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Old 20th May 2012, 01:57 PM   #1
elac310 is offline elac310  France
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Default 18" woofers - which have high Qts (+low Fs)

Hi,

I'm now planning a subwoofer project which will make use of 4x 18" woofers, probably in some kind of Ripole/Ripol arrangement mounted in a low table of 120x120cm, about 50cm high (4x4 feet, 1,5 feet high)

I've spent some time identifying suitable candidates with a high Qts (but retaining low Fs); I need 8 ohm versions and high sensitivity speakers - which excludes most car subwoofers currently made, as it seems. Here are my results:

-Eminence Kilomax pro 18a: Qts 0,47 (Fs 32, xmax 10mm)
- Fane Sovereign 18-500: Qts 0,56 (Fs 33, xmax 6,3mm)
- Ciare 18-4: Qts 0,52 (but Fs a bit high at 40 Hz, xmax 13mm)
- Mac Mah CWA46 (a French-rebadged Asian production, I think): Qts 0,45 (Fs 27)
- P-audio SN-18 ELF: Qts 0,53 (Fs 29, xmax 7,5 mm)
- P-audio AM-18 ELF: Qts 0,52 (Fs 26, xmax 6 mm)
- Selenium had plenty of high Qts woofers until very recently; now SWS 1100: Qts 0,50 (Fs 34, xmax 9,3)
- AD Audio (a German relabeled Asian production) R1830: Qts 0,64 (Fs 34, xmax 7,4 mm)

Who knows others?
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Old 20th May 2012, 09:24 PM   #2
bjorno is offline bjorno  Sweden
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Hi,

Pyle - PL1890BL - 18'' 1800 Watt DVC Subwoofer

b
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Old 20th May 2012, 10:03 PM   #3
mightym is offline mightym  United States
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Bear in mind that a Ripole alignment will both lower the Fs, and raise the Qts of the driver when you make your selection.

What about the Goldwood 18" pro driver that everyone uses in the H frame OB subs?

John

Only now I notice you are in Eu. Maybe shipping/customs would be prohibitive for the Goldwood ?
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Old 21st May 2012, 11:57 AM   #4
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by elac310 View Post
..I've spent some time identifying suitable candidates with a high Qts ..Who knows others?..
FYI,

Don't rule out low Qts low fs drivers(high BL),i.e. Drivers with a low Qes/ high Qms that have a mass roll-off = 2Fs/Qes at or above~160 as they are easily converted into high Qts by adding an appropriate series resistance.

This approach is especially useful when its possible to parallel more than two drivers making the series Qts altering resistance staying at a very low value,this when including a series inductance with a similar loss resistance.

Have a look at the submitted example picture where two (H-Frame) Ripole with 2xSd /front area = 2/1 slots are stacked vertically(stacking horizontally would even work better).

b

PS: The in post# 2 suggested Pyle driver in Car action, Note the wiggling excursion.. It's a Duck driver!:

18 inch subwoofer knockin hard live2shred.blogspot.com - YouTube
Attached Images
File Type: jpg 4xDayton-PA460-8-in-parallel_H-Frame-or-Ripole-config.JPG (502.3 KB, 1032 views)
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Old 21st May 2012, 08:22 PM   #5
elac310 is offline elac310  France
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Quote:
Originally Posted by mightym View Post
Bear in mind that a Ripole alignment will both lower the Fs, and raise the Qts of the driver when you make your selection.

What about the Goldwood 18" pro driver that everyone uses in the H frame OB subs?

John

Only now I notice you are in Eu. Maybe shipping/customs would be prohibitive for the Goldwood ?
Thanks for that.
Yes, I know the theory but obviously, there is limit to the mutation of parameters and I can't transform a Qts 0,3 woofer into a Qts 0,6 woofer just like that. Of course, I can add also series resistors, but I'd like to avoid that. I need sensitivity to match my existing Onken W bass enclosures (2x38cm woofers per side) and I use Crown Studio Ref amps, with their incomparable bass.

AFAIK, Goldwood is not distributed - indeed - in Europe. But I suspect that this is just OEM rebadged production; maybe available under another import name. I'll have a look. Thanks for the hint on this brand (which model, BTW? there are 3 different 18" woofers, as it seems).

Chris.
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Old 21st May 2012, 08:31 PM   #6
elac310 is offline elac310  France
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Quote:
Originally Posted by bjorno View Post
FYI,

Don't rule out low Qts low fs drivers(high BL),i.e. Drivers with a low Qes/ high Qms that have a mass roll-off = 2Fs/Qes at or above~160 as they are easily converted into high Qts by adding an appropriate series resistance.

This approach is especially useful when its possible to parallel more than two drivers making the series Qts altering resistance staying at a very low value,this when including a series inductance with a similar loss resistance.

Have a look at the submitted example picture where two (H-Frame) Ripole with 2xSd /front area = 2/1 slots are stacked vertically(stacking horizontally would even work better).

b

PS: The in post# 2 suggested Pyle driver in Car action, Note the wiggling excursion.. It's a Duck driver!:

18 inch subwoofer knockin hard live2shred.blogspot.com - YouTube
Hmm...Interesting proposals. I need to think about all that. I'm usually much more into powerful woofers and all this high Qts business is quite new to me, in fact. And the choice is very limited among pro sound/PA drivers, so ways to stay with "classical" superwoofers are of course welcome.

The attachmment is a bit small, even when I use maximum magnification. Can you send it to my pm?

Chris.
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Old 21st May 2012, 09:55 PM   #7
elac310 is offline elac310  France
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Beyma 18LX60V2: Qts: 0,48, Fs 35, xmax +/- 9mm (xdamage +/- 58mm)
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Old 22nd May 2012, 02:11 AM   #8
mightym is offline mightym  United States
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I've heard this one in an " H " frame sub. I liked it. With room gain was getting into the 20's.

Goldwood GW-1858 18" Pro Woofer 290-386

Price ( at least in US ) is reasonable too.

John
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Old 22nd May 2012, 10:14 AM   #9
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Check out the BMS 18N862 very serious driver. You can most likely get away with using one driver for the build instead of four..
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Old 22nd May 2012, 07:41 PM   #10
elac310 is offline elac310  France
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Quote:
Originally Posted by mightym View Post
I've heard this one in an " H " frame sub. I liked it. With room gain was getting into the 20's.

Goldwood GW-1858 18" Pro Woofer 290-386

Price ( at least in US ) is reasonable too.

John
Ok, that's the one then. Tech data says :

GW-1858/Specifications: • Power handling: 220 watts RMS/310 watts max • VCdia: 2.5" • Le: 0.6 mH • Nominal impedance: 8.0 ohms • Re: 5.3 ohms • DC resistance: 6.2 ohms • Frequency range: 30-2,000 Hz • Magnet weight: 50 oz. • Fs: 30.3 Hz • SPL: 94.3 dB 2.83W/1m • Vas: 18.50 cu. ft. • Qms: 6.7• Qes: 1.3 • Qts: 1.1 • Xmax: 2 mm • Net weight: 11-1/3 lbs. • Dimensions: Overall diameter: 18", Cutout diameter: 16-1/2", Depth: 7-7/8", Magnet diameter: 8-1/2", Magnet height: 1-3/4.

Qts is indeed (very) high and Fs is OK, but I'm concerned about linear max excursion of 2mm. Isn't that a bit low for a di/ripole set-up???
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Last edited by elac310; 22nd May 2012 at 08:04 PM.
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