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  #11  
Old 02-25-2013, 08:50 PM
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Boat: MasterCraft, X15, 2007, MCX, Acme 5 Blade, Pair of WetSounds Rev410's, WetSounds SD6, 2 JL 12w6v2 subs in sealed box, JL HD750/1, WS402SQ
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I must be rrrrreally thick because I just don't understand how the amp would know if there was one or two subs at the other end???

If its identical power...how would 2 JL 750/1's be any different than just the one JL 750/1.
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  #12  
Old 02-25-2013, 09:21 PM
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Zach,

The amp only "sees" a load in the form of impedance. This impedance can be changed by how we wire multiple subs or speaker, or how we wire DVC subs. In the case of the JL amp, its output is the same, when it sees any load within is proper operating range. Its output will always be 750 watts rms, regardless of the number of speakers or subs, or how they are wired, as long as the impedance stays within the amps operating load. Now, with any amp, its output will be divided between any 2 or more speakers wired to a single chnl. With the JL 750/1 above, with 2 identical subs connected, they will share that 750W, with each receiving 375W. With a pair of 750/1, each driving a single sub, then each sub would receive 750W, so double what they would receive if both were wired to a single 750/1.
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  #13  
Old 02-25-2013, 09:37 PM
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A single 12W6 deserves an HD750/1 to itself. So with two 12W6s you really should have two HD750/1s.
I know it's at the top of the thermal rating but JL subs are rated conservatively. Plus, in an open-field-environment you need considerable more power than running the same driver in the enclosed cabin of a vehicle.

David
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  #14  
Old 02-25-2013, 09:51 PM
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Zach,
Also, I assume that the enclosure is down-firing. If so, I would make a minor alteration before carpeting. Notch out several sections of the long sides to allow more free radiation to flow away from the drivers. Down-firing will take advantage of the sole as a re-inforcing plane. However, any small reduction in the surface area of the drivers will create a small reduction in output. One that you wouldn't notice in a vehicle, but in a boat you need every bit of acoustic leverage. Also, from the tip of the surround center times the circumference should be no less than the woofer's effective surface area. So sometimes a little elevation off the sole helps. The previously mentioned polymer stand-offs would serve two purposes---one to offer a bit more elevation---two to provide isolation from moistore being wicked into the MDF. All small details. But collectively they can make a difference that costs you nothing more.

David
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  #15  
Old 02-25-2013, 09:59 PM
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Join Date: Jan 2012
Boat: MasterCraft, X15, 2007, MCX, Acme 5 Blade, Pair of WetSounds Rev410's, WetSounds SD6, 2 JL 12w6v2 subs in sealed box, JL HD750/1, WS402SQ
Location: Southeast
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Rats....I was hoping to STOP SPENDING MONEY ON STEREO EQUIPMENT. Rant over.

I've already had similar power in the 350 range when I was powering the single 12W6 with my Syn6. I really really liked the jump in boom when I repowered with the JL 750/1.

I wander what a single JL 1200/1 HD would do over doubling up on the 750/1's...I heard the 2 750's are sssssssssick but I'd be happy with sssssick!!

I'd rather keep my amp count to three but the JL's HD's are stackable so that's not a strong deal break, the batterys are so cramped with the power leads but a distribution block answers that one (2 gauge to 4 gauge).

I'll just run the 750 for now and see how it all sounds when I have a chance to surf through my playlists.
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  #16  
Old 02-26-2013, 09:01 AM
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Zach,
I would have zero problem with running a single HD1200/1 to drive two 12W6s in the air conditioned cabin of a vehicle knowing that the supply voltage will always be in the 13+ range. But keep in mind that an HD1200/1 is a major jump in power with the same heatsink mass as an HD750/1. And usually in marine things get run very hard and close to maximum with much lower supply voltage. So I like staying on the conservative side in this instance.

David
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  #17  
Old 02-26-2013, 04:25 PM
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Boat: MasterCraft, X15, 2007, MCX, Acme 5 Blade, Pair of WetSounds Rev410's, WetSounds SD6, 2 JL 12w6v2 subs in sealed box, JL HD750/1, WS402SQ
Location: Southeast
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Thank you David...

I need to add that I'm having the box made in a local stereo shop in Roswell, Ga (BenchMark Audio) they are awesome guys to work with.

I have passed the helpful tips along to them and they have been gracious about modifying their box...

There are some pictures of the rough glass work before the carpeting. The fiberglass should provide the moisture barrier as its on the inside and out. I hope the notches are close to the as directed info.
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  #18  
Old 02-26-2013, 04:35 PM
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Interior glass work...
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  #19  
Old 02-26-2013, 05:11 PM
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Notches are perfect.
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  #20  
Old 02-28-2013, 05:15 PM
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ZachDaddy ZachDaddy is offline
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Join Date: Jan 2012
Boat: MasterCraft, X15, 2007, MCX, Acme 5 Blade, Pair of WetSounds Rev410's, WetSounds SD6, 2 JL 12w6v2 subs in sealed box, JL HD750/1, WS402SQ
Location: Southeast
Posts: 251
But what if I do use a JL HD1200/1 what kind of negatives are there over 2 750/1's powering the subs?

My system for the summer is going to look like this:

Syn6 for the JL M770's - 2 pair

SD 4 for the pair of WS REV 410's

JL HD 750/1 or 1200/1 for 2 JL 12W6v2

I have a Pro Mariner 3 bank charger and a 2 bank Interstate series 27 deep cycle dedicated stereo batteries.

Do I have enough engine off stereo play time in the 2-3 hour range with my current setup?
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