Differences in subs concerning VAS

[Bass Addict 10+ year member]

if two speakers have the same wattage output and in the same vented box and one has a vas of say 12.6 and the other has a vas of 66.what would be expected of the sub that has the vas of 66 vs the 12.6 vas in a perfect invironment ? i know the one with the vas of 66 will have a looser suspension.so does that mean the sub can bottom out more easily than the 12.6 ? appreciate any input //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

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[THATpurpleKUSH 5,000+ posts]

If im not mistaken the higher vas sub will be suited to a smaller box than the lower vas sub.

 

[Danometal 10+ year member]

If im not mistaken the higher vas sub will be suited to a smaller box than the lower vas sub.

I think it maight be the other way around; little box controls little Vas, and big box controls big Vas. I'm not 100% on that though...

 

[Tupolev 10+ year member]

Well, I would think that the looser suspension would need a smaller box so it doesn't unload.

 

[Bass Addict 10+ year member]

If im not mistaken the higher vas sub will be suited to a smaller box than the lower vas sub.

this makes sense as i have my d6 in a 2.3 cube box.it has a vas of 12.6 and it will not bottom out.when i had it in the spec'd sealed box,it had high excursion and bottoming out.

 

[Bass Addict 10+ year member]

Well, I would think that the looser suspension would need a smaller box so it doesn't unload.

good points and basically thats what i needed to know.thanks everyone for the helpfull responses //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[mylows10 5,000+ posts]

Well, I would think that the looser suspension would need a smaller box so it doesn't unload.

he means so that the woofer loads properly

 

[THATpurpleKUSH 5,000+ posts]

My Boston G5s have a fairly high vas and they are suited to small sealed boxes. My old Kicker Solo Classic (09 model) had an even higher vas and they were intended for only small sealed enclosures. Im fairly certain the higher vas indicates the ability to utilize a smaller box. We need audioholic in here //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[hispls 5,000+ posts]

It will have more to do with how good it sounds in a particular size box. Heavily damped woofers require less air preasure to prevent them from ringing (sounding "boomy")

Looking at Vas without considering Qts and what you're actually trying to accomplish doesn't really tell you much.

 

[THATpurpleKUSH 5,000+ posts]

So the high vas would go well with a low qts to sound good in a small sealed enclosure? The previous examples I mentioned both have fairly low qts, .47 on the G5 and .464 on the solo classic.

 

[Danometal 10+ year member]

Man I'm confused. I wonder which it is. I once was told my RE SE/x 15 needed a large sealed box because of its high Vas. But, all the above comments make sense, so... I dunno.

 

[Ryan shaw 10+ year member]

"Vas Volume of air equal to the driver compliance.

This can be thought of as how stiff the movement of the cone is. The value is given in litres or cu inches. There are a lot of variables that determine the Vas, so you can’t really say that high values of Vas mean a certain thing or are better. A single or double suspension spider will affect Vas, so does the size of the cone. The temperature of the air and also the humidity will affect Vas and so it is one of the hardest parameters to evaluate."

 

[hispls 5,000+ posts]

So the high vas would go well with a low qts to sound good in a small sealed enclosure? The previous examples I mentioned both have fairly low qts, .47 on the G5 and .464 on the solo classic.

.4 and .45 is pretty much middle of the road Q.

Anyway, this is a decent quick read that correlates those parameters. Take this with a grain of salt, not sure if it is trying to get optimum ouptut, optimum "flat" response, or maximum low extension.

QTS parameters How to Pick the Right speaker for your Speaker Cabinets

 

[audioholic 5,000+ posts]

"Vas

Measured in litres (L) or cubic metres, is a measure of the 'stiffness' of the suspension with the driver mounted in free air. It represents the volume of air that has the same stiffness as the driver's suspension when acted on by a piston of the same area (Sd) as the cone. Larger values mean lower stiffness, and generally require larger enclosures. Vas varies with the square of the diameter. A typical factory tolerance for Vas spec is ±20–30%" - Thiele/Small - Wikipedia, the free encyclopedia

So a larger Vas means a looser suspension, and a looser suspension means (usually) a larger box. But as said by someone above, just looking at Vas in a vacuum (not considering other specs) will only serve to give false conclusions.