Blow through enclosure question

[jakedubb]

Sorry but I posted a similar question in the car audio section before realizing it......

Anyways I need ideas for a blow through enclosure using a mm10 in it's original box. I have a std. cab p/u and no space! I was thinking of mounting the grill inside the truck and everything else in the bed (weather proofed of course). I have never seen this, how will it sound? Any response is appreciated!

[neomagus00]

-Deleted-

[LittleCar_w/12s]

It would work just fine, but keep in mind that the bed of a pickup is separate from the cab. So..... take the pickup bed off (troublesome but worth it to do it right). Build your enclosures to the cab of the truck, seal well, and use METAL, Dynamat inside very much. Make sure they are sturdy, but the weight of the sub should be mounted to the cab first, then the enclosure to the back of the cab. This enclosure doesnt have to look great.

Next, measure how much you will have to cut in the front of the bed, then cut it out. put the bed on, then build yourself a new front to the bed to cover the hole and the sub enclosures. Make sure there is clearance between your cover and your enclosures, as the bed is meant to torque on the frame when loaded.

If you do it right, it will look nothing more than a tool box, and you will get sound that is unmatchable from behind seat enclossures.

have fun!

[neomagus00]

wouldn't you worry about the small bed movements that are independent of cab movements shearing off the box? like a rolling/twisting motion?

[jakedubb]

Nice! Thanks man. I've seen guys use accordian type seals for the weatherproofing and is supposed to work really well. As far as the flex of the bed & etc. I was told that leaving a small amount of space and filling w/ soft foam type material is best for protection. Sound right?

[neomagus00]

hmm... yeah, that would prevent wrenching your box to pieces, but it would also negate the point of having a box (i would think). if you've got 3/4 inch wood all around, and a little strip of foam/accordian stuff, the foam's gonna take a lot of abuse, between the twisting of the truck and the pressure of the sub. i'd say it wouldn't hold up for very long. in fact, i wouldn't go with a thru-enclosure at all. pbd came up with a novel idea recently, for his truck. it's around here somewhere, see if that could work for you.

[jakedubb]

I've decided against the blow-thru option due to the pro's and cons. I've got the mm10 w/ the plexi enclosure and love it but it takes up to much damn room. I bought a sheet of 3/4" mdf today and have decided to build my own enclosure. I need 0.66 cu. ft. for proper sound/etc. I haven't researched much about determining the cu. ft. Anyone know how to convert the math to cu. ft? Not gonna start on this until I have it fully researched :)!

Seems to me that all I have to do is subtract from the original box width and add the demensions to my new box's height. This would allow the cu. ft. to stay @ 0.66 right? As long as I don't include the mdf in my math I should stay the same. Any suggestions or links for mathmatical conversions would be a huge help! Thanks guys!

[neomagus00]

hmm... good choice on the learning bit, i congratulate you (this is where much equipment gets broken). okay, you really can't do the math without taking the mdf into account.

you must keep in mind your space limitations. for example, if the box can be a maximum of 14 inches tall, and you're using 3/4 mdf, you have (14 - (2*3/4)) = 12.5 vertical inches internally. more complex box shapes will need to be divided into parts and the volumes added. if you want, i can whip up a design for you; ive actually just finished one for someone else here.

for your reference, 0.66 cubic feet is equal to 1140.5 cubic inches.

sample design - if the box is 14 inches tall and 14 inches wide, it needs to be 8.75 inches deep, rounded to the nearest quarter inch (not a bad thing). this is because the internal dimensions, 12.5 * 12.5 * 7.25 = 1132.8 cubic inches, only 7.6 cubic inches off the goal, less than 0.7%. no biggie.

[neomagus00]

oh, and taking the time to plan your cuts helps. that is, once you have your box designed on paper, you need to figure out precisely how you're going to cut the wood. larger pieces overlap smaller pieces. thus, in the preceding example, the front/back of the box, being 14*14 inches, would overlap the top/bottom piece, being 7.25 * 14 inches, which in turn overlaps the side piece of the box, being only 7.25 * 12.5 inches (see attached image). use liquid nails and long screws, in that order, with predrilled holes. note that this box design does not take into account carpeting. also note that the image is way not to scale.

after you know the sizes of the pieces (in my example, 2 each of 14x14, 14x7.25, 12.5x7.25), you can lay them out on a piece of mdf. again, see pic, and again note that it is only slightly to scale.

[jakedubb]

Hey neomagus00,
Thanks for the help! It is very much appreciated. I found the calculations for cu. inches to cu. ft. and etc. I went in to this knowing nothing and have learned a great deal in just a few hours time.

Great box example by the way! I follow 100% Here are my measurements behind the pass. seat (only losing a few clicks for the passenger) 20" (width)x 18" (height)x 8" (depth). The depth @ 18" needs to decrease to 4" or so. These measurements allow for a little extra to play w/. I've designed a box but would certainly like to see what you come up w/ for comparison. I'll probably use your design anyways! he! he!

Thanks again for taking the time to help!- Jake

[jakedubb]

Oh ya, I borrowed a friends table saw to insure a perfect cut & etc. I was planning on using bondo on the interior (for sealant) rather than using caulking. Good idea? Or bad?

[neomagus00]

i know approximately nothing about bondo, so i can't help u there.

this is what i came up with: 18" tall X 7" deep bottom to 3" deep top X 18.75" wide (if you want carpeting, this will end up being 19.75"); what did you have?

good idea borrowing the saw, the box i designed will have some strange angles. those are some tough limits to make an easy-build box in. no big deal tho.

[jakedubb]

My main concern is that the sub sits back 5.25" at top of sub. This doesn't allow much room behind the sub. Does that matter? Also should I use an insulating material?

This sub's specs say that it can be used in a sealed or bandpass application. I was unable to find a cu. ft. for a bandpass box for the mm10. My truck already has 4" cutout's (round) in the bed and cab from the previous owner. They have been sealed and appear to be back to stock but are already cut. Back in the day I used to see many 7th order bandpass enclosures, but really haven't seen them for about 7-8 years. Any idea why this isn't so common any more?

How would the mm10 sound using this type of a set-up? I'd use 3 or 4" ports directly into the cab of my truck. I haven't abandoned the interior box idea but am contemplating other applications due to space :) Set me straight! Please! Thanks!

[neomagus00]

there are two issues one has with bandpass boxes. the first is quality - bandpass pounds, but doesn't sound nearly - nearly as good as sealed, or even ported. second, bandpass takes up a buttload of room, cause you're taking a sealed box and attaching it to a ported box. room is something you do not have in abundance.

yes, i'm glad you mentioned the depth of the driver - i had forgotten this bit. the box dimensions i posted may be enough to clear it, maybe not. what you may have to do with that limited space is actually kinda crude - you may have to make little cardboard profile cutouts of everything - that is, make a life-size cutout of what the box would look like from the side (a wedge that's 18 inches tall and narrowing from 7" to 3" deep) and draw in the lines of where the empty space is inside (that is, draw a 3/4" border all the way around). then, make a cutout of your subs, same way, it should look like... well, like a speaker (profound, no?).

ensure that both are accurate representations, life-sized, and then put the other on top of the one. if the magnet of the sub has a minimum of one inch of clearance on all sides, you're golden. if not... you may need to be more creative. keep in mind that you can't snug the box right up against the seat, because the cone's gonna move a lot and you don't want it banging into anything.

insulation - nope, for sealed and this driver it's not necessary. if you really must, a lining of polyfill stapled to the inside of the box is cool. shouldn't make a difference tho.

you really may wish to find pbd's recent thread, he's had some space issues as well.

[LittleCar_w/12s]

When I work with MDF, I prefer liquid nails, it's a great glue for mdf AND is a flawless seal. Just remember that MDf is glue and paper bits... so use screws to draw pieces together, but the liquid nails will actually bond it much better.
--Jerry

[neomagus00]

jerry - do you seal the inside seams with liquid nails, too, or do you use something else?

[jakedubb]

Hey guys,
Again thanks for the help! I went with the sealed enclosure. So far I've got the pieces cut but am waiting to find a friend with a scroll saw or zip saw to cut out the 9 1/4" sub hole. I need to invest in some pwr. tools of my own....someday. I picked up some Liquid Nails const. adhesive before seeing you post about it, so I made a good decision there. I'm waiting on my new carpet for my truck to arrive so I'm not in any hurry to finish. Know where I can find a seal for the sub? I've been to local stereo shops and haven't found one yet. I haven't taken my Momo out of teh original box so I'm not sure if I should find a new seal or not. I guess I'd rather have a new one than use the old seal. We'll see....

[neomagus00]

the new one should have a seal. if you're carpeting, and if you've never done it, crotchfield's advisor thingy has two good articles on box-building. there's an advisor link in the upper right or u can shop for subs then find the 'learn more' section. specifically, they teach you how to carpet a box and make it look very clean.

did you ensure that the box has enough space and that it will fit where you need to? did you make sure the sub will fit in the box, with at least one inch of clearance on all sides of the magnet? if so, great, have fun.

[jakedubb]

Originally posted by neomagus00
the new one should have a seal. if you're carpeting, and if you've never done it, crotchfield's advisor thingy has two good articles on box-building. there's an advisor link in the upper right or u can shop for subs then find the 'learn more' section. specifically, they teach you how to carpet a box and make it look very clean.

did you ensure that the box has enough space and that it will fit where you need to? did you make sure the sub will fit in the box, with at least one inch of clearance on all sides of the magnet? if so, great, have fun.

Ya I've read Crutchfield's basic info. to many times this past few months! Keep thinking there will be something new I guess...hehe! I've built boxes before but they were for buddies. When it comes to my truck I won't do any mods unless they're 100% perfect. I always take time to do research, as you can see!


Ya sub will be good to go for room. Just wondering how it's gonna sound!!!??? I'll only lose two clicks on pass. side. You think this sub will perform OK 1-1/2" behind a seat? I've noticed that some subs benefit from the tight quarters but haven't heard my Momo like this yet. I guess we'll see.

[neomagus00]

in the tight space of a truck, i think that you'll be just fine. you said it's 1.5" behind the seat... what's the xmax of the sub? and i assume you're attaching the box to the floor in some manner?

[LittleCar_w/12s]

? about sealing with liquid nails:
You can, but when you glue the box and screw the pieces tight, plenty will ooze into the inside, simply spread it out. You can do this on the outside too, but it will be a cleaner edge if you grind and sand the excess off... but more work nonetheless.
The last box I build I just used L.N. and that's it. The crappy box I have my 2 12's in was a freeby and is only stapled together (crappy store thing I guess) I used Industrial air-duct sealant for that. It's really superior to ANY kind of caulk, but takes a week to air off the fumes.
-Jerry

[jakedubb]

Originally posted by neomagus00
in the tight space of a truck, i think that you'll be just fine. you said it's 1.5" behind the seat... what's the xmax of the sub? and i assume you're attaching the box to the floor in some manner?

Not sure what you mean by xmax.......The box is going to be secured with small brackets and screws. The Momo box came with brackets so I'll be re-using them. HHHMMMM damn still don't know what xmax is! Sorry :)

[neomagus00]

no prob - xmax is how far out the cone can move; i am lazy, so i didn't bother looking it up, but for the mm10 it's one inch (less if you don't let it distort), so you don't have to worry about the cone banging into the back of the seat.

the reason i asked about securing the box is the same, i've seen people with truck boxes just let it go free. the box ends up sliding forward and it pushes the sub right up against the chair - bad for sub.

jerry - how much is the industrial stuff (when i get around to mine, i want it to be perfect in every way)?

[jakedubb]

Oh OK gotcha! I'll be using my grill from the orig. box as well so this will also help protect it. I think I'll be able to finish it up today, just need to find some carpet. This is gonna be sweet! I removed my truck's 60/40 bench and replaced it with gray/black racing seats, added new carpet (still waiting for it), painted dash bezel, white face glow gauges, and added remote sub level control. Next is a custom console :)

[neomagus00]

wow, that sounds like a lot of work... hope the sound keeps up! (nah, of course it will, it's polk :D)

[jakedubb]

Originally posted by neomagus00
wow, that sounds like a lot of work... hope the sound keeps up! (nah, of course it will, it's polk :D)

It has been lots of work! I had back surgery last Summer so I've been off of work. Just keeping myself busy! Expensive entertainment though!!!!!!

As for the sound keeping up, one word.........Warranty!

[LittleCar_w/12s]

Hmm industrial sealant for the inside of the box.... I will have to look that up. I got mine from my father who is a sheet-metal duct worker. --Yeah the real industrial stuf comes in like a HUGE caulk tube.
--Jerry

[neomagus00]

hmm, i could always find other uses for the excess eventually.

u think your dad would make me a new exhaust line if i asked real polite?

[LittleCar_w/12s]

lol, nah, he works with air duct that you could walk inside of man.... Like hotels and highrises.... but he's been sick anyway (terrible recovery from cancer surgery) so I don't think he has any caulk tubes laying around.
But someone has to sell the stuff ;)
-Jerry

[neomagus00]

my condolences for the cancer man; anyways, you think you could find out who sells it?

btw, j/k on the exhaust :D