrids don't have to worry about low-frequency diaphragm drumhead resonances, but they do have box colorations and radiation pattern incongruities to deal with. My vote is for full-range panels, where practical.
Esoxhntr, congrats on being a CLS owner! In my opinion, that's the most physically beautiful loudspeaker ever made. And they sound wonderful as well. The CLS was my favorite Martin Logan speaker, and I sure was sad to see it go. I spend some time talking with Gale Sanders a couple of nights ago, and tried to convince him to bring back something along the lines of the CLS.
Duke