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Ricci wrote:
 Yes, I'm quite aware of all of this. That's why most of us are suggesting PR's or sealed. A 6" port would not be ideal, but it wouldn't be a major issue until very high output levels. This is a very hard driver to port correctly. Many people are using a single 6" port with 15's that move just as much air as a 13w7. The SVS uses almost exactly the same port area as a 6" port. Not more. It is 3 3.5" ports. |
And the LF output of that SVS unit has about a 50 percent output reduction near maximum output levels around the tuning frequency due to port compression.
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The box that you are suggesting is not a bad alignment, but it takes nearly 2500watts to get all of the out put from it and I'm not sure that the 13w7 will take that much power thermally when it is at the minimum motion point near tuning. The slot port is going to take up nearly 2 cu ft of enclosure volume, so your enclosure is really about 6.5ft also. I just would like to see a lower tuning to get more output down low 14-18hz if he's going to port or PR it.
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I modeled the driver with 1000 watts. It produces extremely high output levels across a very wide band, and this was with substantial de-rating I assumed, to account for thermal and other non-linear behavior(s). The real key to performance here is the port - a properly designed port with larger than standard cross section allows for a substantially higher LF output ability.
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No it won't. Where is your proof of this and exactly what are you considering LF's? 25hz? I can think of at-least 4 units that would have higher out-put anywhere below 80hz.
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What commercial product examples would these be? Perhaps some subwoofers with multiples of drivers(
the only case where I can think of this possibly occurring, considering the currently available products of which I am aware of)? I need some form of evidence - 3rd party tests like Ilkka's or the other site that does similar measurements would suffice.
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Yes, and you can clearly see the effects of those in many loudspeaker measurements. They can also be audible. Greatly attenuated by the crossover? I don't think so. It's not even an octave away from 80hz. Again what if you need to cross over at 100hz? You are going to be very lucky to have 12db's of attenuation at 107 with an 80hz crossover. Still could be quite audible.
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You are correct, that the output will -12dB, I made an error in that regard. It is still not an issue that I can see will be of any consequence - as this frequency - which is substantially clear of the xover range - can be cascade filtered and/or notched, IF YOU ARE WORRIED about it. Pretty much no one seems to care when the port resonance resides in the 200-500hz range(extremely common) on most vented high-fi speakers of high regard. I contend, that I prefer there to be no such chance, and I do provide for ways to make this a non issue in the subwoofer design I presented.
-Chris