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Suggestions needed, replacement sub


Rdiz

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Short Version: I need a suggestion for best loudest low bass response sub and enclosure limited to about 1.25 cf of airspace and 300w rms at 4ohm under $250.  If you really want to know why the stupid constraints, see the long version...

 

Long Version: I have a system installed on my seadoo 300 RXT.  Warning, it may seem like I am aware of what I am talking about here but it is mostly greek and consider me a parrot. Without getting into the failures by the installer, the box and subs need to be replaced.  What was in there originally was a pair 6.5 Oz Audio subs in an ATrend box (6.5 DVME hyper vented shallow box, 20w x 13h x 5.75d). They sounded surprisingly good but they are now toast with the box.  The challenges, biggest to smallest in order, is SPACE, limited power, and the fact that this seadoo will be replaced in 1-2 years so I am not sinking money into temporary.  The objective is to not go over $250.  The space is so limited that I need to consider a "screw it and glue it" solution of building (or rebuilding) the box into the enclosure area.  The footprint of usable area is roughly a 16"w x 12"h x 14"d.  The other box fit by dropping it in sideways, then tilting it, then slapping some lube on it etc, pure fun, and then it sat leaning at an angle. Power is from a Rockford Fosgate marine amp of 300w rms @ 4ohm bridged stable.  The whole thing runs off an XS Power battery (just a battery so power needs to stay efficient at 4 ohms). Efficient louder bass means ported so of course here comes the space problem. Since I have to replace the subs, of course I'd like to get more bass if possible.  The best options I could come up with were:

 

#1 Pioneer TS-A2500LS4 10" shallow mount 4ohm 300w rms sub .6cf ideal space $124  (Kenwood Excelon KFC-XW1000F would fit these specs but is it worth $60 more?)

Qpower shallow 10" ported box- 18x13x5.25 .53cf  5/8 mdf  approx $25  or  Qpower qbomb shallow 10" ported box- 20.875x13.25x6.375 .75cf 3/4 mdf approx $50

 

#2 Kicker  43TCWRT104 single 10" 4ohm sub w/ passive radiator 400w rms prefab.  Even though it says 400 they say it works best with 300w rms. approx $250

 

#3 Considered a Massive Audio shallow mount UFO10 in the recommended box but saw to many failure complaints, plenty more than options 1 and 2 at least

 

Neither are thrilling options but I believe should still outperform a pair of 6.5s.  With option #2 being a sealed option a couple people keep trying to convince me that the passive radiator is going to be like a weak 2nd speaker...

 

Opinions and any other suggestions for me to consider would be appreciated

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So everything changes for a marine build.  I did a double-take when I read that this build was for a seadoo.

 

1st off - your sub enclosure will need to be essentially impervious to water.  When I 1st started building boxes I built a box for a single 10" sub for my boat.  I re-built that box 3 different times using MDF and trying different ways to protect it against the elements and all 3 times I had problems with the MDF swelling due to water contamination before the end of a boating season.  I ultimately made the enclosure out of fiberglass and then promptly sold the boat.

 

Here is a link to a boat box build I did for the local shop where I live using expanded PVC and acrylic: 

 

 

For a seadoo where space / weight / power budget are all at an even higher premium, I think a fiberglass box would be the best way to go.  Use expanded PVC or some other similar synthetic/manufactured material that isn't MDF/wood for the sub ring(s) and supports etc.  You could even mold a plastic Aero port in since you are going for a ported enclosure.

 

Also make sure you are using marine grade connectors and do your best to solder and heat-shrink/seal any connections where you can (you may not be able to with your sub since most are spring loaded terminals.

 

With the enclosure details sorted, next make sure that any subs you are looking at are marine grade.  Preferably a sub or subs with an IP66 rating or better.  This will narrow your choices but will make sure that you aren't throwing good money after bad.  

 

I have personally had good experiences with Polk Audio MMs, JL Audio and DD Audio subwoofers for marine application.  There are also marine specific brands like Fusion and Wet Sounds.  I've not heard any of the Wet Sounds subs, but their amplifiers are nothing short of incredible for marine application.

 

As far as efficiency/maximum volume, the biggest thing to look at is the subwoofers sensitivity rating (measured in dB)  The higher the sensitivity rating the louder the sub plays, you should probably be looking for a sub with a sensitivity rating in the low 90s.  The good news is, lower powered subs (like in the 300w range) tend to have a higher sensitivity by default because they have less mass and more pliable soft parts (meaning it doesn't take a lot of power to get them moving)  When you get into subs that can handle 1000+ watts, it takes a lot of power before they start to reach their full potential.

 

If you were pretty happy with a pair of 6.5s before your box melted and your speakers shorted out, maybe look at a pair of marine grade 6.5s in  a fiberglass box.  If you have room for a single 10, there are definitely options out there.

 

Another thing you might consider for your enclosure would be molding in a petcock valve/drain in a low spot of the box so you can drain any standing water in the enclosure, especially handy if you are doing something crazy on the seadoo and end up capsizing or putting it otherwise under the waterline.

 

 

I know this is a long post, and probably not what you wanted to hear necessarily, but the biggest takeaway is that MDF and water don't mix and any efforts made to seal the MDF are at best temporary and or slow the failure process to an extent.  Going with a fiberglass or synthetic plastic material like expanded PVC is the only way to get away from that issue.  From there, pick a sub or subs that are legit marine certified.  That way if when you pull out your seadoo next season and the woofer/woofers are all corroded and f*cked off, you are getting them warranty replaced rather than having to buy more new gear.

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That was one hell of a box build!

 

Plenty of good info there that does help not just for now but in the future (next build will definitely not be mdf).  Surprisingly enough the previous box lasted almost 5 years and it was completely untreated.  Some water gets in that compartment sometimes but very little.  Riding season here is normally 100-110+ degree weather so what little gets in dries out fairly quick.  As far as all the connections, I had 2 different shops run this setup on 2 different pwcs and no one seems to get it when it comes to the moisture and abuse.  Next time I will do it myself.  I have already had to redo all the connections and did it in the manner you discussed.  Funny you mentioned the spring loaded terminals on the sub, for that I used brush on electrical tape and on the amp silicone sealant.

 

The amp is marine grade, the 2 6.5 mids are JL marine, but for the sub when comparing cost and output I'm ok with with throwing the good money after bad in small amounts in the right place and I think this is it. I don't want to get into a custom build on this replacement so I am looking at a box that is sprayed in bedliner that I will then give a coat of waterseal. I have been going nuts trying to find the right sub for the job and I'm thinking I need to just cough up the $200 and go for the 12" KENWOOD EXCELON KFC-XW1200F shallow mount.  According to Kenwood, optimal space is .8cf for sealed or ported (odd its same for both but was the case for the Pioneer).  Seen some videos where people have got some crazy output on these with low wattage.  If it doesnt sound great sealed then I can drill a hole and stick in a port and hopefully get better.

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I loved the Excelon stuff back in the mid to late 90s.  I've used some of their amplifiers in more recent builds but I haven't used any of their subs or speakers recently.  I would be curious to hear how it turns out if you go with the Excelon woofer.

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  • 2 weeks later...

Just wanted to make sure to satisfy your curiosity after you took the time to give all the info that you did.  Considering the fact that it went into a sealed box with only .7 cu ft and powered by 300w, it sounds awesome, better than expected.  Gain is set at less than half.  Its exactly the low cost, low power consuming high bass output that I was looking for.  

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