Amp too powerful??

[SonicRed]

Is 75 watts RMS too much for speakers rated at 45 watts RMS??

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[SonicRed]

The setup would be:

Amp = Alpine PDX-5 (5 channel amp)

Speakers = Rockford Fosgate R165X3 6.5

Subwoofer = Polk DB+ 8” (SVC 4 ohm)


Will the amp blow the door speakers??

 

[YourNameHere 10+ year member]

no...just set your gain low and watch your volume,got any more completely retarded questions?

 

[Lasherž]

The setup would be:

Amp = Alpine PDX-5 (5 channel amp)

Speakers = Rockford Fosgate R165X3 6.5

Subwoofer = Polk DB+ 8” (SVC 4 ohm)


Will the amp blow the door speakers??

It's totally fine to have an amplifier of higher rated power than the speakers. You just have to be careful since you can't trust the clipping lights that might be included with the amp. Glancing over your amplifier it doesn't appear to have one of those lights anyways. Set your gains using 0db sine wave test tones like on kicker's website, a multimeter, and ohm's law. For example, for setting each channel to 45W you'll need the ohm that it's connected at, in your case with those speakers it's 4 ohms.

Voltage = current x impedance -- at 1 ohm voltage and current are approximately the same, and at 4 ohms voltage is 4 times larger than current. So you can plug in 45W and 4ohms like this V = √(45Wx4ohms) = 13.416V

Once you know the expected voltage value (13.416V) for 45W @ 4 ohms you can unhook your speakers from the amplifier and hook up your multimeter to the amplifier + and - for that channel on AC voltage mode. Play 0db test tones of various frequencies at very low gain, as low as is audible, but as high volume as you regular play music on the head unit, at least from 40hz to the 150hz range and whichever tone yields the most voltage without touching the gain or volume between tones, play that and turn the gain until it reaches 13.4V and then you're done and can hook up your speakers again knowing you're getting close to the maximum performance you can get from them.

 

[Slo_Ride 5,000+ posts]

Yes

 

[hispls 5,000+ posts]

Will the amp blow the door speakers??

You will need to be mindful of breaking them mechanically if you attempt to run them full range. On smaller components/coaxials power handling is generally mechanically and not thermally limited first. I'd expect the speakers to survive if you used HPF from the amp or your head unit (if it has one). 80hz is typically a good place to start then you can dial it in from there.

 

[SonicRed]

Thank you for all the advice.

 

[ThxOne Premium Member]

"If you can prevent the power amp from clipping (by using a limiter), use a power amp that supplies 2 to 4 times the speakers continuous power rating per channel. This allows 3 to 6 dB of headroom for peaks in the audio signal. Speakers are built to handle those short-term peaks. If you cant keep the power amp from clipping (say, you have no limiter and the system is over driven or goes into feedback) the amplifier power should equal the speakers continuous power rating. That way the speaker wont be damaged if the amp clips by overdriving its input. In this case there is no headroom for peaks, so you'll have to drive the speaker at less than its full rated power if you want to avoid distortion." - Crown by Harman

 

[OldFartAudio]

I would think you should be fine as long as you set the gain properly. I have not learned much since the Car Audio and Electronics magazine closed up shop but I have always heard that distortion is what blows speakers. They tested an 8" JL Audio sub with, I think it was an Earthquake amp, that was rated at like twice the power of the 8" and it played fine. Understand that this was back in the mid 90's though. Recently I watched a video of a subwoofer burn its coil out from shear power. Back in the day the largest amps we had made 1000 watts maybe on 14.4 volts. This was a Rockville sub on a 1500 watt amp I think. Anyway, the point is, with normal power and the distortion avoided I doubt you will have any problems. Don't play pink noise at max volume and max gain though.

 

[Lasherž]

I would think you should be fine as long as you set the gain properly. I have not learned much since the Car Audio and Electronics magazine closed up shop but I have always heard that distortion is what blows speakers. They tested an 8" JL Audio sub with, I think it was an Earthquake amp, that was rated at like twice the power of the 8" and it played fine. Understand that this was back in the mid 90's though. Recently I watched a video of a subwoofer burn its coil out from shear power. Back in the day the largest amps we had made 1000 watts maybe on 14.4 volts. This was a Rockville sub on a 1500 watt amp I think. Anyway, the point is, with normal power and the distortion avoided I doubt you will have any problems. Don't play pink noise at max volume and max gain though.

Good branded speakers often do outperform their rating, but it's not a reliable metric. The reason almost every speaker fails is heat, dirty power (distortion) causes heat, that's true, but there's more that goes into it. It can play one song just fine but blow on the next one depending on the frequencies. If you think of the cooling method of a speaker it uses vents to **** and push air over the voice coil. If there's less movement there's less cooling. The worst situation is where it clips, this means that despite putting more power into the speaker, its excursion is halted at the peak of the wave and no venting is taking place. In this case there's a decent chance it'll be fine with most songs at that elevated power, but if it hits a low note I have no confidence that it will be able to a) avoid overexcursion with a recommended enclosure (ported) or b) be able to vent away more than its rating in heat with an air dampening setup (sealed).

More basic information on damaging speakers and under/over-driving speakers.

Why Too Little Power will NOT blow Your Speakers

This page of the bcae1.com site explains why too little power will NOT damage speakers.

www.bcae1.com