car audio guys... need opinion,

[killer025]

Ok, I'm looking to throw a sub/amp combo in my work beater, the stuff I currently have is a rockford P2d4 12, in a ported box, and an RF power 1000.1bd. The p2 is 250rms, and the power 1000.1 is 750rms@2 ohm...
My concerns: the amp is obviously a little large for the p2, but it technically falls between its rms/max rating, so provided I don't beat the shitt out of it, is there any real danger to the sub in running this combo? I'm kinda concerned about using the ported box, and i do have a sealed box (cheapy scoche) I can use.
Ideally I would get another p2, but I'm broke and this is a beater car, so I'm using what I have.
What do you guys think? This amp has cooked 2 decent quality subs in the past, a punch hx2 12 d4 and an alpine type r 15 d4, but they were both old, used, and probably abused before I got them. This p2d4 is less than a year old and has never seen more than 300 watts and never been turned up loud enough to make it clip. It was also broken in properly.

[Nati]

Set the gains correctly and you wont have any issues

[Funkmaster]

Originally Posted by Nati

Set the gains correctly and you wont have any issues

What he said.
What you want to do is get out your multimeter, and get a CD/MP3 with a 50hz cycle. Disconnect any other speakers/amps while setting your gain for the sub amp as you dont want 50hz cycles playing thru any speakers.

So what were looking for here is the proper output voltage on your amp.
The voltage number will be equal to the square root of (desired power output * resistance (ohms) of your speakers).
In this case 400w RMS * 2ohm. SQ root of 800 = 28.3 Volts
Connect the leads from your meter to the speaker outputs on your amp.
Turn the gain on the amp all the way down, fully open any crossovers, disable any bass boosts, etc. Then turn the stereo up as loud as you would ever play it. Play the 50hz CD and set to repeat/loop. Your meter should be set on vDC with a range of like 0-50 or whatever is closest to that. Adjust the Gain on your amplifier until it is as close to the correct voltage as possible. If the Gain is all the way down, and is still over the desired output, I would probably just leave it there and try to be gentle with the sub, or perhaps turn the volume on your stereo down and adjust the gain for your 4 channel amp if you have one.

[stang99gtv8]

What cooks subs quick is under powering or unclean distorted power-meaning you are driving too much from the radio to the amp and it's distorting at the input source and then driving that signal. The above explanation is a great technical way to check your power and be precise with it.

I personally just make sure I never get to a point of distortion by giving a smooth input (read no crazy bass boost and then max out the lows on the radio) and then raising the gain on the sub until it's slightly louder than I want it to be at comfortable listening volume. If it's distorting before that level, then back it down to get the most you can from it, if it isn't, go just above comfort level and then back down the bass on the radio so you can thump when you want to.

A P2D4 according to their site is a dual 4 ohm voice coil 400 RMS, 800 Max, which should be able to hold clean power of 1000W max in 2 ohms without issue unless you are trying to thump the car in front of you. Just don't distort it.