which is better 18mm or 25mm for box

[busterno1]

i am rebuilding a set of boxes they are a 2 1/2 way contains 2 6 1/4 vifa drivers with vifa tweeter volume of box is 50 ltr .

the current boxes are made from 25 mm mdf.

Would it make a difference that i can hear if I make the new set out of 18 mm mdf ?

I have been told that any box above 50 ltr should be made from 25 mm . thanks

[postman]

All depends on how you construct the box. 18mm is fine for a 50 litre enclosure. Ive built a 100litre box with 18mm mdf and pieces of wood in the corners inside the box and it was strong enough to stand on and jump on.

[planet10]

Originally posted by postman
All depends on how you construct the box. 18mm is fine for a 50 litre enclosure. Ive built a 100litre box with 18mm mdf and pieces of wood in the corners inside the box and it was strong enough to stand on and jump on.

My preference is for thinner, but very well braced walls. 1/2 or 3/4" plywood with a lot of irregular internal bracing. Given it is a 2.5 way you might also consider mounting the 0.5 driver on the back loaded push-push, which will reduce the load put on the box by the motion of the drivers. It also hides the part of that woofers response where it is rolling off at the top (the part where it is out-of-phase with the driver going up to meet the tweeter.

dave

[busterno1]

I was told that the 25mm is better for stopping box resonance.

Planet 10 .Do you mean to have 0.5 driver fire out of the box. wired in push push

[OMNIFEX]

My recollection on this is, large drivers require thicker wood
to maintain the drivers weight, and, withstand the abuses
of the speaker when used under High SPL operation.

Two 6.5 inch drivers in my opinion is too small to hear
a difference using 25 mm opposed 18 mm.

[busterno1]

sorry I meant have the driver firing out of the back of the box

[planet10]

Originally posted by busterno1
sorry I meant have the driver firing out of the back of the box

Yes....

There are (broadly) 2 schools of thot. The thick wall, heavy box, and the thin wall, heavily braced box where the idea is to push panel resonances high enuff that they won't get excited. I prefer the latter. I've enen build subs with 1/2" (althou lined in & out with formica). 3/4" (19mm) is generally easier to work with.

dave