Design help for Ascendent Avalanche 15

[bigjppop]

I know there's some cabinet designing whizzes out there and I was hoping you guys could help me slam out a quick design for the Ascendent Audio Avalanche that I recently acquired.

I will be driving this sub with the following amp:

The Apex Junior Subwoofer Amp

I am wanting a sealed design, probably front firing (someone talked me out of down firing by saying it would wreck my floor), and mostly for HT use. I would like to have the option to use it in my 2 channel set up as well so I'm guessing this is another one of those "I want a musical sub" threads.

Both my HT room and my 2 channel room are not huge so glass shattering output is not a priority, overall sound quality is.

Thanks in advance for any help.

Here are the T/S specs:

Fs 15.7Hz
Qms 3.5
Qes .334
Qts .305
Vas 300.6L
Re 3.2ohms (coils in series)
Znom 4ohms (coils in series)
Xmax 27mm
Sd 748cm^2
Mms 269g
Vd 4.04L
RMS 800w
Le 2.4mH

Mounting info

Cutout Diameter 14.125”
Mounting Depth 7.875”
Diameter 15.5”

Read more: FS: 2 15" Ascendant Audio Avalache - Home Theater Forum and Systems - HomeTheaterShack.com

[tb46]

Hi,

Sealed, anything larger than 2ft^3.

Regards,

[bigjppop]

That's all I need??? Just bigger than 2 ft.^3?

[chris661]

Sounds like it, but don't go too big, as you get to a point of diminishing returns...

[tb46]

Hi,

Just some easy net numbers on sonotube enclosures (you did say "slam" and "quick" :-) ) :

Regards,

[bigjppop]

Alright, I guess I'll shoot for around 3 ft^3 (minus whatever I loose for the space the amp/driver/bracing use). That should keep my overall volume over 2 ft^3 but not too terribly large.

From my VERY limited understanding of the world of subwoofers, it sounds like exact volume is not SUPER important for a sealed design; correct?

[tb46]

Hi,

I would shoot for something around 4ft^3 net. That will give you some room to play with the results, 2ft^3 net is about the minimum. The attached Hornresp SPL compares 2 to 4.4 ft^3.

Regards,

[bigjppop]

Alright, a little more follow up here. I did some more reading and finally decided I should at least try to use WinISD and here's what I've found. The manufacturer of this driver stated that it was designed to be used in a sealed design as small as 2.2 ft^3 and that is just about what WinISD told me as well. I read several other places that this sub is happy around 4 ft^3; just wondering if I'm doing any harm going bigger than the 2.2 ft^3.

Next question, read somewhere else that "for music a Q of about .7 is perfect." I really have no idea what that means and would appreciate some clarification on that point. I don't know what Q measures and the other didn't say why a Q of .7 was perfect for music.

Last question, the nuts and bolts of construction. I've read conflicting opinions on lining the intererior of the box; I think I'm planning on using the polyfill stuff but just want to confirm that I'm on the right track. Also, I'm assuming for a sealed sub that you really want it sealed. Does that mean I should use something like latex caulk to seal the interior seams? Also, do I want to use anything around the driver and the amp when I mount them?

Thanks in advance for all the help.

[tb46]

Hi,

All else being equal, the bigger a sealed box the lower the Qtc. Often manufacturers will reduce the box volume until they get a slight low frequency bump, or in other words a Qtc of .8 to .9.. Many listeners will prefer the gentler roll-off of a Qtc .5 box. Building a slightly larger box will allow you to tune the Q through the addition of damping material and wooden blocks, etc.....

Speaker Box Calculations

As to the nuts and bolts: polyfill (or fiberglass) is fine, caulking interior doesn't hurt (but the glue joint should be sufficient), and the speaker and amp should be sealed (including holes in connectors), e.g.: foam weather stripping (silicone caulk).

Regards,

[seagrasser]

I opted for a ported enclosure (around 4 ft^3, tuned to 27 or so). I love it, but I have a behringer EP1500 providing the power. These subs are not that efficient. You may want to consider a more powerful amp.