New helm subwoofer encloser design help for malibu 247

[rjones]

Hey all...... I have made some decent progress the last few nights on running RCAs, Power Wires, and just cleaning up the previous installers job. So up to this point I have wired in my new WS-420 and have it operational. I "tuned" my cabin/tower speakers per the instructions in the manual and it seems to be so much louder/clearer. I never really changed my gains, low/high passes, and messed around with my amps much at all until now and it made the world of difference! My REV 8's absolutely scream and they are underpowered I feel like with my XDI80.4 Arc Audios. Now I just have to get a box designed and fabricated for my 15" XXX. Now onto a few update pics......

I forgot to mention, I kicked my WS LED controller on for my lights and of course I have noise in the speakers now. The LED controller is powered off of the medallion box underneather the dash that has a power strip to tie into. The power from the strip is going to an on/off switch that heads to the controller itself. What is the best way to remedy this issue? I am guessing I should make some home runs back to the house battery for my power/grounds for the lights?

Look at this sexy, 2000+watt gobbling, manly sub of a subwoofer! Cant wait for this thing to pound this summer!! :rockon: :rockon:

Edited March 4, 2015 by rjones

[MLA]

My REV 8's absolutely scream and they are underpowered I feel like with my XDI80.4 Arc Audios

240W rms x 2 @ 14,5, so 200W + to each @ 12.5V for sure. Thats not too shabby for 2 pair.

[rjones]

240W rms x 2 @ 14,5, so 200W + to each @ 12.5V for sure. Thats not too shabby for 2 pair.

Dang you are correct, I just looked up the specs on the amp. I thought I was only getting 120 per can not thinking about the amps being bridged! Well in that case I can see why my rev8's are screaming now and I have been very impressed with these small amps. They really have a small footprint for much power they are putting out.

[rjones]

Well in between time from work and life its been hard to work on this project as much as I'd like but here are a few updated pictures. I have my cardboard mock-up box done for the most part and I hope to be cutting some wood next wood! I know it looks hideous but its gives me a good idea of my cuts I need to make! Surely the completed product will look a little better.....

[MLA]

That steering cables looks awfully close to clearing the end of the enclosure. Any way you can just get it behind the enclosure rather than that notch? We typically find a little play in the cables.

[rjones]

I have about 3 inches to end of the enclosure from the steering cable notch. I would much rather not mess with notching but I was hesitant about pulling on the steering cable to hard. I will see if I can get any play in it but from the little I have tugged on it, it seems pretty dang stiff in there. I am running that 15" XXX, which calls for 4^3ft so I am trying to squeeze every inch out of the helm I can.

[David]

You don't want to place that cable in any kind of a bind or shrink the bend radius. You could have issues down the road. But you can elevate the enclosure a bit and you can slot the floor a bit.

I like the reversed 'Z' shaped enclosure because it requires no compound angles and makes good use of the open space high and to the outside.

If you are using bass-reflex you can run a portion of the port on the enclosure exterior. As long as the numbers are right, an interior or exterior port makes no difference.

[rjones]

Thanks for your input david. After looking at the boat last night, I will definitely have to notch the box to clear the cable. One thing I hadn't thought of though is to notch the floor as well, which I plan on doing after looking at things. I don't like the idea of the box sitting on top of the cable pinching it off on the fiberglass where it comes out of the floor. The steering cable itself seems very durable and rigid but with a 80 lb sub + box weight sitting on top of it I could certainly see that being an issue from the cable rubbing through over time. I am planning for the box to sit on top of the fiberglass lip to left under the helm, so it will already be elevated 3/4".

On another note.....I am still trying to figure out my port and what I am going to do there. I am leaning towards just doing a slot port like nyryan did on his box and tune it to the note of 34-35hz.

[nyryan2001]

rjones... if I were doing the box DIY... it'd likely have an Aeroport vs a slot port like Shawn has on his. Muuuuuch easier to build, allows larger net cf for the enclosure... and its easily tuneable to a specific hz after the build and after sub installation.

Would need David to answer the technical aspects in output and sq of an Aeroport vs a slot port.

[Murphy8166]

Have you guys ever considered adding the slot port to the outside of the box. In that picture above, think about adding a slot port on the side of the box where the ballast hose is. Port does not have to run the height of the box as well. This is a great way to use that added space that the outward angleing on the hull creates

[David]

Pertaining to the cable, my main concern is the resistance I feel when that cable is in a bind or placed in too tight of a radius. I worry that could lead to issues between the cable and the jacket down the road. Just a concern. Maybe a conversation to have with BU.

No doubt that an Aeroport is far more convenient in every sense as compared to a slot or rectangular port as an integral part of the cabinet build.

You can radius the mouth of any port and I recommend that you do that in any case.

My only reservation with an Aeroport is that you only have the 4" size to select from. 6" is too large. That's about 12.5 sq.in. of surface area. For a really long excursion 12-inch subwoofer I would like to be in the realm of 20.0 sq.in. surface area. With all the pros and cons of larger vs. smaller ports, on balance the 20 sq.in. is a good number for a 12-inch with major Xmax. The smaller the port surface area the greater the velocity of air traveling through the port, which is the primary issue with port noise.

A port with a larger surface area requires a longer length of port to tune at the same frequency. That increases the overall port displacement which also increases the overall cabinet displacement. That's the trade-off.

[rjones]

Hmmmm you guys definitely have me scratching my head and re-thinking my plans before I get to far into the box build. Ryan, I agree the aero ports would be much easier to work with and install but I like the look of the slot port. Who's gonna really be looking at my box port though? lol Murphy, I actually thought about trying to design a port off to the right by the ballast hoses but that makes the box much more challenging to build. The thread below is a box design for exactly what you're talking about.

http://www.themalibucrew.com/forums/index.php?/topic/50863-247-stereo-build-rgbs-and-lasers/

David thanks for the explanation. I am going to sleep on this and do a little more research before I decided on port design. Port noise is one of my major concerns with this 15" sub that has 54mm Xmax.....it will be moving a ton of air through the port and I feel like that would be an issue with aero ports.

[nyryan2001]

David-

I just ran the numbers on a port calculator for a 6" Aerport:

1 round 6" Port, 3.5cf enclosure at 35hz

requires a 13.3" length port. thats 19" port surface.

rjones- whats the depth of your box? you are at 16-18" deep arent you?

[David]

ryan,

I'm a little confused by those numbers.

Surface area is (R X R) X 3.14. So a 6" port would have a surface area of 28.26 sq.in.

As the surface area increases so must the length of the port in order to offer the same resistive value and tune at the same frequency.

A 13" port length just sounds really short?

[rjones]

Ryan - I am right at 22" depth on the box if I recall correctly. I don't have my measurements in front of me but I know it was right over 20. So if my understanding is correct.....the more surface area your "mouth" of whatever port means you must have a longer port to make up for the "bigger hole" in simple terms to increase the resistance due to the loss of resistance with a bigger port?

[nyryan2001]

Rjones, that's correct.

Find and Aeroport calculator online.

A 6" round port for a 3.5cf box at 35hz requires the port tube to be 13.3"... Plenty of room with your 22" box depth. And with 28+" of port surface area... Assumes no port noise.

I am following your build closely... Cuz if my box sounds like doo doo I'll rebuild along these lines.

[David]

Ryan,

Okay, without checking it I think I understand. First, that is a really BIG box which cuts down on the required port. Second, the port length excludes the flared fixtures at both ends of the tube which does extend the overall port length.

So will you need to increase the enclosure size by the net external displacement of the port?

[nyryan2001]

Maybe... Just trying to play with the numbers to see what's possible. We know 4cf is possible under dash in a 247.

Also I didn't subtract out the sub volume.

[rjones]

I am trying to get as close to 4cf as I can since that is the called for spec for the 15" xxx ported. I was pretty surprised with how much space was under the helm after I got all the wiring cleaned up and heater taken out. You just have to work with some goofy angles to take advantage of it. For big boxes 3cf+ it comes down to how much leg room do you want to sacrifice?

[nyryan2001]

[nyryan2001]

[nyryan2001]

If you compare that ^^^ padded section on the right... It's approx 3-4" cut shorter from OEM.

[rjones]

Ryan I did think about having to cut back the lower right padded section. Did you just have the front cut down and move the weight/safety warnings down? It doesn't look like it will be hard at all. Looks like I will have to remove staples from back side, cut the plastic mold back 3-4", move safety warnings down, and then re-staple the vinyl fabric back down? I need to get my box built before I worry about this step though I guess.....

[rjones]

Hey all I wanted to update with a few pics on how my build is going. Once again with work, relationships, and life in general it is hard to devote as much time as I'd like to this project. These compound angles and using a handsaw are definitely testing my woodworking skills. Slow and steady wins the race though......

[Draggin Nutz]

I'm right behind you rjones. I will start mine next week but I'm no where close to that much power! I have all Alpine and Wetsound equuoment so stayung with that. Ibhave a Type R 12 that sounds really good so Im going with an Alpine Type R 15" and pushing it with the 1100watt Alpine PDX amp. Glad your leading the way and I can't wait to see it!

So, even though my power will be less, can I go with the same size box and port size???