Construction tips for SEAS L26ROY closed box subwoofer

[bassmann4020]

I’m building 2 passive subs and have a few queries on construction (but I’ll cover the project details first).

• The subs are for music only so don’t need to be super low, rather looking for something reasonably flat and tight.

• Have opted for a Closed box design using a SEAS L26ROY and 28L volume. Internally H390 W 240 D310 is 29L so have allowed some leeway for bracing. This should give a QTC ~ 0.64
• Back and Sides are cut (see photos) from 18mm MDF. The front will be 2x18mm glued and chamfered

Questions

• I was looking for a narrow footprint so went with the dimensions quoted above. With the boxes cut, I am a little concerned the external box width is not wide enough at 276mm given the drivers diameter is 269mm. My cuts and routes need to be precise.
  • Will this be fine assuming my cuts / routes are good
  • Or Can anyone think of any problems going with the width this narrow?
  • Should I consider gluing say a 12mm panel to the sides to compensate?

• Bracing – where can I find information of how to adequately brace this enclosure?

• Connection will be a Speakon like say a NL4MP or NL4MPR. Given it’s a closed box, is there anything in particular I should do to maintain internal pressure at the socket? i.e. do others silicone these in.

 

[Davey]

Seems like you have some questions that should have been answered before you started building the boxes. They're going to look funny like that.

How 'bout turning the boxes sideways and make the front/back into the sides...and the sides into the front/back?

Dave.

 

[bassmann4020]

Hi Davey,

Yeah - should have answered some of these things first...but here i am. I focused on the internal dimensions and forgot about the rest.

Sideways could work, but I'd prefer the narrow format if I can make it work.

When you say it will look funny, could you elaborate (noting i will be recessing the driver into the panels).

Cheers,

 

[Electrone]

Should I consider gluing say a 12mm panel to the sides to compensate?

I think the more stiffness would be good for solid bass.

 

[bassmann4020]

Update:

1) I have decided to glue panels to the sides to widen and strengthen just a bit...

2) Have found some resources on bracing on Youtube. Final design tbc but points me in the right direction.

3) Still not sure how how to maintain pressure on the Speakon socket (or even if that's needed on a closed box). More to research here.

 

[chris661]

SpeakOns are, for all intents and purposes, airtight.
They're used everywhere, even on really big subs with a lot of air pressure acting.

Chris

 

[Ron E]

Sideways could work, but I'd prefer the narrow format if I can make it work.

Bass is omnidirectional so it won't matter if the drivers point sideways.

In a box that small, doubling up the baffle is pointless.
Ribs about double the wall thickness, glued onto the panels, spaced every 4" or so, and along the long dimension of panels, will work fine, you can tie the largest opposite panels together in a couple places if it floats your boat...

 

[bassmann4020]

Hi Ron E,

Yes I like the idea of the Ribs so will do that in ply. I have already glued my baffles.

Update - I have glued 9mm panels to the sides to widen more for aesthetic reasons than strength.

I guess in summary, Ive over engineered this project for the size of the box. I figure the main impact is weight, but these sub's are not going anywhere.

I'll post some pics with updates as to where I get to prior painting.