Laminant vs. MDF Box Q.

[SikSS 0]

I've got a pal who I'd like to tell is wrong, but need some technical advice to confirm my intuition.

I have a Mach5 MAW-12(350wts) I've built a 1 cube(plus sub space taken) sealed box for in 3/4 MDF, as per spec's and am running off an MTX Amp with 460wts max.

My good friend purchased 1 15" JBL apparently capable 650 watts(don't know the model, but a new purchase), and running off an older PG 500 wt amp. He has built a temp box he's happy with, about 1.8cubes sealed, but made of 5/8" plywood.

Although his lows seem to be lower, I don't think his volume nor his sound could be if he built a new MDF Box, instead of the plywood box he currently has. I don' think he's getting the volume he should, and don't think it's much louder than my 12 to tell you the truth. It doesn't sound nice though.

Would his box make all the difference to improving his sound and his volume?

[thekl0wn 0]

Much of it can have to do with the TYPE of plywood. IMO, a good high-cored ply is just as good as MDF... But then again, using 5/8", you're losing an 1/8" of strength as well as mass on the box, meaning, there's a good chance that his box is "flexing" more, which is bad.

So all-in-all, to answer your question... It could be the problem, but without more info on the setups, a definite answer can't really be given. Simply going off of power handling doesn't give much info. His sub may be like a Type R, and thrive in large ported enclosures and suffer horribly in sealed. It may need a bigger/smaller enclosure.

Edited August 22, 2007 by thekl0wn

[JimJ 11]

With the difference in drivers, cone area, and power, who knows if it's actually the box that's the issue here...

[SikSS 0]

Much of it can have to do with the TYPE of plywood. IMO, a good high-cored ply is just as good as MDF... But then again, using 5/8", you're losing an 1/8" of strength as well as mass on the box, meaning, there's a good chance that his box is "flexing" more, which is bad.

So all-in-all, to answer your question... It could be the problem, but without more info on the setups, a definite answer can't really be given. Simply going off of power handling doesn't give much info. His sub may be like a Type R, and thrive in large ported enclosures and suffer horribly in sealed. It may need a bigger/smaller enclosure.

You're mentioning you need more info on the setups, I'm thinking highly specific technical dynamics which I don't think I'll get from him?

Generaly he built a sealed box to suit the specs of the sub. We are running off similar power in wattage, or at least that's the way it seems. His box and sub are bigger and can throw pretty well all the power to it, while as I crank the volume up on mine, and up the power on my subchannel, the sub starts working too hard. But there is a point at which seemedly the volume level is matched. I'm not seeing any abnormal flexing in his box, if that's possible, and hearing a very clear and very nice hit. The plywood he's using is basic grade 5/8" flooring plywood(sanded on both sides and you could see there are about 5 sandwiched layers) which he has screwed the crap out of, but never bothered gluing or sealing...It's currently screwed into his rear quarterpanel with 2 metal L shaped brackets and so no movement. I guess the gravity is doing the rest.

I was hoping that the answer would be clearcut to win my point, but will have to admit to him I'm not right or wrong, but there are more intangibles that I'm not going to spend too much time considering on his behalf. I really like my MAW-12 but wish I had bought a MAW-15 now. I'm sure the 460Wts I have out of my MTX 895.5 on my subchannel would have been able to take more power and provide an even better quality and voluminous sound. Shoulda woulda coulda...it's my first sub.

Sound is definitely an addiction, and although I've had my system in for a few months, I'm thinking I should upgrade. My wife keeps my grounded however.

[thekl0wn 0]

Screwing and not gluing could cause air leaks... The subfloor grade plywood would not be my first choice in a build either. Find out the model on his sub as well.

[fuzzyping 0]

Screwing and not gluing could cause air leaks... The subfloor grade plywood would not be my first choice in a build either. Find out the model on his sub as well.

I just re-read that statement about screwing and not gluing. It's almost guaranteed there's a leak, however minor, if they're not using glue and/or silicone.

[///M5 2,833]

Your friends box sucks and should be rebuilt. Floor grade isn't good, 5/8" isn't thick enough, and not gluing the edges completely destroys the box.

[SikSS 0]

Screwing and not gluing could cause air leaks... The subfloor grade plywood would not be my first choice in a build either. Find out the model on his sub as well.

JBL GTO 1504 D is what he has as he's found his box, he was wrong when he said it was a 650wts capable it's actually more I think. It has RMS Wattage of 300, but power handling of 1200W, says that on the box.

I don't know what that means compared to my Mach5 MAW-12 which is rated for 350W of power handling.

I know I paid 3 times less than he did and feeling pretty proud of that.

[///M5 2,833]

The GTO's are nice, but his box is lame. He should have bought wallmart drivers if he was going to build a box that isn't even wallmart quality. Booo!

[Xibalba 0]

Everything covered thus far is right. I dont know a bunch about different subs and such, but I do know wood. First off, is he using the everyday run-of-the-mill plywood or is he using something nice like Baltic Birch? Normal plywood used for everyday things are 3 or 5 ply. Nicer plywoods like the previously mentioned birch are about 7 to 11 layers, depending. This type of wood is compressed and very strong and sturdy. Comparing MDF to this and even "crappier" plywoods: MDF kills them in sheer density. This allows for better acoustic resonance and allows for the proper reproduction of the music. MDF is also a lot easier to work with than a lot of other plywoods due to the material is is made of. Only downfall, cant get wet. THe sheer density of it though can act as a sound damper, which is wanted in a box. Some really crappy plywoods have a tendency to absorb a lot of the sound waves causing a slight decrease in performance. So, I would think that a box made from MDF would make a decent improvement unless he is using some really expensive wood, which I doubt since you said it is a temp box.

[JimJ 11]

I don't know what kind of MDF you've been using, but any of the stuff I've used has torn up saw blades faster than even 13-ply cabinet grade plywood.

A lot of horn builders choose plywood over MDF, for its resonance characteristics...so it depends on the application.

[///M5 2,833]

Good plywood can surely be better than mdf for knocking out resonances, but the OP isn't referring to void free 11+ layer wood.

And most definitely mdf is hard on blades, considering it is made of glue and wood particles the glue really tears into your tools.

[ramos 2]

But it smells so damn good when your cutting it

[thekl0wn 0]

But it smells so damn good when your cutting it

And that Formaldehyde is so good for you too!

[ramos 2]

Yeah man puts hair on your chest while your alive , and slows your corpse from rotting afterwards

[SikSS 0]

My buddy and I were reading all your replies on my blackberry while on our way to Princess Auto in Hamilton, Ontario(a tool and supplies centre) to pickup balljoint splitters and steering wheel puller. It got him thinking enough that we ended up going to the lumberyard just down the road to price some better plywood.

We were both kind of shocked at the price per sheet 4x8 (3/4") Birch, Appleply and a few other types of "high density" ply's. He was adamant to try and make an improvement, so we went with 2 sheets of 3/4" high density MDF(on sale no less), bought a predrill bit, some nice screws(fewer but wider threads), glue and some caulking as well to make sure air doesn't escape the box. Even picked up some polyfill at Walmart.

We got to work building the box the exact same size today, but thought I'd check the web to find the specs on the sub and it say's that you need to build a 1.50 cubic foot box, plus the sub space taken, not the 1.8 he used for the sealed sub. He was happier that it was supposed to be smaller. So we got it built in about an hour, spent another 2 hours letting it dry with a high-wattage lamp facing it. He'll carpet later, so he says.

Got the sub into it, after playing around with lining the sides with the polyfill, wired it all up and wow, definitely a difference. It seemed to hit notes better, was definitely a bit louder but generally the quality of sound was much better. It seemed to rattle the trunk lid a lot more than previously. This is one really nice sounding sub let me tell you. Way way better than the Rockford Punch he had in there before.

All in all, definitely an improvement. I think we narrowed down the power issue to the amp though. It must not be putting out the wattage we thought even though it say's it has more than my MTX 5 channel(460wts tops on the subchannel) or he's layed a good beating on it. He's going to look for a deal down the road.

Me... I'm glad I've got the Mach5 MAW-12, but makes me want to go to a MAW-15. The diff in a 12 to a 15 is considerable. I may make another box myself, but a vented one this time to improve the low's to get it to sound like a 15 if thats possible. Just have a hard time giving up trunkspace.

Anyway, thanks all for you're input. It's greatly appreciated!