Ascendant Atlas 15 - IB install pics (1 Viewer)

[Jack Gilvey]

Here are some quick pics of my Infinite Baffle sub using a pair of Atlas 15's from Ascendant Audio . I currently have the 4 Ohm coils in series and the 2 Ohm coils open for a Qtc of 0.6 or so. As you can see, they're mounted antipodally in as small a manifold as possible...they just barely make it. The backwave is (kinda) contained by a ~128 ft^3 closet, the door of which is barely surviving the onslaught.

 

[Jack Keck]

No matter how it sounds, and I'm sure it sounds fantastic because I've heard an IB before, this has to be the way to go for someone who wants to DIY, but lacks cabinet finishing skills. Now that I think about it, it must be a challenge to attach the manifold to the wall/door. How much do you think the whole assembly weighs?

 

[Jack Gilvey]

The drivers are 24lbs each, the box is fairly light being Baltic Birch ply.

 

[Patrick Sun]

Is there some support underneath the box in that closet space? Or is that not a good idea, vibration-wise?

 

[James W. Johnson]

Nice, I have not heard of these drivers before, how long have they been around?. Those baskets look alot like my Blueprint 1804 baskets.


That closet looks like it would be a vibration nightmare. If you have any problems id suggest reinforcing the closet itself, also the box you built looks a little thin even though it is baltic birch. ALso id consider coulpling it to the ground somehow if it give you any problems.

 

[Jack Gilvey]

Well, I'll deal with the closet as-is...if it doesn't work out, I've got a huge reflex box planned. It's ok so far. The manifold itself isn't a problem...the drivers cancel each other's forces out, and the 3/4" birch seems more than sturdy enough for such small spans. Don't think I need any ground support, I can almost stand on it. The weight is not an issue, and the vibrations are largely cancelled by the opposed drivers.

 

[Scott Simonian]

Wow, Jack. Good to see you jump on the Ascendant Audio band wagon. You are inspiring me to make my closet in my theater room an IB now. Where in the room is your closet located? How much power are ya using?

 

[Jack Gilvey]

Yeah, I actually received the 15's two months ago but just got a camera. The closet adjoins my theater room. I was originally running 150 watts to the 2 Ohm coils in series (really, really loud!), but just upped it to about 900 watts to the 4 Ohm ones.

 

[Scott Simonian]

Damn! That sounds like a lot of power for an IB. Since earlier I have been contemplating a closet IB as well. In unibox I used: four Atlas 15's in 3900 liters, walls covered, tuned to 16hz with 90 watts each. I got flat response from 15hz and up. Ruler flat! And it was 121db from 15hz and up. Sweet.

Oh yeah, it gonna be a vented IB! Sounds killer. Hahahaha!


EDIT: This is also using the high Qts wiring.

 

[Bryan Michael]

how do you stop the wall from shakeing? and the wall behind that? i just got 4 18 avalanch installed in my ib and i cant stop anything from shakeing.

 

[ThomasW]

'Shaking' would be the primary reason for buying and using something as outrageous as 4-18"s.

The room is 'energized' by the sound waves coming off the cones, not the mechanical vibration of drivers mounted in opposition in a manifold.

Turn it down

 

[Bryan Michael]

anything over 80 db starts the walls to rattle. i just want less rattle from my drywall.

 

[ThomasW]

If the drywall itself is rattling on the studs with 80dB output, there are some build issues with the structure.

If you can access the backside of the wall stiffen it with a layer of 3/4" OSB or 2"X4" diagonal bracing and tighten up the drywall using screws.

Another option is to veneer a second layer of drywall over the first. This adds a tremendous amount of mass to the wall, particularly if you use 5/8" material

 

[James W. Johnson]

Thats not loud at all, you have some issues then. For starters the IB should be mounted solidly to the inner wall structure which is really the frame of the house and if you think about it that is going to be stronger than any box you can make because the house weighs tons.

My 2 18's are mounted on a 1.5" birch ply baffle then mounted next to a wall corner where the strenght is higher. I have to get into the 100db+ range before I get any rattling and even then its minimal because I have dealt with alot of it.

You cannot beat an IB for SQ period.

They dont have that auto sound kind of loudness/distortion that some people desire, even in an HT subwoofer but really all that is is exagerated and distortion if you think about it.
Mine has given me a new outlook on what I expect from a subwoofer from here on out.

 

[Bryan Michael]

all the walls are cosmedic and non structual. they were bult using the wideest gap you can use but still be in code. i think i am going to do 3 things. add more screws to the drywall. add more braceing to the wall. diag braces to the manafold atached to the concrete floor. thanks for the help the bass from the ib is so great. at 80db the power of the bass is just so strong. compared to my dual av15 in a ported box. old sub was loud but did not have the ommph. i also olny have about 1 hour on the sub and not all the cracks are sealed yet so i have about a few more hours of work left.

 

[Chris Brock]

also something that I made sure of when the drywall was being hung was that a good bead of adheasive was being used to attach the drywall in addition to the screws. That way they is no chance of the drywall hitting rattling agenst the stud at any point. The only time I really notice any rattles at all is when I am playing a test tone. Any other time there is normally enough content in the rest of the spectrum that it drowns out any rattles.

 

[Jack Gilvey]

Yeah, it is. Like I said, I got amazing output from 150 watts into the 2 Ohm coils, but increasing power and using the 4 Ohm coils (700w combined Pe) has given me more headroom above 30Hz or so. One thing about these drivers, and something Chad told me, is that you cannot bottom them. Even on the various bass demo scenes and this much power, I've not heard a "clank".

 

[ThomasW]

We do know that these drivers aren't designed to be driven only from the 2 ohm VC, don't we?.... :wink:

 

[James W. Johnson]

Hey Jack, Thomas.. how would those Avalanche 18"s compare against my Blueprint 1804s?

 

[Bryan Michael]

wll i got another 20db befor i can hear a rattle. now i have a few more places to add drywall screws and the finishing tuches.