New Box Design + calculations=aren't adding up.. PICS

[shizzzon 461]

that link is just like WinISD, it does NOT calculate what will happen in the car.

I'm sure this design you want is going in a car.

That link i sent you is accurate.

Also, i just got done reviewing the RE calculator, and to my surprise, it's WRONG!

WAY OFF. Well, not WAY off but not pleasing.

I did a test-

24" high

24" wide

24" deep

INTERNAL GROSS so far - 6.59 cuft.

Port height - 22.5"

Port width - 4"

Tuning 34.711 hz

OK, this is where everything starts to be wrong!

Total port length - 34" (that's wrong, it's suppose to be 32" because it's a slot but for Mike P.'s sake, we'll let it slide)

Port length 1 - 19.25" (that is correct)

Port length 2 - 8" (this is oh so wrong, not because it's suppose to be 32" total, oh no, it's wrong on it's OWN PART!) See for yourself-

Port length 1 - 19.25"

The width of the port is 4" so the internal corner is a 4" square.

When measuring a port's length, you measure down the center only.

So, when the port bends, you measure down the center, but how do you know the length?

Simple, Pythagorean Theorem.

What is half of a 4" square? 2" square.

a^2 + b^2 = c^2

So, 2^2 + 2^2 = c^2

So, 4 + 4 = c^2

c^2 = 2.83"

So we add that to 19.25" and get - 22.08"

Now remember, Even RE said we need 34" total length, i say we need 32" because it's true.

We only have 22.08" now and the L bend has already started, so according to RE, we need 12 more inches...

So why does RE say we only need 8" more? That's only 30.83"???

I do not know why but it is wrong. That would increase tuning.

Ok, you may think being off 2" raising tuning 1.5-2hz isn't that big of a deal... Well, that isn't the only thing that is wrong.

RE's calculated port displacement - 3060 cu inches internal...

WRONG!!!!!! wrong wrong wrong wrong wrong...

Do you know what it did? It did not calculate the total internal port displacement like it said it did...

It calculated internal port displacement as if the port NEVER bent.... that is 100% wrong.

And of course we are going by the picture, there is no 45 degree brace in the corner of that port so the whole 4" square is there.

The following is if the port never bent to prove how the calculator is wrong( again, in a minute)

Total INTERNAL port displacement of 22.5" x 4" x 32" = 2880 cu in (this is what it should be, but only if port never bent)

Total INTERNAL port displacement of 22.5" x 4" x 34" = 3060 cu in (this is what it says but it never even reach 34" long... pathetic.

Total INTERNAL port displacement of 22.5" x 4" x 30" = 2700 cu in (this is what it told you to make port but what ti calculated and what it told you length needs to be is different so it confused itself!)

Now, it then calculated that Port displacement, which is after wood thickness... is only 19 cu in more than internal displacement?? WHAT?!?!? this calculator is full of ignorance!

Now you will see what total displacement is after wood thickness-

22.5" x 4.75" x 32" = 3420 cu in (this is what displacement would be if port never bent)

22.5" x 4.75" x 34" = 3633 cu in (RE calculated 3079.8 but it never even achieved this length to begin with...)

22.5" x 4.75" x 30" = 3206 cu in (this is what it told you to make it but still didnt equal it's calculated 3079.8, wrong again....)

Now, you WILL SEE TRUE DISPLACEMENT-

When a port bends, it's displacement compared to a straight port changes obviously.

Compare the total displacements i just showed you above to see how wrong this program is once again.

22.5" x 4.75" x 32" with L bend as shown in pic - 3393.27 cu in

22.5" x 4.75" x 34" with L bend as shown in pic - 3607 cu in

22.5" x 4.75" x 30" with L bend as shown in pic - 3179.5 cu in

Numbers are in fact just slightly different then a straight port, less displacement even..

But small miscalculations consistently can and will eventually change something.

Oh and also, it doesn't account for sub displacement because hey, why would it? they obviously forgot to put that in there too.

So RE's calc is what Mythbusters would say BUSTED!

Since it can't do sub displacement... how are you gonna get a precise calculation? simple the reason way how you are gonna get a precise calculation on every other thing it's off on.

IT likes to use numbers in the .xxxxxxxxxxx value and still can't get simple math right.

I'm ranting but i'm glad i finally tested their calc.

[snb778 1]

You should ask him, how he calculates all this or what he uses and share it with us

I sent him a PM, he hasnt been on today yet but I dunno if he will just because he's bankin off of it... Could be usin a program, or he's just real experienced and knows how to use the equations. I have them all from when I went to school, but I just dont know how to apply them.. .sad ain't it!

[snb778 1]

that link is just like WinISD, it does NOT calculate what will happen in the car.

I'm sure this design you want is going in a car.

That link i sent you is accurate.

Also, i just got done reviewing the RE calculator, and to my surprise, it's WRONG!

WAY OFF. Well, not WAY off but not pleasing.

I did a test-

24" high

24" wide

24" deep

INTERNAL GROSS so far - 6.59 cuft.

Port height - 22.5"

Port width - 4"

Tuning 34.711 hz

OK, this is where everything starts to be wrong!

Total port length - 34" (that's wrong, it's suppose to be 32" because it's a slot but for Mike P.'s sake, we'll let it slide)

Port length 1 - 19.25" (that is correct)

Port length 2 - 8" (this is oh so wrong, not because it's suppose to be 32" total, oh no, it's wrong on it's OWN PART!) See for yourself-

Port length 1 - 19.25"

The width of the port is 4" so the internal corner is a 4" square.

When measuring a port's length, you measure down the center only.

So, when the port bends, you measure down the center, but how do you know the length?

Simple, Pythagorean Theorem.

What is half of a 4" square? 2" square.

a^2 + b^2 = c^2

So, 2^2 + 2^2 = c^2

So, 4 + 4 = c^2

c^2 = 2.83"

So we add that to 19.25" and get - 22.08"

Now remember, Even RE said we need 34" total length, i say we need 32" because it's true.

We only have 22.08" now and the L bend has already started, so according to RE, we need 12 more inches...

So why does RE say we only need 8" more? That's only 30.83"???

I do not know why but it is wrong. That would increase tuning.

Ok, you may think being off 2" raising tuning 1.5-2hz isn't that big of a deal... Well, that isn't the only thing that is wrong.

RE's calculated port displacement - 3060 cu inches internal...

WRONG!!!!!! wrong wrong wrong wrong wrong...

Do you know what it did? It did not calculate the total internal port displacement like it said it did...

It calculated internal port displacement as if the port NEVER bent.... that is 100% wrong.

And of course we are going by the picture, there is no 45 degree brace in the corner of that port so the whole 4" square is there.

The following is if the port never bent to prove how the calculator is wrong( again, in a minute)

Total INTERNAL port displacement of 22.5" x 4" x 32" = 2880 cu in (this is what it should be, but only if port never bent)

Total INTERNAL port displacement of 22.5" x 4" x 34" = 3060 cu in (this is what it says but it never even reach 34" long... pathetic.

Total INTERNAL port displacement of 22.5" x 4" x 30" = 2700 cu in (this is what it told you to make port but what ti calculated and what it told you length needs to be is different so it confused itself!)

Now, it then calculated that Port displacement, which is after wood thickness... is only 19 cu in more than internal displacement?? WHAT?!?!? this calculator is full of ignorance!

Now you will see what total displacement is after wood thickness-

22.5" x 4.75" x 32" = 3420 cu in (this is what displacement would be if port never bent)

22.5" x 4.75" x 34" = 3633 cu in (RE calculated 3079.8 but it never even achieved this length to begin with...)

22.5" x 4.75" x 30" = 3206 cu in (this is what it told you to make it but still didnt equal it's calculated 3079.8, wrong again....)

Now, you WILL SEE TRUE DISPLACEMENT-

When a port bends, it's displacement compared to a straight port changes obviously.

Compare the total displacements i just showed you above to see how wrong this program is once again.

22.5" x 4.75" x 32" with L bend as shown in pic - 3393.27 cu in

22.5" x 4.75" x 34" with L bend as shown in pic - 3607 cu in

22.5" x 4.75" x 30" with L bend as shown in pic - 3179.5 cu in

Numbers are in fact just slightly different then a straight port, less displacement even..

But small miscalculations consistently can and will eventually change something.

Oh and also, it doesn't account for sub displacement because hey, why would it? they obviously forgot to put that in there too.

So RE's calc is what Mythbusters would say BUSTED!

Since it can't do sub displacement... how are you gonna get a precise calculation? simple the reason way how you are gonna get a precise calculation on every other thing it's off on.

IT likes to use numbers in the .xxxxxxxxxxx value and still can't get simple math right.

I'm ranting but i'm glad i finally tested their calc.

Wow... i see where your numbers very, and understand it, but I'd NEVER be able to figure that out on my own. You seem to really understand everything in the construction of a box... any chance you design simple ported/sealed enclosures? Just for the future....i'd toss ya a few bucks.

Edit: I hope someone from RE reads this, or you should inform them because if they don't know its calc. wrong, im sure they would love to know/fix it.

Edited May 5, 2008 by snb778

[shizzzon 461]

i'd only do it if they promised to sell to SSA members RE's product line for the price they USED TO BE, before US amps decided to come in to play.

I've helped 418Fi quite a bit on boxes, he still has my Steak waitin for me in Florida.

HEY 418FI!!!

DON'T FORGET, hehe

I could help you built it yourself.

The LEAST required tools to do it right is the following-

Skillsaw or table saw

jigsaw

Drill

screw driver

That's all you need for minimum.

IF you got all of that, then i can help u build your own box for probably under $45, if not, just another sheet of MDF which would put your total cost around $60.

[snb778 1]

i'd only do it if they promised to sell to SSA members RE's product line for the price they USED TO BE, before US amps decided to come in to play.

I've helped 418Fi quite a bit on boxes, he still has my Steak waitin for me in Florida.

HEY 418FI!!!

DON'T FORGET, hehe

I could help you built it yourself.

The LEAST required tools to do it right is the following-

Skillsaw or table saw

jigsaw

Drill

screw driver

That's all you need for minimum.

IF you got all of that, then i can help u build your own box for probably under $45, if not, just another sheet of MDF which would put your total cost around $60.

I would only need a design from you.. I gotta start to learn how to build these things myself... Gosh I've probably spend near a $1000 having people build em for me because i'm to lazy/afraid to try myself and F-it up... Ex: I built a box for a 15"XXX... despite all the Hype, I don't think i'd ever try it again because I was completely unimpressed, but odds are it was the box

P.S. Thank you all for the help..... MUCH quicker and more helpful than "Another Forum" im a member of, with the exception of a few people.

Edited May 5, 2008 by snb778

[shizzzon 461]

hey, u never told me if u got those tools or not?

IF you do, i'll walk you through the whole process.

I'll even get down to the itty gritty on how to apply the glue because hey, if i don't, you won't be impressed with the box.

IT's not hard, trust me. I am not a wood worker, a lot of people aren't that build boxes but it's easy, well it gets easier and easier depending on the tools you have but i gotta tell ya, if you got all those tools, to make life 8x easier,

Get a couple saw horses and about 6 clamps. That's all you need besides all the dimensions you need to cut.

[snb778 1]

hey, u never told me if u got those tools or not?

IF you do, i'll walk you through the whole process.

I'll even get down to the itty gritty on how to apply the glue because hey, if i don't, you won't be impressed with the box.

IT's not hard, trust me. I am not a wood worker, a lot of people aren't that build boxes but it's easy, well it gets easier and easier depending on the tools you have but i gotta tell ya, if you got all those tools, to make life 8x easier,

Get a couple saw horses and about 6 clamps. That's all you need besides all the dimensions you need to cut.

I appreciate the offer. My mom works for a local High School, so she said the Woods teacher would cut the pieces for me so all I gotta do it put the pieces together. I have wood glue, dry wall screws, clamps, maybe some left over resin. Probably have some caulk layin around....

I've been tryin to ask people if you can use Bondo in the corners and edges instead of caulk...?? any idea.

Do you have AIM? that'd be a lot easier while I was doin the build if I need some assistance.... Only thing I see havin trouble doin is lining up the 45Deg. in the opposite port corner, and gettin the screws in the center...not sure how to line that up properly.

[amatt85 0]

not sure if your question got answered b/c i didnt feel like goin thru 3 pages, but from your original pic, i get a net volume of 6.66cubes with the actual length of wood for the port 10.5" for a tuning of about 38hz...(the actual port length however is 14" b/c of end correction and the thickness of the baffle)

[shizzzon 461]

it got answered.. hehe, you should go through and read page 2, all of it.

After that, you can see any more talk about numbers is an instant headache, hehe.

I've never used bondo for a box before. I've heard people have but know nothing of it's results.

What i do as a sealer is this-

I use titebond II or III to actually glue pieces together.

Then when everything is put together, i run a bead of liquid nails over every joining corner of the box from one end to the other.

I let it dry for 24hrs. or if you are in a hurry, let it dry for bout an 1hr i think is long enough.

Next, i go back over it with Silicone II sealant and let it dry.

Make sure each time you go over it with this stuff, stuff that comes out of the caulking tubes for sealing purposes to use your finger to actually spread it along on down the line.

Meaning, run a bead from end to end then go back with your finger and run it along the bead from end to end, this will get the stuff filled into the corner and small gaps that you can't see.

Yes it's messy but the trick is this-

IF you apply both liquid nails and silicone in the same day, something inside the silicone eats the liquid nails right off your finger so instead of pickin at it for a day or two, as soon as a gob full of silicone is caked on the same finger(s) as dryed liquid nails is, rub the silicone around your finger(s) for a few seconds then grab a paper towel and with slight force wrap it around your finger(s) and pull everything off your finger(s). You will see that a lot of liquid nails comes off with it and when you go back to pull more off, your finger(s) are a lot smoother and the liquid nails practically just comes off with a touch.

Pretty neat really. Beats scrubbing forever.

[snb778 1]

it got answered.. hehe, you should go through and read page 2, all of it.

After that, you can see any more talk about numbers is an instant headache, hehe.

I've never used bondo for a box before. I've heard people have but know nothing of it's results.

What i do as a sealer is this-

I use titebond II or III to actually glue pieces together.

Then when everything is put together, i run a bead of liquid nails over every joining corner of the box from one end to the other.

I let it dry for 24hrs. or if you are in a hurry, let it dry for bout an 1hr i think is long enough.

Next, i go back over it with Silicone II sealant and let it dry.

Make sure each time you go over it with this stuff, stuff that comes out of the caulking tubes for sealing purposes to use your finger to actually spread it along on down the line.

Meaning, run a bead from end to end then go back with your finger and run it along the bead from end to end, this will get the stuff filled into the corner and small gaps that you can't see.

Yes it's messy but the trick is this-

IF you apply both liquid nails and silicone in the same day, something inside the silicone eats the liquid nails right off your finger so instead of pickin at it for a day or two, as soon as a gob full of silicone is caked on the same finger(s) as dryed liquid nails is, rub the silicone around your finger(s) for a few seconds then grab a paper towel and with slight force wrap it around your finger(s) and pull everything off your finger(s). You will see that a lot of liquid nails comes off with it and when you go back to pull more off, your finger(s) are a lot smoother and the liquid nails practically just comes off with a touch.

Pretty neat really. Beats scrubbing forever.

so you're sayin use wood glue to put it together, and use tightbond 2 or 3 for the seams and edges instead of a caulk?

[shizzzon 461]

Use titebond to put the pieces together, then use Liquid Nails caulking as a bonding sealer for the inside then after it dries run Silicone II over that.

You don't "have to" but that's what i do.

Edited May 6, 2008 by shizzzon

[snb778 1]

Use titebond to put the pieces together, then use Liquid Nails caulking as a bonding sealer for the inside then after it dries run Silicone II over that.

You don't "have to" but that's what i do.

alright if all those aren't to pricey I will give em a try... I dunno if I'll have to go to that extent though since these aren't in an optimum box...but at the same time might be all the more reason to seal it up really tight. I should start on it Thurs. Ill start a build log for it

[shizzzon 461]

Damn! We got everybody viewin this thread, hehe.

I bet if you were installin an 18" BTL, we would be in competition with Meade's thread, lol.

None of that stuff is expensive.

Depending on size of bottles you choose, titebond, LN and silicone will be around $12-20

[Blazinloud 0]

www.Subwoofertools.com

might help