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If you have baffle space for a 12" driver, the RSS315HO-4 provides more displacement than the 8W7 and very good Q alignment in your box size restrictions at less than half the price. The RSS line of drivers are commonly used in "high" crossover (for a sub) implementations.
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Most of the drivers you are comparing have very similar EBP (around 60), so are all at about the same point in their transition from resonant to damped behavior in your comparisons, resulting in very similar efficiency at ~30hz in equal boxes.
For a direct radiator system, displacement is directly proportional to SPL at a given frequency provided all other conditions remain equal (space loading, for example). I think too often we make the mistake of using T/S parameters to see the OUTCOME of a particular input level, when really, the more appropriate way to "use" these tools, is from the inverse perspective. T/S parameters give us the ability to find out how much input power is required to achieve a particular amount of displacement (for whatever frequency is in question) for a given driver in a particular box.
Driver electrical/mechanical characteristics become much more important when working with sophisticated box designs that trade bandwidth for output (controlling high Q resonance with a strong motor becomes critical). As far as the simple sealed box system goes, the T/S parameters will primarily just change what your EQ settings look like. Since you have locked in a box size, and are looking at a lot of drivers in the same EBP class, the only remaining characteristics to look at is Vas, as that will effectively "set" your Q alignment, and Xmax, which will set your maximum displacement and output. Work backwards to find out how much power you will need to take advantage of the available Xmax in the resulting alignment. Keep in mind there may be additional usable Xmax beyond the rating, especially in conservatively (overhang/2) rated drivers. I'd suggest enough clean amplification to be able to get into this territory.
Eric
If you have baffle space for a 12" driver, the RSS315HO-4 provides more displacement than the 8W7 and very good Q alignment in your box size restrictions at less than half the price. The RSS line of drivers are commonly used in "high" crossover (for a sub) implementations.
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Most of the drivers you are comparing have very similar EBP (around 60), so are all at about the same point in their transition from resonant to damped behavior in your comparisons, resulting in very similar efficiency at ~30hz in equal boxes.
For a direct radiator system, displacement is directly proportional to SPL at a given frequency provided all other conditions remain equal (space loading, for example). I think too often we make the mistake of using T/S parameters to see the OUTCOME of a particular input level, when really, the more appropriate way to "use" these tools, is from the inverse perspective. T/S parameters give us the ability to find out how much input power is required to achieve a particular amount of displacement (for whatever frequency is in question) for a given driver in a particular box.
Driver electrical/mechanical characteristics become much more important when working with sophisticated box designs that trade bandwidth for output (controlling high Q resonance with a strong motor becomes critical). As far as the simple sealed box system goes, the T/S parameters will primarily just change what your EQ settings look like. Since you have locked in a box size, and are looking at a lot of drivers in the same EBP class, the only remaining characteristics to look at is Vas, as that will effectively "set" your Q alignment, and Xmax, which will set your maximum displacement and output. Work backwards to find out how much power you will need to take advantage of the available Xmax in the resulting alignment. Keep in mind there may be additional usable Xmax beyond the rating, especially in conservatively (overhang/2) rated drivers. I'd suggest enough clean amplification to be able to get into this territory.
Eric
Do you have any FR measurements for an 8W7? It's a driver I've been curious about, but not enough to buy and play with because there's a high probability it won't meet my expectations. The reason is that it has a very long voice coil and no shorting rings in the motor. So while BL linearity over stroke may be outstanding due to the carefully optimized polepiece, inductance is high and inductance variation over that stroke is large.
I have played with the 13W7, and it sounded like other very high inductance bass drivers I've tried. Killer driver to move tons of air below 40Hz or so in a small box with megawatts, but just not well enough designed for use much above that. If Jello would control inductance variation in the motor with the same care as they optimized BL(x), these things would be ridiculously good.
Hi Pallas,
I must have read into the claims of the 8W7 incorrectly. I was under the impression there must have been some strategic copper placement as the claims of ultralinear behavior and optimized motor sort of lead me to "assume." As such you may be absolutely correct in the line of thinking that it may not be suitable for higher midbass response. (>~80hz).
In which case for this box size, the RSS315HO-4 looks that much better still.
I must have read into the claims of the 8W7 incorrectly. I was under the impression there must have been some strategic copper placement as the claims of ultralinear behavior and optimized motor sort of lead me to "assume." As such you may be absolutely correct in the line of thinking that it may not be suitable for higher midbass response. (>~80hz).
In which case for this box size, the RSS315HO-4 looks that much better still.
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