Couple of Tempest Sonosub questions, (1 Viewer)

[Tyson]

A couple of friends and I are about to start building 3 Tempest based subs. I downloaded LspCad a while back & have been playing around with it for quite a while. We all decided to go w/ a sonosub design, 300L (just under 11 ft3) internal volume, dual 6ID inch ports 29 inches long, tuned to 18hz.
Ok, my questions are, what kind of real world SPL levels can I expect from this guy using a 250 watt amp? Where can I find an inexpensive outboard amp to power these guys? Will I need to use some kind of subsonic filter with these subs to protect the driver in the above configuration?
I tried searching both here and hometheatertalk to get answers to these questions, but couldn't really find anything (but I did find a LOT of other good info about subs in general and the Tempest in particular). Thanks in advance.

 

[Andrew Pratt]

Tyson My sonosub is almost exactly like what you propose to build and I've got a response plot on my site (link below) if you want to see what you can expect. These are max SPL's mind you but in general it can easily shake your pant legs on DVD's like Titan AE
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The Pratt Home Theater
Link Removed

 

[Tyson]

Thanks Andrew, I actually have been doing some of my research at your site - I have to say that the look of your sub is stunningly good, the endcaps are beautiful!! But aren't you using a Shiva driver?
Also, you say that those ARE max SPL's? If so, maybe the project is not worth it - I was hoping for output in the 110db range, as my single SVS 20-39 will get me close to that & I was hoping to improve signifigantly on its performance, since the Tempest has a bigger cone area, longer throw, and a larger enclosure.
But, mainly I am concerned about driver protection. With 300 watts, I don't think I will be able to surpass the drivers excursion, so above 18hz I don't think it will need "protection" in the form of a limiter. What I am concerned about really is the drivers behaviour below 18hz. Will a strong signal at, say, 14hz cause it to start "flapping in the wind"? Should I get some type of subsonic filter like the one used in the BFD (course the nice thing about the BFD is you get yourself a nice equalizer along w/the subsonic filter, so we may get one regardless).
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"Remember Sammy Jenkins"

 

[Patrick Sun]

You won't get subsonic filtering with the BFD.
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PatCave ; HT Pix ; Gear ; Sunosub I + III ; DVDs ; Link Removed

 

[Phil Olson]

Tyson,
I also downloaded the software from the Adire site and did a simulation for a dual Tempest, sealed 460L sonotube that was 112 dB flat, 4 dB down at 20 Hz. That's not a problem for me since I have a nasty room mode at 20 Hz anyway. This was driving each with 400W.
I e-mailed the simulation to Dan for his review and he said it looked great so I ordered the two Tempests on the spot.
If I can get this out of a sealed design, there's no reason you couldn't do at least as well using a ported design.
If you'd like, e-mail me and I'll send you my simulation.
Phil