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Re: 4 Ultimax 15 or 4 SDX 12 sealed for small room
I don't know, I may be one of the very few around who have worked with both the CSS SDX12 and the Ultimax 12. In the case of the 12" drivers there is very little comparison in motor design. The SDX12 is not really a close brother to the SDX10, by the way. It actually weighs a little more than twice as much as the UM12 does, and the UM12 seems like a "small" 12" sub in comparison.
I was the person who did a lot of the initial testing of the SDX12 for the published parameters, and my numbers agreed very well with the samples sent for Klippel measurement, so the published numbers should be pretty accurate. My measurements of the UM12 where right on spec too, so both sets of published data should be good for modeling. I would assume the same to be true of the Ultimax 15.
The SDX12 is an underhung motor, dual gap XBL^2 design, so its BL curve is different from a typical overhung motor like the Ultimax. The rated Xmax of the SDX12 is +/- 28mm. It's hard to imagine someone would need more, but I have never heard this comment about only pushing them to 75% of this number, and frankly, I do not know if it applies to this driver, as it is different than early XBL versions.
Whether someone would want to use the UM15 or the SDX12 depends on a number of things. The SDX12 has a lower Qts and would have a lower Qtc as well, so its roll-off would be more gradual. The UM15, in a sealed box, could extend deeper though before roll-off. The SDX12 would be happier in a smaller box. It's a matter of system preference by the user.
Your recommendation of the Dayton DVC310-88 is a good one. I recommended it to my brother for his car due to the very well optimized T/S parameters. He later tried the UM12 in its place, and ultimately went back to the DVC because he liked it better in his car. It is a very good subwoofer for the money.
Jeff B.
I don't know, I may be one of the very few around who have worked with both the CSS SDX12 and the Ultimax 12. In the case of the 12" drivers there is very little comparison in motor design. The SDX12 is not really a close brother to the SDX10, by the way. It actually weighs a little more than twice as much as the UM12 does, and the UM12 seems like a "small" 12" sub in comparison.
I was the person who did a lot of the initial testing of the SDX12 for the published parameters, and my numbers agreed very well with the samples sent for Klippel measurement, so the published numbers should be pretty accurate. My measurements of the UM12 where right on spec too, so both sets of published data should be good for modeling. I would assume the same to be true of the Ultimax 15.
The SDX12 is an underhung motor, dual gap XBL^2 design, so its BL curve is different from a typical overhung motor like the Ultimax. The rated Xmax of the SDX12 is +/- 28mm. It's hard to imagine someone would need more, but I have never heard this comment about only pushing them to 75% of this number, and frankly, I do not know if it applies to this driver, as it is different than early XBL versions.
Whether someone would want to use the UM15 or the SDX12 depends on a number of things. The SDX12 has a lower Qts and would have a lower Qtc as well, so its roll-off would be more gradual. The UM15, in a sealed box, could extend deeper though before roll-off. The SDX12 would be happier in a smaller box. It's a matter of system preference by the user.
Your recommendation of the Dayton DVC310-88 is a good one. I recommended it to my brother for his car due to the very well optimized T/S parameters. He later tried the UM12 in its place, and ultimately went back to the DVC because he liked it better in his car. It is a very good subwoofer for the money.
Jeff B.
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