Subwoofer install

[Samuelp63]

Good evening folks.

I started on a sound system a couple months ago. I have two 8” Rockford fosgate tower speakers and JL audio 6.5’s all the way around powered by a 900x4 kenwood amp. The highs and mods sound great. And I have extra power to play with if I decide to add another set of tower speakers.

Now I’m ready to do subs. I know everyone here loves wetsounds but honestly they are out of my budget. I plan on building my own box and wrapping with fiberglass. I have a 2000x1 mono kenwood amp. I’m debating on two things, placement and single/dual subs.


Placement.
So the “easy” options are build a simple box two go in the storage locker in the console on the passenger side of the boat. Lots of room and it will be nicely tucked away. I would put the box on the right side of locker and could face the speakers either inward (towards the center of the boat) or outward towards the side of the boat.

The not so easy option would mean building a box to go under the driver console where the drivers feet would be. My only issue with that is you see the subs and it takes away from how clean the boat looks. Building this box would be very easy for a single sub but much more complicated for two, yet doable.

Subs.
Now I know I’m going to catch crap for this but it’s what I’ve always used. I could use two 2” Rockford fosgate 10’s (or 12’s) and not be underpowered.

Option b, and this would be more heavily considered if I go with a single sub, an L7. They can handle the power and require very little airspace.

Please keep in mine, budget busget budget. I want to use the amp I have and I can do everything else for under $500. I also plan on adding an additional battery and a cut off switch. Any opinions would be appreciated.

[Samuelp63]

Should add it’s a 2000 21v

[chpthril]

Please keep in mine, budget busget budget. I want to use the amp I have and I can do everything else for under $500. I also plan on adding an additional battery and a cut off switch.

Do that $500 also include the dual battery setup? This budget is doable, but it depends on your expectations. Do you want to add some bass, you know, fill in those missing ranges, or ripple water? Dual woofers or Kicker L7 type setups are going to push that $500, leaving little or nothing for the battery setup. A more mild woofer setup with solid bass, can certainly be done, and leave some left over for the battery setup.

Placement, under the helm is better then just about any other spot. It can be done to look good and not out of place and with little loss of leg room, but it will take a lot of time and planning. Closed in the port locker is going to be like reducing the amp power by half! Its becomes a boat shaker and less of a bass maker. The way to go here is to vent the locker with a grill.

Dont get wrapped up in woofer brands right now. First get the design and alignment worked out. Woofer size and/or number, enclosure type, size shape, placement. Then focus woofer build quality and characteristics. At this point, some brands and models will naturally fall off the radar and others that you had not thought of, might end up on the list.

What are the RMS wattage outputs of that amp at the 4 ohm, 2 ohm and 1 ohm of that 2000x1? This is going to aid you in choosing the right woofer and proper coil configuration. RMS is whats important, ingore those peak marketing numbers.

[Samuelp63]

Good afternoon sir.

I wasn't factoring for the batteries in the $500 budget. My boat has an old car battery and no switch in it for some reason. Going to do two autocraft marine deep cells (800 cca). They run $90 each.

After some research, and some help from a buddy, i was able to swap out my amp for a rockford fosgate 1200 (includes rms certificated showing just over 800). I ordered a single 12" P3d4 (600 rms 1200 peak). I'm going to wire with a 2ohm load and mount the sub underneath the helm and build a box 19x15x9 to go inside the helm locker. This will give me exactly the advised airspace (1.02) and keep everything nicely tucked away.

Once I get it hooked up i'll see how much the sub will handle. if all goes well i may consider adding a sub to the port locker. the amp can handle a one ohm load and those two subs paired will work under a one ohm load as well. Going to start preparing tonight. Will likely have to move my amps around in an effort to keep it out of site.

Thoughts? Thank you sir.

[chpthril]

800W rms at what load?

1.02 ft3 sealed or ported?

Sounds as if you are front loading the woofer in the helm wall, with the enclosure back loaded through the locker access. Consider doing a ported locker and you just may not need to load that amp down to its minimum impedance doing a 2nd woofer.

[Samuelp63]

2ohm.

sealed.

You are correct sir. Please elaborate ported locker sir.

[Samuelp63]

Also while i have you, what do you suggest for prop? I've got the 350 black scorpion with blue v drive. I'm overpowering the crap out of the current prop, acme 537.

[chpthril]

800W rms @ 2 is perfect for a 600W rms woofer and the amp runs pretty conservative. Going to dual woofers at a 1 ohm load, you max the amp out for only another 400W rms. Thats a lot of work to gain the benefits of the extra woofer surface area.

Doing a ported enclosure would nearly double the output, without even asking the amp to do any more work.

1433 is a great prop for that boat. Maybe go a little more aggressive if you boat at a higher elevation lake.

[Samuelp63]

We are in Florida. I hate not having a spare prop, i'm going to swap them out and keep my current as a backup.

As far as porting the box, i'd have to see how wide the helm locker is. I'm maxed out at 15 high and 8 wide to get it into the locker. I'll have to look into ported boxes, i've never built one. Would it counter productive to port into the locker or would it need to face the same direction as the sub (through the wall)? Need 1.79 for a ported box.

[chpthril]

Yes, you want to port into the cabin with the woofer for best effect. Into the closed locker will somewhat negate the benefits.

[Samuelp63]

Looks like the box would have to be 28"wide, i couldn't imagine i have that much room. I'll verify tomorrow.

[chpthril]

If to of your dimensions are fixed, meaning no more space to go larger with them, then doing a proper ported enclosure will be tough if you have to move the 3rd dimension out to 28W. The next best route is to go with the 15" woofer

[Samuelp63]

How should i wire the switch? Do i leave the amps connected directly to one of the batteries?

[tigemech]

possibly run the amps to a buss bar close to the battery then use 1/0 gauge wire from buss to switch to battery? chpthril will know the right route to go. But you can buy this kit https://www.westmarine.com/buy/blue-...iABEgJ8A_D_BwE for your switch and battery isolator.

[chpthril]

Great kit linked above, but its vastly different then a traditional 1/2/BOTH switch setup. Either way, depending on where you get it from, some come with custom wiring schematics.