Dual 15" Dayton Titanic MKIII Design Help - diyAudio
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Old 16th January 2006, 04:10 PM   #1
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Lightbulb Dual 15" Dayton Titanic MKIII Design Help

Ok, so I found this forum a while back, and decided to build my next sub. I ordered a 12" Titanic MKIII with the 500W Bash Digital amp. I choose the Bash because heat is always a problem between my fish tanks, 5 computers and Stereo. I put it in a simple sealed enclosure and love it. I max out the 12 occasionally and have to turn the Bash amp down to about 50%.

I had planned on adding another 12, but after seeing the displacement volume of the 15", I went ahead and ordered 2 of the 15" MKIII's. They arrive sometime next week. I would like to build a well designed box for them, and I have some questions.

First off the layout, the room is about 20x20 with 6 separate doors and hallways that go to other parts of the house. So it's very open, and it has 12' Vaulted ceilings. The floor is currently carpet but will go to hardwoods in a year or two. Don't think I get too much room gain. I want the subs hidden so corners of the room are not an option, plus there's only 1 that's not a walkway.

I'm also building a projector and my plan is to build a side board about 30" tall with 3 cabinet doors to sit under the 100" projection screen. The doors will have cloth centers (I'm going to make them). I plan on housing the subs on each side, with the computer and center channel speaker in the center compartment. The rest of the speakers are all in the ceiling, So it will look like a normal living room that doesn't even have a TV! (hehe) The receiver is racked up in the computer closet in the adjacent Study with the rest of the whole house audio system. I listend to an equal mix of music and movies.

So I put the parms into win ISD, and it gave me an optimal sealed box dimension of about 19"Wx12"Dx30"H. I could make it deeper
by going up to 18-20" to cut down on the height.

The current 12" MKIII is in an 18x18x22 cabinet + spikes which is what I was planning to build the sideboard cabinet around. So looking at a ported design in winiSD gives me 24"Wx37 1/2"Hxx15"D 180 Liters. That's too high! I need to keep it under 30"H to fit in the sideboard, and have the sideboard fit under the screen. The largest I could probably build is 24"Wx28"Hx20"D which is also 180 Liters.

So my questions:

* With a room this size would 2 ported 15" overpower it? I'm running each with a 500W Bash. Should I just go with a simple sealed enclosure?

* Most of the ported boxes I've reviews are really deep, how does changing the shape affect performance?

* On the ports, does 2 smaller instead of 1 larger affect performance? Does it matter if I put them above the sub? (I don't want them blocked by the cabinet base they are going to sit in.

* Do you guys build a sealed compartment for the plate amp? If so, why?

*The bash amp has to sit at about 50% volume so the sub doesn't max out. Is this normal, or a result of running everything from the computer and having 3 different volumes?


If there are good threads/pages to read that would help, they would be much appreciated as well. I'm lost on tuning frequency, a good link would be appreciated.
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Old 16th January 2006, 06:01 PM   #2
simon5 is offline simon5  Canada
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You can't overpower a room hehe! You'll just adjust the gains on the amplifiers to have a balanced system. You can go sealed if you want to.

Ported boxes can be of any shape, it's not important.
You can put the ports anywhere if you plan on tuning low. You could use passive radiators too.

Yes you can use 2 smaller ports, but why do you want to do that? It will be the same length as one bigger anyway.

If the amplifier is perfectly 100% sealed, doesn't leak any air on the outside, there's no need to have a sealed chamber for the amplifier.

On the Bash amplifier, you're playing with the gain, this is to adjust the volume of your subwoofers with the rest of the system. Yes it's normal that loud passages will overload the subwoofer if the gain is too high. It's probably overloading the amplifier too.

Good website to start learning a bit :
http://www.diysubwoofers.org/

Tuning frequency is the lowest frequency your subwoofer will produce or so without problems. It's the frequency where you tune the box to have a higher gain at that frequency and near it.
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Old 17th January 2006, 02:49 PM   #3
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Thanks Simon, that helps. I think I'm going to build a simple sealed enclosure. IF I understand it correctly

A couple of other things:

From what I've read, I can't make the box too big, it will simply help it perform better at lower frequencies. I also shouldn't need any stuffing, because of the box size and it won't have an effect on the low frequencies anyway. Is that accurate?

Does anyone have a complete .wdr file for the 15" MKIII? I followed the help files on how to populate it and I get a division by zero. When I tried filling everything out If just tells me there's a problem in one of the 30+ parms. Really time consuming and frustrating.

Also, how do I tell the tuning frequency from winISD?


Subs are arriving Thursday, this is going to be fun. . .
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Old 17th January 2006, 03:29 PM   #4
chops is offline chops  United States
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I've got the .wdr file but I don't know how to upload it to the site. If you give me your email address I can send it to you that way.
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Old 17th January 2006, 06:46 PM   #5
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Default That would be great

My E-mail is chance <underscore> 11@yahoo.com

Thanks for replying. I've been follwing your post by the way.
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Old 18th January 2006, 01:04 AM   #6
simon5 is offline simon5  Canada
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If you go sealed, you can use stuffing if you want to, it will be bigger acoustically for the driver. Can help you design a smaller box than usual. As you said, it's not necessary on the other hand.

You are using WinISD Pro alpha? You followed the help files and it didn't work? You sure?

I'll simplify the procedure...

Enter Fs.
Click in another box to change the focus.

Enter Re.
Click in another box to change the focus.

Enter Sd.
Click in another box to change the focus.

Enter Le.
Click in another box to change the focus.

Enter Xmax.
Click in another box to change the focus.

Enter Pe.
Click in another box to change the focus.

Enter Vas.
Click in another box to change the focus.

Enter Qts.
Click in another box to change the focus.

Enter Qes or Qms.
Click in another box to change the focus.

Every useful box should be filled by now.
Don't change the other parameters.
Save.

Done.

You can see the tuning frequency in the box tab in the small windows that was opened with your project.
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Old 18th January 2006, 11:18 PM   #7
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That did the trick. Not sure what I did wrong before. Now It's all starting to make sense. After looking at the output of a sealed vs ported I'm pretty sure I want to go ported. The box

The one thing that bothers me is the group delay at 20Hz is 30ms. Is that value too high?

So the box dimensions I've decided on, that I think I can still fit into the cabinet I'm going to build are:

26"L x 20"D x 29.5"H

The Internal dimensions are going to be:

24.5"D x 17"D x 24.5"H

That should give me right around 181L.

Since I'm using 3/4 MDF, 1 divider in the middle of the box, and 2- 3/4 boards on the front so I can flush mount the sub, and be able to flare the ports with a router.

To keep air velocity under 20 m/s I need 3- 4" ports that are 10", which would have to be doubled to 6 for the other sub.

No way am I going to spend $13x6 = $80 on port tubes when I can make them look just as nice with PVC.

One question, when adding multiple tubes the lengh in winISD is multiplied by the number of ports, so I divide that to get the length per port right?

As I was typing this, one of the speakers showed up a day early. It's big alright. If you guys see any problems or have any suggestions for me, please let me know. Thanks for the help so far. . .
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Old 20th January 2006, 04:34 AM   #8
simon5 is offline simon5  Canada
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Quote:
Originally posted by chance_11
The one thing that bothers me is the group delay at 20Hz is 30ms. Is that value too high?

To keep air velocity under 20 m/s I need 3- 4" ports that are 10", which would have to be doubled to 6 for the other sub.

One question, when adding multiple tubes the lengh in winISD is multiplied by the number of ports, so I divide that to get the length per port right?
30 ms at 20 Hz isn't that bad.

You don't divide by the number of ports. WinISD reports the correct length for each port. One 4" port will tune to a certain frequency. Two ports will need to be ~twice as long to tune at the same frequency because the air mass spring is less strong.

You could use two full length precision port 4" to get a 23 Hz tuning in your 181 liters box. That would be a nice compromise.
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Old 20th January 2006, 03:58 PM   #9
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Thanks Simon. Luckily I can still fix it. I see by adjusting the lenth of the port in winISD how it moves the tuning frequency.

I thought I would post my measurments in case somebody wanted to try and build this. Here they are for 1 sub:

Front/Back: 26"x29.5"
Internal: 24.5"x28"
Top/Bottom: 19"x24.5"
Sides: 29.5"x19"

You need 2 of each of the above. I made 4 of each for my 2 boxes and did it with 4 sheets of 3/4 MDF.

I test fit one of the boxes with corner clamps to ensure everything was ok, and then started to layout the speaker and ports. I decided to put the speaker in the center and ports in the 4 corners.
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Old 20th January 2006, 04:03 PM   #10
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Then I stacked 3 board together and lined them up with some scraps. That way I could drill the holes for the circle jig, and they should line up perfectly when I assymble the box. I think this is better than trying to measure each board because they will vary slightly. Anyway, I used a centerpunch to start the drill bit correctly, and I used an attachment on my drill that almost creates a mini drill press, so I'm sure to get 90 degree angles on all the holes.

I drilled 3 at a time (drill bit depth limitation) and then used the top one to redrill other boards for the second box.
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