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Old 8th October 2010, 10:55 AM   #11
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Why rule out open baffles? The only disadvantage I can see is that they must be large to provide much low bass.

The EQ required is very simple, in fact a passive 1st or 2nd order network before the power amps should do it all.

Power requirements can also be very low. I rarely exceed 1W with my own open baffles, even if I do like to play rather loud.
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Old 8th October 2010, 05:24 PM   #12
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There is this relationship for sealed boxes-

(maximum efficiency)= (2E-6)*(F3)*(F3)*(F3)*Vb

Where efficiency is in acoustic watts, F3 in Hertz, and Vb in cubic meters. Believe this is the formula for a sealed box but it could be the formula for a vented box. The only difference between the sealed box and vented box formula is the constant in front. The key point is one can see there is a relationship between box size, F3 cutoff frequency, and efficiency. This is why there are no small woofers with loud bass. Please notice there is no mention of woofer cone area because cone size does not affect the outcome of the relationship. Cone area does affect the maximum SPL and so on. As example, I have a little woofer that in a quater cubic foot sealed is -3dB at 40Hz but is very low efficiency and will only play like 85dB max.

With this relationship in mind I look for woofers which come close to the maximum efficiency in a given box size with a given cutoff frequency.

Here is a 10 and a 12 that come moderately close to the max if no error was made in calculation:
Peerless 830500 12" XLS Subwoofer | Parts-Express.com
Peerless 835016 10" Aluminum Cone XXLS Subwoofer | Parts-Express.com
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Old 8th October 2010, 05:28 PM   #13
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One more thing- this woofer gives about 97.5dB for one watt in like an 8 cubic foot box down to 40Hz.
Eminence Sigma Pro-18A-2 18" Cast Frame Driver | Parts-Express.com
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Old 8th October 2010, 09:51 PM   #14
Flaesh is offline Flaesh  Russian Federation
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90dB\2.83V@1m @2pi @40Hz in 8 cubic foot box.
why 97.5
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Old 8th October 2010, 10:13 PM   #15
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>>> In my opinion, open baffle offers a bass quality that cannot be matched.

I love my H-frames and think they sound better than plain open baffle speakers without sides... in my room anyway. My sealed powered sub sits unused in the laundry room. It could not match the H-frames in any way. I believe they get down into the mid 30hz range and spoil me daily with rich, full, effortless sounding bass. Imo, the best sounding home setups would include H-frames... perhaps stacked H-frames... they sound amazing!
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Old 8th October 2010, 10:50 PM   #16
Helmuth is offline Helmuth  Netherlands
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High efficiency driver for closed box.

The eminence kilomax 18"
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Old 8th October 2010, 11:55 PM   #17
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http://www.parts-express.com/pdf/290-427s.pdf has the IEC baffle response showing nominal efficiency at 97.5dB which is the right size box should come out about -3dB at 65Hz not 40Hz- oops. A little EQ will bring out the rest of the bass and might still qualify for high efficiency. Everyone makes errors- sorry for this one. The 10" and 12" are good though but not so efficient.
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Old 9th October 2010, 02:01 AM   #18
CLS is offline CLS  Taiwan
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Please don't let those numbers spoil the fun. In reality, these woofers are not that bad.

I remember, years ago, before I built the cabinets, I tried using the woofers just in their own cardboad boxes

I just opened the four lids of the box and let the woofer show its cone upward, done! How quick! (that's really a 'fast' bass, LOL) The cardboard 'frame' inside the box for supporting the woofer forms a small baffle, and the box itself is a very leaky sealed box, so the small volume is not bothering.

Later I took another woofer, faced it down and covered the one in the box, an isobarik box was done I used them this way for a while. Pushed the box into the corner, and they played quite loud and not boomy at all - they were actually better than the 'real' cabinets I built later (with 24mm thick MDF and heavily braced) in this regard. What a ooxx....

With large enough cone area and decent motor, the sensitivity, or the acoustic power eventually, is not a major problem, if we step back a little and see the whole picture. There are many ways to tune them to get what you need.

With the size of ordinary woofers, they tend to be omni in their operation range if enclosed. So the in room response is largely supported and increased by boundaries. Since I used 18" pro woofers, my major problem is always too much energy, instead of the opposite. They are just easily overflowing the house. So now I use them on OB.

With 2 12~15" per side, in ordinary home environment and under sane SPL, I don't think there'd be any lacking. (15" would be my choice if I start over.) Active xover helps a lot, too.

Have fun!
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Old 9th October 2010, 07:22 AM   #19
Helmuth is offline Helmuth  Netherlands
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Line array closed box using 4X sls265. 40Hz 94 dB. 180L without stuffing. 150L with stuffing.
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Old 9th October 2010, 11:40 PM   #20
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By the way,- we all here prefer to use low Q in box, 0.5 or less, and EQ to end up with flat bass in a calibrated system. Never have been in a room that did not have problems in the bass so EQ has always been used.
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