HELP building ported enclosure

[Deephaven]

Is there motor force if you have no current traveling through the voice coil?

David

Ha funny. Wrong word. Suspension is stiff as hell. :P

[jrad12381]

OK dynomat would take up less cubic feet. Am I better of using dynomat or another layer of MDF?

[Earmark Marine]

jrad,

Dynamat is really good at damping resonance and eliminating coloration but it can't do much in the way of increasing the material rigidity as applied to a sub enclosure. So I would separate these two issues and benefits. Any degree of enclosure flexibilty translates to lost acoustic energy. To increase the enclosure rigidity you can either increase the material thickness or you can divide up the surface area with internal stiffening braces from wall to parallel wall. I think .75" construction is the mandatory minimum for a 15-inch sub and a thicker 1" baffle is a good idea. The internal stiffening braces consume less displacement than the thicker walls and add less weight.

David

[jrad12381]

Thanks David I will have a double baffle, and internal braces as you mentioned. I downloaded winISD but it wont let me continue after I had T/S numbers. It just says consistency check on the following groups failed.

[jrad12381]

Would anyone help me figure out port size needed for the sub and box dimensions listed above. I should be able to get 4.4 net volume after displacement of sub and bracing, not counting any port displacement. I am interested in both slot port design as well as aero port design.

Thanks

Jared

[jrad12381]

Ok so it's time to update this thread. I will have to say that with some playing time the ssa xcon came to life in the sealed box and really started to sound amazing, and loud. With that said with hesitation I built a ported box for this sub. I used 1"MDF sealed with spray on bedliner. I ended up with 3.9 ft^3 after displacement for sub, bracing, and ports. I went with 2 aero ports and the box is tuned to 32 hz. It was a major pain in the a** to fit under the helm, but with a lot of disassembly of the boat it fits like a glove. If I were to build the box again, I would make it smaller. On a side note the output is redicolous, it is very loud, low, and sounds great.

[Stevo]

Gonna knock some dust off this thread as I have a question for a friend.

14' 23lsv and he has a JL12w7 and he wants to build a slotted enclosure . What sort of benefit does a slot vs ported enclosure have?

JL website does not differentiate between slot v port, only sealed 1.5cu, and 1.75cu ported

[David]

Stevo,

I'm not entirely sure what your question is but here are some random definitions.

'Ported' means a type of enclosure loading the woofer. In this case 'ported' means 'bass-reflex'.

A 'slot port' is simply the shape of the port such as rectangular versus round.

You can freely convert a slot port to a round port and visa versa as long as the port surface area and port length remains the same.

Although you have additional port options, I hesitate to get into them until I know you want that.

If that does not answer your question then be a little more specific.

[teamerickson]

Gonna knock some dust off this thread as I have a question for a friend.

14' 23lsv and he has a JL12w7 and he wants to build a slotted enclosure . What sort of benefit does a slot vs ported enclosure have?

JL website does not differentiate between slot v port, only sealed 1.5cu, and 1.75cu ported

Does your friends 14 23lsv have the 350? Do they like it.

[Stevo]

Does your friends 14 23lsv have the 350? Do they like it.

No 409, but my wave is better

[Stevo]

Stevo,

I'm not entirely sure what your question is but here are some random definitions.

'Ported' means a type of enclosure loading the woofer. In this case 'ported' means 'bass-reflex'.

A 'slot port' is simply the shape of the port such as rectangular versus round.

You can freely convert a slot port to a round port and visa versa as long as the port surface area and port length remains the same.

Although you have additional port options, I hesitate to get into them until I know you want that.

If that does not answer your question then be a little more specific.

Yeah I'm not sure either, he for some reason is not happy with the way it is tuned, and in convinced a "slotted port" will solve his problem. I am almost completely ignorant here and was just trying to tap some knowledge

[David]

Stevo,

As you understand exactly what his needs are, get back to us.

But I can tell you this, if the port displacement (in ratio of length & surface area) is correct then changing between rectangular (slotted) or round will not make a significant difference in what he is experiencing. The exception would be if a slot port is extremely narrow in one dimension for the size and excursion capacity of a particular subwoofer.

But there could be dozens of execution reasons why a subwoofer is not performing up to its potential.

[Stevo]

He want it tuned to 35htz, and 1.75 cu box, but is getting conflicting measurements on the slot length , one is reading 19 inches and the other is 29, which seams off

[David]

Stevo,

The W7 is at the top of the food chain in subwoofers so if it isn't extremely impressive there is definitely something wrong in the execution, which covers a lot of ground.

35 Hz is a good target number.

The 1.75 enclosure is net, net, net, internal, without the woofer displacement, and without the port & port wall displacement.

The port length is dependent on the port surface area. It's an interdependent ratio. If you change either one without changing the other, you modify the tuning frequency.

Most dealers have a dependable enclosure design program. You can verify the tuning frequency with a test disc or signal generator. Probably even a phone app. The woofer will display the absolute minimum movement at precisely the tuning frequency.