Mondo Sub Enclosure

[yukon2007]

I’ve spent the past few days reading this forum and the internet on sub enclosures and have a few requests/advice.
I currently have a 10” Kicker KMW sub (free air) mounted under the helm to the factory panel. This sub has its own dedicated amp. I need more ‘thump’ from this sub. I’m looking at buying a prefabbed enclosure or making my own. I’m very handy so making my own is an option. But at the moment some pre made ported and sealed boxes are on sale in my area for much cheaper than what I can make. I’m not sure it will fit as the boat is in storage. So my questions are for Mondo owners:

1. What prefabbed enclosure are you using and is it ported or sealed?
2. If custom is it ported or sealed?
3. Thoughts on tubed ported vs rectangular ported in a custom design? Tubed easier to install!
4. Please provide me with pictures of your install.
5. What prefabbed enclosure are you using that fits behind the factory panel?

Thanks

[Holdmybeer]

So not a Mondo owner. I have no idea the room you have under your helm.

However, a sealed box is an easy choice. I used a prefab and was able to attach my helm panel to the front and install it in the factory location. I also upsized the 10" free air to a stranded 12" sub with the 1.2 cubic feet box and it delivers much deeper bass and has better response. The sub I used was lower end strictly to keep the same amp and power the sub run close to max RMS. It was a super tight fit but it worked great and didn't bind my steering cable.

You can get measurements by going under the bow sest if you don't want to remove the panel just yet.

[yukon2007]

Thanks for the response.
I just got off the phone with Kicker and the tech guy is saying go with a custom built sealed enclosure with the model of sub I’m using. He’s saying the ported vented enclosure can cause distortion issues in a custom build when sizing and space is an issue. And tuning (build design and port size/placement) is very technical. He also said longevity of the woofer is better in the sealed. He says the enclosure should be between 1.1 and 1.5 cubic feet.
So sealed it is. I’m not going to debate the tech guy.
Opinions/thoughts on this one?

[MLA]

I’m not going to debate the tech guy.

I will, but first, lets do a little house keeping.

Is the woofer a KM or a KMF? The "F" denotes its the actual free-air model and is designed to run free air. The plain KM version is designed for a small sealed or ported enclosure. Historically, Moomba used the KM version with no enclosure AND mounted in a false wall thats open at the top. These two issues result in poor woofer performance, and the woofer gets all the blame.

Placing the KMF in a small enclosure, as opposed to the large air space of a proper free-air installation, reduces its bass extension and narrows its band width. The turn its into one note wonder.

Lets presume the woofer is the proper KMF woofer and everything about the install is correct. Lets talk amp wattage and tuning. Tuning of both the amp and the media unit. Any shortcoming in this department would transfer right over to the new setup.

Now, on to debating the tech guy.

He also said longevity of the woofer is better in the sealed.

If the enclosure specs are within a reasonable window, not too small, not too big, and the amp is tuned correctly, the woofer will last as long as it would in a sealed enclosure.

The KM is ideal for both sealed and ported. It WILL NOT distort, over-excursion unless the ported enclosure is grossly oversized. I can guarantee you will not get an enclosure that big, under the helm.

Yes, ported takes more planning and is less forgiving then a sealed enclosure. The ported enclosure will also be larger also. About 2.2 to 2.5 ft3 to net a 1.75 ft3 area for the woofer. A tube port would allow for a slightly smaller external dimensions v's a port structure built in with 3/4" plywood. However, those euro ports can be about 6" dia, which drives the dimensions of the front wall, up.

If the woofer is the KM and you do plan to do a sealed. 1.5 ft3 is a bit large for my liking. 1.0" is a great spot. A little smaller and its a bit peakier. Larger and its a little more mellow.

Download Kicker's box building app.

Pre-fab enclosures: DO NOT, I REPEAT, DO NOT get an off the shelf carpet covered MDF road box. They will start soaking up moisture and can show signs of deterioration after one season. Buy a proper marine grade, such as the Roswell ported enclosure, or build a custom from scratch.

In terms of output, a ported enclosure will have greater output then sealed or free-air. When all things stay unchanged, a sealed and free-air will have very similar output. They will not sound the same though. The FA will have a little deeper bass extension and the sealed may have a little greater amplitude on the middle bass range.

[MLA]

Heres a Mondo with the standard "KM" woofer and false wall I spoke of. Not only the wrong woofer for FA, but the helm cant even support and FA woofer. Building an enclosure makes a HUGE difference.


thumb_951_640_480_0_0_auto.jpg

[yukon2007]

Thanks MLA so much for the reply. The woofer is a KMW 107LC that is affixed directly to the panel at the helm as seen in the photo you posted above. Behind it there’s no top enclosure or panel there. I confirmed again with Kicker it’s not a FA woofer and they were surprised that type of woofer was installed that way. So based on your recommendations I’m assuming it’s probably best to go with a custom built sealed for ease and space with the KM? And with it not being a FA and not enclosed, enclosing it will improve bass from where it’s currently at?

[larry_arizona]

Would it be better/easier to simply do the free air sub inside the helm doghouse like where Supras mount the second sub?


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[MLA]

Larry,

If I understand the model and setup you are referring to, those Supras have a complete wall that the woofer is mounted to. The 2nd issue with the moomba, is that the wall is open at the top. In addition to a true free-air woofer, you need to have 100% isolation between the front of the woofer and rear of the woofer. It is not practical to do this on a moomba with the helm wall like pictured above.

[larry_arizona]

Larry,

If I understand the model and setup you are referring to, those Supras have a complete wall that the woofer is mounted to. The 2nd issue with the moomba, is that the wall is open at the top. In addition to a true free-air woofer, you need to have 100% isolation between the front of the woofer and rear of the woofer. It is not practical to do this on a moomba with the helm wall like pictured above.

I mean the passenger side doghouse. Supra has a fiberglass sub holder,but I wouldn't call it a sub box.

But it thumps hard with the sub inside that storage area.


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[MLA]

I dont recall it looks like, but you might be able to answer your own qustion.

1) I would not add a 2nd woofer into the system while leaving the 1st woofer setup with the 2 serious flaws it has.

2) as an example, the "KM" series enclosure needs to be small and air tight. any leaks and its performance will fall off.

3) the "KMF" does not want a small enclosure/air space/cavity. However, the large space does not need to be air tight sealed. What is does need, is to have 100% front cone to rear cone isolation. You need a solid wall/cavity structure to prevent the air coming off the rear of the cone to mix with the air coming off the front of thee cone.

If you location you speak of, offers #3, then you could go with an FA woofer. An example of this would be a Nautique G boat. Free-air woofers in the port locker and helm cavity. If said location is small and sealed (or could be sealed with a little fiberglass or marine caulk work like ive done on a Tige ASR), you could use a non FA woofer.

Now the final challenge. Anytime you place a woofer in a closed locker, you rob some performance. So ideally, you would want to put in a vent to let the bass radiate out.