OK speaker/stereo guys... Honest opinions on my idea

[Pyrojodge]

So as some of you know I am planning a major stereo upgrade. I have a designated spot for two 10'' JL audio subs... I plan on mounting them under my rear storage bays on either side of the cockpit. I had to have atleast .5 cu ft for the speakers. With my design I have over .8 cu ft of inside space... Here's some pictures of what I am planning on building. I am going to use MDF and then seal with west systems epoxy. Then I will paint them to match the color of the boat gel coat...

Here's some pictures!

Side

Front

To show the fillets

Final product color matched!!!

OK seriously guys what do you think, do you believe it will be sufficient? Or do you have a better idea...

Thanks guys here's to a great 2012!:thumbsup:

 

[MasterFab]

Your design looks quite good. The angled baffle helps reduce internal standing waves, which will contribute to smooth response and a lack of resonance. The internal brace is also good design practice. Be sure to maintain an internal volume appropriate to your drivers Thiele Small parameters, and you should enjoy good sound for quite some time.

Dale

 

[mrclark321]

Jason make sure you account for vibration noise and rattling when mounting, I just had the JL 10" sub mounted in the cockpit on the side of the helm seat and the access door vibrates like hell from the bass, had to use some bumpers on the door to stop the vibration. They sound great, I just went with 1 10" sub and 4 6 1/2" M series with the 5 channel 700 watt amp and love it. The deal at the boat show was too good to pass up!

 

[Escapade]

I mill alot of MDF. It does not hold fine treads well. You could mill in a through hole and put in a tee nut from the back side? Justa thought looks like a great idea. Mike

 

[HIFI]

I assume you will be using the JL M10W5 Sub Woofer for sealed enclosures. If so your enclosure should not exceed 1 cubic foot. If you are containing two drivers in same cabinet I think I would build it so it has two 1 cubic foot cavities or contact JL direct for an optimum cabinet dimension for the pair. I would bet they suggest two 1 cu ft cavities. That is my choice for me.

If your thoughts were to have two different mounting locations I would recommend locating one Sub up front in helm area and the other in rear area. Outdoor bass is hard to contain and with all sub bass rear loaded you are likely to have large bass volume drop outs as you move fore and aft. I am always concerned about the captain seat. For me, I am the captain, I want the best sound if I am at the helm. I would want the same outcome in my car and my home listening spot as well.

FRONT SUB UNDER HELM

REAR SUB IN AFT BENCH

 

[Pyrojodge]

Thanks everyone! I do plan on fastening the boxes using 1/4 28 T-nuts.


Hifi, I missed a period on my dim. They are .8 cu ft each. So this is within range of .5 to 1 cu ft. I have read about fiber fill as well to help a small enclosure. True false forget it?

Most of my music listening is in the rear cockpit or on my swim platform. The only room I have to mount them is where I plan. I will try and get you guys some better pics of where I have planned in the comming weeks...

Is sealing the MDF with resin a good choice or is there a better one?

 

[Escapade]

Jason-

Might be good idea to put a layer of ( Fiberglass ) chopped strand matt on them w/ the resin. Even better machine your profile in reverse as a mold and seal w/ primer. Wax it up and make the enclosure out of glass.

 

[EarmarkMarine]

All resins are micro porous and will eventually wick up moisture if set directly on the sole. Polyester fiberglass resin is okay. Epoxy resin is definitely superior. But for either to last the enclosure execution needs to be perfect with every seam and every staple/nail/screw hole filled and sanded smooth prior to coating the enclosure. Radiused corners help thicken the application as any coating will withdrawal and thin at hard corners. A solvent-based fiberboard such as MEDEX will give you a better option and holds screws much better than standard water-soluable MDF. In any case you should elevate the enclosure off the sole with HDPE or KingStarboard risers. Also, make sure you are using a quality terminal cup or binding posts. A caulked hole won't keep an airtight seal for very long.

Placement depends alot on the particular boat. Collected and symmetrically aimed subwoofers sum much better. However, for an expansive cockpit you may not get even coverage. But different locations, different surrounding boundaries, different types of sub loading and asymmetrical aiming can produce some real serious phasing conflicts resulting in some hot and cold spots around the cockpit. I would keep it simple and keep the subs collected in most boats.

David
Earmark Marine

 

[HIFI]

Placement depends alot on the particular boat. Collected and symmetrically aimed subwoofers sum much better. However, for an expansive cockpit you may not get even coverage. But different locations, different surrounding boundaries, different types of sub loading and asymmetrical aiming can produce some real serious phasing conflicts resulting in some hot and cold spots around the cockpit. I would keep it simple and keep the subs collected in most boats.

David
Earmark Marine

OK . . . with that said . . . .

I think the op is describing two individual sub enclosures that are mounted in rear and facing each other. If so is this going to generate the greatest opportunity for phase issues? As a follow up question what do you think of using each rear corner and firing drivers forward? In my thoughts this uses boundaries/loading/summing to the advantage.

I am not sure the OP has the space for the aforementioned set up on his star side. I just thought it good consideration, even if he goes with just one on port side rear.

 

[Pyrojodge]

Thanks again guys...

I have a couple pics of where I wanted to mount the boxes. They will be 4 inches off the deck hanging down from my storage lockers...

port

stbd

What about that?

 

[EarmarkMarine]

I understand that in many cases you have to take what the boat gives you so you may be choosing the leper with the most fingers. It may be less than ideal but the best of all available compromises.

If given the option I would always select the mounting position that places the two woofers at one extreme of the boat cockpit with both woofers aimed in the same direction and aligned (meaning staged at the same depth).
I'm not too concerned when two woofers are playing directly at one another if the distance between the two is a small increment of the highest frequency wavelength that the woofer is expected to reproduce and provided that both woofers are loading off symmetrical boundaries. For example if one woofer is firing forward and the woofer is firing towards the opposite coaming I can live with that if they are both tucked into the same corner. That would be a very good scenario and the 90 degree difference in orientation wouldn't matter much.

Most people recognize the correlation of the distance between two woofers in different locations and the differences in phasing at various listening positions throughout the cockpit. But they overlook the fact that different types of loading, different boundaries, whether direct radiating or enclosed in a vented locker or compartment, can have a significant impact on phasing also.
So again, for most I would recommend that you keep multiple woofers collected, symmetrical, similarly oriented and as simple as possible whenever the boat cooperates.

David
Earmark Marine

 

[EarmarkMarine]

It looks to me like you are taking the best advantage of what the boat is giving you.

David
Earmark Marine

 

[HIFI]

I understand that in many cases you have to take what the boat gives you so you may be choosing the leper with the most fingers. It may be less than ideal but the best of all available compromises.

So again, for most I would recommend that you keep multiple woofers collected, symmetrical, similarly oriented and as simple as possible whenever the boat cooperates.

David
Earmark Marine

Great help David . . . So new question . . .

I am following the OP’s plans and I think I would not want the sub drivers centered in the cabinets. Anything he can do to get the drivers into the most rearward corner takes advantage of boundaries. Therefore the driver need to be moved to left of center on baffle. And of course right of center on baffle for opposite side cabinet. Do you agree?

 

[EarmarkMarine]

That is a very good point. If the two enclosures were built mirror image rather than identical with the woofers at one extreme of the cabinet, then you could get both drivers closer into the corners. Every reinforcing plane helps.

David
Earmark Marine

 

[EarmarkMarine]

I might add this one small note. I would go no farther to one extreme of the cabinet than 75/25 percent. That is already a very elongated enclosure shape. Woofers located at one extreme of an elongated enclosure tend to behave like they are in an undersized enclosure. So go with 75/25 and move the enclosures to the rear extreme of the pockets if all that is possible.

David
Earmark Marine

 

[DougLas]

With a box for the sub's it would seem as if a 2 inch hole should be put in the front of the box so it will allow better air movement of the sub diaphragm.

 

[Pyrojodge]

Doug, if you are up for it I would love to stop by and see your system...

Thanks guys for all of your help. I am rethinking the set up at your advice... I will keep you posted. I will be on the boat the next 5 days so I will have lots of time to mull it over...

 

[HIFI]

With a box for the sub's it would seem as if a 2 inch hole should be put in the front of the box so it will allow better air movement of the sub diaphragm.

This would not be a good idea for more than one reason so I would keep enclosure sealed.

 

[Pyrojodge]

Hifi, David,anyone else,

Rethinking the sub placement. Thinking of putting two 10" in the cockpit still. What about center line? I have a large storage compartment in which I could install an IB. Then farther back centerling behind my rear seat mount another 10". Is there any issues having them on center all facing forward? I'm thinking of this route so they are not opposing sides of the boat?

 

[HIFI]

OK . . . I like that you are considering other options but I don’t know if they are better/worse.

When you think about your sub(s) placement think too about boundaries . . . boundaries being your floor, side walls, rear transom area. Anything you can do to use these as a starting point for your sub bass you are ahead of things. This is part of and referred to as “loading”. Loading the sub bass is going to provide the most efficient use of power and driver. There are also adjacent/reflecting panels that will reinforce your bass for you as well that should be considered.

For example . . . David and I recommended moving the drivers in your cabinets off center to put woofer itself deeper into rear corners of structure. This is an example of using starting boundaries to your advantage.


I am not saying this is the ONLY way to place a sub. As David said, you take what your boat gives you to work with.

Loading for a listening area is what I look for first. If you provide all of your options I can assure you we can, without doubt, pick the one that provides the most impact and/or best sound.

I hope this is somewhat helpful.

FYI . . Because you said your main listening is in rear . . . I like a rear corner and low if possible. I am willing to forgo accuracy in the outdoor environment and am not afraid of infinite baffle systems if loaded correctly.