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08-21-2012, 11:42 PM #1
2002 LSV Sub, Amp(s) & Battery -- Help!
I need some help with picking and placing a new sub, amp(s) and sub location for my 2002 Moomba LSV open bow. I just got the boat at the beginning of this season and have decided to keep it
I just picked up 3 pairs of Kicker K65s for the in-boats (2 pair in the main cabin area and one pair up front in the open bow) along with 2 more pairs of KS65s located in four tower mounted DIYwake’s speaker cans. I did not go for HLCDs because we mostly listen to music after boarding in “cove” sessions
Right now I have an Alpine sub located right at the driver’s foot, it sounds bad and I hate the location as it takes up too much room
I would like to put the new sub in the port side storage locker, add a second battery and need a few recommendations;
- Which sub?
- Which amp for the sub?
- Which amp for the KS65s (total of five pairs)
- Can the amp(s), sub, enclosure and two batteries fit in the storage locker?
If mounting in the storage locker;
- Do I need to build a custom enclosure?
- Would adding one or two ports like these in the vertical panel between the locker and the walkway help?
08-22-2012, 10:36 AM #2
Acoustically, placing a sub in the port side observers locker is a bad idea. Ideally, you want a direct radiating subwoofer.
The port locker with the adjoining gunnel cavities is a massive displacement. Any venting as a ratio to the highly compliant locker/gunnel air mass is very resistive. That sets up storage and filtering. The losses can easily be 6 dB and more at some frequencies. That means the sub and amplifier are working four times harder for the same acoustic output. That can lead to reliability issues. The coaxials that share the same gunnel cavity become sympathetic resonators for the subwoofer so you can forget quality midrange from that side of the boat. The port helm structure is excited and that acoustic energy is counter-productive in several ways. While you should definitely vent the locker, ports/vents with any degree of depth, even an inch or two, set up more resistance which results in more storage, phasing delays and filtering. So a vent must be as shallow as possible and represent a lot of open surface area. All this creates phasing challenges which makes integration between the sub and the coaxials a real challenge and you are dependent on the midbass drivers of the coaxials for the bass tonal definition and quick bass transients/attack. Can you get some 'hit', 'boom', and 'rumble' from the port locker? Sure. But it's more of an indiscriminant boat shaker than a tight and musical bass maker.
I would recommend this. Take a more creative or complex approach to the starboard side even if you have to use a smaller woofer. It will sound MUCH better if correctly designed and executed.
08-22-2012, 04:42 PM #3
Dave's post made me kinda chuckle. Holy tech speak Batman. Putting sound system in a boat is a bad idea acoustically... But we do. Same is true with subs in port side lockers. Eric, in the system you've laid out, it will be a lot easier for you to put a sub in the drivers helm area. It also gives you more room to store your stuff in the port side cubby. If you really want to go port side cubby and give up that space, make sure you vent it directly to the walk thru and you'll be fine.
Here's some basic things to think about on the questions you asked.....
Which sub? -- this is entirely your choice. Talk with guys here that have had good experiences.
Which amp for the sub? -- same as above. key point is to make sure you have a combo that works well together. you dont need 2,000 watts for a small 10" woofer. And you dont need 200W for a monster 12" woofer.
Which amp for the KS65s (total of five pairs) --- typically guys run a 3 amp system, tower / sub / cabin. I'd look at doing this as it will help you with controlling the zones musically.
Can the amp(s), sub, enclosure and two batteries fit in the storage locker? Yup. Sure. happens all the time. But be advised, you wont be storing anything there after you complete the install.
If mounting in the storage locker;
Do I need to build a custom enclosure? You wont need a custom enclosure persay, but you will need some custom installation to vent it properly to hear it. Newty on here just opens his hatch when he wants to get the full force of his port sub. His comments in this thread would be applicable for you.
Would adding one or two ports like these in the vertical panel between the locker and the walkway help? Yup.for sure! This is assuming your going with a bass reflex enclosure.
08-22-2012, 06:24 PM #4
Sure my points are technical....but they happen to be absolutely accurate. If you don't understand something, ask for clarification. It's the difference between just knowing how to build loud and boomy systems where you place the largest possible woofer anywhere and knowing how to build systems that really sound amazing. If you want to hear the kick drum mallet strike the skin so that you feel it in your chest and the attack almost makes you wince then follow my advice. On the other hand, if you want twice the woofer size and twice the amplifier power and are still unable to produce the same effects then ignore my suggestions.
08-22-2012, 08:19 PM #5
Lets start with some preliminary info. You will need to have a 2 amp install at a minimum. One amp will be dedicated to the tower speakers, and the second for the 3 in-boat pairs and sub. The sub choice and its power requirements will dictate whether you stay at 2 amp or go with 3. More on this later.
Tower: I would look for a 2 chnl stereo amp that has a 2 ohm x 2 watts RMS output of 200W plus. This will net you around 100W to each of the 4 speakers. Going with the 2 chnl allows you to run only 2 pairs of 2 conductor wires up the tower. My next choice would be a 4 chnl amp that has a 4 ohm x 4 watts rms output of 100W. These are target wattage, as this is where I like to shoot for for a coaxial tower speaker. A little less wattage and they will still perform fine and a little more wattage is great.
For your in-boats: There are a handful of great hybrid 5 and 6 chnl amp out there. An amp like this would allow you to run a 2 amp system as the hybrid will power all the in-boats and a sub. This requires less space, less wiring, and in some cases, costs less then two comparable amps to drive both in-boats and sub. These amps very on the available subwoofer power. So your subwoofer goals and final choice will have a bearing on whether you can go with a 5 or 6 chnl hybrid or whether you will need to go with a dedicated in-boat amp and dedicated sub amp. I would look for a full-range 4 chnl amp that will deliver a net wattage to each speaker between 50-100 watts rms. With 3 pair, you will have 1 pair in the bow running each on thier own chnl @ 4 ohm. In the main cabin, you will have a port side pair running at 2 ohm on a chnl and the starboard side running at 2 ohm on the last open chnl. So the amp's 4 ohm output will be what the bow pair receives and thr amp's 2 ohm p/chnl output will be what each main cabin speaker pair divides between them. More on that later if needed.
Sub: IMP, the best sub is the one executed correctly. Subs come in a handful of sizes, coil configurations and power handling. Subs typically fall into two camps. SQ (sound quality) and SPS (sound pressure level/comp), with some kinda in the middle. The subs enclosure design and volume can also influence this a little also.
Some things that you need to ask yourself in order to choose the best sub for you is how much bass output do I want and whats my budget. I also recommend getting the horse in front of the cart by letting the available space dictate the enclosure volume/shape. This will directly impact the type of enclosure you can do, the size of the woofer and the amp power needed. You will have far better results if you choose the woofer that best fits the box that boat will allow you to build, and then power is accordingly, rather then buying a woofer, then trying to build a box for it that fits the cavity. The result could be similar to the poor sounding setup you have now with the Alpine.
I would pass on doing a sub stored in a locker, ESPECIALLY if its the primary sub. The time, effort and expense could be spent on executing one under the helm. Even with venting, you still have challenges to overcome unless the woofer is placed right at the vent. You will still get some muffling which requires more power to overcome. The further away the driver is from the port, the worse the time alignment gets.
I would recommend a custom enclosure thats built for the marine environment, rather then an off-the-shelf carpet covered MDF car box. It will not last.
Amps: If your budget will allow, I would highly recommend going with an efficiant line of full-range Class-D or Class-G/H amps over 20th century Class-A/B. Smaller chassis makes installs easier and cleaner and more efficient means more play time on the water, batteries that are not cycled as deep and less time recharger house banks.
Hope this helps
08-22-2012, 09:59 PM #6
You make a great point about coupling the subwoofer baffle surface of the enclosure right up against the compartment vent. If the sub is sealed airtight against the pass-through wall and vent opening then you have effectively nullified the negative impact of the port locker. In contrast, whether the sub enclosure is set back several inches or at the rear of the compartment and not directly coupled to the wall, the direct radiation of the sub driver and the stored/released radiation from the compartment and adjoining cavities will never be in phase. The shorter/higher the bass frequency is the greater the phase cancellations/filtering. MLA, again, that was a great point.
These very basic acoustic principles are also extremely evident in a vehicle. Ever wondered why a sub enclosure in a trunk or rear cargo area sounds better turned around towards the rear rather than forward firing at the occupants? Because you are creating a uniform phase response between the woofer and the rear cavity. Ideally though you would like to seal the subwoofer radiation into the cabin and totally isolate it from the trunk. In fact, bandpass enclosure are commonly used in this application because they lend themselves to sealing the sub radiation from the trunk cavity and into the cabin.
Here is a silly easy test to understand the losses incurred when using the port locker. Play your existing starboard side sub, crawl into the port locker and close the hatch. You will still hear bass but significantly attentuated along with vibration and indiscriminant rumble. You can reverse the position of the sub and listener but the outcome will be exactly the same. Venting will help but you are still left with significant losses until you totally seal the sub output against the wall.
Or, how about the bass sound quality of a sub standing outside of a closed trunk with the license plate rattling. The bass sounds better even in the cabin when you open the trunk but you don't see donks driving around with the trunk lid open.
If you aren't convinced after this simple illustration then I have several other tests that will illustrate how important it is to bass sound quality to properly couple the subwoofer output to the in-boat coaxials' output.
It's the difference between a bunch of bass and plausible music. It may only be a boat but these fundamental principles still make big performance differences.
08-23-2012, 01:14 PM #7
Hey man, I'm guessing you have the sub mounted in the floor board. If thats the case its going to sound terrrible no matter what you do. There are pros and cons to both sides but for space (which there is never enough of in a boat) I'd go under the dash especially with the boat you have, the box size will be really limited by opening on the passenger side.
Brian is right when I open my seat back is almost triples the volume. It also keeps my amps cool. I also have a lot more space.
PWI as usual...
08-23-2012, 04:29 PM #8
Ok, so it sounds like picking amps won’t be that big a problem as I am not on a super-tight budget and we (notice I say “we”) can narrow those specifics down later.
For the sub,
Goal; clean sounding music, not looking for just the big boom. We do listen to a variety of music from AC/DC, Rihanna, BEPS, Foster the People, Phoenix, Rage, Santogold, blah, blah, blah…
I started to follow David’s suggestion about crawling into the port locker, but my wife yelled at me and told me to come inside and eat dinner…actually I understand as that is how we basically locate the subs in a home theatre, by placing the sub (or subs) in the sweet spot chair and move around the room and listen, listen, listen...then argue... then listen some more (then put it where the wife wants it!)
After reading some of the replies about the storage locker, I went out and looked at mine and now have another idea as mine has a brace right in the way where I would like to place the sub.
What if I mount the sub in the vertical fiberglass pass-thru wall on the driver’s side and build an enclosure around it? This would give me more room under the driver’s area and have the sub exposed to the cabin area (though firing at the storage locker). I will still mount the amps and batteries in the storage locker
If this works, would I be better with a;
JL Audio 10” or 12” W7
I just am worried about it being exposed to being splashed as when the sacs are loaded we can get some water on the boat. A sealed enclosure volume = ~1 1/2 cu. ft. or a ported enclosure with about 1 3/4 cu. ft. though the port itself could be a problem
Or a 10” M10W5 with a ~1.0 cu. ft sealed enclosure
Any thoughts or suggestions?
Also, what do you make an enclosure out of if it isn’t MDF, I’ve done a lot of fiberglass work, but that doesn’t seem to have enough mass?
Thanks again for any help, Eric.
Last edited by EricU; 08-23-2012 at 04:33 PM.
08-23-2012, 05:50 PM #9
I typically use a multi-layer void-free hardwood plywood like birch. Then they get 2-part resin inside and out. Even then, elevate the enclosure off the floor. No reason you cant do a fiberglass enclosure. Correct Craft uses one OEM for thier subs. Not a bad enclosure for the MOMO 10"...just in the wrong place, the port locker.
I wouldn't worry about an occasional splash of water on the cone of the woofer, they're all made with synthetic material nowadays anyway.
08-23-2012, 06:11 PM #10
Do a test on the pass-thru with most any 10-inch sub in a .65 to .75 internal gross sealed enclosure.
First, rest it on the sole in the pass-thru between the helm consoles and play it straight up.
Next, fit it under the driver's dash any way you can playing out towards the open cockpit. Remember that a woofer doesn't necessarily have to be visually exposed to still be direct radiating.
Listen to and compare the difference from the most common listening positions.
Let's say the most common listening positions are in the cockpit. In the pass-thru location half of the displaced air will immediately dissipate in the bow direction and half towards the cockpit direction.
Under the dash, you have the boundaries of the helm cavity completely folded around five sides of the woofer/enclosure. Plus, you have additional reinforcing and slightly more protracted planes (the sole and the interior coaming) between the woofer and the cockpit listeners. It stands to reason that you will lose output from the pass-thru orientation and gain output from the under the dash orientation.
We already have a number of test products and have already measured every possible acoustic scenario in a boat. But you should try this simple test for yourself. Maybe you will accept a compromise based on other priorities....but....you will absolutely know how the sub will perform in advance before you commit to a single cut.
More on woofers later.