MattHooper
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With regard to Acora and the idea that Stone is the best speaker material, no doubt because the claim is it is so dense and less resonant, it seems a lot of audiophiles (at least outside ASR) almost take it for granted that the thicker or stiffer the material means less resonance.
But from what I’ve been able to understand, everything resonates, and in that sense, you’re just sort of pushing resonances around. (I experienced this myself in trying different materials beneath my loudspeaker, including a thick marble base, which still resonated).
You can see in the Stereophile measurements of an Acora speaker cabinet, that in a way they’re just moving resonances around, as there is a major resonance around 900Hz.
It seems were most wooden cabinets have lower frequency resonances, this stone cabinet has simply moved it up in the frequency response:
There’s a nice discussion of cabinet resonance and how Magico approach it in the recent Stereophile review of the big Magico S5 speaker. Here:
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This is a massive loudspeaker, weighing 262lb. People often assume that adding mass minimizes resonant behavior, however, this isn't correct. When mathematically modeled, mass behaves as a reactance, either capacitive or inductive depending on the situation, and as any engineer will tell you, you cannot dissipate energy with a reactance. Only resistance will do that, and the mechanical analog of electrical resistance is frictional loss. By itself, therefore, an undamped massive structure is no less resonant than an undamped lightweight one, and in fact, by acting as a bigger capacitor, can make the situation worse. Mass and damping is what is required, along with strategic placement of bracing.
Aluminum rings. I discussed this subject-vibration and mass—with Alon Wolf, who said that people think that's a bad thing. On the contrary, he explained, it's a good thing it rings because it means it releases energy quickly. He told me that before they actually build anything, the design is completely laid down. Three-dimensional modeling-simulation-is used to optimize the design of the S5 2024's aluminum enclosure, maximizing stiffness while enabling optimal damping. Following the simulation, a cabinet is assembled, and a Polytec laser Doppler vibrometer is used to examine the vibrational behavior at many points on its surface. The resultant data can then be used to calculate the sound-pressure levels generated by the vibrations, and the enclosure's construction is then remodeled by the simulator, addressing the problems found by the laser vibrometer. This iterative strategy enables Magico to ensure that the S5's cabinet doesn't add coloration. The end result, Wolf said, is the perfect enclosure.
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Seems Magico know what they are speaking of, here is JA’s measurement of the Magico cabinet vibration. Nothing there:
I think the part I bolded above is likely telling with regard to the resonance found in the stone Acora speaker:
“By itself, therefore, an undamped massive structure is no less resonant than an undamped lightweight one, and in fact, by acting as a bigger capacitor, can make the situation worse.”
Because as I remember, one of Acora’s claims is that the density of the stone cabinet allows them to do away with the need for damping material within the cabinet that would reduce sensitivity, and so they’re able to get higher sensitivity by leaving other damping material out of the design.
It looks like they’re not totally successful in that regard.
But from what I’ve been able to understand, everything resonates, and in that sense, you’re just sort of pushing resonances around. (I experienced this myself in trying different materials beneath my loudspeaker, including a thick marble base, which still resonated).
You can see in the Stereophile measurements of an Acora speaker cabinet, that in a way they’re just moving resonances around, as there is a major resonance around 900Hz.
It seems were most wooden cabinets have lower frequency resonances, this stone cabinet has simply moved it up in the frequency response:
There’s a nice discussion of cabinet resonance and how Magico approach it in the recent Stereophile review of the big Magico S5 speaker. Here:
————————————-
This is a massive loudspeaker, weighing 262lb. People often assume that adding mass minimizes resonant behavior, however, this isn't correct. When mathematically modeled, mass behaves as a reactance, either capacitive or inductive depending on the situation, and as any engineer will tell you, you cannot dissipate energy with a reactance. Only resistance will do that, and the mechanical analog of electrical resistance is frictional loss. By itself, therefore, an undamped massive structure is no less resonant than an undamped lightweight one, and in fact, by acting as a bigger capacitor, can make the situation worse. Mass and damping is what is required, along with strategic placement of bracing.
Aluminum rings. I discussed this subject-vibration and mass—with Alon Wolf, who said that people think that's a bad thing. On the contrary, he explained, it's a good thing it rings because it means it releases energy quickly. He told me that before they actually build anything, the design is completely laid down. Three-dimensional modeling-simulation-is used to optimize the design of the S5 2024's aluminum enclosure, maximizing stiffness while enabling optimal damping. Following the simulation, a cabinet is assembled, and a Polytec laser Doppler vibrometer is used to examine the vibrational behavior at many points on its surface. The resultant data can then be used to calculate the sound-pressure levels generated by the vibrations, and the enclosure's construction is then remodeled by the simulator, addressing the problems found by the laser vibrometer. This iterative strategy enables Magico to ensure that the S5's cabinet doesn't add coloration. The end result, Wolf said, is the perfect enclosure.
——————————————-
Seems Magico know what they are speaking of, here is JA’s measurement of the Magico cabinet vibration. Nothing there:
I think the part I bolded above is likely telling with regard to the resonance found in the stone Acora speaker:
“By itself, therefore, an undamped massive structure is no less resonant than an undamped lightweight one, and in fact, by acting as a bigger capacitor, can make the situation worse.”
Because as I remember, one of Acora’s claims is that the density of the stone cabinet allows them to do away with the need for damping material within the cabinet that would reduce sensitivity, and so they’re able to get higher sensitivity by leaving other damping material out of the design.
It looks like they’re not totally successful in that regard.
