i will start out by saying that i am no newbie to stereos by any means, i have been around them for well over a decade and a half, i use to do comps back in the day and all of that. i understand ohm loads but i am thinking about doing something that i have in the past been against doing (in a car) but in this case i am thinking it will work. i have always been against mixing subwoofers as far as size and coils, with that said i am running a class d crossfire that i previously ran 2 alpine type r 12s on, last year i busted the voice coil off of the cone on one of the subs and i was not thrilled about the setup i had with the box. this year i am adding 2 jl marine 10s, i am wanting to run the 2 10s under the rear bench and the 12" type r in the cabin. so what i am wondering is since i have a class d amp can i run the dual 4 ohm coil alpine in the cabin and the 2 single 4 ohm coil jls under the bench off of it? that gives me a 1 ohm load and with the subs being in 2 locations i do not believe they will affect one another but i am worried about the mixed specs of the 2 types of subs. anyone know if i will be ok or am i setting myself up for disaster?

They will sound different, not sure how much sound fighting may be noticeable.

with the 12 able to handle 1000rms and JL only either 175 or 250 each, the Alpine will be under powered. Not a huge deal, just observation.

Which model of Crossfire amp? does it have enough power?
Crossfire does appear to be 1ohm stable according to most of what I just read but know nothing about the brand.

Enclosure specifics have been left out and are going to be the primary factor.
If the 10s are free air, the 12 will likely over power the 10s in volume.

I assume you will be either cutting down the dual 12 box or using a different single 12 box?

My experience is I went from 2 10" RF P2 in a sealed box.
Added 2 Kicker comps in a sealed box which did increase volume.
Changed the Comps for CVR's (3x power handling) - noticed a major improvement with the RF not as much of a factor if I did not have them hooked up.
Moved to 2 Kicker L7 15" in a ported box and realized several fold gain over the prior 4 x 10 set up.

Personally, if big sound is your goal, the JL 10s will be disappointing.

No offence intended because it sounds like you're experienced, but it depends on the model of the amplifier. Is it a bridgable model to where you have a wattage rating x2 @ a specific ohm load? For example, 300w x2 @ 4 ohms. If yes, you can run the 10's in parallel to maintain the 4 ohm load at that channel and run the 12s' two coils in parallel to maintain the 4 ohm load on that channel. Like ChargeIt said, they will sound different simply because of the power rating per channel and power consumption of the two different brands and 1 vs 2 subs on each channel, but IMHO It's doable. If you have the option, go with matching or 2 amplifiers.

Just my 2 cents...

No offence intended because it sounds like you're experienced, but it depends on the model of the amplifier. Is it a bridgable model to where you have a wattage rating x2 @ a specific ohm load? For example, 300w x2 @ 4 ohms. If yes, you can run the 10's in parallel to maintain the 4 ohm load at that channel and run the 12s' two coils in parallel to maintain the 4 ohm load on that channel. Like ChargeIt said, they will sound different simply because of the power rating per channel and power consumption of the two different brands and 1 vs 2 subs on each channel, but IMHO It's doable. If you have the option, go with matching or 2 amplifiers.

Just my 2 cents...

Sorry for the dual reply... stupid tablet...

Your by far better off wiring for 8 ohms...i know its not optimal..but i doubt very much anyone including yourself would ever know. Why push a amp to burn up over 3db..and on a boat

Well you should know that doing what you are talking about is disaster waiting to happen. Your going to have frequency cancelations all over the place, and have peaks on some frequencies. Resulting in a boomy muddy sounding system. Then throw in the fact that you will be throwing all kinds of strange loads at the amp with that kind of setup. Mixing subs is bad enough then to mix them on the same amp ehh blown subs here we come. I think you knew the answer to the question before you asked it.

If you want more bass, you add more subs or you add more power or both.

Let me ask what kind of box were you running the Type R's in? I am going to guess ported

I do belive the 250 has the same bench seat as the 280. I am running three Rockford P1's on an Autoteck 99. They hammer for what they are. I have heard the Alpine Type R in a car and they do really well with the right power. Maybe go with three of them in 1.25 Cu.Ft sealed boxes. Your gonna need power though.

First off, the crossfire vr1000d or BMF 1000D are both 1 ohm stable amplifiers. They are MONOBLOCK amps, meaning there is only 1 channel. I know there is a a place to hook up two speakers however it it fed off only 1 channel cause it only has one channel. And no don't run it at at 8 ohm, that would be like buying a supercharged 540 and putting it back to stock HP cause it might blow at some point, that's dumb. I have been in the audio industry for long enough to have played with just about every set up configuration there is. I would not use the 3rd woofer. I would properly power the two tens. And enjoy. When you start mixing different subs, enclosures and locations, impedance rise will be a real concern as well as possible cancellation. Run the amp at 1ohm on those two tens and enjoy.

And if memory serves the subs are designed for about .9 cu ft per sub. Build the chambers individually and fill it with some poly fill. Also I always coat the inside of all my enclosures with a smooth but thick layer of polyester resin