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Discussion Starter #1
I posted over at AVS but think this may be a better place. I currently have a MFW-15 but want to try my hand at DIY.

I'm decent at wood working although I don't have all the needed tools. I consider myself well above average in painting or staining wood. I would like to make a sealed sub approx. 18 x 18 x 50
(approx. 7+ cu ft of volume) and make a nice piece of furniture (table) out of it. I'm looking for a quality sub/quality piece of furniture combo.


  • HT/music = 80/20
    carpeted room size 15 x 21 x 8 (approx 2500 cu ft) opened to another room
    sub will be located in the back of the room-6ft from listener...18ft from tv
    I was looking at maybe a Tempest-x2 15" or maybe going up to a maelstrom 18"
    Would like to use a plate amp attached to the back side out of sight( bash or elemental design)
A push in the right direction would be appreciated.

Dan
 

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dan ,
it sounds like you pretty much know what you want to do. You will not be able to use a Maelstrom-x in an 18 x 18 box though.
The Tempest should work though I have not modeled it in your size enclosure. I would also suggest looking at the AV series at aespeakers.
One more plate amp to consider , if you are set on a plate amp , is the O-audio amp.
 

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Discussion Starter #3
dan ,
it sounds like you pretty much know what you want to do. You will not be able to use a Maelstrom-x in an 18 x 18 box though.
The Tempest should work though I have not modeled it in your size enclosure. I would also suggest looking at the AV series at aespeakers.
One more plate amp to consider , if you are set on a plate amp , is the O-audio amp.
Yeah, I figured I would need to slightly increase the box size if I went with the Mael-x.
I ran the numbers for the Tempest through winISD and it figured on a 139L or approx. 5 cu ft volume box, so I figure my larger box could yield lower hz and reduce the need for a higher powered amp.
I really want to stick with the plate amp idea. Do you think 500 watts is good or would 1000 be a safer bet?
 

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I'd move up to the Maelstrom. When you're going to put several hours of work into designing, building, and finishing a subwoofer that you probably intend to use for several years of enjoyment, it just makes sense to spend a few extra dollars now to not have regrets later.

A plate amp will unfortunately be the weakest link of the system - I would highly suggest a beefy pro amp instead.
 

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Discussion Starter #7
I'd move up to the Maelstrom. When you're going to put several hours of work into designing, building, and finishing a subwoofer that you probably intend to use for several years of enjoyment, it just makes sense to spend a few extra dollars now to not have regrets later.

A plate amp will unfortunately be the weakest link of the system - I would highly suggest a beefy pro amp instead.
I'm seriously thinking about the Maelstrom 18", thanks.

If a plate amp is what you want you'd be better off spending a little more money and getting the 1000 watt amp. It will give you the headroom you need.
I was pretty much set on a 1000 watt+ anyways, thanks for the push in that direction.
 

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Discussion Starter #8
I've been working with winISD trying to get a handle on which route to go. Perhaps I'm doing something wrong. Everytime I punch in my info to winISD I don't get favorable numbers. For example:

I punched in the numbers for the Tempest-X2 15" for a slot-ported box 18 x 21 x 50. I got back gain at 18hz...-3db and spl at 18hz...85db. I also ran the numbers for the Maelstrom 18" in a sealed box 21 x 23 x 50 and got back worse numbers. By examples from DIY builds on this site I should get better numbers than that going with either route I choose. Right?

t/s parameters for Tempest-X2 15"
Fs: 19.5 Hz
Le: 0.95mH
Re: 3.8 Ohms (Voice Coils wired in series)
Qms: 3.82
Qes: .47
Qts: 0.42
Mms: 238g
Cms: 0.28 mm/N
Vas: 255L
Sd: 807 cm^2
BL: 15.3
X-max: 26mm
Pmax: 1000W
SPL: 87.9 db/1W/1M
 

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Discussion Starter #10
What box volumes are you modeling for the ported and sealed?
18 x 21 x 50 ported with the Tempest----309 liters (10.93 cu ft)
21 x 23 x 50 sealed with the Maelstrom----395 liters (13.97 cu ft)

I did not take into consideration brace, driver, and fill volume. I'm new at using winISD, although it doesn't seem that difficult to use. Just plug in your info and project it out. Perhaps I entered something wrong.

Thanks, Mike
 

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Here is some "ballpark" modeling as WinISD doesn't take into account power compression.

Yellow is the Maelstrom sealed, orange is the Maelstrom ported and green is the Tempest ported, all allowing for sub displacement, bracing and porting in the given box sizes. All with the P.E. 1000 watt plate amp which has a 3rd order Hi-Pass filter at 18 hz.
Although the ported Tempest and Maelstrom are close in output, the Maelstrom does it with a lot less cone excursion and you have the option to upgrade the amp in the future to maximize the subs capabilities.

TEMPEST MAELSTROM.JPG
 

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Discussion Starter #12
Here is some "ballpark" modeling as WinISD doesn't take into account power compression.

Yellow is the Maelstrom sealed, orange is the Maelstrom ported and green is the Tempest ported, all allowing for sub displacement, bracing and porting in the given box sizes. All with the P.E. 1000 watt plate amp which has a 3rd order Hi-Pass filter at 18 hz.
Although the ported Tempest and Maelstrom are close in output, the Maelstrom does it with a lot less cone excursion and you have the option to upgrade the amp in the future to maximize the subs capabilities.

View attachment 17167
Thanks for taking the time to configure the info for me. I obviously was doing something wrong in winISD. The Tempest or Maelstrom ported look like the way to go. Looks like both of those should do better spl's and dig deeper than my MFW-15.

Dan
 

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Discussion Starter #14
Let us know what sub you decide on and we'll figure out the porting.
Thats probably the hardest thing to decide on. I'm leaning towards the Tempest-X2 15" unless I convince myself or others convince me that there is a better 15" within $150 of the price of the Tempest.
 
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