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Old    John Brine (mnwakerider)      Join Date: Jun 2004       05-10-2011, 11:12 AM Reply   
So I am going to get a new free air sub and I want to put in the driverside kick panel. The structure that is in there is way to thin to mount the JL sub to. Thoughts on what I should do for this?

Have you guys made new kick panels, if so out of what?
Any pics or thoughts on how to do this?
Thanks!
Old     (UNvisible)      Join Date: May 2010       05-10-2011, 11:38 AM Reply   
terrible
Old    Brian (factorykitted)      Join Date: Jul 2009       05-10-2011, 11:41 AM Reply   
my suggestion - six free air 10's
Old    John Brine (mnwakerider)      Join Date: Jun 2004       05-10-2011, 11:44 AM Reply   
Thanks for the help guys!
Old    Timmy! (timmyb)      Join Date: Apr 2007       05-10-2011, 1:45 PM Reply   
You could make a new front out of 3/4" marine grade plywood and put new carpet on it and that would work. Probably want to seal that wood or cover it in a truck bed liner type product just to make sure it's waterproof.
Old    John Brine (mnwakerider)      Join Date: Jun 2004       05-10-2011, 1:48 PM Reply   
Timmy, That is what I was thinking to do, just didnt know if I should also be looking to do a resin coat over the top to seal it up or not.
Old    Shawndoggy (shawndoggy)      Join Date: Nov 2009       05-10-2011, 1:52 PM Reply   
if you are gonna go to all the trouble, why not put it in a box instead of going free air?
Old    John Brine (mnwakerider)      Join Date: Jun 2004       05-10-2011, 1:53 PM Reply   
Got the free air cheap and there really isnt enough room to build a box from what I can tell at this point.
Old    Timmy! (timmyb)      Join Date: Apr 2007       05-10-2011, 2:04 PM Reply   
It doesn't hurt to seal it up but it's not always absolutely necessary. We took an mdf pre-fab box out of my buddy's boat that had been in there for a couple of seasons and there was absolutely no water damage to it at all but your mileage may vary.
Old    Nick Tomsyck (sidekicknicholas)      Join Date: Mar 2007       05-10-2011, 2:57 PM Reply   
Ours we just removed the kick panel, cut the right size hole and popped the sub in (Alpine Type-R 15")..... doesn't hit super hard but definitely can hear it, and looks clean.
Old    John Brine (mnwakerider)      Join Date: Jun 2004       05-10-2011, 3:17 PM Reply   
That is what I was thinking to do Nick. Did you reinforce it all from the backside?
Old    Earmark Marine (david_e_m)      Join Date: Jul 2008       05-10-2011, 7:31 PM Reply   
There is no reason why a true free-air subwoofer can't sound good if its correctly executed. But you will rarely find that is the case.
First, the subwoofer has to be a real free-air or infinite baffle sub. There is no jack of all trade subwoofers. Either they are designated for a narrow purpose or they do a poor job at everything. Countless boat manufacturers use the wrong product for the application.
Second, you need total front to rear acoustic isolation for a considerable distance away from the subwoofer. This means that you CANNOT have a mounting panel that is open over the top, for example.
Third, the mounting baffle/surface must be extremely strong and vibration-free. If you have a 3/4" thick kick panel that covers six square feet or more and is secured around the perimeter then this is not going to be adequate and needs to be reinforced. A shallow 5-sided box mounted to the back side of the panel plus some bracing will make a big difference in the structural rigidity. Or, if you are mounting in a 1/4 or 5/16" thick fiberglass wall of the coaming or seat console then this also needs to be reinforced from the back side.
Fourth, the crossover points and tuning for an IB need to be a bit different.

David
Earmark Marine
Old    John Brine (mnwakerider)      Join Date: Jun 2004       05-10-2011, 10:03 PM Reply   
David,
Thanks for the explanation as always. I am going to be reinforcing the structure that I will be mounting to. I will take a little more care to this per your explanation. I am a little lost as to what you mean by
Quote:
you need total front to rear acoustic isolation for a considerable distance away from the subwoofer.
Can you explain this for me in slightly more laymen terms? I am concerned because the space is more limited behind due to the overall size of the boat.

Thanks for the help. Much appreciated.
Old    Nick Tomsyck (sidekicknicholas)      Join Date: Mar 2007       05-10-2011, 10:39 PM Reply   
Quote:
Did you reinforce it all from the backside?
I think we just added one 2x4" at a 45* to give keep it a little more sturdy -- that 15" has a pretty big magnet..... Like others said - this type-R won't sound as good as a sub designed for open or or the same type-R in a box.... but our goal was just some bass, not enough to shake a board off the tower....

We live on a small lake and only ride mon-thurs (weekends get nuts) so if we're out there blasting music people will know it is us. Don't want to have the neighbors hate us.
Old    Earmark Marine (david_e_m)      Join Date: Jul 2008       05-11-2011, 7:42 AM Reply   
John,
As the front side of the woofer produces a positive movement it pushes or compresses the air. Simultaneously the rear side pulls or rarifies air. And the inverse occurs on a negative movement. If the opposite front and rear radiation are allowed to meet they cancel out the energy. Also, any air mass, even an infinite one, has some level of resistance which serves to help damp the woofer. When there is no acoustic isolation this damping effect is also canceled.
The distance, as a percentage of a waveform that gets longer as the frequency gets lower, between when the front and rear excursions meet determine the lowest frequency that can be produced without cancellation. If the woofer is in a smaller compartment then the isolation distance needs to be greater. If the woofer is in an expansive compartment then a slightly shorter isolation distance is required.
All woofers, including 'free air' or 'infinite baffle', need a baffle (wall) or enclosure for front/rear isolation. In the case of an 'IB' woofer the volume of air needs to be large enough that it has little to no impact on the woofer's 'Q' or self-sufficient damping. This is usually in excess of two cubic feet for a true 'IB' 10-inch. Anything less and you lose bass extension and induce some non-linearity. Any larger displacement has no impact as long as there is front to rear isolation for an adequate distance.
Here's a crude but simple analogy. A wall or attic fan exchanges alot of air...an entire household. A shallow box fan or boxless fan only moves air directly in front of the fan in a narrow pattern and the air movement dissipates almost instantly because its mostly circulating air around the fan rather than away from the fan.

David
Earmark Marine
Old    Rob (DealsGapCobra)      Join Date: May 2010       05-13-2011, 6:54 AM Reply   
John,

I have just installed a 10" JL Audio IB sub (from Earmark) in my Ski Nautique. It is mounted through the side panel to the under passenger seat storage which isolates the front and rear of the speaker. I will say that I wired the speaker and had it on the floor of the boat prior to installation and it sounded very weak. I was disappointed but decided to install it anyway and see if it would do. When installed it sounded excellent! I noticed that it is great with the passenger seat closed and not quite as good with it open but in both cases much, much better than the test on the floor. Now that I read David's remarks it all makes sense! No wonder I was so disappointed with the premounting test!

Here are two shots of my installation.



Old    John Brine (mnwakerider)      Join Date: Jun 2004       05-13-2011, 8:37 AM Reply   
Rob,
Thanks for the pics and the explanation. I started doing my reinforcements last night to the kick panel. I also made some general rings out of MDF and the shapped them to fit the countours of the kick panel. I then coated it all in resin to seal it up. I am planing on going a little overboard with making sure that the structure is as solid as it can be from the back. I am going to reinforce it with more glass and a couple of "stringers" to make sure there is no real movement or flexing to get the most.

I think I am with you on this Nick, I am not looking to go to a bumb contest or anything like that. Just want to have a little more bass for the days when we "kick it new school".

I will post up some pictures and more info once I get it.
Old    John Brine (mnwakerider)      Join Date: Jun 2004       05-16-2011, 1:45 PM Reply   
Just got the sub working last night. I ended up doing an extra layer of glass over the entire back of the panel. Then around the outside I did a stringer like structure with 3/4" HDPE. I did 2" wide strips that are the entire outside and then around the sub opening and bracing in a cross pattern over the rest of the panel. Super solid. I then did two expansion rings on the front of the panel as the sub was going to be rubbing against a steering cable. For this I cut to two rings out of 3/4" MDF and then covered them in resin, screwed them together and then glassed over that once on the front of the panel. There was some odd shaping involved with this as the panel bumps out for the steering column. To get the rings to lay against the panel correctly I had to cut/sand the countour into the rings. Turned out better than I thought it would as I am no body work guy...
Then covered the panel back up with carpet (great way to cover my sub par body work finishing skills). I am super happy how it looks. Everything is smooth and flows nicely. My body work guy looked at it and was generally impressed with it!

As for how the sub sounds. I did what Rob said and just hooked it up before hand with the sub just in my hands. Meh... Nothing to write home about. After tuning the my amp (had to get a new JL 400/4 to do the rest of the setup justice...) it hits pretty damn good for what it is. Really happy with how it all came out. I will post up a couple of pictures later once I get some more time.
Old    Jamie Corvin (Bumpass1)      Join Date: Oct 2010       05-16-2011, 2:54 PM Reply   
John
You know that you show post pics, right?
Old    John Brine (mnwakerider)      Join Date: Jun 2004       05-16-2011, 3:07 PM Reply   
Quote:
Originally Posted by Bumpass1 View Post
John
You know that you show post pics, right?
Not following you bud, did I miss something?
Old    John Brine (mnwakerider)      Join Date: Jun 2004       05-16-2011, 3:25 PM Reply   
Just shot these with my cell -
Attached Images
  
Old    Jamie Corvin (Bumpass1)      Join Date: Oct 2010       05-16-2011, 3:41 PM Reply   
Should not show. Auto correct, sorry

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