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Help confirming some calculations for my Shiva X build (port length)

post #1 of 3
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I finally sucked it up and started my Shiva X build after what one might call "analysis paralysis." I was shooting for basically a 6.0 or so cu. ft. ported enclosure. I ended up taking the below design and modifying it to use (2) 4-inch precision ports. When I calculated the actual internal volume of the enclosure I have build thus far, I came up with a total internal volume of 6.93 cu ft. . When I subtract out the volume taken by bracing and the driver, I was left with 6.465 cu. ft.

Question 1 - Port Length: I have up to about 25" to play with in the enclosure, but I wasn't sure how close I can / should go to this. I looked at tuning it to 22 Hz, and Precision Port's length calculator on their website gave me a "Flare Length Port required" of 19.74 inches. WinISD, which I am horribly amater-ish with, came in at 19.32 inches, which is pretty close. But...should I go longer on my ports?? I guess I am unclear on any concept here of what the "optimal," if there is one, port length would be.

Question 2 - Amplifier: I've done a ton of reading and realize an amplifier with some type of DSP capability is likely the best way to go (whether built-in or added on). Overall, what wattage range should I be looking? I was looking at the Behringer iNuke series, such as the 1000. Are there any other amplifiers in the sub-$500 range I should consider (with or without DSP, and if without DSP, then what would a simple option be) ? I should mention I wanted to avoid plate amplifiers. And some head room on power would be nice, but a quality amplifier is most important to me really.

Thanks for help in advance - these forums are amazing for getting help on this stuff!

post #2 of 3
Port length, I would shoot for as long as you could fit in that box giving ample clearance. You want to leave clearnce behind the port about equal to the diameter of said port. I think you can stretch it to 21-22" and at that length tuning should be closer to 20hz. There really is no one optimal port length its more of an optimal range and in that box it is from about 18 to 40" (22-16hz tune).

For an amp I’d say you want something that puts out a solid KW, but I am not the best for making suggestions there as i don't have anything with that much power. The DSP in the inukes are a little limited, nothing below 20hz but if you are tuning right around there that would be all you need. Another popular DSP option is the MiniDSP which is quite flexible.

That should be quite a decent sub when you are finished.
post #3 of 3
Quote:
Originally Posted by mtg90 View Post

Port length, I would shoot for as long as you could fit in that box giving ample clearance. You want to leave clearnce behind the port about equal to the diameter of said port. I think you can stretch it to 21-22" and at that length tuning should be closer to 20hz. There really is no one optimal port length its more of an optimal range and in that box it is from about 18 to 40" (22-16hz tune).

For an amp I’d say you want something that puts out a solid KW, but I am not the best for making suggestions there as i don't have anything with that much power. The DSP in the inukes are a little limited, nothing below 20hz but if you are tuning right around there that would be all you need. Another popular DSP option is the MiniDSP which is quite flexible.

That should be quite a decent sub when you are finished.

I heard one of the Shiva's in a build like this and it was fabulous. I was at the Great Southern Shootout and it was a stellar performer.

Keep cranking,

Robert


MJG100 has one of these. It was his that was in the Shootout. He has all the dimensions. I liked it very much.
Edited by robertcharles - 1/11/13 at 10:05pm
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