Subwoofer Enclosure Boxes

[txav8r]

I have shifted direction and gone with the JL M10W5, acoustic suspension subwoofer, over my previous sub, the M10iB5. Both are pretty much the same sub, but the W5 is tuned and built to be in a box, and the 10iB5 is built to be a "free air" or "infinite baffle" sub. As my friend @David Analog, Earmark Marine founder and owner (retired) tells me, they are virtually identical from low through moderate gain, but that is where the AS sub will separate itself from the IB sub. My buddy @PEARCE , used the word, "tighter" base or more responsiveness. I don't know the technical terms nor can I describe it like a fine wine. But I can tell you that I have matured a bit in my desire, so in comes the AS sub.

Box building. I am going to do an MDO or MDF with a solvent glue verses a water based glue...for obvious reasons, were in a boat on water! But my question to all of you that have undergone or even applied a ready made structure is this...Our walls, even the straight ones, are anything but. The floor in the storage compartments on the 240 series is lowered about 3" as well as being set back. This is going to require some pretty significant "one off" customization. I have a call into David on angles and sound properties. I am not certain on any of that. I am getting that this sub is designed to be installed in an enclosure that is from 1/2 CU FT to 1 CU FT of internal volume. David has already told me to stay close to the 1 cu ft size with allowance to drift below if needed, but shoot for 1 cu ft vs .5 cu ft. My question is this, with some unique angles present as well as radius'ed walls, what is acceptable? Can you have more or less than 90 degrees on angles? Can you have a shelf cutout? Can you have a mounting wall that is sectioned with several angles? What does this box do, other than provide an enclosure of sealed airspace to allow maximum resistance for the woofer to work from? If it is literally a volume of air, are angles of importance?

Hope you guys have some practical application and discoveries you want to share!

 

[harsh]

I have shifted direction and gone with the JL M10W5, acoustic suspension subwoofer, over my previous sub, the M10iB5. Both are pretty much the same sub, but the W5 is tuned and built to be in a box, and the 10iB5 is built to be a "free air" or "infinite baffle" sub. As my friend @David Analog, Earmark Marine founder and owner (retired) tells me, they are virtually identical from low through moderate gain, but that is where the AS sub will separate itself from the IB sub. My buddy @PEARCE , used the word, "tighter" base or more responsiveness. I don't know the technical terms nor can I describe it like a fine wine. But I can tell you that I have matured a bit in my desire, so in comes the AS sub.

Box building. I am going to do an MDO or MDF with a solvent glue verses a water based glue...for obvious reasons, were in a boat on water! But my question to all of you that have undergone or even applied a ready made structure is this...Our walls, even the straight ones, are anything but. The floor in the storage compartments on the 240 series is lowered about 3" as well as being set back. This is going to require some pretty significant "one off" customization. I have a call into David on angles and sound properties. I am not certain on any of that. I am getting that this sub is designed to be installed in an enclosure that is from 1/2 CU FT to 1 CU FT of internal volume. David has already told me to stay close to the 1 cu ft size with allowance to drift below if needed, but shoot for 1 cu ft vs .5 cu ft. My question is this, with some unique angles present as well as radius'ed walls, what is acceptable? Can you have more or less than 90 degrees on angles? Can you have a shelf cutout? Can you have a mounting wall that is sectioned with several angles? What does this box do, other than provide an enclosure of sealed airspace to allow maximum resistance for the woofer to work from? If it is literally a volume of air, are angles of importance?

Hope you guys have some practical application and discoveries you want to share![/Q

 

[David Analog]

Angles do not matter. A square or rectangle or wedge shape does not matter. The enclosure will essentially function the same as long as the displacement is the same. All this holds true to a point. Really extreme angles or an extremely elongated enclosure will begin to change the behavior of the air mass. But you will not need to get that extreme. So if angles are limited to 30 degrees and dimensions are within +/- 50% of the middle dimension then don't be concerned. The enclosure will mostly mount via the baffle surface. If you want a secondary support then make this as a screw-on appendage. Use birch or HDPE for the appendage. If resting upon or mounting to any carpeted surface, use a small HDPE/ ABS/ polymer pad and keep the contact surface area to a minimum.

 

[harsh]

I just finished up a install on my 212x. Always been a jl guy but went with a ported kicker l7 12. I installed box behind steering column and was able to get 2.25 ft out of it. Sounds way louder than my previous 2 12" jl w3. Figured it was wasted space anyway. Didnt want to loose any storage or ballast space. I am driving it with a alpine pdx 1200 watt mono

 

[jetboater4life]

I just finished up a install on my 212x. Always been a jl guy but went with a ported kicker l7 12. I installed box behind steering column and was able to get 2.25 ft out of it. Sounds way louder than my previous 2 12" jl w3. Figured it was wasted space anyway. Didnt want to loose any storage or ballast space. I am driving it with a alpine pdx 1200 watt mono

Any pictures?

 

[0627Devildog]

Any pictures?

+1

 

[harsh]

View attachment 9539

 

[jeremy0011]

View attachment 9539

Where did you get your box?

 

[KXCam22]

I always glass the inside of my Sub boxes with FG resin for extra SQ. It seals the MDF against air absorbsion (there is a technical term for it). The extra angles inside actually help since you are trying to avoid having parallel surfaces that the sound will bounce between. Cam.

 

[David Analog]

I just finished up a install on my 212x. Always been a jl guy but went with a ported kicker l7 12. I installed box behind steering column and was able to get 2.25 ft out of it. Sounds way louder than my previous 2 12" jl w3. Figured it was wasted space anyway. Didnt want to loose any storage or ballast space. I am driving it with a alpine pdx 1200 watt mono

So how does the bass energy get out of the compartment?

 

[harsh]

Bass is such a low frequency it seems to travel just fine. I did vent under the steering wheel with 2" holes which helped out the air flow..

 

[harsh]

I made the box out of birch wood and lined it with truck bed liner before I put carpet on it for the moisture barrier

 

[jeremy0011]

Can you share your box plans? I'm assuming it went in under the seat then tilted up? How did you attach it? I have been thinking about that location for my install but other projects keep getting in the way.

 

[Geiger41]

View attachment 9539

You fit that through the backrest opening ? Or slide it under?

 

[harsh]

You fit that through the backrest opening ? Or slide it under?

I
I took off the entire dash. I will look and see if I still have the dimensions

 

[txav8r]

Bass is such a low frequency it seems to travel just fine. I did vent under the steering wheel with 2" holes which helped out the air flow..

No disrespect intended, but without a vent of equal size, aren't you losing 50% of the energy inside the compartment. I considered the pass thru walkway from the bow to helm as a location, but even in the open, 50% of the output goes forward, and 50% goes backwards. I did an IB sub before and it was great. I wanted to see the difference with an enclosed sub. I suspect putting a sub inside a compartment without a vent of equal size to the woofers output is seriously muffling your bass output. No doubt that nice driver has thump and bass, but you have to be restricting it severely. Maybe a vent under the helm of equal proportion to the driver and face the driver towards the vent? It would still have some loss but not near what your getting now. I'm a rookie at this stuff, but I study and research, along with inquiring of the true sound engineering experts, I want to get as close to 100% of what I can from my drivers...I am paying for them, I want to get that output! How did you get that box in the helm compartment? That is serious watts behind that sub!

Thanks @David Analog for the explanation on the angles. The interior of that compartment behind the drivers seat is a challenge. I wish I could just pull the carpet and use the two walls themselves but I know those thin fiberglass walls would really be a poor surface for acoustics. MDF is a very poor surface to sink a fastener into and expect long term hold, if there is an pull on it whatsoever. So in fastening the box to the subwoofer, with the wall sandwiched between, I am thinking the only way is with a thru bolt with washer and nut inside the box. I can't see a screw, even 6 of them, hold long term inside the easily pulled fibers of MDF. Am I on the right track?

 

[KXCam22]

I agree with txav8r. Its like a sub fully enclosed in the trunk of a car. It you port it into the living area the sound SQ goes up dramatically. With respect to the screws pulling out, you can find a number of threaded inserts to put into the MDF. They have a nice course thread outside that you can screw and glue into the MDF with a machine screw thread inside. They might work. Cam.

 

[jeremy0011]

If I can figure out how to get a sub inside the helm I will put in a louvered vent or two to get the sound out, I really don’t want to give up any under seat storage.


You can find stainless threaded inserts for wood here. http://www.mcmaster.com/#standard-threaded-inserts/=t4vtbq

 

[David Analog]

Ply, Medex or MDO will hold a screw a bit better than standard MDF. In any case, with six screws supporting just the enclosure, the adhesion of a silicon gasket, and another six screws mounting the woofer, passing through the fiberglass and into the enclosure, I don't see the enclosure going anywhere even on a flat bottom towboat and hard chop. A jet boat is an easier task. The woofer is supported independent of the enclosure. The collective sandwich becomes crazy strong. But I would error on the side of over-engineering simply because it is no extra trouble....and, well....because it's you, Mel. Pre-mount the enclosure with six 1/8th flathead S.S. bolts, lock washers, double nuts and a silicon cap. Access through the 10-inch opening is a breeze. You can add an appendage bracket or support from underneath. Then you should be able to stand and bounce on the enclosure.

 

[Evil Sports]

Im stupid, why do you want to put it in a box and have it inside a closet