Tempest vented EBS subwoofer

BrianGT

diyAudio Moderator Emeritus
2002-01-21 2:42 pm
near Atlanta, GA
www.chipamp.com
I started my tempest EBS enclosure for my sub. It is built to the design on adire audio's website:

http://www.adireaudio.com/tech_papers/tempest_apps.htm

It is the vented ebs subwoofer. It is quite large and will be 4' tall with the feet on it and 2' x 2'. 320L volume

[IMGDEAD]http://brian.prohosting.com/aak.sized.jpg[/IMGDEAD]

I haven't finished it yet. I am waiting for the polyfil that I ordered and I still need to caulk the inside corners. Even though the top is not screwed down and the driver and ports are not yet mounted, it sounds quite good with my leach amp driving it with my denon digital decoder acting as a low pass filter.

I will eventually cover it with 1/4" baltic birch on all sides.

It will be downfiring when it is finished.

--
Brian
 

BrianGT

diyAudio Moderator Emeritus
2002-01-21 2:42 pm
near Atlanta, GA
www.chipamp.com
another pictures:

--
Brian
 

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BrianGT

diyAudio Moderator Emeritus
2002-01-21 2:42 pm
near Atlanta, GA
www.chipamp.com
When I cover the entire sub with 1/4" birch, it will make the bottom more flush. the sub sticks up 3/4" over the bottom including the foam part on the woofer. If you disregard the foam part, the metal part only sticks up 1/4" off the bottom. I am thinking of putting more 3/4" birch on the bottom instead of 1/4" and making it more flush.

Is it worth the effort? Will it effect the sonics for a sub?

--
Brian
 

BrianGT

diyAudio Moderator Emeritus
2002-01-21 2:42 pm
near Atlanta, GA
www.chipamp.com
JasonL:

I also figured what the hell... I am building my own sub, and don't have to worry about the wife acceptance factor for this... so why not build the one that looks to be the best... I was going to build a smaller sub that was almost 2'x2'x2' but I figured that this one takes up the same floor space but is twice as tall...

--
Brian
 
BrianGT said:
The braces are directly down the middle.

The brace is a good idea, and you did run it the long way (a good thing), unfortuneatly right down the middle is the worst place to put it. It does little to brace against the 1st harmonic of the unbraced panel resonance or its harmonics. Because it clamps a zero-crossing it can actually raise the Q of these resonances. Best is to have braces divide a panel into 2 irregular trapezoids or if that is too much work at least 2 unequal rectangles. Hopefully the picture gets the idea across.

dave
 

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BrianGT

diyAudio Moderator Emeritus
2002-01-21 2:42 pm
near Atlanta, GA
www.chipamp.com
Dave,

I didn't even consider that. I just followed Adire Audio's cabinet design which divides it into quarters with the brace. The braces have holes in them so it is not exactly a full division, so I didn't consider it. It makes sense now how this might cause problems.

A lot of Adire Audio's applications have boxes cut into quarters with divisions making 4 equal square sections. If I build this again, I will consider this.

Where I got the design from:
http://www.adireaudio.com/Files/VentedTempestApplications.PDF

Would dampening help eliminate this problem. I will be following their suggestion, putting 64oz of polyfil in the box. Is there anything else I can do?

fcel: the idea of too large didn't cross my mind until I actually assembled it. how big is carver's?

One more think.. This thing is very heavy.. made of an equivilant of almost 2 sheets of 4'x8' plywood

--
Brian
 
The smallest Carver's subwoofers enclosure is somthing like 10"x10"x10" with amp built into it and claimed to have very impressive spec ... and thus I make that comparison in relation to size of box. I have not heard any of Carver's sub though. Your Tempest Sub may walk all over the tiny sub ...
 
I am waiting for the polyfil that I ordered...

I was just wondering how much polyfil you ordered.

Is there going to be a shortage on the east coast
because of you?

Thanks for the pics. Seeing someone else's work always
motivates me to get going on my own ...

P.S. Have you run any calcs like Linkwitz did for his Thor
to get an idea how much amp you need? I'll bet with your
box size and vents, you can drive it to Xmax at 20hz for
less than 200 watts...
 

BrianGT

diyAudio Moderator Emeritus
2002-01-21 2:42 pm
near Atlanta, GA
www.chipamp.com
The box will take 64oz of polyfil (4 lbs) I ordered a 5lb bag of it.

I haven't run calculations for the power needed for the speakers yet. They seem to go plenty loud with the Leach amp, so my Aleph 2s will be good when I finish them for it.

As goes the wife... I have no wife so there is no problem.

I have more pics on my website:

http://brian.darg.net under the amplifier stuff part

--
Brian