Speakers and Amp(s) Configuration for 2009 Chevrolet Cobalt LT sedan

[H3br3wHamm3r81]

Hello,

I'm installing some audio components for my wife's car, a 2009 Chevrolet Cobalt LT sedan.

As of now, I've only acquired a pair of Polk Audio DB651 6 1/2" coaxial speakers. The main reason I decided to buy speakers is because the stock front door speakers are utter trash (and are inoperable), and they are necessary to hear the turn signals and door chimes.

At that point, I got the bug, and I said, well, might as well put a better head unit in to take advantage of these nice speakers. So I decided on the Alpine INE-W927HD 7" navigation receiver unit.

Ideally, I didn't want to buy an amp, as it's less wiring, and of course, less cost.

The specs of the DB651 6.5" speakers are:

Nominal Impedance

4 ohms

Efficiency

92 dB

Power Handling

-Continuous

60 watts

-Peak

180 watts

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The specs of the Alpine head unit are:

CEA-2006 Power Rating: 4 Ω @14.4V Ƈ%THD+N, S/N 80dBA (ref.1W into 4 Ω), 18W x 4

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I don't think the head unit will drive the speakers adequately.

So, I considered buying an amp. Another thing I was questioning was whether I should bother replacing the rear 6x9 speakers with Polk Audio DB691 3-way coaxials.

The specs of those speakers are:

Nominal Impedance

4 ohms

Efficiency

93 dB

Power Handling

-Continuous

125 watts

-Peak

300 watts

From what I understand, if the front and rear speakers had the same RMS, I could buy a 4-channel amp and call it a day.

But, 60w (front) and 125w (rear) RMS is a good difference.

So, what would you do in my situation?

Ditch the rear speakers altogether then power the front speakers off the head unit?

Ditch the rear speakers altogether then power the front speakers off a 2-channel amp?

If I am to keep the front and rear speakers, how do I compensate for the difference in RMS? What kind of amp configuration would I need (2 2-channel or 1 4-channel)?

I need your help. Thank you in advance.

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[LosIsATool 5,000+ posts]

You don't want more power going to the rears. That will pull your stage behind you. It's totally fine to underpower speakers. That's what happens when you turn the volume down. Most focus on the front stage, that's what matters. Rear fill is not needed at all. Normally not wanted at all.

 

[H3br3wHamm3r81]

Hmm...okay, so no speakers in rear. So, should I buy an amp for the Polks in the front or just power them off the head unit?

 

[LosIsATool 5,000+ posts]

Amp them for sure. Way more output and dynamics. You can never have to much power, you can always turn it down and headroom is a wonderful thing.

 

[H3br3wHamm3r81]

One more question, if you don't mind. The Polks are 60w continuous (RMS) and 180w peak. How many watts should I look for in a 2-channel amp?

 

[adulbrich 5,000+ posts]

I'd say between 75 to 100 per channel. I agree that headroom is a wonderful thing to have.