Need db/ohm help

[laser_vaper]

I hope someone here can help with my quandry.
This is a car audio question.
My vehicle came with a premium sound system and the speakers were shot. So I decided to upgrade the head unit (Alpine ilx650) and door speakers.
From what I understand the stock amp is pushing 2ohms.
I am not certain of the wattage rating of the amp, my questions are as follows...
1- should I install 2 ohm speakers as opposed to 4 ohm
2- if I have a set of two way 4ohm speakers with w/91db sensitivity and a set of 2 way 2ohm speakers w/88db sensitivity, which is the better option?
Bonus Question...
Adding an amplified head unit to an existing amped system (not bypassed), does the head unit add wattage to the system ?

*2010 Kia Soul

Any and all feedback is appreciated.

Thanks

 

[BOUXY]

Maybe try asking under this:
"Wheels, Wings, Mud, and Water"

 

[whoaru99]

I hope someone here can help with my quandry.
This is a car audio question.
My vehicle came with a premium sound system and the speakers were shot. So I decided to upgrade the head unit (Alpine ilx650) and door speakers.
From what I understand the stock amp is pushing 2ohms.
I am not certain of the wattage rating of the amp, my questions are as follows...
1- should I install 2 ohm speakers as opposed to 4 ohm
2- if I have a set of two way 4ohm speakers with w/91db sensitivity and a set of 2 way 2ohm speakers w/88db sensitivity, which is the better option?
Bonus Question...
Adding an amplified head unit to an existing amped system (not bypassed), does the head unit add wattage to the system ?

*2010 Kia Soul

Any and all feedback is appreciated.

Thanks

If the stock amp is geared towards running 2 ohm loads then 2 ohm speakers will optimize the amount of power delivered. The impedance, in itself, is not an indicator of sound quality.

Can't make an apples to apples comparison of the 4 ohm/91dB speakers to the 2 ohm/88dB speakers. Have to see the fully qualified sensitivity specifications for both. A fully qualified spec would look something like this, 91dB/W/m or 88dB/2.83V/m. Need it for both speaker options.

Bonus answer:
No, adding an amplified head unit to feed into a system that has its own amp will not add power. In fact, it's possible it would cause a problem instead if the amplifier input is not intended to accept high level output from the head unit.

 

[laser_vaper]

If the stock amp is geared towards running 2 ohm loads then 2 ohm speakers will optimize the amount of power delivered. The impedance, in itself, is not an indicator of sound quality.

Can't make an apples to apples comparison of the 4 ohm/91dB speakers to the 2 ohm/88dB speakers. Have to see the fully qualified sensitivity spec. Is it 91dB/W/m or 91dB/2.83V/m or what?

Bonus answer:
No, adding an amplified head unit to feed into a system that has its own amp will not add power. In fact, it's possible it would cause a problem instead if the amplifier input is not intended to accept high level output from the head unit.

Both are Sensitivity (1W/1M)

 

[whoaru99]

Then the 4 ohm speakers will play 3dB louder (which isn't very much) for equal amounts of power relative to the 2 ohm speaker.

But, if the amp is geared toward 2 ohm loads it will put out (in theory) half the power at 4 ohms which is -3dB, and effectively negates the 3dB higher sensitivity of the 4 ohm speakers.

 

[laser_vaper]

That's kinda what I was thinking.
The lesser resistance would make up for the 3db difference.
So it's like tomato / tomahto

 

[GordonW]

Then the 4 ohm speakers will play 3dB louder (which isn't very much) for equal amounts of power relative to the 2 ohm speaker.

But, if the amp is geared toward 2 ohm loads it will put out (in theory) half the power at 4 ohms which is -3dB, and effectively negates the 3dB higher sensitivity of the 4 ohm speakers.

Yes. Which one will be "louder" will be a matter of whether the amp is voltage-limited, or current-limited.

If it's not current limited- especially if it has a voltage-regulated power supply- then, the power at 2 ohms will be exactly twice that of what it will put out at 4 ohms.

If it IS current limited- but not voltage limited (i.e, not regulated power supply)- then, the power at 4 ohms will be slightly higher than half of what it is at 2 ohms- it will be able to drive a slightly higher voltage to the speaker- which will result in a little more headroom at 4 ohms.

Many amps nowadays are current limited- this protects them from blowing up under extreme use. If so, you might have a very slight advantage with the 4 ohm speakers. Whether or not you could actually hear the small difference in output level, though- that's a really good question, and the answer probably won't be found unless you directly compare the two sets of speakers in the car.

Regards,
Gordon.

 

[laser_vaper]

Gordon, thanks for the clarifying info. I've had a difficult time finding specs on the stock amp.
Yes, 'louder' is one thing of importance, but more importantly I'm trying to get the truest crispest output.
And, yeah I know the best way to determine all of this is by trying both sets installed, which I was hoping I wouldn't have to do.
If the difference is negligible at moderate volume (occasionally I crank it up), then the entire thought experiment is moot.

 

[whoaru99]

If the difference is negligible at moderate volume (occasionally I crank it up), then the entire thought experiment is moot.

In the condition mentioned by Gordon, the difference, if even big enough to detect, I opine would really only show up in a high output/pushing the limits type situation.