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Old 12-14-2014, 12:40 PM
BudmanV24 BudmanV24 is offline
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What do you guys think would hit harder?

At the moment I have the one factory JL M10IB5 subwoofer. It's infinite baffle, rated at 250wrms, and has a one way x max of 13mm.

I have two jl mhd900/5's, so I have 1000wrms available for subs.

Option 1 is add another M10IB5 directly across from the existing one. One benefit is that they would take up minimal space, but I'd also have to keep the gain in check to keep from overdriving them. Although at the same time, cutting that huge hole is a little un-nerving.

Option two is installing two Image Dynamics IDQ10 ' S rated at 750wrms ea with a 19mm one-way x-max, in a sealed enclosure behind the driver seat. I'd canabalize a jl marine sub so that I could have a open port to the cockpit next to them. I was thinking mount them down firing in the compartment. One downside is they would probably take up most of the compartment.

Thoughts on appreciable difference in output between option one and two?
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Old 12-14-2014, 12:51 PM
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clrussell clrussell is offline
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Are you saying a down facing porter box under the seat behind the driver seat with a port using the factory sub?

I like this idea..
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Old 12-14-2014, 01:06 PM
BudmanV24 BudmanV24 is offline
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Quote:
Originally Posted by clrussell View Post
Are you saying a down facing porter box under the seat behind the driver seat with a port using the factory sub?

I like this idea..
Nah, I was gonna go sealed. I'm not usually a huge fan of the peaky response of a lot of ported enclosures. I just figured if I put a grill in the factory location I'd get more output in the cockpit.
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Old 12-14-2014, 01:24 PM
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clrussell clrussell is offline
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Quote:
Originally Posted by BudmanV24 View Post
Nah, I was gonna go sealed. I'm not usually a huge fan of the peaky response of a lot of ported enclosures. I just figured if I put a grill in the factory location I'd get more output in the cockpit.

I still like this idea. I got a couple more subs for my star the other day and was thinking I would put them through the under dash on driver side with a box made on to it.

I like your idea better.. Right now my sub other than factory is a 12" alpine type r under the observer seat. It sounds pretty good as is. But I want that storage back an more sub.
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Old 12-14-2014, 01:29 PM
BudmanV24 BudmanV24 is offline
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I've had some people tell me that when you stick subs under the observer seat you don't realize their full potential unless you have the observer seat open. Not really interested in that, lol. So thats why i figured the old subwoofer opening could act as a vent to the cockpit. Tune it right and the boat would be a bandpass enclosure, lol. I've also heard that you get max output if all bass drivers are grouped together.
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Old 12-14-2014, 04:54 PM
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clrussell clrussell is offline
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Mine sounds pretty good with a single 12 under that seat. It's noticeably louder with it open, but not quite by any means closed.

I was in a x30 this summer that had 2 subs cut into the under dash and it just sounded so much better at low levels. Not sure how it would have been cranked as we never turned it up much.
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Old 12-14-2014, 06:16 PM
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David Analog David Analog is offline
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Infinite baffle subs are limited in excursion. They can sound very good when executed correctly at limited levels. But longer under-control excursion is their drawback.
Btw, it is totally pointless to compare excursion specs between brands.
Obtaining more excursion requires much more power. Never as efficient as more surface area.
I know you where joking but there is nothing positive that would resemble a bandpass in your scenario. You'll get all the filtering aspects but none of the positive boost.
The best SQ will come from direct radiation. One option is to use an exterior mount acoustic suspension woofer in the factory location with a sealed enclosure on the interior side with the two sandwiching and sealing against the seating console wall. The ideal location for a second sub would be immediately next to it oriented in the same direction.
Certainly mounting a couple of enclosed subs inside the seating console and using a grill as a vent has the benefit of more surface area. But even though you will net positive output at the lower end the sound pressure losses are substantial, the bandwidth is limited, and the phase response is in the toilet so there is no chance of a seamless integration with the cockpit midbass drivers or quality tonal construction. Keep in mind that the seating console and adjoining gunnel cavities represent a massive and very compliant displacement. The vent/grill is relatively small and resistive in comparison and as a ratio represents considerable resistance. So there is less impetus for the bass pressure wave to enter the open air cockpit. Again, you'll definitely net something in SPL with double the surface area and double the power but there are SQ trade-offs. Less midbass attack. Less articulate. Less transients. Less tonal construction. Big phase delay. The smaller the seating console displacement plus the larger the vent surface area the better the scenario becomes. Of course you only have so much control and ultimately you have to take the best that the particular boat gives you.
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Old 12-14-2014, 07:08 PM
BudmanV24 BudmanV24 is offline
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One of my concerns was whether the one 9" hole would be a bottleneck for two subs (and also the risk of "port noise").

The factory location in a 2nd gen xstar doesn't allow for two subs to be mounted next to each other. I would assume that directly across from each other would be the next best thing.

I could find one 10" sub that handles 1000wrms, and mount it in the factory location with a sealed enclosure behind it, but then I'm rolling the dice by powering each voice coil off separate amps that aren't strapped. I wouldn't be increasing surface area, only power handing.

I'm not interested in spending a bunch of time, money, and wasting storage space if it will result in less than optimum results.
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Old 12-14-2014, 07:43 PM
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Quote:
but then I'm rolling the dice by powering each voice coil off separate amps that aren't strapped.
Not really. Not easy to tune, but doable. But, I would try to go with a larger sub or more subs first. but even then, driving a single DVC 12 via 2 amps would not be a deal breaker.
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Old 12-15-2014, 12:00 AM
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David Analog David Analog is offline
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No chance of port noise. You could fit almost five 4-inch ports inside a 9" hole plus you have serious losses within the seating compartment. Not much pressure passing through the 9" hole.
No issue with one amplifier/channel per each voice coil, especially if you use a voltmeter to set the levels identical.
Concealed double 10"s or double 12"s will certainly get you a real jump in output. It's just not the most musical approach. A couple of JL Audio 10W3s or 12W3s would fit your power perfectly. Doubling the vent area with a second grill would help a lot. Plenty of vent options without destroying a woofer.
If you cut in a sub on the opposite side I would do both as air suspension in sealed enclosures.
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