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Old 17th October 2006, 01:16 AM   #11
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Default Andrew look at the Peerless SLS 315...

Have a look at the Peerless SLS 315 which you can probably find for about $80.00 CND on your side of the pond. This is just about made to order for a "W" dipole cabinet with very low rear noise. Regards Moray James.
http://www.bmm-electronics.com/Produ...roduct_ID=4296
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Old 17th October 2006, 10:09 PM   #12
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Check out the ACI SV-12
http://www.subwoofers.cc/HomeAud/HDrivers/SV12b.asp

Out of production now, but taken up by Meniscus Audio SW-1284 same speaker but they have lowered the VAS from 250lt to 170lt this could be ok.

http://www.meniscusaudio.com/speakercomponents/

Here's a pic of it, I have it working from 25hz to 160hz in 85lt stuffed sealed, sounds very good.
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Old 17th October 2006, 10:10 PM   #13
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And another,
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Old 17th October 2006, 10:11 PM   #14
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One more.
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Old 17th October 2006, 10:50 PM   #15
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I question whether low Vas is something desirable as a driver spec. Sure it reduces the box size for a target Q, but otherwise I don't believe it's something we want. It is a component of CMS, mechanical compliance (the higher the Vas, the higher the compliance), and compliance is a good thing. It is also a component of RMS, mechanical resistance (the higher the Vas, the lower the resistance), and RMS is a bad thing. To me it boils down to wanting a driver's operation to be controlled my its motor, not it's suspension. Wouldn't a perfect world driver have no suspension at all and unlimited motor control ?
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Old 18th October 2006, 03:26 AM   #16
Ron E is offline Ron E  United States
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Not to sound as if I am arguing semantics, but saying Vas is a component of Cms is like saying that wavelength is a component of the speed of sound.

There is not necessarily a correlation between Rms and Vas, either.

Whether the damping is electrical or mechanical is immaterial.
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Old 18th October 2006, 04:10 AM   #17
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Ron,

That's just semantics. There's a direct correlation between Vas and CMS, and an inverse relationship between Vas and RMS.

I must take exception to your statement regarding the source of damping, because I've yet to hear a low Qms (high mechanical damping) driver that sounds really good, and I can say the same for drivers with low Vas in relation to their size. IME stiff suspension corresponds directly to poor sound.
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Old 18th October 2006, 07:42 AM   #18
AndrewT is online now AndrewT  Scotland
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Hi,
am I right in thinking that all PA type drivers are optimised for high SPL and the direct result of this optimisation is low Vas (& high Fs)?

If that hypothesis is correct then it supports John's contention that low Vas =poor sound quality.
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Old 18th October 2006, 10:08 AM   #19
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Oh god I wish you could get these in the UK I'd put two per side on an open baffle. The best thing you can get for that price here is a "tiny" 15" woofer with a paltry 4mm xmax only useful in OB, compared to that 18" driver with 12mm that can even go in a ported box!
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Old 18th October 2006, 11:18 AM   #20
AndrewT is online now AndrewT  Scotland
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Hi Bigwill,
you think BIG!
Each 18inch with 12mm Xmax is equivalent to about 4 of my 15inch Tannoys.
You want a pair per side.

That is equivalent to 16off 15inch drivers in one room.

How long will the room last!
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