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thadman 9th November 2006 12:10 AM

I want my Avalanche 18 to go flat to 15hz
I've got one Ascendant Audio Avalanche 18 and have decided it'd be put to better use in a Home Theater environment.

I'd like it to extend 15-50/60hz and reach reference levels >110dB.

I can fit virtually any enclosure (8' sonotube with a diameter of 30-36" isnt out of the question, >45 cubic feet) and I have 2400 watts @ 4ohms from a Behringer EP2500 to work with. Im also highly considering purchasing a DEQ2496 or other parametric equalizer for christmas.

The room is quite big, its actually a partitioned basement so I doubt room gain will play much of a role in the design.

Is my goal practical with only one woofer?

What design should I shoot for to achieve my goals? Linkwitz Transform? Ported around 15-16hz or a Transmission line? I've seen designs where they use multiple tubes within another to create an extremely long TL.

JinMTVT 9th November 2006 12:15 AM

i don't know the maths ...
but i doubt that it is possible with only 1 driver as urs

get a few of them ..

unless u will sit like 1f or less from the woofer
even then ..

thadman 9th November 2006 12:30 AM

1185cm^2 surface area, Fs of 16hz, 27mm xmax
...pretty big displacement

I know it seems like a daunting task, but you sure it isnt up to it?

Another option, would be selling the 18" Avalanche and purchasing 4 Mach5 audio 18" subs (1029cm^2 surface area and a 12mm xmax). They would be wired to 4ohms stereo (each woofer receiving 375 watts from the EP2500)

demon2091tb 9th November 2006 04:16 AM

Sup bro,

Was reading around, get an amp that can do 600, 10cf ~ 14hz, that'll do it.

BHTX 9th November 2006 05:39 AM

My suggestion is to contact SteveCallas. I know he's on AVS Forum (, might be on here too, not exactly sure...I've seen him on other forums as well. If I were you, I'd seriously consider his Sonotube "LLT" design that he built for his Avalanche 18.

I currently have 2 Avalanche 15's, and plan to build a 300 liter sonotube for each, tuned to about 15Hz with 600 or 700 watts.

Also, make sure you talk with him about your room size. Perhaps it's a bit too large for that AVA18 to fill, but I seriously doubt it...just depends. If needed, he could help you come up with a good size for spl versus extension in your particular room. And...buying two used Avalanche 15's myself in mint condition from eBay, I'm well aware of how difficult it is to still find these things. Finding another 18 would be extremely rare, and I don't think it should be counted on during the design of this enclosure.

demon2091tb's suggestion sounds about right, and probably isn't far off. See if you can contact SteveCallas though.


demon2091tb 9th November 2006 05:04 PM

Yea i was reading around and found those specs for it, thats SteveCallas' specs on his actually....from a giant subwoofer thread.

thadman 10th November 2006 12:23 AM

I searched and couldnt find the design for the sonotube LLT on and Did the design incorporate the Avalanche 18? Did it use a sonotube within a sonotube?

Nichol1997 10th November 2006 02:07 AM

I don't think there is much information on the avs forums, instead go here:

How big is the room that it is going into?

thadman 10th November 2006 03:14 AM

Hmmm, so its just a simple ported design? I thought it was a transmission line.

Are there any detailed threads on the construction of one of these beasts? All ive found was threads showing off the behemoth and totings its power.

thadman 10th November 2006 03:17 AM

Its a partitioned basement and their are no doors from the stairs leading down, so room gain shouldnt play a factor at all.

The main room of the basement is probably 40 x 20 feet and then another room thats 15 x 10 or so and then an 8 x 8 room.

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