Westra KW-200-1338: Usable drivers, or junk?

KozmoNaut · 3rd August 2007, 08:18 AM

I am quite the n00b in this field, but having recently gotten my hands on two Westra KW-200-1338 8" (more like 7") woofers for absolutely free, I was wondering if they could possibly be used for a decent subwoofer that could reach below 30hz.

The only specs I have for them are as follows:

fs=29
Re=7,7
md=20,5
Qt=0,67
Qe=0,8
Qm=4,29
Vas=106

The diameter of the speaker cone is approximately 16cm, and I would guesstimate (very roughly) that Xmax is 8mm, very likely a bit less.

I tried using them in WinISD, and it keeps recommending a closed box of around 1850 litres, which is a bit too big for my tastes ;-)

Are there any more parameters needed to use them, and could I measure them myself?

Thanks :-)

Petriej · 3rd August 2007, 02:18 PM

Since you have two of them, try doing an Isobarik configuration to minimize the enclosure size. It may be difficult to get these guys much below 30Hz, but in a nice ported box they could have a decent chance.

mashaffer · 4th August 2007, 12:06 AM

The high(ish) Q makes this a pretty decent candidate for an open baffle woofer (though not really a sub in the traditional sense). Response wise they would give you the response that you want in an infinite baffle but being so small and with no doubt limited xmax they would not give you a lot of earthshaking bass before self destructing.

Maybe someone with some aperiodic box experience could suggest whether that is a viable option. As a simple experiment you could build a U or H shaped baffle (with top cap) for them and see how it sounds. You should be able to get very nice bass down to 40 or 50Hz but sub 30 would require more driver or more baffle I think.

As you saw when the Qts of the driver is equal to what you want the final system Q to be you need a really big box.

Another option would be to build a small box and EQ the crap out of it like this .

mike

Moondog55 · 30th August 2007, 11:46 AM

rough and dirty calculation.
80 litre box, lightly stuffed with polyfill, heavily damped shelf port equal to the box width to give area of 18750mm2 and at least 150mm deep, equal to "Q" of .9, Fs 38Hz F3 of 31 Hz, tall narrow box, deeper than width, mount the tweeter underneath
Ted

3rd August 2007, 08:18 AM	#1
KozmoNaut diyAudio Member Join Date: Jul 2005 Location: Struer	Westra KW-200-1338: Usable drivers, or junk? I am quite the n00b in this field, but having recently gotten my hands on two Westra KW-200-1338 8" (more like 7") woofers for absolutely free, I was wondering if they could possibly be used for a decent subwoofer that could reach below 30hz. The only specs I have for them are as follows: fs=29 Re=7,7 md=20,5 Qt=0,67 Qe=0,8 Qm=4,29 Vas=106 The diameter of the speaker cone is approximately 16cm, and I would guesstimate (very roughly) that Xmax is 8mm, very likely a bit less. I tried using them in WinISD, and it keeps recommending a closed box of around 1850 litres, which is a bit too big for my tastes ;-) Are there any more parameters needed to use them, and could I measure them myself? Thanks :-)

3rd August 2007, 02:18 PM	#2
Petriej diyAudio Member Join Date: Jun 2007	Since you have two of them, try doing an Isobarik configuration to minimize the enclosure size. It may be difficult to get these guys much below 30Hz, but in a nice ported box they could have a decent chance. __________________ Signature: Optional signature you may use to appear at bottom of your signatures.

30th August 2007, 11:46 AM	#4
Moondog55 Dilletante, tinkerer and beggathoner supreme diyAudio Member Join Date: Jun 2007 Location: Norlane; Geelong: Victoria: Australia	Aperiodic box rough and dirty calculation. 80 litre box, lightly stuffed with polyfill, heavily damped shelf port equal to the box width to give area of 18750mm2 and at least 150mm deep, equal to "Q" of .9, Fs 38Hz F3 of 31 Hz, tall narrow box, deeper than width, mount the tweeter underneath Ted __________________ QUOTE" The more I know, the more I know, I know (insert maniacal laugh >here<) NOTHING"

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4th August 2007, 12:06 AM	#3
mashaffer diyAudio Member Join Date: Jun 2004 Location: Indiana	The high(ish) Q makes this a pretty decent candidate for an open baffle woofer (though not really a sub in the traditional sense). Response wise they would give you the response that you want in an infinite baffle but being so small and with no doubt limited xmax they would not give you a lot of earthshaking bass before self destructing. Maybe someone with some aperiodic box experience could suggest whether that is a viable option. As a simple experiment you could build a U or H shaped baffle (with top cap) for them and see how it sounds. You should be able to get very nice bass down to 40 or 50Hz but sub 30 would require more driver or more baffle I think. As you saw when the Qts of the driver is equal to what you want the final system Q to be you need a really big box. Another option would be to build a small box and EQ the crap out of it like this . mike

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