Question on Subwoofer cabinet shape. (1 Viewer)

[Derek Theil]

Do subs have to be square or rectangular?

I would like to hide a sub behind my entertainment system. It’s a three-piece unit from Sauder. The center section is 8” away from the wall, which gives me an area of 8” deep x 33” wide x 40” tall to work with.

Can the enclosure be 8” deep as long as there is enough overall volume for the given speaker being used?

As far as details, I plan on using ¾” thick MDF, a 10” woofer taken from a Bazooka Tube that’s been collecting dust, and an AudioFile Home Theater VRS 1205 w/Remote Subwoofer Amp. Just bought a Kenwood VR-6050 and a Philips DVD793CH.

Thanks, Derek

 

[Dustin B]

Shape matter not (well unless one of the dimensions starts getting up past the 5-6 foot range). All that matter is net internal volume and that the walls don't flex.

 

[Geno]

your last name is Thiel and your asking that? hehe
I actually disagree with Dustin when he says shape matters not. There have been numerous tests on sound cavities and whatnot but because the box is the cheapest way to manufacture a cavity, that is what 90% + speaker boxes/subs are... just look at the success of SVS.

ps, to exclamate my point, look at these...

http://www.passdiy.com/speakers.htm

 

[Brian Bunge]

As long as the enclosure is constructed properly (this would include bracing, etc.) it doesn't matter what the shape is. And if a box was cheaper to manufacture than a tube based sub I doubt that SVS would be charging slightly more for their box subs. I don't think it gets much more simple than slapping a couple of endcaps on a tube.

This is an over simplification, but a box is definitely more time consuming to construct. And time is money.

 

[Geno]

Brian, then how come you dont see any tube shaped speakers at BB or CC?

 

[Brian Bunge]

Number one, because most of the population probably wouldn't buy it. Number two, Asian labor is super cheap and most of the crap at BB and CC is made of 1/2" or 3/4" particle board.

Those subs you linked to are transmission lines. Check out a transmission line built within a box. It's much more complicated to build a labyrinth inside a box as opposed to just attach a tube to a box.

 

[Dustin B]

Shape can matter at higher frequencies. As standing waves of higher frequencies can form in dimensions much smaller than your average speaker enclosure.

Bass wavelengths on the other hand are very long. So unless you get one of the dimensions long enough to support a standing wave the shape of the enclosure won't matter (provided the walls don't flex and your net internal volume is appropriate for the driver and allignment desired).

That's the only clarification I wanted to place beyond what Brian has already said.

 

[Brian Bunge]

Dustin,

Now that you have a job you sure don't post much anymore!

 

[Dustin B]

Funny how that works :p)

 

[David Lorenzo]

The success of SVS isn't because of them using cylinders. They are comming out with a full line of box subs that I'm sure will be just as popular as the cylinders, but will all cost slightly more than their cylindrical cousins due to the higher costs of building a quality box.

 

[Derek Theil]

Thanks to every body for yor input. I will start construction tonight. Should have the amp early next week.

 

[Dave Milne]

Derek,

The experts have eloquently explained why a sub box shape doesn't matter. But one more thing: If you're using

a 10” woofer taken from a Bazooka Tube

you either need to duplicate the exact volume and alignment (vented, sealed, etc) of the Bazooka tube or redesign a new enclosure for the driver based on it's T/S parameters. And if a "Bazooka Tube" has a built-in amplifier... be careful. The designers may have electronically assisted the alignment such that duplicating the enclosure (without the electronic assist) would yield disappointing results.

 

[Brian Bunge]

Dave,

I'm glad you mentioned that. In all the box vs. cylinder stuff I forgot to throw that info. in there as well.

 

[Derek Theil]

The tube was vented and unamplified. I have tried to use the paramaters I found on their web site, along with WinISD beta to calculate the volume. I am having trouble deciding weather or not to us any stuffing/fill. I am going to spray the interior with ruberized unbdercoating to help seal the seams. This box will be tight.

 

[Dave Milne]

Derek,
'Sounds like you're on the right track. I haven't used WinISD so I don't know if it models the effects of damping/fill. Generally for vented subwoofers all you need is some lining on the walls to attenuate "stray" higher frequencies (driver distortion, wall vibration, or external noises).

Accurately cut, glued and clamped joints should seal perfectly and obviate the need for "rubberized undercoating". But if you like it, go for it.

Let the chips fly...


Dave