Recommendation For Boat Install

[needmoresound 0]

I am planning to utilize the space under the rear bench of a boat for a sub for listening in open space. I would like to get the most punch with this volume and I'm looking for recommendations. My overall goal is a balance between loud efficient bass and a decent flat response for bass frequencies suitable for most kinds of music. After MDF board thickness, I have an internal space of 3.5 cubic feet to work with. Since this is a boat installation, I assume that it would be advisable to consider an enclosure designed for home use as they are better suited for open space for this application. If I went with two RL-p12's, each would have 1.75 cubic feet available volume. If I went with four RL-i10's, each would have 0.875 cubic feet available volume. Which would be best suitable, and in either case how do I even begin to tune?

[dopey 0]

You'd be better off spending the majority of your budget on mids and highs. Bass tends to vanish on a boat.

I'd go with the 10's...in a spl style box.

[needmoresound 0]

How about two sealed RL-p15's in that space compared to 4 vented RL-p10's?

[Mark LaFountain 1,054]

because your in a boat, you'll loose alot of sound, thats why I would recommend a 4th order bandpass with one respectable 15". Thats what I would do, IMO

[needmoresound 0]

That makes a lot of sense. What frequency would you tune to?

[Mark LaFountain 1,054]

That makes a lot of sense. What frequency would you tune to?

if your talking about my post, I would do the lower the better, say 35hz or so

[needmoresound 0]

Yes, thanks very much. I have only experience with sealed and vented enclosures so I have some research to do.

[Mark LaFountain 1,054]

Yes, thanks very much. I have only experience with sealed and vented enclosures so I have some research to do.

no prob, good to see more and more new members around here. thanks for joining

[///M5 2,833]

Personally I'd give up on the low-lows and use pro audio drivers. Like stated, I'd focus on mids & highs instead of subs as well.

[needmoresound 0]

Thanks for the help, and the welcome, I really appreciate it. I haven't been into sound in over a decade and so overcoming the open space aspect is a real learning experience. To me sound without great low end is dull and I'm weighing all of the options for the best compromise in an open space environment. As higher frequencies carry further and are much more efficient in open space, I'm wondering if the correct compromise is to get the most audible bass by tuning more to the 60 HZ range. While not as low as tuning to 35 Hz, 60 Hz is noticeably louder in open space where there is no resonation to boost audibility of lower frequencies.

Using Boxplot, I'm getting some decent results with the Soundsplinter RL-p15 dual 2-ohm in a vented enclosure, tuned 60Hz@127dB or tuned 80Hz@133dB. This is more impressive than the results for using three RL-p12's which estimate a peak range of 123dB@70Hz through 125dB@90Hz. That is after adding 6dB for three drivers. Using four RL-i10's on the other hand estimated a peak range 124dB@60Hz through 128dB@80Hz, after adding 9dB for four drivers. I have no method to calculate SPL for 4th order bandpass configurations to make any comparisons though.

In a sealed enclosure, Boxplot estimates the RL-s15 at 117dB over a smooth range of 20 Hz to 200 Hz, and the RL-s12 not as smooth nor loud. But Boxplot also estimates these with a massive sealed enclosure. The details about the RL-s12 and RL-s15 on the Soundsplinter website claim that they can be used within an an closure small enough for my application, using what they refer to as "net volume sealed" and "infinity net volume sealed". What are these exactly? Might they be applicable? I'm still interested in finding a way to compare a 4th order bandpass to all of this though.

On a side note, I found someone that achieved 144dB in a competition on his boat with a single sealed 15". Although that measurement was from just under 2 feet away, comments from attendees praised his system as much louder and clearer than any other boats, even one with eight 10" subs, but I'm sure those subs were not nearly as powerful nor optimized as the Soundsplinter configuration I've considered. I'm wondering if the calculations I'm making for myself would be comparable considering they are at 1 meter as opposed to under two feet away. His system can be seen at http://www.wakeworld.com/MB/Discus/message...html?1178822473

There could probably be a section for boating stereo since it's such a different animal than both auto and home stereo. People love loud music on boats, and it's legal. Again, I appreciate all your input.

[///M5 2,833]

I think we need to take two steps back.

1) Some info would be really helpful: What kind of boat is it? What engines/alternator/battery configuration does it have?

2) You misunderstand my low-lows comment completely. Most pro-audio drivers do roll off, but we are talking about below 60hz. If you tuned a ported box that high it will roll off harder than the roll off I am talking about. Either way you can't tune to 60hz, it really won't sound very good. Realistically IMO 60hz should be played by midbasses and not subs, if at all possible I take my mids even lower than that.

[needmoresound 0]

1) The boat is a Mariah Z302. It has three marine batteries with room for plenty more, but aside from the extra space in the engine compartment, the boat is the most thoughtfully designed layout taking advantage of all space. Even though it's 30 feet, everything is perfectly molded and there is no space for a large box that wouldn't completely butcher it; the only exception being just the center section of the three-section rear bench. I wish it wouldn't be foolish to use the engine compartment.

2) Ok thanks, that's the kind of thing I really needed help with: determining what really is and is not a feasible compromise. So 60 Hz is more suitable to drivers that can utilize much less space than this, that's good news. Then I would like to go with dedicated low lows, and also mid bass with separate drivers. If I can get away with a single 15" for the lows, I'll have more to spend on other frequency ranges, kind of in-line with you're first suggestion to not be more concerned with lows over anything else. I have to be careful because I can't exactly break the bank on this. I'll re-calculate the options to optimize this space for the 35 Hz range. I still wish I had a way to determine how much more effective a 4th order bandpass would be than what I've considered. If it's generally well-known that this is much more effective I would just take one's word for it and go that route. Any suggestions for mid bass as well?

Edited May 29, 2007 by needmoresound

[///M5 2,833]

I am not sure that a single 15 will be enough in a boat to really get down low and boogie. I also assume that the z302 is a single screw with no genset? If so, you are quickly going to run into a voltage problem supporting a system that really wangs on the low end. Efficiency is your friend on the water.

What sort of music typically gets played? Is this going to be for when the boat is running or mostly for when it is parked? A budget would be helpful as well. It takes way more money to get a boat to thump than a car.

[needmoresound 0]

Yes, the power comes only from the single alternator so efficiency will be key here. Would like it to be adaptable to most types of music, the ability to play bass music would be great but also would like rock to sound somewhat proportionate. Both running and parked. And while I'm asking so much, may as well throw in the best bang for the buck.

[Tirefryr 1,742]

I'm currently doing a boat install myself. A pair of MJ-18s will be on call for bass. Luckily, this is a deckboat and I have all the underseat access in the front of the boat to use for enclosure space. I am going with a 38Hz tune. Low enough to hear a little thump, but I will gain gain efficiency and not have to worry about a super low and flat passband with a low tune. The way this boat is designed, there are channels to load the bass on both the floor and sides, so hopefully, I should get some decent response. Mach 5 is hard to beat for bang for buck. I had also thought about the pro audio route, but most of the drivers willnot stand up to marine use for more than one boating season. Plastic or coated cones are a must.

[///M5 2,833]

I had some paper coned fosgates in my boat for nearly 10 years. They were treated, but paper nonetheless.

The real question is how long do the batteries have to last playing while you are sitting still. This will define what you can and cannot get out of your system.

[dopey 0]

I had some paper coned fosgates in my boat for nearly 10 years. They were treated, but paper nonetheless.

The real question is how long do the batteries have to last playing while you are sitting still. This will define what you can and cannot get out of your system.

And bass will drain those batterys FARRRR faster than mids/highs. A marine enviroment is already tough on engines/electrical (hence the 3 batterys, standard) don't get stuck on the water because you bumped too hard too long. Chicks don't care about the stereo if you can't take 'em home.

If it were me, I'd look at a MAW15 (cheap to replace, decently loud, low power requirements) in a slotport (or bandpass, as M5 suggested) box. See if you have a drywell you could use to house a good portion of the box.

Then I'd REALLY beef up the mids and midbass with 6.5 mids, and some 8" or even 10" midbasses. Poly cone would be an asset here.

I'd put the (metal) tweeters under the dash or someplace dry and protected.

[needmoresound 0]

I'll be using the house batteries to power the stereo so even if they go dead the engine battery will be unaffected. After more thinking, practicality is very important because when you're on the water partying nobody wants to be tinkering around with their system. Things can go awry quickly here in the Lake Erie/Niagara Falls region, downpours can overcome you before you have time to get your canvas up, and by then the high wind and piercing rain make each zipper and snap a battle of their own. The women around here are die hards, they don't mind the turmoil, but speakers and amplifiers do. I'm under the impression that the bandpass is a power-efficient and space-efficient way to get some lows so I'll be looking into that. Even though all other frequencies are more critical, they don't take up that kind of power and space so that's why I'm taking my time on a good solution for the lows. I'll check out the MAW15. I'll be looking for a software program that can optimize a bandpass driver and estimate it's performance. Thanks again for all your help.

[needmoresound 0]

Ok, I've done a lot of work based on the direction you've pointed me in and I'm finding that I can get more than twice as much sound when tuning a sub to 40 Hz as opposed to 35 Hz. I googled around and see that most people urge tuning to 40 Hz over 30 Hz. The pro audio driver suggestion was great as well. It's amazing how minute changes in design can affect results by several orders. I'm taking a lot of time to choose the optimal combination of the best drivers suitable for each application in the system and I'm now expecting the results to be amazing. I'm thinking to get the most SPL at a decent SQ, as far as the low to mid range of the system, I should go with a 40 Hz tuned sub and pro audio drivers crossed at around 70 Hz. What do you think about 40 Hz tuning as opposed to 35 Hz?

[dopey 0]

What kind of music will you be playing?

Rock and radio type crap...40hz will be ok. IIRC FM radio wont carry signals below 40hz anyway.

Rap and hip hop (cd) 35 would be better.

Edited June 2, 2007 by dopey

[needmoresound 0]

It would be nice to go crazy with the bass for when ya want it but it's just not practical as far as watts alone. So my goal is to make a system that at least has a somewhat flat frequency range that extends naturally into the lows. I decided to go ahead and make use of the cabin for a sub. According to my estimates with Boxplot, if I under-power larger subs in as large an enclosure as possible, I can get real good bass with not much strain on the battery/alternator. I'm leaning towards two Soundsplinter RL-p18's in 8.88 ft3. The dual 2-ohm version produces better results than the dual 4-ohm, which seems to be the case for almost all of the bass drivers I've calculated. I'm probably going to go with a Hifonics BXI1606D monoblock amp at 2 ohm. Is it better to wire each driver as 1 ohm and series the two together to 2 ohm, or better to wire them each as four ohm and parallel them together to 2 ohm? Not sure if it makes any difference.

Also, in a ported enclosure, can I place one driver on one panel and another driver on an adjacent panel, or do they need to be on the same panel for these calculations? I would need to place the two drivers on adjacent panels to fit in a practical location in the cabin.

[needmoresound 0]

...Ok, I just realized that my understanding of tuning was way off. I was assuming that the peak of the frequency response curve was the tuning frequency but it's far from it. When my peaks were at 50 Hz as I preferred, I was assuming that it was tuned to 50 Hz, now I see that I actually was tuning to 35 Hz perfectly, which is exactly what you recommended. Thanks. Also, The MJ-18's appears to perform as well as the RL-p18's. I still would like to know if it's ok to place two drivers on adjacent panels on a vented enclosure.

[///M5 2,833]

If I understand you adjacent panels I would say most likely. Not so sure on your MJ and RLp comparison though...I have a ton of respect for both drivers but they aren't the same.