Help me choose a 15" driver for my 110 liter box!

[Exocer]

Hey guys,
I have a sealed 110 liter box (thanks again steve), and an Ep1500 (on the way) screaming for a 15" driver. Some of the popular choices come to mind...SS Rl-P 15", Titanic 15" etc. I've gotten used to the low inductance of the Rythmik driver and am affraid i'll have to really EQ a driver with highish inductance to keep it tamed in the upper frequencies, and all I have is a BFD for Eq. A question comes to mind...How important is inductance when crossover over as low as 60hz?

So following this criteria, some more choices come to mind.
Tc-2000 15" SVC
Adire Brahma 15" d2(Qtc might be a bit high in a box this size according to A-V specs, but has an incredibly flat FR due to super low Le,can we conclude this driver has the lowest THD in this list? Idont know..)
Exodus Audio Ex-15" when they become available.
Ascendant Audio Arsenal 15"(Low Le, but seems to like a larger box according to Unibox)

The list is in order of interest. Anyone care to share their input? It would be much appreciated. Thanks.

[Amphiprion]

Le distortion is usually last on the list of distortion causes, the biggest two being Bl and Cms. So long as Le isn't huge I wouldn't worry. And it only really matters if it isn't linear vs excursion, so even high Le can be ok.

Personally I would go with the TC, just because A) Adire hasn't been too reliable lately and B) I know nothing of the others. But TC has never been a bad choice for woofers.

[Exocer]

Thanks mark,
So I think I get it...So Le is barely an indicator of distortion, rather an indicator of how well a woofer plays into higher frequencies?

What relationship is there between Bl, Cms and distortion?

And yeah, I've had nothing but great experiences with my 12" Tc2+ driver

[derekbannatyne]

Don't you have a tumult??

[Exocer]

Yeah, I do have a Tumult. I have my reasons for looking elsewhere.
Im looking for something I don't have to worry about failing on me, or tinsels slapping. Basically I have to limit output as to not cause the tinsel slap.

Edit: for the sake of anyone reading, this is last generation's Tumult. Only time will tell how the current batch performs

[Exocer]

Ok, Back on topic. I've been looking around the web for answers to my question above, and I find nothing ops:

Edit: Found this site http://www.caraudiomag.com/testrepor...ers/index.html
I am reading through it now, hoping to get an understanding of this relationship. Be back tomorrow with more questions :T

[Amphiprion]

Le does come into play for distortion, just not as much as Bl and Cms. If Bl and Cms were perfectly linear, then Le distortion would probably dominate. It's just that, in most drivers, Bl and Cms are usually bigger sources of distortion. When you get to really low distortion drivers with good Bl and Cms curves that cover wide frequency bands is when you'll see faraday rings put to best use.

Here's a link to a review of the Ascendant Audio 6.5" woofer. You can see the Bl, Cms and Le curves, as well as their contribution to distortion:

http://www.diymobileaudio.com/forum/showthread.php?t=4814

And another for an TC Sounds manufactured LMT based subwoofer:

http://www.diymobileaudio.com/forum/showthread.php?t=4147

In both cases Le distortion is the least contributing factor.

So unless Le is unusually nonlinear vs. excursion, Bl and Cms nonlinearities will probably dominate. Therefore, its predominant effect will be to roll off the high frequencies.

[Exocer]

Ah ha! Gotcha. Sleep can wait, I'll go check out your links.

Ok, so the more linear Cms and Bl are across the excursion range, the more likely Le nonlinearities will effect distortion and vice-versa. In an ideal situation, Le Cms and Bl would be linear accross the excursion range of the speaker to have the least amount of distortion. Cms and Bl are more commonly non-linear accross the excursion range of the speaker, causing them to be a greater source of distortion.

Just saw the links, I see a relationship here. My understanding above seems to be pretty spot on IMHO. My oh my are those LMT drivers linear or what? :T

[Amphiprion]

Yep, those LMT drivers are tops in my book. There was actually a little offset problem on that unit with the voice coil, they are usually more linear than that (or so Kyle of TC Sounds says). Just wish they were a little cheaper...

[Exocer]

Yeah, I noticed this too. Even off center it still looks hella stronger than your typical Bl curve close to Xmax I guess. I'd love to see a Dumax report on the TC-2000 15" or any driver using the Tc9 motor for kicks/comparison to the LMT motors.

[Exocer]

Thanks a lot for the breakdown Mark, It feels good to learn something new

[Amphiprion]

No prob man, I just hope everything I told you was right I'm an amateur at this stuff too.

[Exocer]

Haha, I hope you're right too! Its a pain the arse to re-learn something you thought you had such a good understanding of

[Amphiprion]

One more thing I should mention: In both those examples, Cms was the main factor in distortion. I think this is because those drivers use linear spiders (at least that's what I assume looking at the Cms graphs). Cms will be much flatter in drivers that use progressive spiders, in which case Bl might be the larger contributor. Most good sub drivers intended for home audio use progressive spiders as far as I know (progressive and linear refer to their construction, not their actual linearity).

[Remotia]

*knock knock*

v2.0

http://www.tcsounds.com/lms4000.htm

[Exocer]

I found an Avalanche 15 cheap :B .
The LMS 4000 15 would need a much larger box to hit a Q of .707 even with lots of stuffing. Excellent driver though! :T Too bad my box is already built..