H E L P!!!!!!

Systems

I am trying my hardedst to build the best system i can for the money and put it in my civic clean but i keep hearing mixed reviews on the type of box i should be using for my 2 mm124's. I hear BP and selaed back and forth. Please someone shed some light on which set up would be best for me. I have a 700s running the subs and a 500x running my 2 pair of mm6's. Each amp has a 1 farad cap. I havent put not even one piece of this stereo in because I want to make sure its done right. Please if you have a suggestion i would love to hear it....thanks

Jstas

What are you goals?

A sealed box is probably the best way to go. They can perform with the volume of a bandpass but still be clear and accurate. You will need to put a good deal of power behind the subs in a sealed box to acheive that though. Seems like you have a good deal of power with that 700s so it should be fine. I think you would be much happier with a sealed box though.

As far as bandpass goes, I think you would have wasted your money and time if you used mm124's in a bandpass enclosure. They are far better suited to a sealed enclosure.

MOMOcivic

should i have them in the same box or keep them seperated....are there any designs out there for single boxes...i see some on here from time to time and wondered if anyone had one for this application...if you know anyone please let me know....thank you

Jstas

If they share the space, they will not be quite as tight as seperate enclosures. Frequency response and range won't be affected. it just that things like standing waves inside the enclosure can color music and make notes sound a bit muddled. Have a seperator baffle to make 2 chambers in the same box would be a better way to go.

As far as getting one, almost any professional install shop should be able to custom construct a box to sufficient specifications. It's probably better to have that done anyway. That way you aren't limited to a bulky, typical shape. They can make something work for your application. They will most likely use better materials too. Cause like someone said on here already, the pre-made boxes tend to be pretty cheap.

MOMOcivic

i am gonna make my own box...i was just wondering if anyone had the plans already wirtten up.....thats all

Jstas

Well, construction is simple. Design your own box. Remember you geometry from high school. find out what volume is needed for the speaker and build you box for about 15% more volume to get your external dimensions. If you are a beginner, that will get the box close enough in size to where it needs to be. Use at least a 3/4 inch thick sheet of material. anything thinner will not support the speakers or the amount of vibration they will produce.

Otherwise, time to get creative! If you are going to build you own box, you can utilize your available space to the best of your ability. Good luck with it.

[Deleted User]

This website has some useful info on box building. It also has some dimension calculators.the12volt

MOMOcivic

that site wont seem to work, i really wanna make these 2 subs sound the best possible and i dont want to have to do it twice....thats why i am looking for hte best box design i can find

Jstas

Originally posted by MOMOcivic
that site wont seem to work, i really wanna make these 2 subs sound the best possible and i dont want to have to do it twice....thats why i am looking for hte best box design i can find

You're missing the point man. Box design has two levels. Form and function. The form can be anything as long as the basic requirements of:

- volume
- symmetry
- sealed joints
- solid construction

are met. You need to find out what the ideal enclosure's internal volume is and then base you design around a volume of space that matches that volume. It can be any shape. You have to ensure that your woofer is mounted as squarely in the enclosure as possible. Having the woofer spaced equally from the sides of the enclosure eliminates standing waves and resonances. It's not as important in a sealed enclosure but, uneven air distribution inside the sealed box can cause pressure differences which result in cone distortion.

I'm having a hard time explaining this but basically, unless there is enough space on the opposite side for an uneven pressure wave to dissapate, you will not get peak performance from your speaker. If you have a 12 inch woofer in a 16x16x16 box, mounting the woofer an inch off center will create issues. Mounting the woofer in the center ensures that you will have clean, unmuddled sound.

Lastly, make sure your box is solidly constructed. Screws and glue for each joint and the inside is sealed with caulking. So is each opening for the speaker and the terminal cup. Drill pilot holes for the screws because the screws can split the material being used and a split can end up being an air leak. It will also, most likely rattle.

Use your head and make whatever you want to fit the vehicle. Stop worrying about the "best design you can find" because the best design is teh one that works properly and fits your application. Just follow the manufacturer's recommendations about enclosure design and build it any way you want.

PoweredByDodge

i think Jstas just about covered every base here, and he's right.. there is no "best" enclosure... when you're dealing with sealed at least...

a sealed 0.88 cubic foot box is the same whether its a rectangle or a square or a trapezoid or a triangle or a sculpture...

3/4 " mdf or birch plywood is the way to go.. the BP is lighter but costs an arm and a leg.

use 1.5 - 2 " drywalls screws spaced 3 inches apart, a thin "weatherstipping" 1/16th inch thick foam gasket in between each joint (3 bucks a roll at home depot / lowes) and then silicone seal all inside joints.

this is perhaps the only "beef" i have with some pro shops -- they're impatient... a GOOD pro shop, as Jstas said, will do a kick **** job and could probably build an mdf box in 30 difft shapes to fit into any space and if not they'd glass it... a HALF **** shop will build you a box, but instead of gaskets and screws, they'll use nothing in between the joints and then they'll use a brad nail / stapler gun to hold the joints together... this is NOT a good thing. if you ever do have a shop do any boxes for you, DEMAND screws.

when doing your first box, or if you're not really that adept at it... just keep it simple... like Jstas said, its all geometry.. L x W x H --- that'll give you your cubic foot measurement - the momo's want 0.88... anything from 0.75 to 0.95-ish will be "ok"... a hair above 0.88 being the "ideal" usually (depends on what you listen to... if you're slamming rap all day you might want a hair below 0.88 so that the heaviest of the heavy bass is "weeded out" and you keep your speakers moving linearly... listen to a lot of classic rock / easy listening kidn of stuff.. hair above will draw more of the low note out of hte music..... usually... not always... usually).

Thom

Originally posted by PoweredByDodge
use 1.5 - 2 " drywalls screws spaced 3 inches apart, a thin "weatherstipping" 1/16th inch thick foam gasket in between each joint (3 bucks a roll at home depot / lowes) and then silicone seal all inside joints.

this is perhaps the only "beef" i have with some pro shops -- they're impatient... a GOOD pro shop, as Jstas said, will do a kick **** job and could probably build an mdf box in 30 difft shapes to fit into any space and if not they'd glass it... a HALF **** shop will build you a box, but instead of gaskets and screws, they'll use nothing in between the joints and then they'll use a brad nail / stapler gun to hold the joints together... this is NOT a good thing. if you ever do have a shop do any boxes for you, DEMAND screws.

Wood glue is pretty strong. When I make test boxes here, I use glue on every joint, and staple the box togther. The staples are only used to hold it together until the glue dries. If a box has served it purpose and is no longer needed, we'll smash it up before throwing it in the dumpster, and when breaking boxes up we've seen the mdf pull apart since the glue is so strong (the box doesn't just break along the seams). We've never had a problem with a box leaking.

When I went to Fukuda's fabrication course years ago he showed us a quick way to cut out boxes, and he stapled them together. Even he said that the wood glue is more than strong enough.

Jstas

I use waterproof wood glue in my enclosures and a finishing brad nailer to hold the whole box together. Using brads, you don't have to drill pilot holes and they will hold just fine until the glue dries. The glue is construction material and plain old waterproof wood glue is very strong. If wood glue isn't enough for you tastes, go for Liquid Nails. I promise you that box will never come apart at the seems. If you use something like Liquid Nails, make sure you let the box air out for a few days before mounting speakers or carpeting. The fumes from the adhesives and the caulking will damage the speaker surrounds and I have even seen it melt some cheap brands of nylon carpeting. It is very important to let teh box air out after caulking too. Two reasons, one teh caulking won't dry correctly and may pull away from the joints thereby totally negating the use of caulking and the fumes will dry out the surrounds on the speakers making them brittle and fragile.

If you use enough glue, you usually don't have to run a bead of silicone on the inside but i do anyway because it helps eliminate sharp edges inside the enclosure which can cause standing waves which...well, I'm guessing everyone gets the hint by now.

As far as material goes, MDF, like Thom said, will pull apart. Also if you punch too many holes into it, it starts to crumble. Using the same holes over and over again makes the holes a bit wider each time so they don't grip the screws as well. Granted, you get the same problems with any wood based material but the plywoods are much better at retaining strutural stregth than fiberboards are. They also don't disintegrate when they get wet.

As far as birch plywood goes, it's quite expensive. You can usually get something with just a birch veneer on the finished side but made up of assorted hard woods and softwoods depending on your application. However, one major thing about plywood, you need to use the highest grade possible. Construction and sheathing grades are no good. You need a finishing grade for cabinetry or other furniture. It has no voids and it uses different glues between the layers. Much stronger than MDF or OSB or any other kind of fiber or chip board. No voids and even glue coverage between the layer means no vbibrations, resonaces or chances of leaking.

Also, if you do go a fiberglas route, cut your self some mounting rings for the speakers. **** a sub directly into fiberglas will crack it.

PoweredByDodge

hmmm.. really?

are there difft kinds of liquid nails? because i tried that on my first box and it just went straight to hell... but maybe i used like "indoor" instaed of "outdoor" or some other variation ya know...

i'm really surprised about the brad nailer glue vs/ screw thing... but i'll try it... i've gotta build a box for a 12 sooner or later... i've got enough scrap material to make two.... give em a week.. then i'll take the hammer to em... i know... its retarded... but i'm really curious about this.. REALLY curious... u'll find as much screw / gasket / caulk ppl as nail / glue ppl... and its always a semi heated debate...

hopefuly.. i'll find the glue is just as strong ... god knows it woudl be an easier way to build a box.

Jstas

Caulking should be common to any box. They don't work unsealed.

Yes there are different types of Liquid Nails. There is a reason they call
it Liquid Nails. It's tough stuff. I saw a demonstration with it on This Old
House where a guy covered a 4x8 sheet of plywood with a random bead of
Liquid Nails and stuck it to the side of a mock house in a wind tunnel. They
spun the fan up to 160 MPH winds before the sheet started to come loose. It
blew off at 174 mph winds. Using it for cabinet construction is not the best
application though. It's a construction adhesive and should be used that
way. Liquid Nails will not work well with MDF. Since MDF is made of
compressed particles, Liquid Nails will grab on to and hold the compressed
particles rather than the whole board. Liquid Nails will work on solid
surface materials like plywood or concrete or masonry or metal very well.

Normal wood glue is strong enough to hold the box together. The waterproof
glue won't come apart because of moisture or excessive humidity or anything.
In an automotive application, waterproofing is a good thing. Water can get
in anywhere and when the AC is running, moisture can condense on cool metal
parts and run down into the area where the box is situated.

Nails will work just as well as screws. How many houses are held together
with nails? The only problem with nails is, the fatter they get, the more
risk you run of splitting the material. Brads are thin and light. They are
plenty strong for holding a box together. Since a speaker box is not a
stressed construction in the sense that it doesn't bare a load, brads work
just fine.

If you are going to use a brad nailer, make sure you use one with some power
behind it. The faster the brad or nail goes in the less chance you have of
splitting the wood or MDF or what have you.

I don't understand how it can so heated though. Any carpenter will trell you
that for whatever material you use, be it MDF, plywood, particle board or
even solid wood, glue and nails will hold just as well as screws. Both nails
and screws work on the same principles. They are held in by friction. Screws
act upon that friction in a different manner than nails. Most people see the
threads of screws as braces or cleats that inhibit the screw from pulling
out of the hole. But that is not how they work. They use a simple inclined
plane to spread the frictional force out. The force is applied in a radial
pattern. A nail uses friction in a linear manner. That is why it has to be
driven. It makes it's own hole and squeezes between the fibers of the wood.
The wood's natural elasticity creates the pressure against the nail that
cause the friction. MDF doesn't have those fibers which is why nails are a
poor solution for MDF why glue should always be used when constructing
things with MDF.

However, most people who preach nails and glue probably have a more than
average skill level and experience level in carpentry and sound construction
techniques. I have have assembled quite a few boxes and my first one was
with MDF. It was put together nicely and very cleanly. However, I was
extremely dissatified with the results. My second enclosure was done with
plywood after my father yelled at me for using such crap like MDF. That
second enclosure is standing on its side in my basement waiting for another
set of 8 inch subs. The box outlasted the speakers.

If anybody has a Ranger and wants 2 8 inch subs behind thier seat, let me
know. The enclosure is yours for 150 bucks. It has 2 ported enclosures
joined by a common back panel. In the center there is a perfect and ample
space for an amplifier, I designed it that way. It is a perfect fit for an
83-87 Ford Ranger standard cab. It sould work in an 89-92 with little
fanfare and it may be a squeeze for a 93 and newer Ranger. It has 2 L
brackets to screw it down to the cab floor so it doesn't grow legs on you
and it has a vented cover panel for the amplifier so it is virtually
invisible from the outside of the vehicle. There is a switch installed for
turning off the sub amp. It is uncarpeted but very incognito. I will clean
it up and replace the nasty old ports with new ports. It is perfectly
capable of being carpeted. The construction is 3/4 inch plywood with 1/2
inch thick plywood dattoed into the 3/4" plywood sides for the speaker face
and lower panel. There is some internal bracing and the thinner wood was
used to save space. The boxes were constructed to an internal volume of .62
cubic feet. It's been held together for 9 years with the original nails and
waterproof wood glue. The caulking could probably stand to be replaced too.
It's very strong and I have used it for a foot stool too.

PoweredByDodge

i think that's the whole issue here (mdf vs plywood)...

when you said most ppl who preach brads/nails and glue/LN are experienced carpenters (or at least to the box building end of it)... they're using better materials.

far as the debate i was talking about --- i've had "pro shop" guys tell me that MDF --- even particle board (agast!) --- is "fine" with liquid nails and 1.5" staples. and that's the type of box they wanted to build for me or whoever i was bumming at the shop with at the time. i've never seen anything good happen with LN and particle board.. i dont think anyone has.

what you said about LN not working on MDF is probably why the first time i tried to use the stuff it all of fell apart on me. same goes for the nails... i tried to do a "bracing" deal in a car where i basically just needed two small supports for a box on either end... tried to nail mdf together with pretty thin finishing nails... i hadn't even noticed the wood splitting until with only a moderate amount of pressure it came apart and i see like the nail hole with two "slits" where the board has split on either side.

i've yet to attempt a box with cabinet grade plywood ... i was going to do my two boxes for my maxes with baltic birch 3/4 inch plywood but then, as i said, i saw the price tag.

but in retrospect and in light of what i've soaked up here, the next time i take a crack at it... i'll probably hunt down some of htat cab. gd. plywood.

i know at least one thing for a fact -- i doubt my subwoofer boxes will outlast my subwoofers... once i unmount them (hopefully not for a couple years) i'll end up having to scrap the boxes.

Jstas

Just to clear someting up for you here, birch plywood would be a furniture or cabinet grade plywood. Most birch I have seen has a finished side to it. However, birch plywood can be quite expensive. There are other plywood types that will work just as well with a less expensive wood and veneer layer. Type meaning the type of wood used in the plywood. The grades are different. You can see a physical difference between the grades. Lower grades look like crap and are usually warped. The higher grades look like they were cut with lasers. Nice sharp, clean edges with a very uniform look. Usually one side has a soft, un-knotted finish to it. When you get into lower grades, they have very large knots in them and that is what causes teh voids and rattling and actually weakens the plywood. When the sheets are being sliced to make the plywood, the knots will pop out. They don't always get filled in and even if they do, they don't always get filled in properly and the filling rattles and such.

Usually, I goto Home Depot or Lowes and pickup a 4x8 sheet for about 60-70 bucks.

The reason I mention carpenters is because they have training and experience and will tell you what the best material is to make something good and strong like a subwoofer cabinet. Most will tell you that the best stuff is plywood or solid wood but to do it on the cheap, MDF and screws will work just fine. Some won't even talk to you if you mention MDF. They consider it a scourge and not real constructing material because of it's propensity to fall apart. One guy won't even use MDF for a peg board. He has a jig he uses to cut peg boards out of 1/4 inch thick plywood.