MDF for Box Mounting

Okay today I went to my audio dealer to grab some plywood for my floor mount and back wall that will be used to Mount my 2 12” Subwoofer Box which will be made from birch wood.

I was told not to get mdf but this place insisted I should only go with mdf…it is better for sound dampening (even though I’m in the process of dampening everything already). The price is cheap but when I mentioned just regular plywood they argued with me definitely get the mdf you will not regret it.

I thought mdf was terrible to use for use of supporting my box. I hear it’s weaker…prone to warp.

Also they said it will help further sound deadening and also help with absorbing the sound of my box. Do I really want to absorb sound here? Lol

I’m new at this but I’m putting 2 Audiofrog GB12D4’s in the back of my GEN 2 Access cab and it’s just the wood for the box to sit on and wood for the back wall as I removed the factory plastic wall.

Im kinda at a loss…this place seems legit but again I have read that mdf is pretty much cheap junk.

Would I be making a mistake using mdf? They are going to install everything for me oh and the box is being made my Mr. Marv.
Marv mentioned to me basic plywood is all I need problem is damn the prices are high at all local hardware stores and this place sells this mdf for much cheaper and the asking price for everything installed is very fair…just again they insist I use MDF I won’t regret it.

Any answers here? Thanks in advance.

 

i'm not a build expert either, but i do know some about it from experience, and i have a birch box from Marv as well. the birch is strong when thin, so it's light and doesn't eat your space back there. with a big 13" sub i had no room for anything, barely enough room for sufficient dynamat on the back wall, so i couldn't go thick and Marv had to dial it in to allow for full excursion without contacting the backseat. in a previous build i had a MDF sealed box holding 2 10W7's, and honestly the box sounded absolutely great as it was also built to JL specs for the subs. but it was a massively heavy pig, it required two layers of 3/4" MDF at the front end to support the subs, and over time, as MDF does, a corner picked up some moisture and then bulged and broke apart at that corner from moisture. MDF can't handle any moisture, even though that box was carpeted and all that. since this is going in a Tacoma, i'm not sure MDF is a wise choice at all.

 

For making speaker boxes they use MDF because it dampens vibrations. SW’s I used baltic burch ply. For mounting I guess the same logic applies. How much weight does it need to support?

 

I appreciate your advice here but I’m only referring to using mdf for the wood to mount the speaker box which will be one strip where the access seats used to be and other piece for the whole back wall as I pulled the stock plastic wall out…the box for the 2 GB12D4’s Marv is indeed making out of birch wood as well as the amp rack which is going in the middle

 

yep, common problem with me is i reply to things i read w/o my glasses. i'm sure you mentioned it. lol

 

I have no idea right now I do not yet have the box or speakers in hand.

Again it’s 2 Audiofrog GB12D4’s with an ArcAudio 1100.1 amp mounting in the middle…box wood all he’s making with birch.

 

you deleted that last post?

i would say simply that if that shop has a way to use MDF as a support or mounting point then it's on them to make it right, but the focus in my mind would be controlling moisture absorption, since that's the thing that will make the MDF a problem. if it was a couple little blocks or pucks, i'd hit them with plastidip or similar paint/sealant after they are drilled. but that's if i was doing it myself, i'm not a pro installer and some of those guys are around here.

 

Well…common problem I have is I tend to read too fast…you actually sort of answered my question…from what I gather with birch wood being lighter the mdf would probably work…but a full on mdf box…which I know is heavy…no way!!!

Thanks

 

Yes because read my latest reply to you…you actually answered my question in a way.

 

all good, but you may get more replies so stick around.

 

I live in Louisiana and it is a hot muggy wet mess down here…kinda doubting mdf unless like you mentioned…they put some decent coating on them first. I reckon I can ask them kindly to do this for me?
These guys do up to 17 cars a day…they seem to know what they are doing and they all insist…mdf for supports.

If this were Winter I would be doing this but I’m not built for this hot muggy @ss weather, lol

Also anyone notice having to edit their posts over and over? I swear this forum does not like my typing here or something?

 

I think plywood would work fine, just to act as a platform for a box.

That said, MDF will be fine UNLESS it gets wet. Personally, I wouldn’t bat an eye at 1/2” MDF and roll some bedliner onto it.

 

For a platform I’d consider HDPE if you can find some cheap enough. Non conductive, easy enough to cut, won’t absorb water, extremely durable.

For the box itself, as mentioned above.

 

You may laugh at this so get ready…I had to look up what “I wouldn’t bat an eye at” saying and it appears that means to show no concern for correct? Lol
Is that a saying down where we live because if so I’m kinda disappointed on my terminology here maybe I shouldn’t bat an eye about never have hearing of that saying before eh?

So some Bedliner ( waterproofs wood correct) over mdf sounds okay to use you are saying?

Thanks again and hey I just learned a new saying . But correct me if I’m wrong. I honestly thought you were telling me not to bat an eye I’m like (what the heck is that) lol

 

Please don't put mdf in your.... Anything! You will never be able to seal it completely. It will draw moisture and fall apart. It's about the worst material when exposed to moisture which includes high humidity.

 

Yes that’s seems to be the general answer here why not to use mdf.

I’ll stay away from mdf…not even for just using as a mount for my box.
Thanks for the reply.

UPDATE: yeah just watched some YouTube videos on the difference from mdf vs plywood yes obviously no mdf in my truck. Looking at my tv shelf that is so heavy to move and sags on top…just now realizing it’s mdf…other side of my room much larger table…very light to move…tons of weight on shelf’s…no sag…plus seeing the wood crack from screws and heck even the bottom of my shelf is all deteriorated looking on the bottom from when my tub overflowed one time, lol

 

And every time you run your truck’s AC, it dehumidifies the air inside the truck.

I’ve made sub boxes out of MDF for years, never had a problem. Also had it in unconditioned garages, no issue. Only gave me trouble if it got wet, at which point it goes to crap immediately.

 

My truck is in the garage and the ac is on before I back out.

Great…now being pretty much sold on not using mdf this dealership is willing to do a whole install so cheap but it’s treated mdf…I have time to think about this. …but just remember this mdf is for the wood to use to screw and mount the box onto and the back wall…the box for my subs and amp rack is being made out of birch wood.
I think it is wise to stay away from mdf just from what I’m gathering here though…but their prices are great carpeting everything installation everything…it’s tempting to just let them do what they really want to do…again this place (near us in Mandeville actually) always uses MDF with great success…and they even showed me some of their mdf cabinets…heavy!!! But they do very awesome work.

Im lazy because it’s so hot outside and muggy otherwise I would have this done already. Finishing up dampening now and easy enough but im sweating hard out there!

 

It’s your truck, your call. All I’m saying is I wouldn't throw the baby out with the bath water (there’s another one for you).

I wouldn’t make a drawer system or anything out of MDF that could come in contact with water, but I’ve built sub boxes that lasted for years in a car without any adverse effects.

 

All that said, the reasons I got Marv to build me a birch box were:
1. A comparably strong Baltic Birch box is quite a bit lighter than MDF.
2. Baltic Birch can be stained which MDF can not.
3. It looks like this once stained and urethaned.