Birch, oak, MDF, plywood????? - AVS Forum
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post #1 of 23 Old 11-10-2013, 06:15 PM - Thread Starter
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Ok I see alot of you are using plywood to build these custom boxes and horns from. Others I see preach birch birch birch, and yet some just use a nice laminet plywood. However I haven't seen anyone using MDF! What's the reason? Coming from car audio where that's all that is used to seeing it never used in home, I'm a little curious as to why?

Any insight?

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post #2 of 23 Old 11-10-2013, 06:21 PM
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It has a different resonant frequency then ply. That's at least pertaining to horns.
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post #3 of 23 Old 11-10-2013, 06:35 PM
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because mdf.... sucks.

its heavy

It doesnt take screws

Water destroys it

amongst other reasons. Its only positive trait is its low cost and smoothness.
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post #4 of 23 Old 11-10-2013, 06:37 PM - Thread Starter
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^^^^ lol how do you really feel lol
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post #5 of 23 Old 11-10-2013, 06:42 PM
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Originally Posted by 417 Motorsports View Post

I haven't seen anyone using MDF! What's the reason?
The question to ask is why do manufacturers use MDF? The answer is that it's cheap, it takes veneer well, and it's so dense that you can get away with minimal bracing, which reduces labor costs. For the DIYer it's a PITA to work with, and a well braced plywood cab can come in at half the weight of an unbraced MDF cab of equal vibration resistance.
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post #6 of 23 Old 11-10-2013, 06:55 PM
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I have been grappling with this for a while now. A few points from the information I have been able to gather together (this just applies to timber sheet and ignores polymers etc):

1. Ply is stiffest = good and takes bracing well
2. MDF is heaviest but not stiff
3. Chipboard provides good damping
4. Multiple layers of different material provides damping

My plan was as follows for the LCR’s:

19mm birch ply outer shell (stiff), then
19mm mdf (weight)
green glue (damping)
19mm chipboard (more damping)

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post #7 of 23 Old 11-10-2013, 07:05 PM
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I very much like building with mdf. It's cheap, easy to shape, glues strong, doesn't warp if braced well. Is great for indoor speakers that don't need to be packed around. But it's heavy, cancerous, and melts in water.
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post #8 of 23 Old 11-10-2013, 07:09 PM
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did I really just hear the words "very much like building with mdf"? does your body run on cancer dust?

sorry, just joking.

I really dislike it because after one build (even with a face mask), I felt like my lungs had been severely violated.

also:

elill, you really intend to make LCR's with 57mm thick walls? wat?
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post #9 of 23 Old 11-10-2013, 07:21 PM
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Yeah I Love breathing in urea formaldehyde biggrin.gif
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post #10 of 23 Old 11-10-2013, 07:32 PM
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Quote:
Originally Posted by BadmanSound View Post

also:

elill, you really intend to make LCR's with 57mm thick walls? wat?

Unless its a bad idea?

.....I'm not planning on ever replacing what I have planned, so if a little extra work at the start is no big deal

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post #11 of 23 Old 11-10-2013, 07:34 PM
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it just seems... excessive? my arms are quite thin though. The perceived benefits in my mind do not outweigh the tripling in mas, and increase in overall volume. I could easily be wrong though. smile.gif

I complain when lifting an average sized speaker built out of 19mm thick material.
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post #12 of 23 Old 11-10-2013, 07:42 PM
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Quote:
Originally Posted by Elill View Post

My plan was as follows for the LCR’s:
19mm birch ply outer shell (stiff), then
19mm mdf (weight)
green glue (damping)
19mm chipboard (more damping)
Are you building a speaker or an M1 tank? I don't use more than one layer of 1/2" plywood, ever. And my cabs don't vibrate.
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post #13 of 23 Old 11-10-2013, 07:50 PM
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The rationale was more for damping then anything else.....

Speaking of which, I have read all sorts of guff about internal linings (fibre glass etc). I had planned on just 2 layers of 1" with some plastic in between (same way I build "absorber" panels). Anyone have a definative guide to this? noting its for mains so 60hz-20k+ not subs which will just be an empty box

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post #14 of 23 Old 11-10-2013, 08:00 PM
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+1 MDF related complaints! MDF dust.. that's some bad shxt! tongue.gif from a former MDF addict..

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post #15 of 23 Old 11-11-2013, 05:27 AM
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Quote:
Originally Posted by Elill View Post

The rationale was more for damping then anything else.....
That's one way to do it, but IMO not the best way.
Quote:
Speaking of which, I have read all sorts of guff about internal linings (fibre glass etc).
Damping is almost always required to reduce internal reflections. That includes subs, as the motion of the cone creates harmonics that must be damped. The exception is a folded horn sub, as the bends of the horn filter harmonics.

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post #16 of 23 Old 11-11-2013, 05:57 AM
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MDF dust from years ago was not the best thing to breathe in. But the newer stuff is no where near as bad.

Inhaling dust from any wood product is not great on your lungs. Then again, either is walking downtown during rush hour and inhaling exhaust fumes.
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post #17 of 23 Old 11-11-2013, 06:39 AM
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Quote:
Originally Posted by Erich H View Post

MDF dust from years ago was not the best thing to breathe in. But the newer stuff is no where near as bad.

Inhaling dust from any wood product is not great on your lungs. Then again, either is walking downtown during rush hour and inhaling exhaust fumes.


mmmmmmmmmmmmmmmmmmmmmmmmmm fumes!
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post #18 of 23 Old 11-11-2013, 10:40 AM
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MDF only for me. I don't like the exposed end grain you get from any of the ply options. Sure I could miter all the ends but I'd rather not.

It's purely an asthetic choice.
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post #19 of 23 Old 11-11-2013, 11:24 AM
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I rather have to deal with extra bracing of plywood over MDF any day.

I will never build with MDF ever again. I don't care how much cheaper it is than plywood. The dust is a pain in the rear to clean.
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post #20 of 23 Old 11-11-2013, 05:30 PM
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19mm baltic birch with bracing every 6" works very well.

Too bad Mahogany is so expensive. I ran some through my router last week and it actually smelled really nice when cut!

Mike
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post #21 of 23 Old 11-11-2013, 06:51 PM
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Arauco, if you can find it, is pretty inexpensive. Most particulate is bad for you in some form or another, which is why we should all just smoke and get it over with.
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post #22 of 23 Old 11-11-2013, 07:00 PM
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I ran some through my router last week and it actually smelled really nice when cut!

Could you send a sample my way? smile.gif There are a few things I like better about MDF though, it's been mentioned except for not chipping possibly..

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post #23 of 23 Old 11-12-2013, 11:49 AM
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Quote:
Originally Posted by steve nn View Post

Could you send a sample my way? smile.gif There are a few things I like better about MDF though, it's been mentioned except for not chipping possibly..
I was restoring a desk organizer from 1810 for a friend. I wish I had enough to use for a speaker project.
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