Help with car amp/speakers

[Vi Percent]

So I have a car amp that states 100w rms at 2ohm and/or 75w rms at 4ohm for each channel and 300w rms at 2ohm for the sub

So I want to run my sub at 2ohm but want my speakers at 4ohms


And from my understanding 2ohm rms is basically double the power of 4ohm

So if that's the case why is the manual saying it's

75w rms at 4ohm and not 200w?

And also does my amp control ohms or is that just solely based off the speaker?

I'm still learning all of this jazz

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[1aespinoza 10+ year member]

And also does my amp control ohms or is that just solely based off the speaker?

The speakers are where the Ohms ratings come from. So the amp will play at what the speaker rating is.

And from my understanding 2ohm rms is basically double the power of 4ohm

So if that's the case why is the manual saying it's

75w rms at 4ohm and not 200w

Most often times it is as you say; when the resistance halves, the power doubles. Not all companies rate this way for some reason but it is nothing to worry about.
You must be using a JL Audio amp, my full range amp has those exact ratings. It is an XD200/2.

 

[HardofWhoring]

No that's not the case, and 4 ohms is not a perfect double of the resistance, of 2 ohms. So even though your question should have been why isn't it 50w (not 200w), that's not how it works because of design and materials.

Your speakers are deciding the resistance.

 

[Vi Percent]

The speakers are where the Ohms ratings come from. So the amp will play at what the speaker rating is.

Most often times it is as you say; when the resistance halves, the power doubles. Not all companies rate this way for some reason but it is nothing to worry about.
You must be using a JL Audio amp, my full range amp has those exact ratings. It is an XD200/2.

Yeah my amp is a JL Audio xd700-5v2, so yeah the speakers I have are rated for 175w rms each at 4ohms, so will my amp actually do 200w at 4ohm or will it limit it to 75?

 

[chillin 10+ year member]

As mentioned before, you have the ohms to power backwards. The power doubles as the ohms drop. If your amp says 100@2, it would be 50 @4ohm. But as HOW mentioned, there are other variables which is why your amp is rated at 75@4ohms. Your speakers will see 75 watts.

 

[audiobaun 5,000+ posts]

There is Stereo Mode and Mono Mode Mixed Mono and Bridged, and a couple others. Most manuals will be a bit vague of explanation ,but these days, the internet has all kinds of information to research to be understood

 

[audiobaun 5,000+ posts]

Yeah my amp is a JL Audio xd700-5v2, so yeah the speakers I have are rated for 175w rms each at 4ohms, so will my amp actually do 200w at 4ohm or will it limit it to 75?

In Stereo Mode /Full/HPF @4 ohms you will see 75watts rms @14.4v continuous, and @12.5v continuous 60 watts rms from the specs I read

XD700/5v2

5-Channel Class D System Amplifier, 75 W x 4 @ 4 Ω + 300 W x 1 @ 2 Ω - 14.4VThe XD700/5v2 is ideal for a complete audiophile-grade, subwoofer + four satellite system, and it fits comfortably in just about any vehicle. With this incredible little amplifier, you can drive two pairs of quality...

www.jlaudio.com