XXX's over-rated...a challenge to you.

Post by **GlassWolf** » Mon Apr 18, 2005 10:47 am

go with the 15" subs and cross them over as highly as you're talking and they'll sound horrid. the larger the sub, the lower you generally want it crossed over.

bigbassman · Post by **bigbassman** » Mon Apr 18, 2005 1:09 pm

the size of the driver is less of an issue than the inductance of the driver..

its inductance that causes lacking midbass / midrange performance...

simply put, take the Re of the coil, and its inductance, and you've got yourself a simple 2nd order crossover...

take the XXX for instance.... low impedence, higher inductance coil, she begins to roll

off above 65-70 hz..... and it wouldn't matter if that coil arrangement was coupled to a 4" cone, or a 24" one....

another glaring example of this... the old model RE 8.... well known to die above 140 hz... this is due it its massive (for an 8") copper voice coil, dual 4 ohm wired in parallel under the dustcap, 1.5" diameter, 8 layer... Re of 1.8, inductance of around .8 mH

so size of the driver doesn't really matter... its impedence and inductance does..

oh, and about Dan giving the rights out for XBL^2... one word.. Royalties.. :)

Loyd L.

Jonathan · Post by **Jonathan** » Mon Apr 18, 2005 4:49 pm

Just because you have a low inductance 15" sub doesn't mean it will sound good at higher frequencies, though. Size makes a difference, from both a mass and a physical size standpoint, it has more to do with resonance and the drivers damping, affecting the frequency response. Added mass is much harder to control than a smaller moving mass, requiring more suspension and generally resulting in more overthrow. With a physically larger driver, you have a higher chance of standing waves since at those frequencies the cone isn't moving as much as a homogenous unit. At these frequencies, you'd do best to think of the sound wave as starting at the base of the cone (at the voice-coil former/cone joint) and propagating outward towards the edge of the cone. When the wave hits the edge of the cone, it is reflected back toward the base of the cone (towards the voice-coil former). When the wave hits the voice-coil former, it is again reflected back towards the edge of the cone, and the whole process starts again. In both situations, significant standing waves result, and these standing waves can produce really, really huge peaks and dips in the response of a driver unless steps are taken to counteract it, but it occurs with all drivers, even $75000 home drivers. The larger the driver, the lower in frequency this occurs at, which is why 15" drivers aren't renowned for higher frequencies, even those with lower inductance. Even on Adire Audio's PDF about woofer speed when they added mass and decreased inductance of a driver and compared it to a lower mass higher inductance driver, while the lower inductance driver was capable of playing a higher frequency, the driver had nastier peaks and dips in the frequency response compared to the low mass driver. Add a lower frequency where standing waves occur, and you have a pretty rough sounding driver at that frequency. Adire was proving that higher inductance affects frequency response, not that mass or size didn't make a difference. If mass wasn't an issue at all, I would think that Adire would be using heavier cones (like metal) and rubber surrounds.

Of course, though, on top of that, 15" subs are generally built more for SPL than their 12" and 10" counterparts, so you'll also get higher inductance coils due to the longer throw the drivers are built for.

Post by **GlassWolf** » Mon Apr 18, 2005 5:51 pm

simple physics with the mass of the moving portion of the driver too.. harder to make it stop and reverse direction at higher frequencies. how much that affects the audible outcome will vary speaker to speaker though.

Mystical_Ice · Post by **Mystical_Ice** » Mon Apr 18, 2005 8:03 pm

ridr4lif wrote:This is exactly why i reccomend these companies. They are Great brands, yet inexpensive in comparison to most of the mainstream companies.

TEDD

$450 for a 15" Brahma, plus shipping, is "inexpensive" compared to mainstream?

ridr4lif · Post by **ridr4lif** » Mon Apr 18, 2005 8:04 pm

I was referring to subs like the "Shiva" and the "Tempest".

Those 2 are fairly inexpensive and sound great.

Oh, welcome to the forums

TEDD

Jszar · Post by **Jszar** » Mon Apr 18, 2005 8:21 pm

when you go to a retailer, and for example we'll just use a w7, you're looking at 500+ for the sub alone (last time i saw one in a store btw, i dont ever look any more). consider buying a brahma in a store.....ouch, that'd hurt the wallet.

Mystical_Ice · Post by **Mystical_Ice** » Tue Apr 19, 2005 7:31 pm

yeah, but no one said the W7 was "inexpensive"

......

Ryan from Ohio · Post by **Ryan from Ohio** » Wed Apr 20, 2005 5:00 am

$450 for a 15" Brahma, plus shipping, is "inexpensive" compared to mainstream?

Who said that? I must of missed it...

RE RE $76... In all my retail adventures I have found there isnt many subs that can top this in price, specs and power handling...