DIY Sub Questions (Atlas 15)

Troy R · 08-12-2005, 08:33 AM

I'm going to start my Atlas 15 project in the next few weeks. I have a few questions that I can't seem to find the answers to...

I was going to use a 6" PVC port. When subtracting the port volume from the internal volume do you figure the port as a solid cylinder or just like it is (with a big hole in the middle)? For some reason I got the impression somewhere that you figure it as a solid cylinder...

How long should the legs of my sub be for a downfiring sub? The Atlas 15 will probalby not be flush mounted.

Is cabinet grade Oak plywood ok to use for the enclosure? I'm sure it probalby is, I just wanted to check to be safe.

And one more general woodworking question. If I use the oak plywood should the grain be running up and down or is side to side ok? I'm guessing whichever I choose it should all be going in the same direction?

Thanks in advance!
Troy

SteveCallas · 08-12-2005, 08:41 AM

I asked this same question for my sonosub. I was told you count it as a solid cylinder.

ThomasW · 08-12-2005, 09:27 AM

Quote:

Is cabinet grade Oak plywood ok to use for the enclosure? I'm sure it probalby is, I just wanted to check to be safe.

The best choice is Baltic Birch ply it's void free. The sides walls of the cabinet should be 1.5" thick. The baffle board should be 3 layers of 3/4" and the insides should be adequately braced.

The leg length has been ask and answered dozens of times, so a search will get you that answer and more...

Troy R · 08-12-2005, 10:25 AM

Thanks for your replies!

Quote:

The best choice is Baltic Birch ply it's void free. The sides walls of the cabinet should be 1.5" thick. The baffle board should be 3 layers of 3/4" and the insides should be adequately braced.

You'll have to excuse my ignorance, but what does void free mean? And why isn't all cabinet grade plywood void free? Is the void free baltic birch any birch plywood that they sell at Lowes or HD? Or would I have to go to a specialty place?

Quote:

The leg length has been ask and answered dozens of times, so a search will get you that answer and more...

I've searched and I can't find a solid answer, I've seen anything from 2-4 inches, or more. And a lot of those answers were based on a flush mounted driver...

Thanks again!

MarkRoberts · 08-12-2005, 12:22 PM

Troy I have cabinet plans for a ported atlas 15 from ascendant audio. I believe it recommends 6" for the legs. I can email them to you if you want. Its a pdf file. Has CAD drawings and cut list. Its a 6.0 cu. ft. tuned to 18Hz uses 2 4" precision ports.

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ThomasW · 08-12-2005, 01:02 PM

Quote:

but what does void free mean?

It means it contains no voids.

Quote:

And why isn't all cabinet grade plywood void free?

Certainly not.

Quote:

Is the void free baltic birch any birch plywood that they sell at Lowes or HD?

Absolutely not

Quote:

Or would I have to go to a specialty place?

Yep

This is what BB ply looks like

Jordan_Brulotte · 08-12-2005, 01:33 PM

For a down firing sub, the minimum leg length is typically half the diameter of the driver. IE a 15" down firing sub should have 7.5" legs.

Troy R · 08-12-2005, 02:18 PM

Quote:

Troy I have cabinet plans for a ported atlas 15 from ascendant audio. I believe it recommends 6" for the legs. I can email them to you if you want. Its a pdf file. Has CAD drawings and cut list. Its a 6.0 cu. ft. tuned to 18Hz uses 2 4" precision ports.

That would be great! Thanks!

email: trrglr at columbus.rr.com (that's a lower case "L" in glr)

sorry about my email address format, but you can never be too careful.

SteveCallas · 08-12-2005, 02:29 PM

No, that can't be right. 7.5" is pretty long, that would put an 18" driver on 9" legs minimum. Looking back through my thread, Thomas recommends the minimum being the Vd of the driver.

MarkRoberts · 08-12-2005, 07:54 PM

Troy,
You got mail.