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Old 2nd December 2007, 06:52 PM   #1
vajolet is offline vajolet  Italy
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Question Large Cone/large VC or several medium sized cones / medium VCs

hi,
new here, hello again !

For a high-power-subwoofer-hifi-system I'm not sure using 2x 15/18" cones - 4"-VCs or for identical cone area 4 or 6x 12" cones with 2" VCs. Does anybody have experience ?

Power-compression/distortion is better at large VC-design one speaker alone compared the 12" alone. Can calculate by speaker-datas cross-limits depending of frequency or SPL.

Several cones-design should have more sound-attack, shouldn't it ...? Thanks for comments !

Rob
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Old 2nd December 2007, 07:08 PM   #2
AndrewT is online now AndrewT  Scotland
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Hi,
the same area from any combination will give the same sound pressure when driven to the same displacement, provided they are kept close together.
If you are using a sub-bass low pass filter then speed is irrelevant.
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Old 2nd December 2007, 08:23 PM   #3
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If not using horns, I go for the max volume displacement possible for the space I have available.
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Old 2nd December 2007, 08:26 PM   #4
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And whenever feasible use pairs of drivers push-push.

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Old 2nd December 2007, 08:46 PM   #5
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Quote:
Originally posted by planet10
And whenever feasible use pairs of drivers push-push.

dave
Absolutely
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Old 2nd December 2007, 10:00 PM   #6
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You also should look at the" xmax " of the drivers, Usually !5s and 18' have shorter ones.

Personally, I'd go for 4 -12" with 12mm xmax, rather than 2 -15/18.
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Old 2nd December 2007, 10:23 PM   #7
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Quote:
Originally posted by marchel
You also should look at the" xmax " of the drivers, Usually !5s and 18' have shorter ones.

Personally, I'd go for 4 -12" with 12mm xmax, rather than 2 -15/18.
There are plenty of 18's with 8-9mm and 2.5x the Sd.
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Old 3rd December 2007, 03:00 AM   #8
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Quote:
Originally posted by Brett
There are plenty of 18's with 8-9mm and 2.5x the Sd.

Even so, The 2 -12s with 12mm xmax will have more displacement than most single 18, and most 18 arent even designed for subwoofer duty, so thier cones are not as rigid as 12" subs .

Added to the fact that, a good quality 18" sub. is much more expensive than 2 good quality 12" subs. And that there are plenty of 12" subs to choose from, whether for home use or car. The same thing cannot be said for 18s.

Therefore , 4- 12" makes more sense to me that 2 - 18s. But that's just me.
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Old 3rd December 2007, 05:24 AM   #9
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Default Re: Large Cone/large VC or several medium sized cones / medium VCs

Quote:
Originally posted by vajolet
For a high-power-subwoofer-hifi-system I'm not sure using 2x 15/18" cones - 4"-VCs or for identical cone area 4 or 6x 12" cones with 2" VCs. Does anybody have experience ?
Rob

A bipole subwoofer line array with mass cancellation from mirrored driver cabinets is very good for charging a room and reducing room resonant modes. The Martin Logan Statement2 used a multi-box line array of bipole subwoofers, each box using mirrored 2-driver mass cancellation. This seems like a good solution to getting deep bass by pressurizing the room below the room's lowest frequency mode.

From my experiemce, the 15" woofers in the market provide the best combination of impulse responise and deep bass. Treated paper cone woofers with 20Hz Fs, strong magnets, and ~15mm Xmax are readily available. Subwoofer harmonics can reach up into midbass vocals, and metal cone break-up is audible even with -24db of Xover attenuation. Many metal coine 15" subwoofers have over 300g Mms, while treated paper cones are tyically under 150g. I favor woofers/subwoofers which produce good human voice at 80-160hz.
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Old 3rd December 2007, 05:27 AM   #10
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Quote:
Originally posted by marchel
[B]Even so, The 2 -12s with 12mm xmax will have more displacement than most single 18, and most 18 arent even designed for subwoofer duty, so thier cones are not as rigid as 12" subs .
I would never use a single driver in a standard sealed or ported box under 150Hz again, except OB's and TH's.
As for cone rigidity: proof please.

Quote:
Originally posted by marchel
Added to the fact that, a good quality 18" sub. is much more expensive than 2 good quality 12" subs. And that there are plenty of 12" subs to choose from, whether for home use or car. The same thing cannot be said for 18s.
Wouldn't know about car gear: not interested and I ride as often as not. Silence in the car is wonderful. I can think of 6 or 8 new 18's OTTOMH that would work well, esp with an LT. Several others as obsolete drivers that are available. JBL 2245 for example. When you factor in the differences in efficiency and power compression, I severely doubt some of the claims for car drivers that I've seen online and by chance in some fora. then when you factor in distortion due to displacement, then those hard working little 12's don't seem so good to me.

Oh, FWIW, I'm going to build some TH with 12's in them next weekend, so they do have some use.

As for price, that's highly variable depending where you are in the world and whether you have to import or not. Go outside of the US or EU and it's very different.

You have your view, fine. I have mine based upon my own experience..
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