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PV Audio
11-25-2006, 01:22 AM
Even after three years, I still see loads of posts asking what to get to build one's first box. So, just to see if I can't help some people out and to cut down on the threads made in this subforum, I'll make another one of my writeups on how to get started with box building, materials, tips 'n tricks, etc. So, without further ado, here we go.

The main thing to understand about box building is that it is indeed both an art, but also very simple. That might not make much sense, so let me elaborate. A perfectly constructed speaker enclosure will make you sit back and say wow, I can't believe I just made that. More importantly, the sound will be astonishing. The best part of all is that it is not difficult to achieve good results. Much like everything else in life, it just takes practice. If you don't make some form of mistake on your first go, then you either aren't trying hard enough or were born knowing all such as Ramos ( :p: ). Anyway, onto the important part: building materials.

The things that you WILL need are as follows:

Wood (more on that later)
Glue (more on that later as well)
Screws, nails, or other fasteners (optional, but highly recommended regardless)
Clamps (look to own various sizes, starting with 24" and going up to 50" if you can)
Drill, nailgun, or equivalent (for drills, torque is ESSENTIAL. for nailguns, just don't be cheap)
Saw and/or router (saw is necessary, router is technically optional but once you use one for your circles, you'll wonder how you cut without it)

1. The wood that you use is extremely important. Do not go by what the wood costs, go by what it does. Your best bet is 3/4" MDF. While the .5" is cheaper, unless you want to see the box itself moving more than the sub, I don't recommend it. If they have it, you can generally stay away from 1" mdf as well since if you're reading this thread for tips, you usually aren't going to be building a serious enclosure just yet. Particleboard is usually something to stay away for because it's weak, not very dense and is just plain cheap and awful to cut and work with. Plywood is good, however, I do not mean the plywood that you made your skateboard ramp out of. I'm talking about multiple ply shelving type oak or birch plywood. Usually costs around 40+ dollars.

2. Glue is an essential part of any enclosure, and anyone who tells you otherwise should either be reading this thread or is mass producing boxes where their customers don't give a **** about how long their enclosure lasts. There is always controversy surrounding the various types of glues, so all that I am going to recommend is wood glue. It's all I use, and it is the best for, wouldn't you know it, WOOD! Wood glue creates a chemical bond between the two pieces of wood which will actually be stronger than the wood itself. This means that the wood of the box will snap before the properly set glue joint will. Gorilla glue, polyurethane glues and the like create strong physical, but nothing as strong as wood glue will. However, wood glue only bonds wood strongly. Otherwise, it's about as useful as elmer's school glue for other things.

3. I won't discuss nailguns here because if you're using one, then you already know what you're doing. However, screws are important. They are indeed unnecessary because in a properly glued box, the screws add zero structural support. The reason you use screws is the same reason you use clamps. To have a proper glue bond, you MUST clamp the joint tightly together. Otherwise, the wood is just stuck together instead of bound. The point of a screw is to hold that tightly clamped joint in place while it dries so that you can continue on with the rest of the box. I have built speakers with no screws only because it's a pain to have to fill in the holes for paint. Otherwise, I recommend drywall or decking screws only for box buidling. Wood screws do work, but they're so much more expensive for a little box that they're essentially worthless to us box builders.

4. Clamps are pretty self explanatory. As I mentioned above, they are imperative to have a proper glue bond, and you should have various sizes for different box sizes. 'Nuff said.

5. What you happen to use to drill and screw the box together is less vital than the rest of what's been mentioned. Make sure it has good torque to firmly set the screws, and enough power to countersink the screws by itself (having the screwheads lay flush with the work surface). Otherwise, you'll need a countersinking bit which can be picked up at any hardware store.

6. Get a good saw the FIRST time. Take it from me with this little story. I purchased an ebay jigsaw around 3 years ago and started making boxes. I thought I was the ****. Little did I know, my saw literally was a piece of ****. I had just changed the blade and firmly tightened it and as soon as I started cutting, the moving assembly came apart and the blade managed to put a nice cut into my foot. Don't cheap out, invest in a good brand (I personally own a hitachi circular and table saw, a bosch jigsaw and a bosch router and couldn't be happier), and don't be like me and spend loads of money multiple times by slowly increasing your purchasing power. Save your money and buy the good stuff. Routers are great for circles, but if you can't afford one just yet, then a jigsaw will do.


Okay, you've got your stuff, and are ready to build. Some tips:

1.Glue evenly, and thoroughly. When you clamp down your joint, if glue doesn't come out on both sides, then you didn't use enough. Unclamp, and add more.

2. Measure your cuts MULTIPLE times before cutting. There's nothing like measuring out a 4x8 of MDF only to have it be completely off by 1/8". Worst feeling ever, and I know because I've done it. Measure folks, measure!

3. Please, PLEASE use a mask when cutting and sanding. You do not want MDF dust to get into your lungs just like you wouldn't walk into a paint booth and start spraying without a mask either. Don't be stupid like me and get yourself a chronic cough, wear a mask.

4.Take your time. There's no rush to get the box done, and when you do rush, you'll just wind up spending more time because you screwed something up.

5. It sounds stupid, but have fun. Building a box to "get it done" or make money is no way to enjoy the hobby. If you aren't enjoying yourself in the least, even when you screw something up, then you should either reevaluate why you're building or find a new hobby.


Okay y'all, that's it for now. Additions and/or revisions are always welcome.

-Dave

iamamp3pimp
11-25-2006, 01:23 AM
good ****

i like this espically


1.Glue evenly, and thoroughly. When you clamp down your joint, it glue doesn't come out on both sides, then you didn't use enough. Unclamp, and add more.



i always run my finger down when i lay a bead just to make sure it coovers the entire surface of the bond.

baseballer1100
11-25-2006, 02:11 AM
Great post!

Casper80
11-25-2006, 02:34 AM
great post.

disreagrad the cost of wood, will the birch ply wood box will sound a lot better than mdf box or our ears will not even notice the difference?

bangandow
11-25-2006, 03:42 AM
Is English your first language?

Casper80
11-25-2006, 05:23 AM
Is English your first language?


if you are reffering that to me. then no. english is my third language.

thank you.

thatkidbob
11-25-2006, 05:29 AM
if you are reffering that to me. then no. english is my third language.

thank you.
i like this guy already lol...

to answer your question: no, the sound will not be effected at all... the main reasons to use birch ply is because its lighter than MDF, as well as being easier to cut and less harmful to your cutting tools. The other reason is because it's MUCH sexier looking :D

Casper80
11-25-2006, 05:35 AM
thanks.

didn't know that birch ply is lighter than mdf. and in fact the birch ply does have a sexier look than the mdf. my car is already heavy as hell with a underpowered engine and my mdf box even though still not in the car yet but it's a workout just to move it in my living room to test fit the flase floor i'm doing.

this thread is great because it list all the steps clearly focus towards beginners to easy understand it.

coolahan
11-25-2006, 05:38 AM
Oh snaps I smell a sticky.

AlpineUser
11-25-2006, 09:55 AM
lol alot better than mine i tried to make i think it shoul be a sticky

80INCHES
11-25-2006, 09:59 AM
To Add To Was Pv Was Saying
Measure Twice Cut Once


80

Hydrastas
11-25-2006, 10:00 AM
that list of the things you will need is just plain stupid, i knew those requirements when i was in 1st grade.

iamamp3pimp
11-25-2006, 10:40 AM
that list of the things you will need is just plain stupid, i knew those requirements when i was in 1st grade.

good for you.

you see threars about it at least once a week.

contribute before flaming.

pimpedout97x
11-25-2006, 10:40 AM
that list of the things you will need is just plain stupid, i knew those requirements when i was in 1st grade.

dont come in and bash his post, its an educational post, and believe it or not, there are people that find that information useful.

want me to recap your "little metal thing in the fuse holder cuase i didnt wanna put a fuse in then it smelt like burning plastic but i left it then it broke" thread? thats kinda "just plain stupid" and i bet i would have "known that in 1st grade"

rocky 59
11-25-2006, 10:50 AM
pv audio i gots a question for ya.

1. dove tailing?? is it worth it? seems like it would make a better "bond" between wood and glue.

saywhat?
11-25-2006, 11:02 AM
ANYTHING dovetail is going to be 10x stronger than a flat joint. That and groove jointing own .

acold7dusta
11-25-2006, 11:06 AM
good post man

whats the difference between the different titebond wood glues? i've been using titebond III but everyone one here has been using titebond II. any reason? i know III is a tad bit more money, and it seemed to do the trick just fine

i hope this will eliminate all the threads created every week on how to build a box

:sticky:

acold7dusta
11-25-2006, 11:07 AM
ANYTHING dovetail is going to be 10x stronger than a flat joint. That and groove jointing own .

what is dovetailing?

saywhat?
11-25-2006, 11:11 AM
a technique of "interlocking" pieces of wood. Usually found on furniture that costs more than life itself.

PRIVATEpastry
11-25-2006, 11:12 AM
dont come in and bash his post, its an educational post, and believe it or not, there are people that find that information useful.

want me to recap your "little metal thing in the fuse holder cuase i didnt wanna put a fuse in then it smelt like burning plastic but i left it then it broke" thread? thats kinda "just plain stupid" and i bet i would have "known that in 1st grade"
Kilt that man. :blackeye:

pimpedout97x
11-25-2006, 11:24 AM
lol i was waiting on someone to comment on my post :laugh:

traksta15
11-25-2006, 11:35 AM
dont come in and bash his post, its an educational post, and believe it or not, there are people that find that information useful.

want me to recap your "little metal thing in the fuse holder cuase i didnt wanna put a fuse in then it smelt like burning plastic but i left it then it broke" thread? thats kinda "just plain stupid" and i bet i would have "known that in 1st grade"

ZING!!!!:up2somet:

IonSQL
11-25-2006, 11:38 AM
Great thread PV! Very informative..... Definitely should be a sticky :D

As far as the glue goes, pretty well ANY wood glue is going to be better than the alternatives (i.e. Gorilla Glue). I've heard that good 'ole Elmers wood glue is pretty good, but I use Titebond II. Titebond II cures a little faster than III, but III's benefit is that it's supposed to be "more" waterproof... but if your box is requiring being waterproofed, you've got WAY bigger problems than trying to decide which glue to use :D

rocky 59
11-25-2006, 11:39 AM
a technique of "interlocking" pieces of wood. Usually found on furniture that costs more than life itself.

i have a dovetailing machine i bought for 69.99 this weekend lol. i was using it for cabinets and such.

my dad sells funiture and he made a comment about it so im thinking of giving it a shot

baseballer1100
11-25-2006, 11:43 AM
Dovetailing would be sweet.

rocky 59
11-25-2006, 11:58 AM
im gonna go head build a dove tailed box and see how it does.

baseballer1100
11-25-2006, 12:01 PM
Do it!!!

acold7dusta
11-25-2006, 12:04 PM
sounds like a real good idea, but dont forget to take in acount the 3/8" or w/e you'd be choppin off

jeepintn
11-25-2006, 12:06 PM
a good tip for beginners that they will often times overlook, when u lay your cut lines out on the wood, dont forget to cut the outside edge of the line, if you cut directly on top of the line, you will be a little off, a blade is usually about an 1/8" and when u take that off all the sides of your cuts, it will make your enclosure smaller.

rocky 59
11-25-2006, 12:06 PM
well the 3/8'' isnt "leaving" just getting a shave. plus the grove you would have to make in the opposite piece would make up for inchs lost

rocky 59
11-25-2006, 12:08 PM
another tip-

though it is advanced if you router your box MAKE SURE THE BRAD NAILS/SCREWS ARE NOT ANYWERE NEAR WERE YOUR ROUTING. this will cost you a bit, a box, and maybe a finger.

iamamp3pimp
11-25-2006, 12:11 PM
i would like to try dovetailing. where would i find a dovwtail machine?

acold7dusta
11-25-2006, 12:11 PM
i know, but if your aiming for say a 2 cubic foot box, that 3/8 all around will effect airspace. not by that much, but if you made the front piece just big enough to house a 15" sub, that 3/8" on top and bottom will add up to 3/4" and the sub may not fit in. just some insight, because it has happened before

rocky 59
11-25-2006, 12:13 PM
mp3pimp i got mine at harbor frieght tools. its not the best machine but hey for 69 bucks compared to 150 bucks i'll take a shot lol

CBFryman2
11-25-2006, 12:14 PM
Gorrila Glue and Polyester Resin will both seap into the wood making the bond a wood/glue mixture. Basically fuseing the two together. The top layre of MDF will tare deeper when you brake thoes bonds than with wood glue. Wood glue uses enzymes to brake down and then bond togather the wood particles on the surface of the wood. It is plenty strong, but I just though I would let you know that Polyester resin and Gorrilla Glue work excelent but are both extremely messy.

ballstothewall
11-25-2006, 12:30 PM
pv audio i gots a question for ya.

1. dove tailing?? is it worth it? seems like it would make a better "bond" between wood and glue.

Yes, a dovetailed joint is stronger, but at that point you are WAY past the point of dimishing returns. It isn't really worth it, and all that would change in the box is the amount of effort you have into it.

PV Audio
11-25-2006, 12:36 PM
pv audio i gots a question for ya.

1. dove tailing?? is it worth it? seems like it would make a better "bond" between wood and glue.
No, it isn't worth it for box building. Specialty joints aren't really worth the time, but for speaker building, then yes, it's a good idea. If you want a better bond, a miter joint would work while not being too ridiculous.

saywhat?
11-25-2006, 12:41 PM
when you say miter.....what do you mean? I would like to see someone do a tongue/groove setup, wouldnt be too hard...

PV Audio
11-25-2006, 12:41 PM
good post man

whats the difference between the different titebond wood glues? i've been using titebond III but everyone one here has been using titebond II. any reason? i know III is a tad bit more money, and it seemed to do the trick just fine

i hope this will eliminate all the threads created every week on how to build a box

:sticky:
There really isn't TOO much difference. My only deciding criteria is the ease of use for each glue. My personal favorites are Titebond II (buy it by the jug) and Elmer's ProBond. T3 is technically stronger, but it takes a decade to dry, and you won't notice the difference unless you're trying to make your enclosure explode. T1 is a good glue for smaller applications. It tends to flake easier, but dries extremely fast. I use T1 on sealed and small ported enclosures where the working time doesn't need to be very high in the first place. ProBond is just about the same as T2, but it sands SOO much easier. Whereas T2 just kinda peels away, probond literally sands off in a powder. I use it on speakers mainly, because it's harder to find around here. T2 is your overall best bet.

PV Audio
11-25-2006, 12:44 PM
when you say miter.....what do you mean? I would like to see someone do a tongue/groove setup, wouldnt be too hard...
A miter joint is done by cutting the edges of the panels at 45 degree angles. That way, you have over 1/5 more surface area (think 45-45-90 triangle) to glue. There also isn't a way for the internal pressure to blow one of the joints apart easily because if you don't set the joint properly, it won't look right. It's an easy way to get more strength, I use it only exclusively in home audio subs though.

PV Audio
11-25-2006, 12:44 PM
when you say miter.....what do you mean? I would like to see someone do a tongue/groove setup, wouldnt be too hard...
Oh, and IIRC, either Jim or Ramos did one some time ago, can't remember.

pimpedout97x
11-25-2006, 01:10 PM
PV check ur PMs lol

CBFryman2
11-25-2006, 01:13 PM
No, it isn't worth it for box building. Specialty joints aren't really worth the time, but for speaker building, then yes, it's a good idea. If you want a better bond, a miter joint would work while not being too ridiculous.

I always use miter joints on boxes I am going to paint. Not because they are stronger but because it makes finishing the box a LOT easier. Miters are easy if you take your time and think about what you are doing.

mtdewelf
11-25-2006, 01:31 PM
Miters are easy if you take your time and think about what you are doing.
I use to cut the miters when finishing up tiling on roofs, takes some getting use to, but they can look oh so **** when done right, never even thought about that with my box though :blackeye:

rocky 59
11-25-2006, 01:32 PM
pics of miters please :D

PV Audio
11-25-2006, 02:02 PM
Gorrila Glue and Polyester Resin will both seap into the wood making the bond a wood/glue mixture. Basically fuseing the two together. The top layre of MDF will tare deeper when you brake thoes bonds than with wood glue. Wood glue uses enzymes to brake down and then bond togather the wood particles on the surface of the wood. It is plenty strong, but I just though I would let you know that Polyester resin and Gorrilla Glue work excelent but are both extremely messy.
No, I'm fully aware that gorilla glue works well, but it's a classic jack of all trades, but a master of none. It expands annoyingly and gets everywhere. If you have a proper cut joint, or even some silicone, then you shouldn't need expanding glue. Also, wood glue is chemically superior for wood only, and it's about over 1/2 as expensive.

PV Audio
11-25-2006, 02:14 PM
great post.

disreagrad the cost of wood, will the birch ply wood box will sound a lot better than mdf box or our ears will not even notice the difference?
No, in fact, it may sound different, but not better. Plywood is lighter than MDF, and is less dense. It tends to resonate more freely than MDF does, which is why most plywood boxes are braced more than an equivalent MDF enclosure. I don't recommend it for sub boxes. Speakers and/or sub enclosures that you are going to stain are good candidates. Otherwise, there really isn't any point. It's harder to cut (it can chip easily), but it routers like butter. If you think cutting circles in MDF is easy, just try plywood. It's like running your finger through sand.

mtdewelf
11-25-2006, 02:25 PM
great, and hopfully i'll be using your tips, on your design this coming week sometime.

PV Audio
11-25-2006, 02:27 PM
great, and hopfully i'll be using your tips, on your design this coming week sometime.
Me? I don't recall making a design for you, at least I don't see it in my files :crap:

PV Audio
11-25-2006, 02:28 PM
Hahaha, disregard previous post, we were only discussing it.

rocky 59
11-25-2006, 02:31 PM
pv how much for a box/amp rack design its a pretty complicated idea lol

PV Audio
11-25-2006, 02:37 PM
I'd have to see what you're thinking, but that's for a PM, not this thread!

Btw, I hope you all know that a mod will never sticky a pv audio thread.

saywhat?
11-25-2006, 02:40 PM
A miter joint is done by cutting the edges of the panels at 45 degree angles. That way, you have over 1/5 more surface area (think 45-45-90 triangle) to glue. There also isn't a way for the internal pressure to blow one of the joints apart easily because if you don't set the joint properly, it won't look right. It's an easy way to get more strength, I use it only exclusively in home audio subs though.

thats what i thought, but my circular saw cuts angles janky, so i try not to use them.

snoopdan
11-25-2006, 02:51 PM
would anyone be interested in me doing a SPL only box rules of engagement / tutorial for new builders? Ive got about 800 pics of boxes I have built for solely for SPL that I could contribute. But if I do it for a sticky, i'll put all the pictures on a server that will never change, so they'll always be posted. ......that is if anyones interested :hide:

saywhat?
11-25-2006, 02:58 PM
why give away the secrets of getting loud....no fun in someone tellin you.

iamamp3pimp
11-25-2006, 03:23 PM
lawl

iamamp3pimp
11-25-2006, 03:24 PM
its less secrets and more expierence.

iamamp3pimp
11-25-2006, 03:42 PM
someone should do a write up on staining wood...

mtdewelf
11-25-2006, 03:44 PM
you the birch master who got the eboner started, only seems fitting if you do ;)

iamamp3pimp
11-25-2006, 03:55 PM
i gotta change my title


lol

maybe ill go learn how to do it first, then ill do a write up

PV Audio
11-25-2006, 04:01 PM
you the birch master who got the eboner started, only seems fitting if you do ;)
With all due respect to pimp, he's been working with it recently, but I know of a few members here who have probably been staining for the past few years. It really isn't that difficult if you prepare and finish the surface correctly. If we could get Vikash to come back, he'd be a great guy to do it.

AlpineUser
11-25-2006, 04:20 PM
o and dont drill too close to the edge i learned that a few times lol

baseballer1100
11-25-2006, 07:19 PM
Alpineuser got any pics?

PV Audio
11-26-2006, 12:53 AM
Yes, I should have mentioned that. Try to keep at LEAST 2" away from any panel edge that is perpendicular to the one you're drilling into. Even with proper predrilling (which is a must, self tapping is worthless in speaker construction), you can still split the wood.

thatkidbob
11-26-2006, 01:07 AM
Alpineuser got any pics?
:laugh:

lilmaniac2
11-26-2006, 01:07 AM
PV u really need to check the loctite wood glue walmart sells

i did some stress tests and it walked all over gorilla glue and liquid nails and was a decent amount better than titebond II

creyc
11-26-2006, 02:10 AM
I spent at least an hour explaining to my buddy that, with the amount of clamping we had available, screws had no place in his box while it was being constructed. He wouldn't believe me when I said that glue will do ALL the structural support and insisted on the physical friction of some screws. :|

I so wanted to kick the screwed joints just to show how little a few screws did, but I was the one building the box. Some people just don't think...

coolahan
11-26-2006, 04:59 AM
PV u really need to check the loctite wood glue walmart sells

i did some stress tests and it walked all over gorilla glue and liquid nails and was a decent amount better than titebond II

is that a bullet hole in your driver side window in your sig? :eyebrow:







Lawl no but really you need to edit the original post and talk about predrilling etc.

thatkidbob
11-26-2006, 05:13 AM
My last 2 boxes were built with Elmer's probond... one was constructed with countersunk screws (2 per joint... 3 on longer joints), the other without countersunk screws (the screws were removed after the box dried.). Both are VERY sound structurally (though i'm adding a dowel to one of them, as its flexing a lil bit more than i think a box that small sound).

As long as its wood glue it doesn't matter what you use... its the wood thats going to break, not the joint...

PV Audio
11-26-2006, 12:32 PM
PV u really need to check the loctite wood glue walmart sells

i did some stress tests and it walked all over gorilla glue and liquid nails and was a decent amount better than titebond II
Hah, I remember you telling me about that before. See, here's the problem. I HATE Wal-Mart more than any other store in the world. I only go in there to buy their waffle weave microfiber towels to dry my car with, and get Armorall Tire foam for my wheel wells. That's it! Plus, they don't let me even buy glue because I'm under 18. Retarded.

AlpineUser
11-26-2006, 01:54 PM
Alpineuser got any pics?

no my dad forgot to bring home his works digi cam but this week i will make him bring it home

kicker06
11-26-2006, 03:22 PM
Dovetail>glue and screws.

PV Audio
11-26-2006, 05:12 PM
Except....95% of people don't have the time to dovetail a subwoofer box, let alone the extra labor it costs when the person buying it won't even realize that it's any different.

GrnEydDvl
11-26-2006, 07:14 PM
someone should do a write up on staining wood...

I would def be interested in a sticky / post on all types of finishes / coverings for enclosures.

GrnEydDvl
11-26-2006, 07:16 PM
Info on dovetailing.

http://en.wikipedia.org/wiki/Dovetail_joint

Lubega
11-26-2006, 09:45 PM
Thanks, man. I'm so glad I joined. I really appreciate good, solid information like this. :veryhapp:

baseballer1100
11-26-2006, 09:55 PM
What about a dado. That joint is sick....

Dynasty
11-26-2006, 10:08 PM
Can someone explain how to tune a box?

Do I need to buy a special tool/instrument in order to tune a box?

PV Audio
11-26-2006, 10:22 PM
To teach you box design, you're better off learning about the way boxes work, and then trying to design your own.

http://www.partsexpress.com/pe/pshowdetl.cfm?PartNumber=500-035&raid=29&rak=500-035

^^ Should help you extensively.

PV Audio
11-26-2006, 10:23 PM
Thanks, man. I'm so glad I joined. I really appreciate good, solid information like this. :veryhapp:
No problem, glad I could help :)

baseballer1100
11-26-2006, 10:31 PM
What about all the formulas for ports and stuff?

PV Audio
11-26-2006, 10:44 PM
Okay, here are the main box formulas, courtesy of DIYsubwoofers.org :

Vb = 20*Qts^3.3*Vas
Fb = (Vas/Vb)^0.31*Fs
F3 = (Vas/Vb)^0.44*Fs
dBpeak = 20*LOG(Qts*(Vas/Vb)^0.3/0.4)

Vb = net box volume (litres)
Fb = box resonant frequency (Hz)
F3 = -3dB frequency (Hz)
dBpeak = maximum peak or dip in system response
Vas = Equivalent air compliance (litres)
Qts = total Q of the driver at its resonant frequency
Fs = resonance frequency of the driver (Hz)
Dv = internal diameter of port (cm)

Lv = (23562.5*Dv^2*Np/(Fb^2*Vb))-(k*Dv)

Dv = port diameter (cm)
Fb = tuning frequency (Hz)
Vb = net volume (litres)
Lv = length of each port (cm)
Np = number of ports

k = end correction (normally 0.732)

The value for k, the end correction, can be fine-tuned by using the following values to derive the appropriate end correction figure for each end of the port, then adding them together

Flanged End: 0.425
Free End: 0.307

e.g. if both ends were flanged,
k = 0.425 + 0.425 = 0.850

if one flanged, one free,
k = 0.425 + 0.307 = 0.732

if both ends were free,
k = 0.307 + 0.307 = 0.614

Normally, k=0.732 is assumed

Slot Ports
If you wish to use a slot port, first determine the diameter of a round port that has the same cross-sectional area as the slot. The following equation can be used to do this:

Dv' = 2*((W*H)/pi)^0.5

where,

Dv' = diameter of equivalent round port
W = width of slot
H = height of slot

nVRuckus
11-26-2006, 10:47 PM
**** dave I havent seen you in awhile where you been hiding?

baseballer1100
11-26-2006, 10:50 PM
Okay, here are the main box formulas, courtesy of DIYsubwoofers.org :

Vb = 20*Qts^3.3*Vas
Fb = (Vas/Vb)^0.31*Fs
F3 = (Vas/Vb)^0.44*Fs
dBpeak = 20*LOG(Qts*(Vas/Vb)^0.3/0.4)

Vb = net box volume (litres)
Fb = box resonant frequency (Hz)
F3 = -3dB frequency (Hz)
dBpeak = maximum peak or dip in system response
Vas = Equivalent air compliance (litres)
Qts = total Q of the driver at its resonant frequency
Fs = resonance frequency of the driver (Hz)
Dv = internal diameter of port (cm)

Lv = (23562.5*Dv^2*Np/(Fb^2*Vb))-(k*Dv)

Dv = port diameter (cm)
Fb = tuning frequency (Hz)
Vb = net volume (litres)
Lv = length of each port (cm)
Np = number of ports

k = end correction (normally 0.732)

The value for k, the end correction, can be fine-tuned by using the following values to derive the appropriate end correction figure for each end of the port, then adding them together

Flanged End: 0.425
Free End: 0.307

e.g. if both ends were flanged,
k = 0.425 + 0.425 = 0.850

if one flanged, one free,
k = 0.425 + 0.307 = 0.732

if both ends were free,
k = 0.307 + 0.307 = 0.614

Normally, k=0.732 is assumed

Slot Ports
If you wish to use a slot port, first determine the diameter of a round port that has the same cross-sectional area as the slot. The following equation can be used to do this:

Dv' = 2*((W*H)/pi)^0.5

where,

Dv' = diameter of equivalent round port
W = width of slot
H = height of slot

Once you've calcula

Woot Woot.

Eugenics
11-26-2006, 10:59 PM
do you need more help building boxes lemans?

PV Audio
11-26-2006, 11:36 PM
**** dave I havent seen you in awhile where you been hiding?
I've been working on getting into college, and now that I'm in, and more importantly, where I want to be, I decided to come back. After having seen the state of the forum upon my return, ain't nothin changed :laugh:



do you need more help building boxes lemans?
:laugh: :laugh: I'm alright, I could use a little more caulk though.

baseballer1100
11-27-2006, 01:20 AM
Ok im confused on the calculations it says diameter wouldnt that be for a round port?

Eugenics
11-27-2006, 01:33 AM
:laugh: :laugh: I'm alright, I could use a little more caulk though.

caulk :yumyum:

PV Audio
11-27-2006, 08:37 AM
Ok im confused on the calculations it says diameter wouldnt that be for a round port?
You need to use the last formula to find out the equivalent surface area. Then, you just plug it back into the original equation :)

nVRuckus
11-27-2006, 04:28 PM
I've been working on getting into college, and now that I'm in, and more importantly, where I want to be, I decided to come back. After having seen the state of the forum upon my return, ain't nothin changed :laugh:



:laugh: :laugh: I'm alright, I could use a little more caulk though.

yeah Im pretty much over it at this point. :crap: I have no tollerance for anyone anymore.

nVRuckus
11-27-2006, 04:31 PM
You need to use the last formula to find out the equivalent surface area. Then, you just plug it back into the original equation :)

round port is radius x 2 x 3.14 x length / 1728 for displacement right?

PV Audio
11-27-2006, 04:56 PM
round port is radius x 2 x 3.14 x length / 1728 for displacement right?
Almost, radius^2 x 3.14 x length /1728.

CBFryman2
11-27-2006, 05:07 PM
No, I'm fully aware that gorilla glue works well, but it's a classic jack of all trades, but a master of none. It expands annoyingly and gets everywhere. If you have a proper cut joint, or even some silicone, then you shouldn't need expanding glue. Also, wood glue is chemically superior for wood only, and it's about over 1/2 as expensive.

You didnt read what I said very well. I wasnt saying Gorilla Glue makes a better box. Woodglue holds up fine. I said it soaks in deeper and makes a stronger bond, whether it be physical or chemical. I can bolt two pieces of metal togather or I can weld two pieces of metal togather. The welded one wont nessicarily be stronger. ;)

And trust me, when you brake apart a box made with gorilla glue or Resin the MDF will tear MUCH deeper than braking a box apart made with woodglue.

iamamp3pimp
11-27-2006, 05:12 PM
in the light of things, i prefer woodglue (tb 2) as it cleans up so quickly with a wet towel.

PV Audio
11-27-2006, 05:17 PM
And trust me, when you brake apart a box made with gorilla glue or Resin the MDF will tear MUCH deeper than braking a box apart made with woodglue.
I don't agree because I've done panel testing on basically every glue suitable for box building that is available at your local hardware store. Woodglue was years ahead of gorilla glue, the bond just kinda sheared off with the gorilla, while I snapped the panel glued with titebond. Liquid nails was worse than both of them, and the elmer's polyurethane glues were the worst of all.

IonSQL
11-27-2006, 05:19 PM
I would be interested to try the Loc-tite wood glue out... their spray glue *****, but maybe the wood glue is OK :D

CBFryman2
11-27-2006, 05:22 PM
I havent done controll testing but here is what I've seen.

WoodGlue: When the corners are broken the MDF brakes or a few layres tare off, depending on how it was broken apart.

Gorilla Glue: When the corners are broke apart the MDF usually brakes, if it tares if tares DEEP

Polyester Resin (what you use to fiberglass and coat the inside of boxes with): It tore DEEP like with Gorilla glue but the tares where uneven and blotchy, they alternated between the two sides of the joint.

Liquid Nails: A joke of an adheasive for box building at best. Just Screws where stronger by far.

Titebond II: MDF broke or tore the top few layres off, similar to woodglue.

Thoes are the only adheasives I've tried. Agian, woodglue works fine. I just saw that gorilla glue and polyester resin soaked in deeper and held stronger.

baseballer1100
11-27-2006, 05:36 PM
You need to use the last formula to find out the equivalent surface area. Then, you just plug it back into the original equation :)

Reading>Me
Thanks man.

nVRuckus
11-27-2006, 08:13 PM
Almost, radius^2 x 3.14 x length /1728.

yeah thats what i ment was working while typing

PV Audio
11-27-2006, 08:32 PM
How's the weather down in Miami?

saywhat?
11-27-2006, 08:35 PM
I havent done controll testing but here is what I've seen.

WoodGlue: When the corners are broken the MDF brakes or a few layres tare off, depending on how it was broken apart.

Gorilla Glue: When the corners are broke apart the MDF usually brakes, if it tares if tares DEEP

Polyester Resin (what you use to fiberglass and coat the inside of boxes with): It tore DEEP like with Gorilla glue but the tares where uneven and blotchy, they alternated between the two sides of the joint.

Liquid Nails: A joke of an adheasive for box building at best. Just Screws where stronger by far.

Titebond II: MDF broke or tore the top few layres off, similar to woodglue.

Thoes are the only adheasives I've tried. Agian, woodglue works fine. I just saw that gorilla glue and polyester resin soaked in deeper and held stronger.



titebond is wood glue :(

PV Audio
11-28-2006, 08:11 AM
Titebond 2 is a good glue, and probably the best value for money as well.

iamamp3pimp
11-28-2006, 10:50 AM
thats the reason that i buy it buy the gallon

PV Audio
11-28-2006, 04:43 PM
^^ Yo tambien, or, me anche for those fellow Italian speakers among us.

grillman6000
11-28-2006, 07:00 PM
what about for extra sealing, like plumbing caulk.......?

baseballer1100
11-28-2006, 07:06 PM
The silcone holds its own.

grillman6000
11-28-2006, 07:07 PM
The silcone holds its own.

ok....
cuz i usually mix up some concrete reely quick to line the corners....

iamamp3pimp
11-28-2006, 07:38 PM
wtf

PV Audio
11-28-2006, 07:40 PM
ok....
cuz i usually mix up some concrete reely quick to line the corners....
Wait, are you serious? :crap:

baseballer1100
11-29-2006, 06:18 PM
If he is serious thats nuts

DeViOuSoNe
11-29-2006, 06:23 PM
Is he?

coolahan
11-29-2006, 06:23 PM
haahahhahahahhahaa

PV Audio
11-29-2006, 11:51 PM
Grillman, please tell us if you're serious or not.

baseballer1100
11-29-2006, 11:52 PM
x2

baseballer1100
12-02-2006, 12:29 PM
Lets get this at the top.

PV Audio
12-02-2006, 03:59 PM
It would be nice if we could keep it at the top ;) :)

baseballer1100
12-02-2006, 04:06 PM
Im doing my best.

PV Audio
12-02-2006, 04:11 PM
Haha that wasn't directed towards you.

baseballer1100
12-02-2006, 04:12 PM
Yeah but i can still try cant i? lol

PV Audio
12-02-2006, 04:30 PM
:) My man.

baseballer1100
12-02-2006, 04:33 PM
Lol one question spl box....resin or silicone?

Immacomputer
12-02-2006, 05:50 PM
Resin. It will fill the pores of the MDF and will also offer less resistance for air movement.

PV Audio
12-02-2006, 06:44 PM
Not necessarily the case. I know of people who have actually lost dB's because they resined the inside of their box. It really depends on that specific box.

baseballer1100
12-02-2006, 07:00 PM
Yeha thanks man.

PV Audio
12-16-2006, 01:16 PM
I'm hitting this back up to the top after seeing some recent threads.

baseballer1100
12-16-2006, 04:55 PM
Its about **** time.

saywhat?
12-16-2006, 05:13 PM
bumpage.

kballa422
01-31-2007, 03:11 AM
thought this could use a bump

PV Audio
09-09-2007, 01:35 PM
I have to bump this after coming back and seeing these questions being asked still.

SQL4Life
12-22-2007, 08:23 PM
this is stupid question but what is that thing that goes on the box that has the wires from the amp connecting to the subwoofer? what is that called/where can i get it. and how would i mount it with the wood on the back of the box.

97gmcsierra
12-22-2007, 09:12 PM
I think you are talking about a terminal cup.

is this it? http://www.partsexpress.com/webpage.cfm?webpage_id=3&CAT_ID=48&ObjectGroup_ID=417 cheapest place to get them.


You just drill a hole according to the size of the cup with a hole saw and either secure it with screws or glue depending on which kind you get. :D

budget76
12-23-2007, 01:31 AM
or you don't use it, and drill two small holes for the sub wires to go through, and silicone them up. Looks MUCH cleaner IMO.

I will NEVER use terminals on a high(er) power system again. Had one fail and melt both wires. Got lucky it didn't destroy the amp/sub:eek:

SQL4Life
12-23-2007, 02:06 AM
or you don't use it, and drill two small holes for the sub wires to go through, and silicone them up. Looks MUCH cleaner IMO.

I will NEVER use terminals on a high(er) power system again. Had one fail and melt both wires. Got lucky it didn't destroy the amp/sub:eek:

sounds good, i did not think of it that way. thanks

THUMPPER
12-23-2007, 02:24 AM
I'm not a huge fan of terminal cups either...
I run the wire right thru the enclosure and have enough
of a lead to reach right to the amp...
no splices or connections between the amp and sub

PV Audio
12-23-2007, 02:28 AM
Meh I just use terminal cups.

emd2260
01-01-2008, 03:22 PM
which order does everyone glue their sides on, and how long should i wait for the next side?

miker
01-01-2008, 03:32 PM
If it's ported, and the port is on the left side, I star with the back wall, and right side wall... Nail/ screw, and glue them. Let them dry. Then I do the front wall, then the port, then the left outside wall.

hempy
01-01-2008, 03:59 PM
Had one fail and melt both wires. Got lucky it didn't destroy the amp/sub:eek:

:wow: How??

budget76
01-01-2008, 10:15 PM
:wow: How??


Must have worked it's way loose from the vibes of the sub:confused: Only thing I could figure, I know when I closed it up they were on 100%, and they were pointing up, so it's not like the wires were hanging pulling down on the connection. Glad I caught it when I did, I have pictures somewhere.

PV Audio
01-02-2008, 12:54 AM
which order does everyone glue their sides on, and how long should i wait for the next side?I use the same technique on every sub, ported or not. Start with the bottom piece, glue on a full length piece (for me, I have all panels screw into the front and rear baffles, so for me, it's the sides). Then, glue on one of your side/baffles that you haven't used yet. You should now have three different pieces glued together representing the XYZ axes if you look at their common corner. Then, I glue on the other side/baffle that is the same as the one you just did, just opposite the enclosure. This leaves you with the side of the box open, with four panels together. This way, I can build the port up and build the rest of the enclosure around it. If that doesn't make sense, just ask me and I'll show you with pics. :)

bjfish11
01-02-2008, 11:06 AM
I do every box the same as well. You can see the order I do it in most of my build logs...

Immacomputer
01-02-2008, 12:44 PM
I follow the same method as PV. I start with one side and then work around from there with the top piece going on last.

helotr3vor
09-17-2008, 05:33 PM
Im going to be starting my first box soon and i was just wondering if i need to put anything inside the port to reduce port noise and sound better or something like that. Or something around the whole inside of the box

miker
09-17-2008, 05:42 PM
putting something in the port would be bad?

Or do you mean something like resin? or angled corners?

helotr3vor
09-17-2008, 05:42 PM
putting something in the port would be bad?

Or do you mean something like resin? or angled corners?

Yeah thats what i mean haha

helotr3vor
09-18-2008, 04:12 AM
bump for my question

miker
09-18-2008, 05:06 PM
Well I don't think you will notice immense improvement, in theory it makes sense to me, but I don't know for a fact.

It will just take LOTS of extra time.

tsunam1
12-10-2008, 05:07 PM
Why isn't this one a sticky? There's no real info on basic construction of a box in the stickies right now

Flomaster
12-16-2008, 01:18 AM
Why isn't this one a sticky? There's no real info on basic construction of a box in the stickies right now

this should be a sticky right at the top.

who can get in contact with a mod to make this a sticky?


-=Jason=-

alvitae
12-16-2008, 01:23 AM
this should be a sticky right at the top.

who can get in contact with a mod to make this a sticky?


-=Jason=-

Go down to bottom of page and click on a mod and send them a message with a ling to this maybe. They will either A. Ignore it. B. Sticky it. Or C. Ban ya for buggin em. /shrug