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Old 20th June 2004, 11:11 AM   #1
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Join Date: Jun 2004
Location: Atlanta, GA
Default Single Tumult or multiple others?

I am preparing to build a sub for my home theater and obviously want the absolute best possible sound. It will be 70% HT, 30% music and should be able to go very low (10-15Hz). Size is not an issue (within reason). IB is not an option. I haven't yet decided on active vs passive - so power can be decided once I have finalized the driver selection.

For the best sound per dollar, am I better off spending $500 for a single tumult or putting the same $ amount towards multiple other drivers (2-3 Shiva's?).

Thanks for your input.
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Old 20th June 2004, 02:55 PM   #2
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Join Date: Mar 2004
Location: Port Angeles, WA
A disclosure.... I sell Adire drivers so I'm not an unbiased source.

First.... don't just focus on the driver. You are designing an entire bass system and every component is important to get good results.

Second..... I doubt you want 10HZ performance. Go for a more realistic goal of an f3 of about 18-20HZ in-room. Most of your program material is above 30HZ anyway.

Third.... really consider what size, shape and quantity of subs will be acceptable in your living space. I don't know how many people I've worked with that started a project thinking a large sub would be just fine and 12 months later they are looking for a smaller sub.

Fourth.... The room is really important to bass performance. It would be useful to start with details on room size & construction in order to give you good input on your project.

If size and number are not an issue you should consider using multiple subs. Stereo subs will give you smoother in-room response. The two real advantages the Tumult will have over other drivers are the XBL^2 motor, which lowers distortion, and the fact that you can fit a lot of subwoofer into a small package. Since you don't need the smaller package you can get by with a couple larger subs that will also use less power. A pair of Tempest in sealed enclosures is a simple project (hard to screw up the box construction), requires little power (relative), and goes tight and deep. You give up a just a little in ultimate displacement but not enough to worry about.

I'd add some room in your budget for some sort of external parametric EQ as that will allow you to tame the inevitable room nodes. A pair of Tempest are $300, budget another $300 on amps & if you are providing the labor you should able to build the boxes and buy some EQ for another $500 for a grand total of just around $1100.
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Old 20th June 2004, 10:16 PM   #3
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Hi Newbie!

Kevin already said most of the important points.
The rooms characteristic and position of the subwoofer
is critical if you want more than just a crazy booming monster.
Nothing is worse than a big nox that does not fit to the right
position in the room...

You are talking about 10Hz, this means you are going for some active low frequency equalizing, right? This gives you some moref possible choices for the speaker, as your sound results will not only depend on the speakers T/S parameters...
But do you really need 10Hz.
Don't tell me that I am also going for a crazy design..., I know.
I am doing that project more for "research" or curiosity, than for any real requirement.

- Check if efficiency is an issue, or if your amp can provide "any" required power..
-For less trouble, stay with high quality speakers, i.e. Tumult, Shiva, Sadhara etc.
There are also acceptable low cost speakers, but you would have to buy and test afterwards, and typically they lead to larger designs, than a TUMULT or a SADHARA....
If you are only looking for best volume displacement per $, then something like the "Raveland AXX" series would also work.
You can get a 12" speaker with +/-9mm excursion for EUR 80,-
or a 15" speaker with +/- 9mm excursion for EUR 100,-
http://www.speakertrade.com/site/
or
http://www1.conrad.de/scripts/wgate/...rch&~cookies=1
.....speakertrade is slightly cheaper than conrad....
May be you can get something similar in US.
I am right now going for 2 Sadharas from ADIRE in two separate enclosures. The Sadharas are 12" speakers with linear +/-27mm excursion, but low efficiency. High power amp needed. Also
pricing is "inconvinient". Well, I do not buy such things very often,
so I will forget this point in some months... hopefully
This design is flexible for positioning the subwoofers in the room and I can handle each subwoofer still with my two hands
and the Sadhara drivers provide quite a high volume displacement for such small speaker....

Bye
Markus
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Old 20th June 2004, 11:04 PM   #4
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When you talk about needing lots of power for these inneficient drivers, are you talking about 500W? 250W? 1000W?

Plate amps or seperate?
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Old 21st June 2004, 03:51 PM   #5
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Power will depend on the box, desired amount of EQ and upon the SPL levels you are aiming for at a given frequency.

So the first thing to determine is a realistic design goal in terms of performance. Second, determine size, shape and physical requirements in terms of placement in your room. Finally decide on a driver, amp and PEQ system to fit those requirements. If you have a budget in mind you may need to trim your design goals a little.

The Tumult will require at least 500W in most applications in order to use it's excursion. If you put it in a small box and use EQ to extend frequency response you will need upward of 1500W to use it's full capability. Plate amp or rack mount doesn't really matter. For these power levels you will have much more variety with rack mount pro-audio amplifiers.
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Old 21st June 2004, 04:05 PM   #6
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OK, sounds like you need a little more information...

The room is roughly 16' x 40' with an 8.5' drop ceiling. The sub can either be placed next to the screen along an outside wall or in a corner where one wall is an exterior drywall wall and one is exposed brick.

18-20Hz is plenty fine with me, I just want it "low"... However, I don't want "boomy", but do want "feel it in your chest".

If I do 2 subs, I won't be able to put each in their own corner. Don't know if that matters, but thought I'd throw it out there.

I know I said size didn't matter, but... My ideal situation would be to have an IB setup where the sub is felt and not seen. However, the drop ceiling precludes me from doing it overhead and the house layout precludes doing it anywhere else.

Hope that helps. Keep the questions coming and I'll try and answer them.
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Old 21st June 2004, 04:55 PM   #7
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What is the construction of the room? Raised floor or concrete? How about the walls and what is directly above the drop ceiling?
Is the room closed or open to other parts of the house?

If you like IB do you have the option of building a false wall on one end of the room? You only need 2' & one side of the room to meet the x10 Vas requirement for two Tempest in IB setup. Since the room is 40ft in length you have plenty in that dimension as long as that end of the room doesn't have anything like windows or fireplace etc....
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Old 21st June 2004, 05:12 PM   #8
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2 walls of the rectangular room are exterior with insualtion and wood panelling, one with windows and a door outside. One is an exterior wall with exposed brick and a fireplace. The fourth wall is between the workshop (garage area) and has panelling.

Above the drop ceiling is abotu 2' of empty space and then the floor joists for the first floor.

There is only one door (from the interior of the house) leading into the room and it is on one of the short walls. The brick wall/fireplace is on the other short wall. I'd hate to wall in 80 SF just to have an IB. In that case I'd probably just drywall the ceiling (but I like being able to run cables up there at will...).
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Old 21st June 2004, 05:38 PM   #9
Vigier is offline Vigier  Netherlands
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Quote:
Originally posted by DIYNewbie
OK, sounds like you need a little more information...

18-20Hz is plenty fine with me, I just want it "low"... However, I don't want "boomy", but do want "feel it in your chest".
DIYNewbie, the feeling in your chest isn't created by frequencies around 20 hz, but frequencies (roughly) around 80-100 Hz.

Grtz, Joris
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Old 22nd June 2004, 10:08 AM   #10
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See, I learn something new every day...
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