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Old 06-30-2014, 02:07 AM - Thread Starter
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Question Single PPSL or two separate sealed subs for Ultimax 15s

Hi Folks,

I'm still trying to decide which way to go with my pair of ultimax 15s. I already have one 15" TL sub positioned outboard of the front R channel, and i have been getting localisation issues due to 'pressure wave' even at low volumes, sub is XO at 80 Hz. The bass response is also uneven in the listening position and throughout the room.. Probably not helped with that being in the corner.

I'm planning to place the ultimax 15s on the outboard of the L channel to balance the subs. 2 separate sealed subs mean i can have have 1 at the front L position, and another to further balance the bass.

The question about PPSL vs dual sealed - on the one hand, i read about the benefits of PPSL in reducing harmonic distortion and also mechanical vibrations. I'm kind of concerned about mechanical vibration at high power with single front firing, even with a heavy, well braced box, with good isolation feet. I'm talking about the entire enclosure moving slightly in equal and opposite motion to the cone, no matter how minute. My 15" TL sub is a tall, slim down firing design, about 150lbs, even at highest outputs it is rock still, no motion felt with fingertips (very sensitive vibration sensor ;p)

I have attached some screen captures from when i was visualising layouts. Candidate for other sealed sub location would be between the couch and the computer table. But that might cause further localisation to the right of the listening position due to nearfield pressures...

Any advice? Am i obsessing too much about vibrations with dual sealed? I also think the Ultimax cones are too pretty to be hidden away with PPSL, but you do get the see the gorgeous motor structure..

Talking about the room, i don't know if it is a good or a bad thing. All the other 3 corners are open, to the main entrance, the kitchen and the bedrooms. So it is kind of leaky for corner modes, but it also makes it hard to pressurise.. It is an apartment, so all walls, floors and roof is concrete. The ceiling is 8 feet.

All comments and input appreciated!
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Last edited by rhapsodee; 06-30-2014 at 02:11 AM.
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Old 06-30-2014, 02:21 PM
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I need to make several clones of my gf too
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Old 06-30-2014, 07:55 PM - Thread Starter
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Originally Posted by niktak11 View Post
I need to make several clones of my gf too
Haha, i was putting people all over to get a feel of the space...
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Old 06-30-2014, 08:26 PM
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Old 06-30-2014, 09:19 PM
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Curious why you would not just add a 2nd TL or 3rd TL to the mix if you need more output or to even out in room response.

I am not a fan of mixing sub designs in the same space.
Sealed,ported,TL's all can sound great when set up right.

I use the um 15 driver myself and that is a great diy driver. Lots and lots of quiet excursion and it does well with just a few hundred watts going to it.
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Old 07-01-2014, 08:25 AM
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I've got a PPSL build thread underway so am naturally inclined to push you in that direction but you could still do dual opposed to reap benefits of motion cancellation. As above, though, I'd be tempted to build more of what you have if you like the 'sound signature'
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