Rockford Fosgate P3 with Alpine MRP-M650

[ChrisC26]

I having trouble figuring out whats wrong with my set up. I don't believe its the amp because that amp has ran a less powerful sub with no problems (A Cadence UD124HFi) and now I just upgraded to the 12 inch Rockford Fosgate P3 2 ohm sub and from what I'm reading the sub and the amp should be perfect for eachother. The P3 has 600 rms and at 2 ohms the amp should be pushing out 400-600 watts rms.

Yet unless I severely set limits on either the gain on the amp or the sub setting on my deck the sub will just short out.

I'm hoping the sub and the amp are not the problem and its a simple fix of wiring differently.

Old sub: UD124HFi - Cadence Sound

Current amp: Alpine MRP-M650 Mono subwoofer amplifier 600 watts RMS x 1 at 2 ohms at Crutchfield.com =mrp-m650&tp=115

New sub: Rockford Fosgate P3D2-12 Punch P3 12" subwoofer with dual 2-ohm voice coils at Crutchfield.com

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[Jeffdachef 5,000+ posts]

Yeah you have the improper impedances. Alpine amp is 2 ohm stable. With that p3 you have choices of 4 ohm or 1 ohm wiring.

 

[C1500martin 10+ year member]

your running the amp at 1 ohm probably

 

[C1500martin 10+ year member]

is this how you have your sub wired>

 

[ChrisC26]

I believe I have it like this.

Is there any way to run the P3 at 2 ohm or must it be 1 ohms or 4 ohms?

View attachment 26552024

Should I have it hooked up like this? (This is for a 4ohm set up though so I wouldn't be using them to their full potential)

 

[C1500martin 10+ year member]

I believe I have it like this.
Is there any way to run the P3 at 2 ohm or must it be 1 ohms or 4 ohms?

View attachment 26552024

Should I have it hooked up like this? (This is for a 4ohm set up though so I wouldn't be using them to their full potential)

yes you are running it at 1ohm as suspected. a D2 can only be ran at 1 or 4 so yes your safe bet is wiring it to 4ohms. or getting an amp that is 1 ohm stable

 

[ChrisC26]

My friend and I hooked up when I got it and we had found this picture on the web, and just jumped to the conclusion that it was correct.

Got it hooked up now and though I only briefly tested it, it sounds very good.

Right now I have the gain at roughly 2/3rd. Would I be safe to turn it up to 3/4 or maybe even 4/5?

 

[LosIsATool 5,000+ posts]

Gain is not a power knob. You need to just slow down

 

[ChrisC26]

But it does change how strong the signal is. And being reckless with it can just as easily contribute to harming the sub. So what I'm asking is what do people generally consider a safe setting for gain?