Dale's Enclosure Build (update: More Pics Added)

[Dale]

official cutlist

--------------

top and bottom ----> 27" X 36" each

right side -----------> 13" X 26.25"

left side -------------> 13" X 25.5" (it is behind the face of the box)

back --------------------> 13" X 36"

Here is how you assemble everything:

--------------------------------------------

Everything sits between the bottom and the top piece. The left side piece is BETWEEN the face and the back piece.

The right piece sits in front of the back. The face is in front of everything and flush with the right side. (the port cuts starts after the face)

[Dale]

again....glad i could help man.

i'll make a detailed explanation of how i arrived at those values, but for now im kinda sleep so i'll do it tomorrow

I just gave you enough info so you can go ahead and build a box.

Dont hesitate to ask me questions if you're not sure about the dimensions

[freestylin]

I will just wait till tomorrow or when you have time to give me some explanation of how you arrived to the values. For building the box I'm not quite sure when I'm gonna do it yet because I'm still in school (Ya my college gets out late) so i might do it in a couple of weeks but ya i shall wait for your next post

[Dale]

Ok here goes....

When you get to your Transfer function magnitude graph (after selecting your sub and alignment), your most important tool there will be that little box that pops up with it.

It should have your driver name, model and the number of drivers selected for you already. The herculean's share of your concentration will be under the "BOX" and "VENTS" tabs.

BOX

===

You should see 2 fields: Volume and Tuning Frequency. Pretty straight forward. More than likely winISD will have preset values in these fields.

Feel free to change them because it's probably some huge volume value that you have absolutely no space for.

Remember that you only have 6.8 cu ft. of space to work with, so select a volume that will leave you enough space for other displacements like port and 45 cuts.

I chose a volume of 4.5 ft^3 and a tuning freq. of 32 Hz. You're probably asking how I knew that 4.5 cubes would work to begin with. But I

actually worked my way backward starting from around 5 cubes and seeing about how much space the port will occupy. Then I adjusted accordingly.

I am showing you this way so you understand WHY I did that.

Notice that changing these values affects the graph. If we move our attention to the graph, we see how the subs should behave in our enclosure thus far.

The Y-axis is dB and the X-axis is frequency (Hz). There is a red line at 0dB. We call that our reference. There is a purple line at -3dB. We call

that our F3. This is the frequency at which the volume has decreased by about half. Note: every 3 dB means you are essentially twice as loud,

with respect to your reference. Anything below that F3 line rolls off until you can't pick it up anymore. And at -10 dB your bass is no longer

"usable"...this means that you will have a hard time hearing it.

This is what your "bass extention" really is: How low can your subs go before the bass is rolled off or attenuated. If you take a look at the

highest point of the graph and click it with your mouse, you will see (to the right) some values depicting dBs and Hz. Our present graph tells us

that your setup will "peak" at around 60-ish hertz. This means that that frequency will seem loudest to the ear. As you can see it is about 5 dB

above reference. Notice also that you have good bass extension down to about 30 Hz (F3). That's good for music. Most rap is around 35-40Hz, so

you are capable of reproducing those frequencies without unloading your subs. But that's a different story.

I know you may be wondering why we peak at 60 Hz when we tuned to 32.

Well the simple fact is that your tuning frequency is not ALWAYS your loudest. Remember that is takes less energy to reproduce higher

frequencies at high volumes than with low frequencies. However, there are ways in which you can tune your enclosure that will essentially shift

your peak. One way is to increase the volume of your box, so it becomes more and more efficient with lower frequencies.

But as we both know, you have no trunk space. So the dreaming stops now. lol.

VENTS

=====

This is the harder part. But still pretty straight forward.

The is where your "create" your port.

First of all we are using one port. And if you click on the object below "Shape", it should change to a square, which is what we'll use.

Vent Diameter:

There are two fields. I want you to leave the first one blank for now and put 13" in the second. This is the height. Everything else the program

will do for you..Length, End correction, cross area. Everything.

The question we need to ask ourselves is how do we determine how wide the port should be? Well first of all, if your port is too narrow, then your

air velocity leaving the port will be too high. You should aim for a maximum of about 17 m/s which is about 5% of that of sound. Anything

higher than that and you run the risk of having port noises. Fortunately, winISD has a feature to allow you to see the maximum velocity and at what frequency.

First, go to the "SIGNAL" tab, and change System input power to 1400 watts. This the amount of amplifier power you need for 2 12" L7s. They

are about 750 a piece. Now move to the graph and at the top where it says Transfer function magnitude with an arrow pointing down next to it--click on that.

Look under "rear port" and click Rear port - Air Velocity.

That should display the graph showing your maximum velocity.

NOW, go back to the "VENTS" on that little box and play with numbers in the first field (the one we left blank). Notice the velocity changes.

Remember you want a maximum of 17 m/s. Your program is probably set to show feet/second units so change it to meters/second. You can do so by

clicking FILE >>>> OPTIONS. Look all the way at the bottom where it says Air Velocity, then two text fields, then the units. If you double-click

on ft/s, the units will change...so double click until you see m/s. then click ok.

At the VENTS in the little box...after playing around for a few seconds, I saw that a value of 6.5" for my port width puts the graph right at 17

m/s. Perfect. That's how I came up with this value. The program automatically calculates the port length based on your height and width in order to achieve a tuning of 32 Hz. You should see about 41"

(Actual: 41.01) in that field. That's the effective port length....meaning, if you draw a line down the middle of the port forming

an L until you reach the end of the port, that line should be 41" in length. And because the port bends, your CUT length is shorter.

so your subs will be seeing a volume of about 4.5 cubes, but in reality your box will be the biggest you can build it..which is 6.618 cubes.

I hope this info helps.

READ THIS, IT'LL HELP:>>> It will help you calculate the cut length of your port walls.

http://mobile.jlaudio.com/support_pages.php?page_id=165

[freestylin]

This really helped I completely understood it clearly probably a little more messing around I will have this down. One question as I reading I notice you put 1400 for the signal input but isn't it supose to be 1500 because 750x2 is equal to 1500 and if that is true the vent lenght would be 42.54 w being 6.63 and h being 13

[getmoney]

dont mean to interupt but be sure to post a build log looks like an interesting project

[Dale]

This really helped I completely understood it clearly probably a little more messing around I will have this down. One question as I reading I notice you put 1400 for the signal input but isn't it supose to be 1500 because 750x2 is equal to 1500 and if that is true the vent lenght would be 42.54 w being 6.63 and h being 13

i meant to put 1400. it's a safer wattage. i've heard ppl saying L7s don't take their rated power. but in the interest of how the program works, it's supposed to be 1500. i chose 1400. you're right.

[freestylin]

I see well which would should i go with and man these sub's full potential wont be released right

[Dale]

MDF is the most popular choice, but it's heavy. However, Birch will be a little stronger and much lighter, but expensive. Bottom line: any of the two would be perfect. Just don't do regular plywood or something crazy like that. LOL

[freestylin]

ight well i think my question wasn't clear but i was asking my subs aren't gonna functioning at full potential and also finally i was wondering if this wiring kit would be good http://www.sonicelectronix.com/item_3935_Kicker+PKD1.html because I can probably find it cheaper online somwhere or should I get each thing seperately