i have 3 12" punch hx2's dual 4ohm and im wondering wat amp to get to kick them at thier rms ratings?
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Rockford Fosgate
First, determine what impedance load you'll get by wiring these three subs together. Use the woofer wiring wizard in the left column.
https://www.the12volt.com/caraudio/woofer_configurations.asp?Q=3&I=42
With a load of 2.67 ohms, this rules out using a two-channel amp whose lowest bridged load is 4 ohms. This means you should look for a mono amp.
Now, what is the continuous power handling / thermal rating / RMS rating of this particular sub? Multiply that rating by 3 for three subs.
You know you have an odd impedance load of 2.67 and that the amplifier specs will give you ratings at 2 ohm and at 4 ohm. Find the middle ground between those two ratings and you've found the output at 3 ohms. That's very close to 2.67 so you can use that number as your guide, and find a mono amp whose output will give you enough to match the RMS of the subs. The amplifier's output into 2 ohms will be higher than the total RMS of your three subs, and its rated output into 4 ohms will be lower than your target number. But at what you figured the 3 ohms output would be, it should just about match the subs' total. And you can always go a little less power.
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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
I think old kicker amps used to be optimal in the 2.67 Ohm range. If your on a budget you might want to look for one of those.