XF212 for PA?

Combining subs, tops and all the rest of your kit.
Bruce Weldy
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Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: XF212 for PA?

#16 Post by Bruce Weldy » Tue Oct 29, 2019 2:21 pm

CSConrad wrote:
Tue Oct 29, 2019 12:34 pm
I'm looking at a room that's wider than it is deep, so horns are not the best choice.
I don't understand this statement....... what about horns would make them any less of an option than direct radiators?

Horns certainly make the cab more efficient, but once the sound exits, what difference does the shape of the room make that's any different than a direct radiator?

Your struggles in this type of room are way more about placement, number of cabinets, and EQ than cabinet type.

I've mixed in these kind of settings.....and yes, they are a PITA to get even coverage.

6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
2 - XF210

"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

Posts: 115
Joined: Tue Jan 20, 2015 4:37 pm

Re: XF212 for PA?

#17 Post by AcousticScience » Fri Nov 15, 2019 10:31 am

To be honest, two stacked and rotated Simplexx 12 if he already has the co-axial drivers, or two stacked and rotated Omnitop 12, or with melded piezo arrays would do what he wanted dispersion wise. The only choice I've experimented with personally is two stacked and rotated Omnitop 12, preferrably with the compression horns diffuser rods lined up. This provided even dispersion and quite a good transition from one box to the other sonically, though still inferior to one.

If he doesn't like the "horn sound" the EQ can be used enough to adjust the balance, particularly on the compression drivers. There would be some interference between boxes but less so than a splayed "cluster array" which unless your tops are synergy horns is riddled with interference problems on most designs.

As for the vented subs, even on 21" it takes gobs of Xmax to get a 25/30 Hz tuned cab to take 3000 watts so I'd limit those amps. The lower the tuning, the higher the excursion for your power. At 40Hz and above tuning, they can take more power. If you don't need extreme volume it's probably fine.

As an example, the following is a model of a B&C 21SW152 (one of the highest power 21" PA speakers available) 4 ohm at 100 Volts in half space (166.9 litre box + 800 cm^2 1m long port tuning 31Hz in half space).
SPL unfiltered:
B&C.jpg (18.12 KiB) Viewed 149 times
Driver excursion (mm) with the minimum recommended 24dB/Octave high pass butterworth filter at 24Hz:
Displacement.jpg (22.56 KiB) Viewed 149 times
Power consumption (kilowatts) at 100V with 24Hz filter:
power.jpg (25.57 KiB) Viewed 149 times
You can see that all the excursion is used with a 31Hz tuning and the highest power is 2.6 kilowatts in the bass range. Whilst there might be a bit of room between Xmax and Xlim, you can see how difficult it is to get loud and low with a bass reflex.

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