best sub for 3 woofer triangular enclosure @ 3400 watts - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 20 Old 06-12-2007, 09:40 PM - Thread Starter
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So I need to make a compact sub and found this design to be a very sweet looking and functional layout... I am, however, a bit worried about magnet clearance due to the depth of some of the high power handling drivers...

Anyone have ideas for this type of layout? Will be powered with a "fan modified" plx3402... pic below



I am looking for insane sq out of what will no doubt be a small box. No budget, sky is the limit. I am open to whatever sized drivers, although I have to say, I haven't really imagined what one of these would look like w/ 18" drivers in it...I believe the ML one is made with 10's and is a great size IMO... will go bigger if gains to be had.

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post #2 of 20 Old 06-12-2007, 10:20 PM
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That's exactly what I'm doing with the subwoofer cabinet I've recently commissioned. Main difference is my facets are larger. Six inch facets with 14" baffles. (Internal measurements.) I'm using three Peerless XLS12's and three of their matching PR's. Internal height (including two shelf braces) is about 27" and total height is going to be 29", for an internal volume of around 110L.

I think that would be a solid recommendation. I'd bridge your amp and series-wire the woofers. They're efficient enough that you won't need all that power. DVC drivers may allow you to better optimize amp power. (Run the amp in stereo, with three coils paralleled to each channel.) Other recommendations would depend on your maximum allowable dimensions, as the above was designed specifically around the requirements of the XLS12+PR.

Keep in mind that a hexagon is less space-efficient than a rectangle, so you'll need more height for this shape than you would for a cube. I think that it may look smaller than it is, and smaller than a big rectangular solid, though.

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post #3 of 20 Old 06-12-2007, 11:03 PM
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Are you looking to do 3 drivers or one driver and two passive radiators? That might be the way to go, as PR's won't have the depth of a high end driver.
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post #4 of 20 Old 06-13-2007, 01:25 AM - Thread Starter
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1 active and 2 pr's won't have any of the "cancellation force" though correct?
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post #5 of 20 Old 06-13-2007, 08:51 AM
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COrrect
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post #6 of 20 Old 06-13-2007, 10:17 AM - Thread Starter
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I guess I (unlike others on this forum) am interested in the smallest box possible to create the most bang. Low extension would be nice, but falls behind high sq as a priority. I am actually contemplating 3 rhythmik kits in one of these enclosures (1.5cuft x 3 = 4.5cuft IV)
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post #7 of 20 Old 06-13-2007, 10:30 AM
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If the sky is the limit, why not a LMS 5400 and 2x TC Sounds 18" PR's, Jmcomp24 (Jai) is using a pair of these setups in his build, I have no doubt that the SQ would be absolutely incredible. Another option would be 3 TC Sounds LMS 5400 15" drivers if you really don't want to do the PR thing. Another option would be 3x TC Sounds TC2000 12" drivers, this would yield a smaller enclosure. There aren't many large drivers with sufficient BL to handle a small box that don't have a lot of inductance, so much of this design depends on what crossover you plan on using. Some of the great drivers like the TC3k and TC5200 would probably sound very good if crossed over at 60Hz or so, but would definitely have problems if pushed past 80.
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post #8 of 20 Old 06-13-2007, 10:37 AM
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Another thought my be to utilize one active driver either top or bottom firing with a PR on each of the three faces...

Regards,

Larry
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post #9 of 20 Old 06-13-2007, 10:43 AM - Thread Starter
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Is it helpful to split up the airspace inside an enclosure like this into 3 sealed compartments? Or is it better to share air bw the 3 woofers?
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post #10 of 20 Old 06-13-2007, 11:11 AM
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Quote:
Originally Posted by 04FLHRCI View Post

Another thought my be to utilize one active driver either top or bottom firing with a PR on each of the three faces...

Regards,

Larry

That does sound hot
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post #11 of 20 Old 06-13-2007, 12:11 PM
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do not vertically fire any of the current gen low fs woofers .. you are just asking for distortion and an early grave

Jim
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post #12 of 20 Old 06-13-2007, 12:26 PM
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So...your saying all these sonosubs are asking for added distortion and an early grave?
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post #13 of 20 Old 06-13-2007, 12:26 PM
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yes

Jim
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post #14 of 20 Old 06-13-2007, 12:40 PM - Thread Starter
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lol
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post #15 of 20 Old 06-13-2007, 12:42 PM
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note I said low Fs drivers ... not all drivers.

Jim
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post #16 of 20 Old 06-13-2007, 12:49 PM
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mmk, please elaborate, I understand the theoretical issue, but have never heard of people having these described problems. The equation I keep on seeing is percent sag = 24,849 (Xmax*FS^2), and you don't want more than 5% sag.
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post #17 of 20 Old 06-13-2007, 12:51 PM
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Quote:
Originally Posted by jjw350z View Post

note I said low Fs drivers ... not all drivers.

And what exactly would you call "low Fs drivers"? 25Hz? 20Hz? 17Hz?
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post #18 of 20 Old 06-13-2007, 02:06 PM
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Jim,

I'm curious too; this seems like a unique and interesting build.
An up/downfiring 5400/18; with three 15" PR's has my attention.

Please elaborate here.

Regards,

Larry
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post #19 of 20 Old 06-13-2007, 02:24 PM
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15-16-ish ... a la some speakers availibe today... now work that thing out and stretch its legs like many do here and you have a 13ish hz driver ...

now you're static at 1.5mm down ... over time it gets worse and worse.

See attached files....first one attached is a relatively well designed woofer with ~11mm of overhang ... centered VC ... notice the nice symmetrical BL curve.

Now see the next file where I have moved the VC 0.75mm up in the gap from rest (I used 0.75mm as its about the same % of VC movement vs. a longer coil design)...you'll notice the light blue is what a symmetrical line would be ... where in reality you have a pretty big skew to it.

Over time .. say we sag another 1.5mm (or in this case, 0.75mm) .. look at our skew now. You'll introduce a fair amount of BL related distortion at higher drive levels...whether or not it self destructs ... thats a question of build quality and mechanical spacing....but I think this illustrates my point that a low Fs driver (sub 20Hz) can and will introduce a fair bit of distortion when mounted in a vertical arrangement.

Passive radiators can be even worse ... most used in these designs have an Fs in the 5-8hz range ... sagging anywhere between 4mm and 10mm at rest. Now you have passive that is probably sitting at a point in its compliance curve that is 15-30% stiffer at rest than it is at 10mm inward/outward (depending on the direction of the sag). Again .. not good for distortion ... and in many cases ... not good for reliability.
LL
LL
LL

Jim
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post #20 of 20 Old 06-13-2007, 02:59 PM
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Well, the PR's would be mounted horizontally, that much I do know is necessary, the LMS 5400 18" has a Fs of 18Hz, I suppose much of the discrepancy lies in how much it will change over time, if TC tested the LMS in the first 50hours or so of moderate use, it would likely have an Fs of several Hz higher than what it would be over time. If they tested it after a couple hundred hours of heavy use, then the quoted Fs would be much less likely to drop. Your take on it is that the drivers Fs will drop 5Hz or so with a bit of use, which is entirely possible with some, the point of contention (and I don't necessarily stand by it) is that TC sounds took this into account and drove the driver hard for a long time before posting its T/S.
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