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post #1 of 4 Old 01-11-2007, 01:16 AM - Thread Starter
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I'm looking to build a 'small box' (<3 cft) HT (almost exclusively) sub on a budget. I'm getting to know WINISD and could use some feedback. I'm looking to start with two of the eD EHQS 12" speakers. Remember, I said budget. In an isobaric config these look to do a decent job. Here are the T/S, etc.:

Power Handing : 200w
Qts: .375
Qes: .49
Qms: 1.506
Fs: 25.5 Hz
Re: 1.8
Vas: 157 L
Mms: 90 g
Bl: 7.2 T*m
SPL: 89.1 dB
Sd: 510 cm^2
Xmax: 9.1 mm
Voice Coil : 50 mm

I see two options that look good. First, a 2.8 cu ft box ported and tuned to 21Hz. With a Dayton 500 Watt amp providing a gain of 4 DB at 21Hz with a Q of .9 I am seeing a graph that looks pretty flat to me to 28Hz and hits -3dB at about 19Hz. I see that Xmax may be an issue. I don't plan on driving these to the edge, so I hope I would still be safe. Second, without the amp gain it looks like I could go to 2.5 cu ft box and tune it to 27 and still be flat to about 35Hz with the -3dB coming at about 27Hz. Any recommendations on which way to go? Anything else that should watch out for? Thanks!
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post #2 of 4 Old 01-11-2007, 05:53 AM
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I've done some modeling of those drivers (have a sub I built with them), but they tend to want a pretty big box to get decent extension. I've not tried isobaric loading on them - I know that will help with box size, but it would seem to me that limiting yourself down to the active area of just one driver, the limited excursion capabilities of these drivers might be a problem. So the only suggestion I have would be to model it, look at the excursion plot, and reduce power until you aren't exceeding excursion any more. Then look at the spl graph and see if you can live with that much output.


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post #3 of 4 Old 01-11-2007, 07:21 AM
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It seems like whatever cost advantage you'd get for using two cheaper drivers in an isobaric configuration you would then loose because you'd need more amp to power it. If you are looking for cheap, you may want to look for something more like a single TC-Sounds or Adire driver with a smaller cheaper amp (like the PE 300 watt BASH or the 380 watt Rhythmik). I imagine in the long run you'd appreciate the nicer single driver more too - especially if you are using boost.

Of course I haven't run the numbers on these yet so I could very well be wrong. I haven't noticed many people making isobarics here so it is nice to see something different.
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post #4 of 4 Old 01-11-2007, 09:30 AM - Thread Starter
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Thanks for the feedback. Very helpful. This is a fantastic forum. Are there any good rules of thumb regarding SPL? I'm looking for a decent HT experience, but I don't need to shake the house off the foundation. Thanks again.
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