Sub Box Materials

[BigDave9387]

I am building a sub box for 2 JBL W12GTi subwoofers. I want to build the box with 1" 15 ply birch marine plywood. I have only found this one place, and I believe that it is going to be cost prohibitive, so what is stronger, 1" MDF or 3/4" 13 ply birch marine plywood?

[Cloth Ears]

This was 'discussed' a fair amount in this thread: working with baltic birch plywood

IMHO, there are advantages to both. The marine birch ply seems to be stiffer, in that it rings more when you flick it with a fingernail. And my guess is that it's less likely to suck up moisture when untreated. But for my next sub, I'm going with 1" external MDF, and all the braces are going to be 3/4" ply. trying to get the best of both worlds...

[paulspencer]

As I understand, the advantages of ply apply more to larger thin walled speakers. They are commonly used in large PA boxes where the extra strength is useful when you are trying to make large boxes as light as possible. A hifi sub should be stiff and well braced, and where this is the case, the extra strength will not have an audible impact, and the cost won't be justified. I would instead focus on bracing, and even using 2 layers of 3/4" MDF. This is going to give you a better result for the money.

[Rademakers]

True,

Second benefit for PA is that ply doesn't dent that easy on the corners as MDF does.

Wkr Johan

[Hezz]

Unless you want a veneer finish on the plywood or the box is a huge size I would go with MDF. As has been stated a good bracing scheme is the most important thing.


If you need an idea of this check out some of the high quality commercial subs where they show a cutaway of the sub. The real good subs will have extensive internal bracing. The important thing is that the box doesn't store any low frequency energy so make the walls as thick and strong as you can and puts lots of bracing. High quality plywood is better for bracing because it is more rigid but the MDF will work just fine.

Hezz

[paulspencer]

Here is an animated example of bracing for a simple sealed sub:

In essence it is 3 intersecting planes, each touching 4 internal walls, with cut outs for the driver, and holes cut out so the box remains as one volume of air and is not divided up into sealed cells.

[Wombat2]

I built the 5 cf Adaire reference sub enclosure for the Shiva. Like Paul has illustrated it has internal braces out of 18mm MDF while the external sides are 25mm MDF Just over a sheet of each I can't lift the sub on my own

David L