" Free Air subs " I just dont get it.....

[jcyamaharider]

Right now I have one under the seat right behind the captains chair and then I have one directly across under the other chair. I am going to vent the cubby along with putting a vent on the side where everyone installs the IB sub. Hopefully this down fire thing will cure my "disease"

 

[David Analog]

Wow, reading all this technical writing is giving me a head ache. If I add a subwoofer to my boat it's probably going to be in a box under the left rear / aft port sets behind the batteries. My simple logic being that there is room there (so no drilling), its close to the power (so less of a cable run) and it "looks" and I "assume" and hope works most like the subwoofer for my home system which I love. So the only questions I have are:

How big? What brand? Class/type of amp? How much power?

If you want the best bass sound quality then the woofer needs to be direct radiating into the cockpit area by one method or another. That means you have to make an opening for either the subwoofer mounting or a bass vent.
You wouldn't place a woofer in a box and place that woofer/box in a sealed coffin and expect it to sound good in your home, let alone an open field boat. It makes for a boat shaker but not much of a musical bass maker. I can explain why technically but common sense should be enough. And oftentimes you don't know what you're missing until you hear it done right.

Class of amplifier for a subwoofer is a no brainer. Class D.
The sub will dictate the amplifier, the enclosure will dictate the sub driver, and the boat will dictate the enclosure. So place the horse before the cart and start with the boat and find how much displacement and storage you can afford to give up. A sealed 12" sub box generally takes around 1.9 cu.ft. external displacement. A sealed 10" sub box generally takes around 1.05 cu.ft. external displacement. A 10" bass-reflex = 1.65 f3 ext. A 12" bass-reflex = 2.75 f3 ext. Rough starting guidelines.
Surface area rules, particularly in an open boat. The less that woofer cone needs to travel to generate a given output, the better the bass will sound.
One of the best approaches is to take a true marine acoustic suspension (not infinite baffle) 10-inch subwoofer and externally mount it through the seating console wall. Then take a sealed enclosure (13.5" X 13.5" X 13.5" external) and mount it to the interior of the wall. The two sandwich and seal against the wall. This way you have direct radiation and acoustic suspension.

 

[woodard1983]

I'd start w/the vents, you may not even need to change anything else....with the way these boats are built if you dont' have a way for the air to escape there is more than enough "area" that it will stay behind the compartments/seats....

not sure if you've done it, but try popping on of the seats off and see if that improves the flow....in the cab of your truck the downfire will work great due to the smaller cabin, in an open air environment I'm not sure that it would work very well (I have not tried or been in a boat that has tried it though)....

in open air environments the name of the game is air movement, hence IB being so popular in our boats

 

[jcyamaharider]

I agree, but I seen @Sotally Tober install and he said down fire made a big difference in his boat. It is an easy experiment for me to try this evening before i pull the boat out.

 

[Cowboy Casey]

Searching for the perfect sound on the boat and my brain is about to over heat. All of my logic with car audio is not even coming close to applying to the AR. I had one 12" sub in the XR1800 and it sounded awesome, mainly due to the fact it was in the open but firing up against fiberglass shell. Tons of bass!!! I have 2 12's in this boat and I cannot get it to sound the way I want. So that brings me to the IB sub "free air". How in the heck can a sub that has no restriction on either side make bass? I understand ported boxes, sealed boxes, and bandpass boxes. I just can't wrap my head around free air. Does it work, there are many out there that say it does, but I do live in Missouri so "Show Me". Please give me some guidance or at least a warm fuzzy that I wont be blowing 275-500 bucks.

Also everyone uses the JL IB sub, but with how crazy everyone is with wetsounds I am surprised I haven't seen anyone use their free air sub.

http://www.amazon.com/Wet-Sounds-Series-Silver-Subwoofer/dp/B00DNJ3WPK/ref=sr_1_2?ie=UTF8&qid=1398388343&sr=8-2&keywords=wetsounds free air

It sounds like you want big huge base.... I went with the car audio route and did this.... Might be something your looking for???

https://jetboaters.net/threads/stereo-system-install-2013-yamaha-242ls.320/#post-3659

 

[jcyamaharider]

That sure is an awesome install @Cowboy Casey !! Not sure how I missed that thread. I have already modded my storage closet to hold all of our other essentials due to the ballast that we have on the boat. Ballast takes up a lot of room. I think I am just going to have to live with the best of both worlds and settle when I get close to what I want.

 

[Sotally Tober]

The box is raised with the subwoofer facing down towards the deck in a sealed box. It's hard to get good pics of it.

 

[jcyamaharider]

@Sotally Tober trying this when I get home!!

 

[Sotally Tober]

I have a sub on both the Port and Starboard side in the same position. This prevents listing and creates an even sound.

Amp
One Arc Audio - Class H - KS 2500.1 - http://www.arcaudio.com/p/ks-2500-1?pp=24

Subs
TWO Arc Audio - Black Series - 12V2 D2 -
http://www.arcaudio.com/c/subwoofers_black-series_black-12v2

 

[jcyamaharider]

Yep me too but I like listing.....

 

[Ronnie]

I have a sub on both the Port and Starboard side in the same position. This prevents listing and creates an even sound.

Amp
One Arc Audio - Class H - KS 2500.1 - http://www.arcaudio.com/p/ks-2500-1?pp=24

Subs
TWO Arc Audio - Black Series - 12V2 D2 -
http://www.arcaudio.com/c/subwoofers_black-series_black-12v2[/QUOTE]

Did you add vents to the compartments that you have the subs in?

 

[jcyamaharider]

@Ronnie, looking through @Sotally Tober stereo install thread I don't see any vents for the subs into the cabin portion.

 

[Sotally Tober]

No vents. Just under the seats

 

[David Analog]

Down-firing is a simple premise. You are using a reinforcing plane to boundary load the woofer. It's like the wall, floor, corner, etc. Identical to side-firing against the hull. Every time you fold another plane around a woofer you gain another +3 dB. It works. However, you need to be careful that the distance between the woofer and adjacent surface is not too small. If you reduce the radiating surface area at any point during the transmission path then you have choked the output and countered a portion of the down-firing benefit. You may even alter the woofer's damping properties. If too choked, you are simply adding more 'shaking of the boat' and transmitting through the boat's sole.
Venting an otherwise sealed compartment is essential for quality bass. Look at what you have with a sub/box within a seating or helm console. The expansive compartment and adjoining gunnel cavities represent a giant and compliant air mass. This air mass is like a bottle. The vent is like the mouth of the bottle. The smaller the vent the higher its resistance to flow. The larger the vent the less resistance to flow. With a tiny vent there is far less impetus for the bass energy to flow from the compartment and much of it is consumed within. It's not a linear function. The upper bass (attack, transients, midbass) is severely filtered. Also, when the sub/box is placed within another enclosure you have seriously altered the phase response so integrating with the coaxial midbass is not nearly as seemless as direct radiating. More bad news. If you don't vent the compartment then oftentimes the coaxials sharing that compartment are the medium where the bass pressure is released. Now the coaxial midbass driver is being modulated, acting as a sympathetic radiator, out of phase, and in a region it is not supposed to play. Now the midbass and midrange on that side of the boat sounds crappy too.
As a test, listen to a sub in the lowpass mode in total isolation and without the fullrange contribution. It will sound slow, soggy and drunk. This will demonstrate how dependent you are on a good interface between the sub and coaxials in order to achieve decent bass tonal construction.
Some are going to be completely satisfied with 'hit', 'hammer', 'thump', 'bump', 'rumble' and all those tactile and percussive descriptions of bass. The more the better. That's not music. That's turning a reproduction device into its own monotonous instrument. Do it right. Go for something that bumps AND maintains musicality.

 

[Sotally Tober]

Down-firing is a simple premise. You are using a reinforcing plane to boundary load the woofer. It's like the wall, floor, corner, etc. Identical to side-firing against the hull. Every time you fold another plane around a woofer you gain another +3 dB. It works. However, you need to be careful that the distance between the woofer and adjacent surface is not too small. If you reduce the radiating surface area at any point during the transmission path then you have choked the output and countered a portion of the down-firing benefit. You may even alter the woofer's damping properties. If too choked, you are simply adding more 'shaking of the boat' and transmitting through the boat's sole.
Venting an otherwise sealed compartment is essential for quality bass. Look at what you have with a sub/box within a seating or helm console. The expansive compartment and adjoining gunnel cavities represent a giant and compliant air mass. This air mass is like a bottle. The vent is like the mouth of the bottle. The smaller the vent the higher its resistance to flow. The larger the vent the less resistance to flow. With a tiny vent there is far less impetus for the bass energy to flow from the compartment and much of it is consumed within. It's not a linear function. The upper bass (attack, transients, midbass) is severely filtered. Also, when the sub/box is placed within another enclosure you have seriously altered the phase response so integrating with the coaxial midbass is not nearly as seemless as direct radiating. More bad news. If you don't vent the compartment then oftentimes the coaxials sharing that compartment are the medium where the bass pressure is released. Now the coaxial midbass driver is being modulated, acting as a sympathetic radiator, out of phase, and in a region it is not supposed to play. Now the midbass and midrange on that side of the boat sounds crappy too.
As a test, listen to a sub in the lowpass mode in total isolation and without the fullrange contribution. It will sound slow, soggy and drunk. This will demonstrate how dependent you are on a good interface between the sub and coaxials in order to achieve decent bass tonal construction.
Some are going to be completely satisfied with 'hit', 'hammer', 'thump', 'bump', 'rumble' and all those tactile and percussive descriptions of bass. The more the better. That's not music. That's turning a reproduction device into its own monotonous instrument. Do it right. Go for something that bumps AND maintains musicality.

Wow. That was intense. Thats breaking it down to a science

 

[David Analog]

Wow. That was intense. Thats breaking it down to a science

It is absolutely a science with very predictable results.

Your system is very, very well done with lots of top of the line gear. You also have BIG power and BIG woofers. You have the leverage to muscle your way through the challenging boat environment. I want to see guys with considerably less equipment and without that extra leverage to get the last ounce of performance from their single 10 or 12".

 

[jcyamaharider]

As always I feel enlightened!!! David you are awesome!!! Turn the box upside down and break out the cutting tools. The operation starts tonight!!

 

[jaybro72]

wow, now im going to mess with my subs and figure where to put vents. dam, more work on the boat. lol

 

[GiddYupJoe]

wow, now im going to mess with my subs and figure where to put vents. dam, more work on the boat. lol

I know @jaybro72. I am working on buttoning everything up to take the boat to lake for the season and now all I am thinking about how I can make something that I thought sounded good 30 minutes ago sound better!

 

[David Analog]

This is one small aspect and we have barely scratched the surface of all the ingredients that can make the same system perform significantly better. When I was in the industry, I used to constantly get people coming in and saying, " I heard one of your systems on the lake. It had half the power as my system and was less expensive than my system and yet it totally smoked my system in sound quality. What can we do?"
If you are wanting to build a system, I would highly recommend Odin with Earmark Marine as your equipment resource. He is the most knowledgeable guy I know in the industry. He'll make sure you select the right equipment. He'll keep you from making mistakes. He will assist you with your installation. And he'll walk you through the system tuning from the perspective of a true sound engineer. Odin is an authorized on-line dealer for Wetsounds, JL Audio and much more. And he has competitive, unadvertised specials including deeper zone and system packaging.