Entry Level 12" Subs

[augie09]

got the sub and amp ordered and figured what the hell, throw in a WS420 to Now I am waiting on the mailman

[Brent Wall]

Looks awesome. That is exactly my goal as well. Did you put the screws on the inside to reduce the chance of moisture issues?

Not really. Screwing it together from the inside was just a natural result of following the golden rule of working with plywood: Always screw into the face of the plywood; never into the end (between the plys). This requirement drove the need for the 3/4 hardwood blocking on the inside and putting the through hole through the hardwood and partially penetrating the plywood with the tapered end of the screw just seems like a better approach. I could argue that your box is more tightly sealed because there are no through holes in the plywood but I'm sure this factor is irrelevant once the box is glued, screwed and coated.

Screwing it together from the inside is really no harder than doing it from the outside. A lot of the blocking can be applied before you tie the box together. In addition, I can offer one BIG tip that makes attaching the kick panel a LOT easier... Don't glue the back of the box on until AFTER you have attached the front panel. Once the front panel is on, you can glue and screw the back on through the subwoofer hole.

Once the box was constructed, I routed a 1/4 radius on all the corners to ensure that whatever waterproof covering was applied would not be thin at the corners. I also routed a 1/4 radius on both sides of the kick panel to make wrapping the carpet around it easier.

I think the 08 vlx has more space by the drivers feet than the 08 vride, so hopefully I can get that same volume box you did without surpassing the current kick panel.

Lots of great subs suggested. Can't find bad reviews on hardly any. Think I have settled for a JL Audio 12w3v3 (2 ohm), requires a 1.125 cu. ft. sealed box, with a Exile 600.1. Thanks!

I assumed that this area on a vRide was the same size as on the VLX since they are the same size boat. In any case, on my box, both the front and back of the box are slanted so I did not have to construct any "notches" in the box to allow access to the stringer access hole. The lower back of my box sits just in front of the hole and the upper back sits just in front of the wall between the helm and the bow.

* The dimensions shown are pretty close but I need to go back and update the drawing with the as-built dimensions.

Edited January 27, 2012 by Brent Wall

[martinarcher]

got the sub and amp ordered and figured what the hell, throw in a WS420 to Now I am waiting on the mailman

You boat is going to sound good man.

[Earmark Marine]

When you are thinking about powering subwoofers in a boat consider a few things.

It requires four times the amplifier power and four times the woofer excursion every time you double the distance to maintain the same amplitude.

It requires four times the amplifier power and four times the woofer excursion to reproduce one octave lower at the same amplitude.

Consider how these acoustic challenges compound in an open environment.

Contrastly, in a vehicle you will get as much as a 2nd order (12 dB per octave) rise below the airtight cabin resonance. That 2nd order rise equates to an amplifier power increase of 16 times with every halving of the frequency.

That is a ton of bottom end acoustic leverage that we do not receive in an open boat.

So in order for any given woofer to sound fully dynamic and agile we like to push the amplifier power up to or just above the rated thermal capacity. That doesn't mean that you use all of it but it makes a big difference having those reserves in a boat. Peak power will not even tickle the thermal capacity of a woofer where as compressed or clipped power is very dangerous. The extra power places your woofer at risk if you don't know how to take care of it and you can't read the signs of power compression. Some can and some can't be trusted with that power. I can't tell you how conservatively or liberally each woofer manufacturer rates their power handling and I can't tell you how conservatively or liberally each amplifier manufacturer rates their power. You would at least expect that the ratings are consistent between products of the same manufuacturer when gauging your power needs.

A typical amplifier may be 50 percent efficient while an incredibly efficient speaker could only approach 5 percent efficiency and we won't be seeing any of those in a boat.

So when we think of what will work best for a boat subwoofer we want a) the maximum power for that subwoofer within reason, b) a woofer that has a good internal efficiency (which is not always indicated by the sensitivity rating) so that the woofer is responsive (particularly in comparison to the available power), and c) to get a little leverage from acoustic loading whether that be from the woofer location and orientation or from the enclosure type.

The output difference between a given size of woofer and the size up woofer of the same series may be 2 dB but a SQ version of a bass-reflex enclosure may give you a 3 dB output increase and its half power point in the low frequency roll-off may extend significantly lower. The added surface area of the larger woofer usually rules but not always depending on the boat. There is not going to be an output difference with the identical woofer between sealed and bass-reflex at 125 Hz. And who cares because that is not where you want or need the contribution. But another 3 dB of output (equivalent to twice the amplifier power) and another 10 Hz of low bass extension can show up as massive!!

As mentioned previously in this thread the matched combination of the amplifier, woofer and enclosure is so important. You might be surprised with what some very moderate subwoofers will do with the right execution.

David

Earmark Marine

[Brent Wall]

got the sub and amp ordered and figured what the hell, throw in a WS420 to Now I am waiting on the mailman

Looks like you better get started on the box. Here are a few more tips.

• I put 3/4" rails on the bottom of the box so that the bottom does not sit directly on the carpet. This allows any water that gets under the box an opportunity to dry.

• I lined up the top of the kick panel with the top of the box. It makes it easier to wrap the top of the front panel with carpet. I also cut the 33 degree angle on the bottom of the kick panel. This makes the carpet fit a little more precisely. The bottom of the kick panel is registered about 1/4" above the bottom of the rails to allow for the carpet wrap.

• I mounted the binding post on the left side of the box. I used individual binding post rather than a terminal cup because it seems that a plastic terminal cup is not as structurally sound as a 3/4 piece of plywood. The two small holes for the binding post are the only two through holes on the entire box.

Edited January 27, 2012 by Brent Wall

[nyryan2001]

David, what are your thoughts about putting a couple 3 -4" ports on a box like Brent's?

Given a specific cubic footage of a box minus displacement of the sub, and your desired tuned hertz, you can calculate the exact length of the port tubes needed for that hertz freq.

While this might not achieve the 3db gain of a high end SQ enclosure, could'nt he get quite an improvement in 30-80hz range with precisely placed ports right in the front of his box?

[Earmark Marine]

Ryan,

Lets not talk about Brent's enclosure as he already has that thing totally dialed in. Its very well thought out and I wouldn't change a thing.

But in general...,

You can sometimes retro a sealed box with ports. If the port(s) wall construction and volume are too large and would reduce the internal displacement too much then you can place all or part of the port external to the enclosure.

Of course you need the Thiele Small Parameters of the woofer to design an optimum enclosure whether sealed or bass-reflex. And certain woofer parameters fit certain enclosure types better.

You can design a bass-reflex enclosure to do a number of things. You can tune it for maximum SPL output with a pronounced peak and kind of a single note character...or you can design a well-damped design that gives you a more limited bump in output but provides a smooth and extended response for SQ.

A small sealed enclosure (also known as acoustic suspension or air suspension) has a roll-off that has a more shallow slope but begins that roll-off at a much higher frequency. So you lose a great deal of amplitude toward the lower registers. I really like a sealed enclosure in certain vehicles because the slope tends to offset a similar and opposing 'cabin gain' rise. When the two opposing curves are similar then you get a very linear and extended response. And I am personally really sensitive to that delicate octave to octave balance.

But in the open field environment of a boat the low frequency losses are so great that a bass-reflex enclosure can make a major difference. A bass-reflex enclosure can significantly extend the bass response before it begins to roll-off. When it does roll-off it might decay at twice the rate. But in a well designed woofer/enclosure system the steeper roll-off is below a useful frequency, at least in a boat.

There can be a lot of debate over sealed versus ported. Some of the bias against bass-reflex comes from those who have been exposed to several examples of poor execution. The bad examples in cars and boats probably out number the good ones by a wide margin. Keep in mind that many of the best studio monitors and esoteric home speaker are bass-reflex and many of those owners (who may be spending $25K to over $100K a pair) are hyper critical when it comes to bass SQ.

But in a boat I look at it this way from having heard and analyzed conservatively hundreds of systems....the subwoofer system that operates the most conservatively while meeting the objectives almost always sounds the best. In other words when you expose the limitations of the system the SQ nose dives regardless of how the woofer is loaded. Its generally the most responsive system with the least woofer excursion and the least amplifier overdrive that sounds the best. And that is normally a well designed bass-reflex system. The other distortion factors are small potatoes comparatively.

David

Earmark Marine

[old skool malibu]

Yep. I have an older 12" T3HP TC Sounds sub in the boat with one of their new TC Sounds Passive Radiators. It is the most musical, but powerful sub I've ever heard. It is being pushed with a JL 1000/1 Slash.

I put an 8" Epic from TC Sounds in the trunk of my BMW. I'm running it off Murphy's old Arc Audio 300.2. It sounds awesome. One amazing thing about the Epic 8" is the smaller the box the better. It still blows me away how low that little thing goes and how tiny the box is.

If your interested here's the build thread and here is a video of it doing what it does best on the water.

Matt - I remember your build a year or two ago. I have never seen or heard a passive radiator before. What made you go this route? Anyone else running a passive radiator? What is the attraction?

[old skool malibu]

Here is what I get when I click on them.

An Error Occurred

Sorry, an error occurred. If you are unsure on how to use a feature, or don't know why you got this error message, try looking through the help files for more information.

[#10342] We could not determine which forum this topic is in.

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I got the same message Trent. Must be a Canuck issue, eha?

[Earmark Marine]

old skool,

A passive bass radiator uses mass loading similar to how a bass-reflex port uses resistance. In the same way a passive radiator extends the bass response to deliver more output in the bottom octave. A PBR will roll off a little steeper than a bass-reflex. A PBR will not require the extra enclosure dimensions for the port volume so in some cases the enclosure is no larger than a sealed enclosure.

David

Earmark Marine

[Malibuzer]

I got the same message Trent. Must be a Canuck issue, eha?

Thanks! I thought I was losing my marbles!

[martinarcher]

Matt - I remember your build a year or two ago. I have never seen or heard a passive radiator before. What made you go this route? Anyone else running a passive radiator? What is the attraction?

I built it for the small size and the awesome frequency response and tight bass. My box is 1 cu ft inside volume. With a 87' Sunsetter DD you know as well as I do you don't have a ton of space under the wheel to hide a sub enclosure, Perfect pass, and a Pelican box of electronics for my GPS Speedo.

Here's the WinISD plot for my sub and passive radiator.....I was blown away by how flat the frequency response is. This means no matter what the note the sub plays it at the same volume. It makes it very musical and isn't a sub that has a favorite note it hits well and the others are "weaker". It also likes the kick drum...nothing like a kick drum that is nice, tight, and responsive.

[old skool malibu]

I built it for the small size and the awesome frequency response and tight bass. My box is 1 cu ft inside volume. With a 87' Sunsetter DD you know as well as I do you don't have a ton of space under the wheel to hide a sub enclosure, Perfect pass, and a Pelican box of electronics for my GPS Speedo.

Here's the WinISD plot for my sub and passive radiator.....I was blown away by how flat the frequency response is. This means no matter what the note the sub plays it at the same volume. It makes it very musical and isn't a sub that has a favorite note it hits well and the others are "weaker". It also likes the kick drum...nothing like a kick drum that is nice, tight, and responsive.

Cool man..makes me wonder why more people dont build they box this way?

[martinarcher]

Cool man..makes me wonder why more people dont build they box this way?

I hear ya. They rock, especially when you design a box that has great parameters, but requires a huge impractically sized port - that's where a PR really can save the day.

Couple things that make it a "bit more of a pain", but certainly not enough to make me think it isn't worth it.

1. The added expense of a Passive Radiator.

2. Designing a box with two woofers in it (usually at right angles so you have to make sure they will clear each other). In 1 cu ft box that can be a challenge.

3. You need a subsonic filter on your amp to keep frequencies below 20Hz from reaching the woofer. See on my WinISD plot how there is a second, smaller peak below 20Hz? That can be pretty hard on a woofer!

4. You also need to make sure the PR's XMAX is not exceeded during you box design. The TC Sounds PR has an impressive XMAX and allowed me to get away with 1 12" PR with a 12" sub which usually isn't the case.

[CRASH]

Look at a Ascendant Audio Havoc good Mid Line Sub

[old skool malibu]

What model does Malibu use for Sub and amp in their boats? I recall it was a 500x2 amp? Does anyone know if they are bridged from the factory as it is a 2 channel amp.

[Brent Wall]

I believe Malibu is currently installing the Rockford Fosgate M212S4B Marine Subwoofer powered by a RF Punch 500-2 amp.

Rockford has recently introduced a new lineup of Class D amps and has announced a new lineup of marine amps that leverage the new Class D designs.

http://blog.rockford...ine-amplifiers/

It will be interesting to see how long it takes for Malibu to start using these amps.

Edited January 29, 2012 by Brent Wall

[old skool malibu]

I believe Malibu is currently installing the Rockford Fosgate M212S4B Marine Subwoofer powered by a RF Punch 500-2 amp.

Rockford has recently introduced a new lineup of Class D amps and has announced a new lineup of marine amps that leverage the new Class D designs.

http://blog.rockford...ine-amplifiers/

It will be interesting to see how long it takes for Malibu to start using these amps.

Do you think Malibu is smart enough to bridge the amp from the factory?

[robtr8]

So after reading this thread I downloaded WinISD and ran my sub/box. (After printing out a couple guides on how to use the program. The one from Home Theater Shack.com was best.) 8" square L5 in 1.47' sealed. It's exactly the correct box for SQ but the graph looks like a limp noodle. So then I modeled .75' and .33' which are Kickers preferred sizes and got better SPL. So much to learn.

I have Pete working on vented box plans for me but I'm also interested in doing a "proper" sealed box and perhaps a PR as well for giggles. I modeled the TC PR with my L5 and got a VERY bumpy graph. Going to take some time to "audition" PR's.

[augie09]

Finally installing all this and had a question.

I am building a false floor under the sub to raise it up 3". This is allowing me to 1) not trap moisture 2) push the sub box further back (towards the bow) since it now will clear the steering cable and bildge/ballast pipes . The false floor is going to be supported by hdpe spacers and then made out of 3/4 birch. Do I need to resin/glass coat the birch plywood?

I really don't want to as I don't know how and it looks expensive for supplies. People at home depot looked at me like I was crazy asking for poly resin. Wondering why I can't shellac it or coat it with water sealant, heck even a aerosol leak sealer. Only way I can see water getting on it is a hard rain that drips in through bow cup holder or bildge area air intake under the windshield. the sub box is from earmark and already resin coated and with the hdpe spacers, how much work do I really need to put in to this birch plywood for water proofing?

[Earmark Marine]

augie09,

If it was MDF then you would have to coat it. No choice there.

If it is birch and it was resting directly on the carpeted sole, even though it's constructed with solvent-based adhesives, it would eventually de-laminate, whether you coated it or not.

But since the birch risers or platform will be elevated off the sole with HDPE pads then it should hold up for a long time without being coated. I wouldn't allow it to pass in our shop for fear of eroding standards but just between you and me, as long as it is birch and elevated it will be okay.

David

[augie09]

Thanks.

[augie09]

Finally finished the install and tested it this weekend. Sounds Great!!! Didn't realize how much I was missing by not having a sub. My friend is going to order the same setup in a few weeks for his 21' cobalt after hearing this.

Re-did all my amps and wiring so I could quickly get to the controls on them for tuning. After adding the ws420, I had to turn the gain down on all my amps, guess line power on the head unit sux. Also added a dual bank battery charger.

Thanks all for the input and to earmark on the great sub box, better than i could of done.

now it's obvious the in-cabin speakers are the weakest link, being stock and not to 'crisp'. always next winter...

[Fman]

I am running the Wetsounds XS-12. Very pleased with it, hits hard and was reasonably priced. I think any Wetsounds or Exile sub would be more than adequate for your needs.

[nyryan2001]

talking about the JL W series subs... I would have not have believed it if I had not seen it for myself. I would never believe they would dry rot and fall apart....I saw stacks of JL12W6s and 13W7s completely deteriorated.... around that foam outside the cone down in Dallas.

That soft foam that allow the crazy excusion will not last vs the more stiff and durable rubber surrounds. Just ensure you go with a rubber surround vs foam.