can i use plywood for my sub box?

Plywood can be used.  3/4 or 1" marine grade is the best.  If you have generic construction grade plywood, use two layers to be safe.  Plywood enclosures resonate and vibrate a LOT more than MDF, so you will need to double your internal bracing and add dampening material to the inside surfaces.  It is best to NEVER mount your sub amp on any enclosure, as over time the extreme vibrations and flexing of the enclosure can destroy the internal amp circuit boards.  But if you MUST mount it there, the best way is to mount it across several braces on a short side of the box and to add two strong braces across the outside of the enclosure and mount the amp on those.

It would cost you around that much and save you from having to brace everything like crazy. MDF is alot stronger then plywood.

I agree with Dyohn in most cases as he has a good strong knowledge base to back up what he states, like the use of plywood for a sub box. Where I disagree to a point (not totally though dude) is when an amp is mounted to a box. For a circuit board that is mounted to an aluminum heatsink to flex with the flexing of the walls of a sub box must be quite a feat. No aluminum heatsink that I can think of will flex when it is attached to a sub box, thus the circuit board inside will not flex as well. I can walk across an amplifiers heatsink and it sure as heck will support my 210lbs of weight without flexing at all.  What will happen or could happen is the circuit board may vibrate from the box vibration of the box, not much though. Any sub system that can cause a vibration in a body panel or mirror will also cause the same vibration on a circuit board, in most cases no matter where it is mounted.Top Secret, I can tell you but then my wife will kill me.

Thanks, Rob.  I have to admit that the only time I have seen an amp taken apart by being mounted on the sub enclosure was an older model JBL Concord amp.  It was bolted to the sub enclosure along the long wall right behind on of the drivers, and it failed after about 3 months of use.  I opened the amp and several components had literally lifted off the PCB.  So I got real gun-shy after that, and recomend to not do it at all if you can avoid it.  Today's good quality amps can probably take a lot more vibrational abuse...

I would also recommend against mounting an amp to a box, this is for vibration and cooling. Also if you are going to use plywood I would recommend that you seal it with fiberglass resin to make it stronger and airtight.Certified Security Specialist

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MDF is cheap enough to buy anyways....might as well drop the 20 dollars and get it.....  As for mounting the amp to the box.....if you have thick enough carpeting on the box, that should absorb enough vibration.  But the problem with plywood would be flex.  Even with 2 layers, its easy to flex plywood.  Without bracing, you could do damage to the box, not so much the amp, when the sub hits (in sealed boxes).  The air inside the box will be compressed with the woofer protruding, causing the plywood to flex in slightly.  overtime, it's possible for the box to crack, since the screws holding hte amp in will create slightly larger holes.................well its hard to explain, and i probably sound like a fool trying to explain...........its all physics...... with the pressure on a plywood box, and the amp mounted to it, trying to fight the pressure, you'll inevitably break somethingMDF is much more difficult to flex, and is a lot stronger.  Carpet it, and mount the amp right on top, using ALL screw holes on the amp, and you should be fine.  Also, if you're worried about hte amp, I know most now come with grommets right in the screwholes to absorb vibration.   If yours doesn't, you can pick a pack of grommets of assorted sizes at an Auto Supply store *like the Autozone* for a few bucks.  That will help with vibration.....As will some rubber washers underneath the amp's mounting holes.....***REMEMBER TO ~wayland

MDF is cheap enough to buy anyways....might as well drop the 20 dollars and get it.....  As for mounting the amp to the box.....if you have thick enough carpeting on the box, that should absorb enough vibration.  But the problem with plywood would be flex.  Even with 2 layers, its easy to flex plywood.  Without bracing, you could do damage to the box, not so much the amp, when the sub hits (in sealed boxes).  The air inside the box will be compressed with the woofer protruding, causing the plywood to flex in slightly.  overtime, it's possible for the box to crack, since the screws holding hte amp in will create slightly larger holes.................well its hard to explain, and i probably sound like a fool trying to explain...........its all physics...... with the pressure on a plywood box, and the amp mounted to it, trying to fight the pressure, you'll inevitably break somethingMDF is much more difficult to flex, and is a lot stronger.  Carpet it, and mount the amp right on top, using ALL screw holes on the amp, and you should be fine.  Also, if you're worried about hte amp, I know most now come with grommets right in the screwholes to absorb vibration.   If yours doesn't, you can pick a pack of grommets of assorted sizes at an Auto Supply store *like the Autozone* for a few bucks.  That will help with vibration.....As will some rubber washers underneath the amp's mounting holes.....***REMEMBER TO PRE-DRILL YOUR MDF!!!   IT IS ~wayland