Making sub enclosures
 

Question for the audio experts. I currently have two 10'' Alpine marine subs mounted under my back seat, facing the bow. Currently, they have no enclosure, well except for the area under the back seat. I'd like to build an enclosure for them. in the woofers manual, they show the specs for a sealed enclosure, but ''N/A" for a ported enclosure. Obviously space is limited under the rear seat, for an enclosure of 4.93 Cubic feet, that they recommend per woofer. Any ideas? Here are the speakers specs.

http://support.alpine-usa.com/produc...M_SWR-M100.PDF

I have always built mine in the past if sealed to the MFG's recommend cubic dims....

I just bought a couple 10's for my boat and I'm having an issue of deciding where to put them...People have said to stick them in the bilge, but I'm afraid they wont be heard....I have thought about mounting them in the glass in front of the engine compartment and trying to seal the box to the glass inside the compartment...Not sure if it will actually work..

I prefur sealed enclosures. They hit so quik n tight. Let the mid bass speakers play the. Whooa stuff. I just purchased some Jl slims. And they require little to nothing. And slam like a mofo. I was astounded on the sound

How close can you get to the 4.93? You can stuff poly fill in the box if you are close which will make the woofer think it's in a bigger enclosure then it really is. If your not close I suggest you think about selling the woofers and going with a pair of JL's or maybe even one JL. JL are know for extremely small box requirements.
You can see in the picture below the box is not much bigger then the diameter of the speaker and only about 12" deep.

http://i69.photobucket.com/albums/i4...b/12641503.jpg

Exactly.

Find what you have room for first, or what room your willing to use, and then go sub shopping.

It's like a boater that wants a big roots blower......'do I really want to cut my hatches to give them the room ?'

There are tons of choices out there including some pretty decent 'free air' subs . Just like everything else we run into with boats, you'll probably be faced with a couple compromises.

Use poly fill to expand the box volume. Make the box as big as you can allow for space, then add the recommended amount of poly fill to get the approximate volume. the closer to recommended box volume, the deeper the bass will be.

Also, you really don't want a ported box for an open air environment like a boat because you have are normally playing it louder than you would in a car.

Those are free air infinite baffle drivers. They want a huge or no enclosure. No sense in trying to put those in a box. The suspension controls the cone. Just give them the power and the will make bass.

I have 2 pair jl 10 infinite baffle subs if anybody interested. Switched to 4 10 inch slims in box that fits under the ledge of my seat n the fiberglass. I think total depth is 5 inches. I finished the front off with white plexiglass and a jl badge. Love them still have all my under seat storage. We'll half air conditioner takes up 1/3 of it. Let me know

Joe. Bill with the 42 has 4 jl 10s under his backseat free air. He has like 14 total cockpit speakers all jl. His stereo sounds amazing. Loud and crystal clear. The ladies love the back seat with subs in it. Lol

Gotcha. So putting these in a small enclosure, would not be beneficial I assume. I have never owned an "infiinite baffle" driver, but what you are saying makes sense.

Just a thought. You could cut the area needed for two woofers in half if you built a clamshell isobaric box...

Isobaric boxes have a very small frequency range and will require you to know the resonate frequency of your cockpit in order to tune the box to sound decent.

Last year I was running these subs of this amp

http://www.crutchfield.com/S-RbetZxL...wer-T8002.html

While its a monster, and cranks out some serious power, its a real voltage sucker. At 2ohms, it puts out over 1000 watts RMS bridged(according to the brith sheet). Plus, its size is very large. I like to run the stereo while at the beach, and having that big fosgate and another old school amp for the mid's, just drains too much power.

I just purchased an Alpine PDX-5M, to run my 4 cockpit speakers, and 2 subs. I'm a bit worried now that this amp may not have enough power for the 2 subs. Rated at 300W RMS (actually closer to 400W according to the birth sheet) to the sub channel at 2 ohms. Considering going to the PDX-V9, which is also a 5ch, but has 500W RMS (around 600w according to the birth sheets I've seen) to the sub channel.

http://www.alpine-usa.com/product/view/pdx-5m/default

http://www.alpine-usa.com/product/view/pdx-v9

dont underestimate that amp .. you dont need 1000 watts to power hard hitting subs ... my first sub amp wAS A, M 1400 JL ,, 250 mono amp .. running two jl infinites .. now run a 1200 by 1 . jl hd amp .. with four 10s .. and i dont think its that much more thumping ... especially for all the extra i paid for them .. i run two kinetic hc 2400 batteries all day long . and roll over the motors just fine at end of day .. .. you need good batteries ... they pricey but people are blown away when my boat starts .. and so was i at first .. .. pdx line are awsom amps run them in my ski boat .. my new system has hd 600 , hd 750, hd 1200 ,, i love great sounding loud music .. good luck . glad you stayed on board love youre threads ..

Thanks Rob! I guess I can try the PDX-5M, and if i feel its underpowered, I can easily upgrade to the PDX-V9 later, since its basically same dimensions and hookups.

Joe, if you look in the manual there should be a table of Thiele-Small Parameters. You can enter this table manually into enclosure design software (I like WinISD) and it will generate a volume for you based on that data and some other stuff you put in, target frequency IIRC.

I have a PDX-V9, it's not installed yet, but it came highly recommended from a few members here, Griff being one of them. I'll have to get out it's birth sheet tonight and see what it says.

Here is a combination I run in one of the boat's a single 12 thin mount...it takes away all of the tuning issue's of a big box......... and use's by far less space........, a single 12 will be just as loud and have a more of a authority (hear Hit) than 10's........... Dual driver's in a boat are a bit like dual drives on a 20' boat....remember your 15' away at best....... proximity is what count's here......... two 10's doing 82 db will not have more sonic output than one 12 doing 84....... As to amp's they are just motor's no more no less....yes there is some integrity issue but the below amp is at the top or the heap in term's of sheer performance...there marketing suck's a bit but that's to you advantage. Don't let the refurb bother you they are under a 3 yr warranty...they pay the shipping and you get a new one back and yes they will run with the alpine line 7 day's a week 24/7 better service than brick&motor.

http://www.ebay.com/itm/Infinity-KAP...item2a312b5114

http://www.crutchfield.com/S-aDxs2Dv...-12TW3-D4.html

http://www.jlaudio.com/12tw3-d4-car-...-drivers-92185

If you build the proper box with that combination your only complaint will be with your boat and how badly it resonate's and you will have money left over for other essential's...

I think you have Isobaric confused with bandpass.

I would definitely go with the larger of the two Apline if you go that route. Both will be less power than you have now. I would suggest getting a bigger house battery for your system. I went from a series 27 that I would kill in a couple hours, to a series 29 that lasts almost all day. I run my system pretty hard at times and that 29 has no problem with it. I run 3 old school Autotek amps and they draw some heavy current.

I think you will be happy with the sound from the Alpine amp in you mid/hi's but not enough power to get the most out of the subs.

Something seems off to me,,, 4.9 cubic feet for a single sub???? How big is the sub?? in general in the car world I used to put 12's in a 1~1.5 cubic foot box and that worked nice. 4.9 is just not making sense to me.

It's because this particular sub was designed to be in a free air application.

Yeah, I think it was the clamshell part that made my mind instantly go to bandpass. Isobaric is something that isn't really recommended except to people that like to waste money or have more drivers than someone else.

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Who needs enclosures, look at this crazy chit!!

if you dont like it ill buy it from u .. always need a good amp

Here are my 4 --- 5.5" tube subs---giggle

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I'll let you know what I decide to do with it Rob. Thanks

I have 4 JL Marine free airs that POUND, most of the quality is in the seat face, mines made of 2.5" of wood and fiberglass to resist the seat facing flex, thats where quality comes to play for feeling and sound, I am a fan of free air with proper amp wattage, I run all 4 off a JL1000@1OHM (STABLE) and 2 JL 4 channels to hadle all the other speakers, the boat sounds amazing, to use free air you need a good clean true watt amp...the sound is bad azz...

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Hey Tim, do you think i'd be better off running the Fosgate amp I have for the subs?

At 2ohms, it puts out 1000W RMS according to the birth sheet. So thats 500w to each sub? the subs state they can handle 300W per sub.

Or, the PDX-V9, which puts out 600w RMS at 2ohm to the sub channel, so 300W per sub?

I personally like Alpine over the Rockford, I run the JL because of the track record and the 1 ohm stability, is that Alpine 1ohm stable? if you can run 1ohm you will get the most power out of it but not many amps can, they overheat and shut down...I am no stereo genius, but I have done many over the years in auto and boat...

The older stuff seems to be great quality like the old punch amps and such, but the newer Rockford does not seem to be a true watt amp... great rule of thumb for amps is 1.00 a watt.... if you pay that you will get good quality power...

A big power amp will push a free air sub properly, I like the free air because if your Fountain is like my Cig the extra space is much needed under seat for things.... and if your seat is not super thick and subs move the seat for sure back it with 3/4" plywood to stiffen it up, so many people overlook that stuff...

Joe I need that amp back for another project I want to do in 2018 :party-smiley-004:

If your Rockford is an older model, I would stick with it.

Here is why I say if it is an older amp stick with it. One of these old Autotek's rated at 99 watts runs three Rockford 12" subs and they pound. And the amps are almost 20 years old.

http://i1087.photobucket.com/albums/...ed_640x480.jpg

http://i1087.photobucket.com/albums/...ed_640x480.jpg

I like old... I, running an ancient hifonics zues with the gain turned way down because Im afraid Im going to blow the mtx speakers out of the boat. And it still hits like the hand of an angry god.

And kills batteries like theres no tomorrow.

actually its not as bad as I thought it was going to be....

They will only kill betteries if the amp has an un-regulated power supply. Most older Orion and Soundstream amps had an un-regulated power supply.

I don't care what they say, it takes power to make power. Amps kill batteries to make serious sound. But watt for watt an old amp "may" use 10% more power if you are running full tilt.