[DracoDan]

Hi, I'm new here but after some reading I'm liking the wealth of information here so I wanted to ask for input from you guys on my stereo plan. I had originally posted this thread in The Hull Truth and had several of my questions answered there, but I the more people I can get inoput from the better!

Back story:
I bought a "new" boat last September, a 2008 Formula 350 SunSport and I love everything about it... except the stereo! It has a full Kenwood system that at 10 years old is just worn out, the boat was previously used in salt water so all the deck and transom speakers have corrosion on them and sound bad when turned up much (plus they trip the amplifiers breaker). I've decided it's all getting replaced, and I like to do things right the first time so I'm very carefully planning this out.

I have all the components bought and so far I have installed the HU and the transom speakers (both are working perfectly)

The boat layout:

• 2x cabin speakers (I don't plan to change these)
• 4x 6.5" deck speakers (little room to increase size)
• 1x 10" deck subwoofer (little room to increase size)
• 2x 6.5" transom speakers (fiberglass is shaped for the cut out, so I can't increase the size easily)

All deck and transom speakers have component tweeters that are installed a few inches away from the woofer.

The plan (already started):

• Head unit: Fusion MS-AV755 - Bought a couple of months ago, so unfortunately I'm stuck with it and can't easily switch to one of the new Apollo units.
• Cabin Speakers: Leave alone alone and use the HU internal amp to power.
• Deck speakers: 4x Polk DB 6502 powered by a Polk PA D4000.4 amplifier. Amp only has 25% overhead, but this should be okay since I don't plan to run these at full power pretty much ever.
• Transom speakers: 2x Polk MM 6502 powered by another Polk PA D4000.4 in bridge config. Amp will have 60% overhead in this configuration - Speakers done and they sound surprisingly good off the factory Kenwood amp.
• Subwoofer: Polk MM1040UM powered by a Polk PA D1000.1. Amp will have 42.9% overhead (lower than the desired goal of 50%) - This was the original plan but it looks like I will have to change. This sub isn't designed for Infinite Baffle/Free Air and therefore will probably fail. I know its Qts is 0.50 but I'm still waiting on Polk to get back to me about its xmax (they don't publish hardly any specs), but I don't have high expectations for its ability to work in IB/FA. The spot for the sub is molded into fiberglass and there are literally no other places to put the sub. I should be able to get a 12" sub in the spot without much of a challenge, but all the good 12" IB subs seem to be more than 12", like the JL that's actually a massive 14"!!! The second best IB sub I've found is the Wet Sounds REVO 12FA at 12.68", this would require me to fill in a tiny spot behind the sub bezel on the right but I don't think it will affect the mounting strength. Once I'm able to post images here I'll post a diagram explaining what I need to do to make it fit.

Thanks!
Dan

 

[DracoDan]

Here's the link to the original post over at The Hull Truth:
https://www.thehulltruth.com/marine-electronics-forum/931925-major-audio-overhaul-critique-my-plan.html#post11431236

 

[Lycancatt]

that all sounds quite good and I like that you did research and thought things through more than most jumping right in. kenwood makes a good amp..if you want to save a bit and keep the current amp, nothing special but sometimes a savings can help. as for the sub? I say try it and see what you get. personally I'd be building a ported enclosure behind the current sub opening to maximize output and get rid of any suspitions that the mm 10 wont work in ib, but I'd wager that's quite hard and that means cutting a new hole for the port somewhere too.

 

[DracoDan]

Here is how the 12.68" Wet Sounds sub would fit into the spot (in mspaint!). I'm worried about the (long term) strength and adherence of the marine-tex considering the large levels of vibration. The filled in area will be an elongated D shape from the front, just enough to hide behind the sub without showing or leaving a lip on the sub. If I do this I will probably use my dremel on the smooth fiberglass to provide better mating.

 

[DracoDan]

that all sounds quite good and I like that you did research and thought things through more than most jumping right in. kenwood makes a good amp..if you want to save a bit and keep the current amp, nothing special but sometimes a savings can help. as for the sub? I say try it and see what you get. personally I'd be building a ported enclosure behind the current sub opening to maximize output and get rid of any suspitions that the mm 10 wont work in ib, but I'd wager that's quite hard and that means cutting a new hole for the port somewhere too.

I looked at ways that I could do a ported/sealed enclosure behind the sub, short of cutting the boat up considerably it just can't be done (the only real access to the area behind there is through the sub hole. I care more about looks than I do the sound, so the plan is to make it as good as I can without hurting aesthetics. I even tried seeing if I could be a tube shaped carbon fiber box made! Unfortunately the diameter/length I could do for the tube didn't give me nearly enough volume (even considering polyfil).

I have now purchased all the components and started the install, currently the biggest challenge is running the wiring for the subs new amp (it's doable but will be a headache). I was surprised at the transom MM6502s using the stock amp, but I'm afraid it is just too under-powered (75w/channel RMS) compared to the speakers (125w/channel RMS max).

One thing that really surprised me was how hard the Kenwood 100w IB Sub hits! I think the old Kenwood HU had the bass turned all the way down - I never messed much with it since it didn't have bluetooth (so I wouldn't have kept it regardless). I hooked up the Fusion HU last night and the bass was loud enough to be uncomfortable sitting near the sub!

So you think the MM1042 would be okay in IB? I'm guessing the xmax would be the deciding factor (still waiting on Polk) since a Qts of 0.50 doesn't appear to be uncommon for IB subs. I already bought it so I guess I'm going to just install it and play the wait and see game. I'll move to the WS REVO 12FA if/when it blows.