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Discussion Starter #1
Hi Guys,

Just wondering what are the recommend box sizes for both the Tempest-X and the Maelstrom-X if you intend to use EQ (DCX) or an LT circuit ???
 

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I'm wondering the same thing, you have to be careful because the Tempest-X can "only" take 600 watts on the coils, more or less. That quickly rises when you use LT... for example, if you put a T-X in a 100L box with 100% stuffing, and use a LT circuit (target Hz 23, target Q 0.5 = system resonance 32.9Hz, system Q 0.848), the driver needs 60 volts at 5ohm at 18Hz which translates to 720 watts. Howeverm ver excursion is no problem until 13Hz. So if you could use a LT circuit and a high pass filter you could do well...

My example isn't nearly perfect though, you could EQ lower.
 

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Discussion Starter #3
Thanks for the reply. 150L + EQ / TL for the Tempest-X then would be better then :)

Would 180L + EQ / TL for a Maelstrom-X be a good compromise on size ?
 

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I went with just a hair over 4 cubes with the Maelstrom, when modeling it compared to the std. 6 cubes, there really was not a big difference. Just a slight rise of a db or so before the roll off, and the roll off happened (IIRC, at work here) maybe 2 hz earlier. The WAF however was much better.
I would say if you have the LT, going to 4 cubes will not be a hurtful thing.
 

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Discussion Starter #5
I went with just a hair over 4 cubes with the Maelstrom, when modeling it compared to the std. 6 cubes, there really was not a big difference. Just a slight rise of a db or so before the roll off, and the roll off happened (IIRC, at work here) maybe 2 hz earlier. The WAF however was much better.
I would say if you have the LT, going to 4 cubes will not be a hurtful thing.
Thanks for the post mate. 4 cubic feet is around 114L. Cheers.
 

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In real use, you tend not to hit thermal limits of any of these devices unless you run test signals through them at continuous high rates. Most low frequency content is down in level to begin with. Add to that the transient nature of most program material and you don't run into thermal problems unless you do something extreme.

The mechanical limits tend to dominate the situation in the first octave and below. As a generalization, as you get above 50Hz or so, most systems tend to then be power limited. That is why power handling is such a big deal in pro-audio devices. They don't need 30mm of xmax but they do need to power handling due to the high levels used and continuous use at high SPL at those higher frequencies.

So.... you can go pretty small with an LT without power concerns. You may clip the amp but I doubt you will smoke a coil with normal use.

Kevin Haskins
Exodus Audio
 

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Discussion Starter #7
In real use, you tend not to hit thermal limits of any of these devices unless you run test signals through them at continuous high rates. Most low frequency content is down in level to begin with. Add to that the transient nature of most program material and you don't run into thermal problems unless you do something extreme.

The mechanical limits tend to dominate the situation in the first octave and below. As a generalization, as you get above 50Hz or so, most systems tend to then be power limited. That is why power handling is such a big deal in pro-audio devices. They don't need 30mm of xmax but they do need to power handling due to the high levels used and continuous use at high SPL at those higher frequencies.

So.... you can go pretty small with an LT without power concerns. You may clip the amp but I doubt you will smoke a coil with normal use.

Kevin Haskins
Exodus Audio

Thanks for the reply Kevin. How small is pretty small if you don't mind me asking? 100L too small for Maelstrom-X ? 120L, 150L, 180L ?
 

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I don't have any problem with 100L. What you find, is that the size of the driver dictates you use at least a 2.5-3 cubic foot box in terms of physical dimensions. The amount of EQ you would use in 2.5 cubic feet vs. 4 cubic feet isn't really all that significant. Your talking an extra 2dB @ 20Hz in terms of EQ when comparing 2.5 cubic feet vs. 4 cubic feet. That is more, but you probably will be mechanically limited rather than thermally limited even with the Tempest-X.

The newest version of the Tempest-X is getting a larger coil too. It is about 2.8" so I'm pushing the power rating up to about 800W-1000W.

Kevin Haskins
Exodus Audio
 

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Discussion Starter #9
I don't have any problem with 100L. What you find, is that the size of the driver dictates you use at least a 2.5-3 cubic foot box in terms of physical dimensions. The amount of EQ you would use in 2.5 cubic feet vs. 4 cubic feet isn't really all that significant. Your talking an extra 2dB @ 20Hz in terms of EQ when comparing 2.5 cubic feet vs. 4 cubic feet. That is more, but you probably will be mechanically limited rather than thermally limited even with the Tempest-X.

The newest version of the Tempest-X is getting a larger coil too. It is about 2.8" so I'm pushing the power rating up to about 800W-1000W.

Kevin Haskins
Exodus Audio
Thanks again for the detailed reply. Good news on the new Tempest-X.

Hmmm think I might aim for twin sealed 150L Maestrom-X's sometime in my future :)

One last question, what electronics would you recommend for doing the EQ? Would a DCX be good enough to perform the EQ job like an dedicated LT circuit would ?
 

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Check this post: http://www.htguide.com/forum/showpost.php4?p=125637&postcount=3

Most of the better digital EQ boxes, e.g. the Behringer DEQ2496 or DCX2496 can do it with ease.

The LT can be replicated as the sum of 3 filters - two band (bell shaped) filters and one 12dB/octave shelving filter. The first band filter changes the Q of the box/driver to 0.7 at it's Fb. The shelving filter changes the response to Q=0.7 at the new desired Fb. The second band filter sets the Q to whatever you want it to be, e.g. Q=0.5, at the new Fb.

In practice, you may not even need the band filters. Just use a shelving filter to boost the lows. If the final response curve looks the way you want it to, it doesn't matter how you get there or what kind of fancy name you give it. It's all just EQing the bass response to be the way you want it.
I can't comment on the accuracy of the above, though.
 

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Discussion Starter #11
Thanks again :)
 

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Discussion Starter #13
No problems, I have a dcx2496 myself and two sealed T-X :), might EQ them some day...
What size boxes?

If you had your time again would you go the Tempest-X's or the Maelstrom-X's ?
 

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