DIY sub question (Titanic 15 w/ 1000w plate amp)

[wackii]

Hi all, I'm new here. I need help from all you experts here. Here is what I've got so far.

1 Titanic 15" MK III
1 built box with internal volumn of 155L
1000 watts plate amp from PE

Question: I'm planning to make a vented box tuned to 18hz. How can I do that? What size of port (length/diameter)? Can I make 2 ports and help them tuned to something like SVS (plugged one, tune =20hz...open all ports = 16hz?)

Thanks in advance. I've play around w/ unibox but I'm lil lost.

Al,

[ThomasW]

Here are some links to simple and easy online calculators

Design the box using this one

http://www.carstereo.com/help/Articles.cfm?id=17

Design the ports with this

http://www.carstereo.com/help/Articles.cfm?id=31

Remember the box volume the program gives is a 'net' volume. To get the 'gross' volume you need to build, add in the amount of air displaced by the port or ports, the driver, the amp and any bracing you use.

[wackii]

Thanks Thomas for the advices and the links. I recalculated the box volume. It's actually 6.23ft^3 or 175.5L. After using the links you provided, I came up with:

1 port --> diameter = 6" and length = 33.5" Or
2 ports --> diameter = 4" and length = 30.8"

Which of this is better? 2 ports or 1 port? Also, is this flare port or just a normal one?

Thanks.

Al,

[ThomasW]

Use flared ports they 'flow' better. You're fine with a pair of 4", they're cheaper and less hassle then trying to find 6" flares.

When using flares add one inch to the calculated length.

[wackii]

Thomas, thank you for your info. Now I need to go find some flared ports with that length. Thanks once again.

Al,

[ThomasW]

You won't find them, you'll need to buy a standard flared kit and supplement the length with PVC pipe

[wackii]

Oh ok. Thanks for your help.

Al,

[wackii]

Peak excursion?

I've plug in the numbers for the Titanic 15
Net volume = 155L
2 ports (4" dia 32" length)
tune = 18hz
1000W PE amp

According to Unibox, it shows the excursion of 21mm is at 43hz? Did I do it right? I'm kinda lost... any help will be appreciated. Thanks.

Al,

[J-Dub]

what are the dimensions of your box height width etc.. so that we can determine the max length of port to use.

I'll try to model it for ya and see what I come up with.

According to Thomas, one 6" port should be better but it will be long!
ops: oops... sorry Thomas just saw previous post that said you reccomend two 4" ports. I can see that it would be much more convenient to use the 4" flares due to availability.

[wackii]

what are the dimensions of your box height width etc.. so that we can determine the max length of port to use.

dimension = 38.5" x 20.5" x 20.5"

I did minus all the braces + woofers + amp and got a net volume of 155L. I'm just lost on the excursion part. Unless I plug it in wrong in unibox. Thanks.

Al,

[J-Dub]

OK, here's what I got just as a quick model...

plugged everything in for the Dayton, 155L, 18Hz tuning, and put peak handling @ 900w.

Fidgeting around w/ room gain etc.. it seems the freq response is about +/- 3db form 16Hz through 100Hz after adding a 12db LP @ 80Hz.

Your excursion should peak @ around 16 to 17Hz. You could tune the box lower but I am showing that two 4" ports tuned to 18Hz will need to be about 35" long each. If your INNER dimention is 38.5 inches you might be able to pull off 18 Hz but not much more.
I haven't modeled a 6" port yet but you may wan't to see how it works out.

As far as excursion goes I show that you will have a large peak around 25Hz but @ 900w you should be @ about 20mm which is dangerously close to a 20.5mm xmax but this is also considering 900w of power! Keep in mind at this kind of wattage you should be somewhere in the 116-119db range considering a little boost from room gain.

Well I hope that helps a little just keep playing around till you get something that works for you. Also, listen to Thomas he knows way way way way..(you get the point) more than I do!

[J-Dub]

I did minus all the braces + woofers + amp and got a net volume of 155L.

did you factor in the volume taken up by the ports? If not; my numbers are all wrong.
Two 4" ports @ 35" = about .575 ft^3

[-Haro-]

wackii

I plugged the Mk III numbers into WinISD and with this box and amp it looks like you might get away with 700W max before hitting XMAX at ~29hz and again around 15hz. Keep in mind there may be some distortion around 30hz with that much power. My suggestion would be to turn down the gain on your amp.

With two 4" flared ports it looks like 35" a piece. That's a bit larger than your box unless you place the port on the top or bottom. Might have to play around with the tuning frequency to bring that down a little bit.

I purchased my 6" ports here with no problems... though they took 2 weeks to arrive.

http://www.2loud4you.ca/

On the other hand I just recieved two 4" flared ports for a new sub I'm building from PE in two days.

[-Haro-]

J-Dub, you beat me to the punch.

[J-Dub]

J-Dub, you beat me to the punch.

Oops, sorry Haro.

Hey at least we came out with the same calculations!

Two heads are better than one :B

[-Haro-]

It's all good JDub... :T

Hopefully we'll get him closer to a functioning sub through all this banter.

[J-Dub]

:agree:

Ok Wackii, just let us know your temperature and we'll do what we can to help. Hope you're having fun!

[wackii]

Thank you J-Dub and Haro. From a few posts above, it seemed like I got my port length off a couple inches. I got the 1000W plate amp from PE but will be sure not to crank it all up (Max would be half or so). Is WinISD easy to use? I'm probably need it to play around w/ that software.

did you factor in the volume taken up by the ports?

Yup, I did factor in the volume of the 2 ports. Matter of fact, I might have minus a lil more volume just to be sure.

All the box sides are cut. Just need to cut the braces and assemble them. Thanks for your help.

Al,

[J-Dub]

You are certainly welcome!

I got the 1000W plate amp from PE but will be sure not to crank it all up

Good Idea!

Is WinISD easy to use?

It will be once you play around with it a while. It seems to be a very popular program around here. I use a different program and have never used WinISD but if Thomas suggested it, it's golden. Like most modeling software you will just have to use it, run into problems, ask questions, use it again and before you know it you'll be a modeling master!

There is probably a way to get your box a little more fine tuned. (pun intended) Just play around with the tuning freq. a little more and look real close at the freq. response. Your design looks very good right now and might not be able to get much better but it never hurts to see what else you can do. Remember that most programs give you an anechoic response so you should get a good amount of extra room gain down in the lower frequencies. In this case something like 16-30Hz relatively. Every room is different and will have peaks and valleys in different freq's but most will boost the lower end. Room placement will be key. Thomas will probably reccomend an FBD (FeedBack Destroyer) made by Behringer which runs around $120. You can find it at Parts Express.

Well I hope that helps! Oh... take pictures so we can all see how it comes out!