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What best rated W for speakers to go with new kenwood dpx-5210u 50Wx4 stereo?

hi all im new to this activity. i have a chevy optra 2008 with stock speakers and stereo (reciever). the sound is good but i wanted more so my friends suggested i go for a stereo but now that i got it, when i set it to max volume the sound isnt clear and breaking so i think the problem in the car speakers? im planning to change them 4 for another 4 ones, will a 300W rated speaker be good? i really dont know but what W should i go for? and do i need an amplifier or not? i really dont want to i can only afford to get new speakers if they make a better sound with the stereo.

I would like to clear up something that has been passed on as some sort of fact, but is, in truth, a misconception.

The power rating of a driver (what most people call speakers) does not directly correlate to perceived loudness or even efficiency. The specification that relates to loudness (and the relative efficiency of that driver) is the SPL (Sound Pressure Level) which is expressed in dB (deciBels), usually with the qualifier of @ 1W/1M (1 Watt at 1 Meter). The higher the number, the more efficient and more loud the driver.

For example, a 4” woofer can be rated at 100 watts, but it’s SPL may only be 83 dB while a 10” woofer may be rated at 50 watts, but it’s SPL could be 93 dB.  Now the 4” woofer can handle more power, but it won’t be as loud as the 10” woofer, even at full power for either. And, to double the perceived loudness, you have to increase the power by a factor of 10. So, the 4” woofer at 1W=83 dB, at 10W=93 dB, and at 100W=103 dB. The 10” woofer at 1W=93 dB, at 10W=103 dB, and at 50W=108 dB. If the 10” woofer was rated for 100W it would produce 113 dB SPL, twice as loud as the 4” woofer.

As for the power rating, this usually (and I say this because you can never tell what the manufacturer really base their numbers on) is the measure of power the driver can handle safely. Never go with the PMPO (Peak Music Power Output) or Peak Power. You want to look for RMS power ratings. These are conservative ratings based on normal use. The higher the RMS rating, the more robust the driver and the longer it will last.

If it has a frequency response plot, look for one that is relatively flat, not one that is full of tall peaks and deep valleys. If you can only find plots with peaks and valleys, the less pronounced they are the better.

Also, try to match the impedance of the driver to the amplifier. I have not looked at your stereo’s specs, but I’m pretty sure that it says 4 ohms. If so, try to get 4 ohm drivers. This will maximize power transfer and keep the stereo in it’s safe operating zone.

As for what power rating you should look for, 50W minimum, preferably 100W for a safety margin.

In summary, SPL sets efficiency (and perceived loudness), look for the correct impedance (in ohms), and get a power rating of minimally your amp’s max output, but preferably about twice that for safety and durability’s sake.

Hope this gives you a better understanding of the amp/speaker relationship.

Qa
mkhaled4 (author)  Quercus austrina4 years ago
i have this head unit.
http://ae.kenwood.com/Car_Entertainment/2DIN_Receivers/DPX-U5120

and got these for my front door speakers
http://au.kenwood.com/Car_Entertainment/Speakers/KFC-M1642A

but i hear a hissing sound, my head unit max volume 35, on old front speakers i had alot distortion from 25, on these new speakers distortion from 27. i feel like i wasted my money on these speakers i dont have an amplifier.
Sorry it took so long to reply.

What you are hearing is from the internal amplifier itself, the bias being amplified. Don't worry if you do not understand exactly what that is. At this point, you are running into the maximum "clean" amplification of the chip used in that particular head unit. After this, you start to get types of distortion due to the design of the chip, so no matter what you do externally to clean up or strengthen the power coming into the unit, you'll have that limitation.

The good news is that the upgrade to the speakers is actually paying off. You state that you had a lot of distortion from 25 and up on the volume scale with the factory speakers. The new ones start (if I am reading that correctly) to distort at 27. This is a good improvement. I am fairly sure (because I cannot be there to personally inspect the setup) that the distortion is in the electronics, not the speakers.

The next good news is that your head unit has provisions to connect to external amplifiers. This will allow you to add more clean power in the future, and configure it in such a way the the most power hungry speakers (woofers and subwoofers) will get the lion's share while the other speakers get more power without the heavy bass causing distortion in them. You will be surprised when you can do this in the future. Just be patient, and be happy that you have a decent foundation for more when you have the money to add to the system.

Oh, and when I say woofer, I don't mean those tiny lttle ones that come in computer speakers (3" to 5"). I mean something at least 6" for mid-bass and no less than 8" to start to even produce real bass in the 40Hz range. I personally would start with 10" for good, solid bass, but that is my preference. Your car could probably use a tube type bass enclosure to great advantage. But that is for the future.

Qa
If the stereo can support up to 50W per channel across 4 channels then get 50W speakers. With 300W speakers you won't have much volume from them since the stereo can't output enough power.