Question about power distribution and wiring three subs to single monoblock

[strykerlee]

Hello everyone, I have a question about monoblock amps.

I have a rockford r1200.1 (1200w rms @ 1 ohm) and intent to run a rockford p312d4 (600w rms) and 2 jl 12w3v2-d2 ( each 300w rms)

I plan to wire the p3 in parallel @ 2 ohms to one side of the amp

and each jl wired in series to 4 ohm, then both in parallel to the other hookup on the amp @ 2 ohm

making a final impedence of 1 ohm on the amp.

So the question is, would the power be split 600w rms to each lead (600 to the rf, and 300 to each jl), or would it power each sub with 400w rms?

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[macsdad 10+ year member]

Dude, no. You do not mix match subs like that, just use the jl's. Since they are d2, you will have a final load of 2 ohms. Or sale the amp and p3, and get an amp that makes it rms at 2ohms, kicker or alpine comes to mind.

 

[Boomin_tahoe 5,000+ posts]

Ditch the single sub and run the other pair.

 

[strykerlee]

Thanks for the reply guys. I will buy a separate amp if I have to, but why couldn't it be wired that?

 

[macsdad 10+ year member]

Dude, your questions were answered to the best of our ability. If you insist on running 3 subs, sell the p3 and cop another jl, seriously.

 

[strykerlee]

Seriously dude... I came to this forum because the members seem to be the most knowledgeable. I was simply asking for an explaination, since my original question wasn't fully answered about how the power would be split due to impedence and how it was wired. From my understanding, that should be how they are powered, and being the p3 will be in it's own specific sealed, and the jl's in their own ported, the only issue I may have is the level of the subwoofers.

 

[tymoto21 10+ year member]

The p3 would get 600 and the Jl's would get 300 each

Now to bigger problems...

Impedance rise will be different on the Jl's vs the p3 due to the subs being different but more so because one will be sealed the others ported.

This will cause even more fluctuation in power.

Also it will most likely sound like a flabby ******* farting

Build a good box for the Jl's and you will be happy

If not get different or bigger or more subs and more power

 

[hispls 5,000+ posts]

Seriously dude... I came to this forum because the members seem to be the most knowledgeable. I was simply asking for an explaination, since my original question wasn't fully answered about how the power would be split due to impedence and how it was wired. From my understanding, that should be how they are powered, and being the p3 will be in it's own specific sealed, and the jl's in their own ported, the only issue I may have is the level of the subwoofers.

Mix matching subs is a recipe for trouble.

First and foremost, your "2 ohm" wooofer isn't 2 ohms when playing music, it's all over the place. It'll be roughly this shape (blue line):

Your different brand/box woofer will be sort of the same shape but at different frequencies so you'll have power being distributed between the two wildly lopsided 99% of the time.

Mix matching woofers also becomes an acoustic nightmare. It may sound louder but if it sounds better it'll be pure blind luck.

Trust us. Many of us tried this and learned the hard way 25 years ago (before the internet was around so we could know better). The jury is in, mix matching subs is a terrible idea unless you have some precision test equipment, powerful sound processing, SEPARATE AMPS, really know what you're doing, and have a good reason to want to mix match going into it.

 

[tymoto21 10+ year member]

He even has a graph!

 

[strykerlee]

Thank you tymoto 21 and hispls! I didn't realize how the 2 and 4 ohm would handle the power differently. One final question.

So in theory, If I had 2 300w svc 4 ohm subwoofers, it could be done if they were all ported or all sealed, and all have the same frequency throughout the entire range, and sound decent?

But not as good as two matching subwoofers of course.

 

[Jeffdachef 5,000+ posts]

Thank you tymoto 21 and hispls! I didn't realize how the 2 and 4 ohm would handle the power differently. One final question.So in theory, If I had 2 300w svc 4 ohm subwoofers, it could be done if they were all ported or all sealed, and all have the same frequency throughout the entire range, and sound decent?

But not as good as two matching subwoofers of course.

doesnt matter it has to be the exact same subwoofers with the same build and parts. Every little change to the part changes a sub's electro mechanical parameters AKA (T/S) Theile small parameters and that will completely fk up the whole sound. Best to sell everything and get a pair of 15s. If you can build proper loud custom boxes and understand acoustics aka cabin gain really well, you can build a custom box for those two JL subs and get pretty loud off that by themselves. I've been in a challenger where they had two W3 12s in a 4th order enclosure that was flexing the windshield like crazy almost a few inches worth.

If you cant get moderately loud and move a lot of air off a pair of 12s, then you are doing something wrong with your enclosure, either lack of SPL and enclosure design knowledge or you are using a prefab.

 

[strykerlee]

That's what I was afraid of... 2 15's would be nice lol. I will probably just ditch the 3 sub box, buy another p3 for this system, and use the jl's in a different car.

 

[Boomin_tahoe 5,000+ posts]

2 15's is nice.

 

[hispls 5,000+ posts]

Thank you tymoto 21 and hispls! I didn't realize how the 2 and 4 ohm would handle the power differently. One final question.So in theory, If I had 2 300w svc 4 ohm subwoofers, it could be done if they were all ported or all sealed, and all have the same frequency throughout the entire range, and sound decent?

But not as good as two matching subwoofers of course.

ANYTHING besides identical size/make/model/options woofers in identical boxes (or shared airspace) on precisely matched power will be trouble. I can assure you if you have to come here and ask you have no business attempting to make it work and will wind up worse off than just picking one or another and investing your effort power and space into doing that the right way.

 

[strykerlee]

Thanks for the advice. I am in no way a professional, I have hooked up single subwoofers quite a few times now, but never multiple. So all of this has been very informative. I aprreciate everyones input!