Whats the difference between a 2 & 4 ohm sub and the effect on the amp?

[StocktonJ82]

Whats the difference between a 2 & 4 ohm sub and the effect on the amp?

I'm looking at an Alpine monoblock amp rated: 300 RMS x 1 @ 4 ohms & 500 RMS x 1 @ 2 ohms. Why would I get a 4 ohm sub when I can twice the watts with a 2 ohm sub? Is it a THD thing or something? Could you hear 2% THD in a sub?

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[SomeGuyDude 10+ year member]

You wouldn't if you don't want to. That's just showing what the amp is capable of, and it helps you with flexibility.

Say you have an amp rated for 1500@1ohm and 1000@2. Right now you have two subs rated to do 750 each, so you hook them up and have a great time. But for whatever reason you want to scrap those and just get one sub. The one you want, having listened to a bunch, is rated at 1000. So you get the dual 4 model and wire it at 2 ohms, so now you're giving that sub its rated power and didn't need a new amp.

 

[audioholic 5,000+ posts]

I'm looking at an Alpine monoblock amp rated: 300 RMS x 1 @ 4 ohms & 500 RMS x 1 @ 2 ohms. Why would I get a 4 ohm sub when I can twice the watts with a 2 ohm sub?

Yes, why would you indeed.
And.... 500 is not twice as much as 300.