IB Subwoofer vs Sealed Enclosure Under The Observers Seat

[swatguy]

Ok so the boat is up and now comes the winter upgrade ideas.Getting a little head start here

Stereo is going to be my focus this winter as the factory Polk stuff just isn't cutting it. While I know the Momo's are regarded as a decent speaker I just like a little brighter sound.

Sub is really where I can't decide my options. I have to have it located somewhere in the observers area. I did a post a while back regarding some ideas for how to get the most out of a sealed box under there and possibly cutting a custom hole in the walkway area as my boat doesn't have the cooler/trash can access door.

That got me to thinking what about just mounting a free air IB sub to the walkway wall instead. Maybe a JL or Wetsounds. I am far from an expert on sub placement, but i don't think the seat bases have enough room between the floor and the seat cushion to mount one in the passenger compartment rather than the walk through. Is the IB sub a good alternative in this case?

[ski4evr]

I've enjoyed mine in the walkway. used Advantech flooring to stiffen up the panel after cutting the hole. the only problem is everything in the glove box rattling. other than that it rocks. it is an ib jl 10.

[Paxdad]

I was in the same dilema. I ended up cutting out the walkway and putting in a Wetsounds XS-10FA sub. I really did not want to lose the storage with a box so I thought I would go this route first with plan B being that if I did not like it I would buy the hatch/ door and put it in and then build a box. As ski4evr points out you need to use a stiffening material on the inside wall of the walkthrough as my sub can really move the fiberglass which i am sure is taking away from the subs performance. I am going through my entire system this winter like you and will add the material then.

[xrichard]

Swat--I never tried an IB in mine. Rather, I cut out a good part of the passenger walk through panel to vent the area and tried both a sealed and ported box with a WS XXX. It worked well...but you really felt it in the observer seat. I don't know if an IB sub would solve that issue. Overall, I liked the sealed box in that location. I'd say the overall feeling of bass was greater with the ported enclosure but I liked the tighter sound I got from sealed (and a little less rumble through the observer seat). With the sealed box, I was able to push the enclosure pretty deep into the space--I believe the box was 14.5 inches deep and I pushed it all the way to the back of the bow seat, so there was still a lot of storage.

Doing it over, I'd lean toward stiffening the pass through panel and trying an IB. They aren't that expensive and worst case is you move to an enclosed driver and use the hole you cut as a vent...there are plenty of ways to make the vent look nice. Mine was pretty cheap: I covered it with a double layer of speaker cloth. It looked OEM. The only downside is that speaker cloth fades over time, so it needs to be replaced every few years.

[David Analog]

A 10-inch air-suspension (AS = sub in small sealed box) subwoofer has some limited advantage over a 10-inch infinite baffle (IB = sub loaded by infinite air space) subwoofer in that it has a bit more output (with greater amplifier power) and stays tighter at higher output levels...'IF' both are direct radiating. But in this case, only the IB application would be direct radiating. So the AS sub would be placed within a 20+ cu. ft. locker and radiating through a less than 1 sq. ft. vent opening which translates to a filtered loss. That negates any advantage of AS over IB in this particular scenario.
As mentioned above, for the IB to work well the mounting baffle has to be just as rigid as you would expect a small sealed 3/4" thick construction enclosure to be. With more baffle surface area it becomes more of a challenge to obtain the same rigidity. But that can be done.
One of the remaining uphill acoustic challenges is that the subwoofer in the pass-thru is located beyond the boundaries of the cockpit. So more of the energy dissipates upward and outward toward the bow as that which is funneled into the cockpit listening area. The loss is exponential as you increase the distance away from the sub driver. So with this location you are at a major disadvantage out of the gate, as compared to a direct-radiating sub under the drivers helm and within the cockpit re-enforcing boundaries. It's unfortunate but part of taking what a given boat offers. If using an enclosed sub within the locker it would be more advantageous to place the vent closest to the sole and under the observers seat so that the vent is within the cockpit.
Certainly if you are mounting a sub/box within the locker you can get a nice increase with a 12" driver versus a 10", but with a greater loss of storage. A bass-reflex enclosure, is substantially larger yet, but offers another significant increase in output. One problem with using bass-reflex within the vented locker is that bass-reflex does have a phase delay by design. Add that inherent phase delay with another monster phase delay of placing a vented sub/box within a second vented box, the port locker. That sends bass SQ into the toilet and makes achieving any coherency with the cockpit coaxials midbass impossible, although you will have plenty of tactile bass and boat vibration. But no quick bass transients and really no tonal construction. That doesn't stop people who still want to net a bass increase regardless of the diminished SQ.

[swatguy]

Thanks guys. I am going to try the IB solution probably with the Wetsounds 10FA.

Had a random idea of possibly moving the IB sub that to the rear wall where the reversible seat is. Move it towards the bottom and basically it gives it open space. Not sure if there is enough clearance under that seat. Will have to measure over Columbus weekend

[scottb7]

"Certainly if you are mounting a sub/box within the locker you can get a nice increase with a 12" driver versus a 10", but with a greater loss of storage."

Here is a little food for thought. Over the years I have moved the sub between 2 places. In either case mine is a 12" vs 10".

Under the loveseat. Little better bass sound, but can't place fat sac here.

Behind port stern seat leanback: Allows for placing fat sac under loveseat for maximum lean and fantastic surf wake. No loss of storage, and can still fill 1100 sac nearly full. More then you can possibly need.