My Box Design

[Danny]

Have finally finished the design for my sub box. However could only get 16mm thick MDF, should I glue some sheets together to get a thicker piece (25mm???). Will make sure I get some pics of the building of the box when i get around to it.

D.

[kano32]

That would work fine. You could also glue some 3/4" plywood to the inside of the mdf.

[Darren]

Yup, laminating MDF is perfectly fine. I have done it for several subwoofers. The IB in my avatar is laminated 3/4" MDF.

[Exocer]

If you are able to locate a presentable plywood with a good veneer you can try gluing the plywood on top of the MDF. I've seen a few projects around that employ that technique

[Zene]

Danny .. Why are you using mdf? It's the worst material for sub boxes. It's heavy and needs to be braced like crazy. Sure it machines well. If because it's cheap, fine, but assuming you spent big dollars on speakers and other equipment but won't spend $40 on some good ply. The rationale for mdf staggers me. "Gee, Hon I just spent $3000 on this preamp, what an incredible bargain".
Zene dba Zene

[JorgenMan]

Zene wrote:

Danny .. Why are you using mdf? It's the worst material for sub boxes.

You may not like MDF for sub boxes, but I wouldn't throw the word "worst" around so casually. There are a LOT of people who use MDF with good results. In fact, I don't think it's a big stretch to assume that it's the most popular material for building boxes.

[kano32]

I would agree with Jorgenman. MDF is the most widely used material for speakers and subs. Even expensive commercial brands use MDF. Of course there are exceptions, sonotubes, translam etc. People should use good ply or mdf or a mixture of both. Most large sub enclosures are going to have to be braced whether its ply or mdf. Anyway, just my 2 cents.

[Zene]

Aaron/others .... I guess I should not have said worse, just one of a long list of worse. Its used because it's cheap and handy. Popularity does not make it good. A little engineering search will tell you that you need stiff to control bass. MDF is far from stiff. Once a heavy structure gets moving it obviously wants to keep moving as you know. Yes, bracing can help, but then again adds more mass. Not many want to put a lot of effort into an important component like the box. Too many think its just a shiny receptacle of the right size to house the speaker.
Zene

[kramskoi]

Zene wrote:

Aaron/others .... I guess I should not have said worse, just one of a long list of worse. Its used because it's cheap and handy. Popularity does not make it good. A little engineering search will tell you that you need stiff to control bass. MDF is far from stiff. Once a heavy structure gets moving it obviously wants to keep moving as you know. Yes, bracing can help, but then again adds more mass. Not many want to put a lot of effort into an important component like the box. Too many think its just a shiny receptacle of the right size to house the speaker.
Zene

this is the way it's done with MDF my friend...7 internal braces at 2.25" spacing...2.25" baffles and 1.5" walls...needless to say, cabinet resonance is nonexistent

[Zene]

Been there, done that and more. How about 60 lb density MDF 2 layers thick and bracing or two layers of 1/2" mdf with 3" of cardboard edgewise filled 100%?
Concrete filled with mdf walls .... etc, etc.
That said, where does it say it sounds better than ply?
Dead is no guarantee it is better. All boxes "talk" and primary is to make whatever vibrations it has complimentary to our hearing. Wharfedale sand filled panels went out with Disco.
Zene

[kramskoi]

Zene wrote:

Been there, done that and more. How about 60 lb density MDF 2 layers thick and bracing or two layers of 1/2" mdf with 3" of cardboard edgewise filled 100%?
Concrete filled with mdf walls .... etc, etc.
That said, where does it say it sounds better than ply?
Dead is no guarantee it is better. All boxes "talk" and primary is to make whatever vibrations it has complimentary to our hearing. Wharfedale sand filled panels went out with Disco.
Zene

point taken, but with dual driver cabinets you have to curb your enthusiasm a bit...

with mounting depths of 10-14" and opposite side firing drivers (which weigh over 45 lbs. each), you become limited in what you can realistically achieve with weight and expenditure...in my case, a 200 lb+ enclosure at about $400, which is quite difficult to service if problems arise...but from end to end, only 2 1/4" separates each of the (7).75" braces, right up to the front baffles on each side...i'm extremely satisfied with the results, same as the second box i had built with a 3.5" front baffle and four internal braces...

[Brian Bunge]

If your drivers are mounted on opposite ends/sides of the enclosure then all of that bracing is overkill, IMHO. A couple of braces is plenty as the mechanical forces are canceled out by opposing drivers. With the quad 15" cabinet I just finished you can balance a nickel on edge placed on top of the cabinet while playing at high SPL's and the nickel doesn't fall over. There are only 3 braces in the cabinet.

[kramskoi]

Brian Bunge wrote:

If your drivers are mounted on opposite ends/sides of the enclosure then all of that bracing is overkill, IMHO. A couple of braces is plenty as the mechanical forces are canceled out by opposing drivers. With the quad 15" cabinet I just finished you can balance a nickel on edge placed on top of the cabinet while playing at high SPL's and the nickel doesn't fall over. There are only 3 braces in the cabinet.

i want it better...i want to be able to balance a dime!...more has to be better right?

[canaris]

How did you cut those braces...they look like you used a template and a router..

[kramskoi]

canaris wrote:

How did you cut those braces...they look like you used a template and a router..

sorry, i just designed the box...a local audio store did the building...i'm pretty sure the builder used some high end equipment...they build a ton of boxes...