Difference between 4 ohm and 2 ohm

[yzbat]

So what is the difference between 4 ohm and 2 ohm and how do I get the amp to switch between the two I have an alpine mrp f-450 and it says that it will run at 100w x 2 ohm and 75w x 4 ohm but how do you switch it to do those.

[Mylt1]

you cant "switch" it. it "reads" the speaker and adapts.

[Inyourface1650]

Its about 2 ohms.

[Whiffle]

A 2 ohm speaker has lower impedance than a 4 ohm speaker. This causes the amplifier to put out a higher amperage on the 2 ohm speaker than the 4 ohm. An amplifier is "stable" at a particular impedance because it can put out the amperage without clipping (ie, taking a nice wiggly sound waveform, and clipping off the tops and bottoms so they're square (this is what destroys speakers fyi). ). It deosn't really adjust between the two per say, its just an electrical property.

In short, there isn't any adjustment.

[yzbat]

alright sounds good to me I actually have the polk db6501 and db651 so I will have to see how it sounds just got the head unit in today so setup will be tonight.

[helotaxi]

Originally Posted by Whiffle

clipping (ie, taking a nice wiggly sound waveform, and clipping off the tops and bottoms so they're square (this is what destroys speakers fyi). ).

Clipping does not destroy speakers. The extra average power between the sine wave and the clipped wave is what has the potential to destroy the speakers. If even fully clipped (pure square wave output where the peak power and average power are the same) the average power is less than the power that the speaker can actually handle, it won't damage the speakers. It will sound like utter crap, but it won't hurt the speaker. It will probably destroy the amp rather quickly but the speaker will be fine.

[ToddG]

Originally Posted by helotaxi

Clipping does not destroy speakers. The extra average power between the sine wave and the clipped wave is what has the potential to destroy the speakers. If even fully clipped (pure square wave output where the peak power and average power are the same) the average power is less than the power that the speaker can actually handle, it won't damage the speakers. It will sound like utter crap, but it won't hurt the speaker. It will probably destroy the amp rather quickly but the speaker will be fine.

I don't know about you, but I'm leaving an apple on professor helotaxi's desk when I leave class . . . . . lol.
Great explanation.

Clipping is one of the reasons amps have fuses, built in or inline somewhere for protection.

But yeah, for the OP the speaker(s) determines the load/draw (ohm rating) of the amp.

[08_Nismo]

Originally Posted by yzbat

alright sounds good to me I actually have the polk db6501 and db651 so I will have to see how it sounds just got the head unit in today so setup will be tonight.

I have the same speakers in my truck but I just power them with the headunit. I like them a lot. I am pretty sure the DB speakers run at 4 ohms though

[ToddG]

Originally Posted by 08_Nismo

I have the same speakers in my truck but I just power them with the headunit. I like them a lot. I am pretty sure the DB speakers run at 4 ohms though

The DB series absolutely runs at 4ohms. I had the exact speakers the OP has in my last truck, powered off the headunit and they sounded great. (HU was a Sony rated at 25 watts RMS a channel).

[yzbat]

I got them installed last night and the tweeters sound amazazing but the woofers in the front door I am a little disappointed in.