Looking to build a sub to end all.... - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

Old 02-26-07, 06:50 PM
Elite Shackster

Steve

Join Date: Apr 2006
Posts: 2,398
Re: Looking to build a sub to end all....

Quote:
The vented alignment is set for an Fb of 15hz and this is where it gets puzzling. The output and response is substantially worse
Yeah, something is off in your model - it should look like the attached.

Quote:
Since output is related directly to displacement of the drivers I compared the Titanic 12 to the Q18. Using their published xmax values:

With 8 12's I get a displacement of 1331 cubic inches.
With 2 18's I get a displacement of 1078 cubic inches.
Ok, but each 12" Titanic is \$160....that means you couldn't even get two for the price of one Q18. Using your numbers, one Q18 can displace 539 cubic inches and one 12" Titanc can displace 166 cubic inches. \$310/539 = about 58 cents per cubic inch displacement. \$160/166 = about 96 cents per cubic inch displacement. If you intend on going sealed, size shouldn't really be an issue with either option.
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SteveCallas is offline

Old 02-26-07, 07:39 PM
Senior Shackster
Will

Join Date: Sep 2006
Location: Matthews, NC
Posts: 521
Re: Looking to build a sub to end all....

The Q18 has a linear displacement of about 399 cubic inches.So that is about 78cents per cubic inch of displacement.

And a driver I would consider is the 15" TC-1000. It has a linear displacement of about 234.5 cubic inches. That is about 73cents per cubic inch (including shipping).
WillyD is offline
Old 02-26-07, 08:25 PM
Elite Shackster

Steve

Join Date: Apr 2006
Posts: 2,398
Re: Looking to build a sub to end all....

Well , if it's all about displacement and nothing else, multiple MJ18's would take the cake, no?
SteveCallas is offline
Old 02-26-07, 09:39 PM
Senior Shackster
Will

Join Date: Sep 2006
Location: Matthews, NC
Posts: 521
Re: Looking to build a sub to end all....

Not by enough for me to choose them over the TC's, but hey, whatever floats your boat.
WillyD is offline
Old 02-26-07, 10:12 PM Thread Starter
Elite Shackster

thxgoon

Join Date: Feb 2007
Posts: 1,506
Re: Looking to build a sub to end all....

I was actually beginning to look at the TC1000, I just don't like the silver. Whatever... in the sonosub design you wouldn't see it anyway.

I finally got a good model of a Sonosub LLT and wow! If it really performs the way these graphs show it will and sounds as good as you all claim, then this is going to be an absolute winner. I may not even need to build a second one. Here's some pics.

This is the Q18 LLT (green) vs 4 12" Titanics (yellow)

Here is max SPL with rated power..

The 12's are obviously louder in the >30hz but who cares, this is not necessarily where I'm looking for the oomph. But check out the response for the LLT. WOWOWOW

Something I'm a bit concerned about is the group delay. I don't know much about it so maybe someone can shed some light on it for me. In this picture you can see the delay for the sonosub rises dramatically as frequency reaches tuning.

What do you think? As of now my only concern is that of building this mega structure. sonosub.exe specifies a 9 foot enclosure with a 24" diameter! That won't even fit in my room. How big do they make those things?
thxgoon is offline
Old 02-28-07, 01:35 AM Thread Starter
Elite Shackster

thxgoon

Join Date: Feb 2007
Posts: 1,506
Re: Looking to build a sub to end all....

Ok, so after a little research I found that as long as the group delay is less than 1 or 2 cylces of the driver, it is not detectable by the human ear. The group delay for the LLT is under this threshold by 100% so we're good to go there. Out of curiosity I decided to model an LLT with 4 12" driver. I thought maybe by doing this I could get away with a smaller box and I was right. Check out these graphs. Yellow is the Q18, green is 4 12" Titanics in an LLT tuned to 16.7hz.

Ignore the red graphs, that is a sealed enclosure for comparison...

The 18 has the flatter response but check out the box size. 400L vs 838L. With the 18 I was looking at a sonotube taller than the ceilings in my basement and 24" in diameter. I can get 4 12's in a box half the size of the 18 and according to the SPL plot I can get the same level of output with rated power. In addition I can mount them Push-pull and potentially get more accurate sound. The Dayton's might be a bit more expensive but I was willing to pay this in the first place. If it means the same or better performance in half the box size it would be worth it to me. Am I wrong in these assumptions? What do you think? Thanks.
thxgoon is offline
Old 02-28-07, 05:29 AM
Elite Shackster

Steve

Join Date: Apr 2006
Posts: 2,398
Re: Looking to build a sub to end all....

Why is your Q18 design so big? Try 625 liters with an 8" port that is 25" long and 800-1000 watts.
SteveCallas is offline
Old 02-28-07, 10:45 AM
Senior Shackster

Boom

Join Date: Dec 2006
Location: Fairfax, Va
Posts: 863
Re: Looking to build a sub to end all....

Yeah, a 800+ liter enclosure might be "optimal", but the reduction in performance might not be as big as you think to use something smaller. Since you are planning on investing at least a few hundred dollars into this play around with the volume and tuning a bit more to find somethat that does what you want in the space that you have.
BoomieMCT is offline
Old 03-01-07, 05:58 AM
Brian Bunge

Join Date: Apr 2006
Location: Palm Bay, FL
Posts: 237
Re: Looking to build a sub to end all....

The magnet controls the cone movement. So assuming the driver has a properly designed motor system it will have equal if not better sound quality than a smaller, lighter cone. You have to look at the entire desig, not just one or two parameters. It would be like saying my Civic is faster and quicker than a Corvette because it's smaller and lighter, which we all know is not the case.
Brian Bunge is offline
Old 03-08-07, 11:21 AM Thread Starter
Elite Shackster

thxgoon

Join Date: Feb 2007
Posts: 1,506
Re: Looking to build a sub to end all....

Thank you all for your great replys! The information on this forum and on the AVS forum is invaluable!

I think the final design will look something like this.

2 sonotubes each with:
15" TC1000
400L Sonotube
15.6hz tune (6" dia 18" length)
EP2500
BFD
Some really cool bassy movies

Size and budget got the best of me. While I'd love to build a dual 18" setup, it would just take up way to much room. A dual 15" setup will work much better and is well within my design constraints. 8 Titanics were a little expensive. I talked with TCSounds yesterday and they said the 15" TC1000 should be shipping again next week. What do you all think?
thxgoon is offline

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