Underpowering IB subs: NU3000DSP w/Ultimax

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I have a Behringer NU3000DSP which is powering an Ultimax 18" in a large ported cab.  I am considering getting a 2nd Ultimax 18 for a 2 sub IB manifold and powering them with this NU3000DSP.

The 18" Ultimax is rated at 1000W RMS (and handles even more) but is it still a good idea to underpower IB subs in general and this one in particular?  The way two or four Ultimax 18" subs could be wired would result in about 520 RMS each.  Do you think that this would be adequate power for these speakers?

Thanks.

[ThomasW]

As is explained in the FAQ IB subs are excursion limited not thermal limited.

1000 watts is the thermal limit for your driver, as such it's not relevant when the driver is used in a IB

You can check the amount of power needed for the drivers by modeling them in Unibox, Win ISD or similar. Use the largest number the program will accept for the box size.

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Aug 31, 2015 20:32:17 GMT -7 ThomasW said:

As is explained in the FAQ IB subs are excursion limited not thermal limited.

1000 watts is the thermal limit for your driver, as such it's not relevant when the driver is used in a IB

You can check the amount of power needed for the drivers by modeling them in Unibox, Win ISD or similar. Use the largest number the program will accept for the box size.

So in Win ISD look at cone excursion, then?  Under signal should I enter Watts per speaker or total wattage under "System input power"?

Thanks.

[ThomasW]

Sorry I don't use WinISD, that said, enter the value in both places and see what differences it creates.

Enter an arbitrary value say 200 watts or so, then increase the power until you see it exceeds Xmax, Then back off until you find a power level that matches Xmax.

Understand this is only a sim not real life, but it's as close as you'll get without actually building the sub.

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Thanks