Under pwer vs. Over power

IT DOES NOT MATTER.   As long as you know what you're doing and you set up your system correctly, you can use any amp with any speaker.

The key to that, of course, is "know what you're doing."  This means fully understanding both your amp's and your loudspeaker's capabilities.

FOR MOST CAR STEREO APPLICATIONS, matching the listed RMS rating for speaker and amp is the commonly acceptable approach since most people do not really understand what they are doing.  Then, at least they have a chance of not destroying their gear and of getting the most out of it.

For professional applications, I always recomend a 2X to 3X safety factor between amplifier rating and loudspeaker rating, and always based on the amplifier rating.  Meaning, if your amps are ratied at 250 watts per channel, your loudspeakers need to be capable of handling 500 watts or greater.

And, just one more time for clarity, remember this: THERE IS NO SUCH THING AS UNDER-POWERING A LOUDSPEAKER.  Any amplifier properly set up can be used with any loudspeaker.

The only non-mechanical thing that can damage a loudspeaker is heat.  The only way an amplifier will generate heat inside a loudspeaker is through TOO MUCH POWER.  The ways an amplifier can supply too much power is through CLIPPING (which generates heat both from straight rail voltage being passed through and by causing the mechanical motion of the voice coil to stop) or by simply producing higher power output than the loudspeaker's thermal limits.

This is exactly what I meant when I said the average person does not know what they are doing.  "Achieving the full potential of the components" is a very dumb thing to think about but it is how most people think.  It drives me mad sometimes.  "Turing the amp gain to 100%" will, indeed, create clipping and is a very dumb thing to do in ANY case.  This should never, never be done.  It will destroy speakers and maybe destroy the amp.  It causes severe clipping.  There is no way around it.  This statement indicates the owner does not understand amplifier gain.  Amplifier input gain is NOT a volume control!!!!!

Bottom line: if the amplifier gain is set correctly, matched to the head unit output, the amp will never clip and it will put out its full capability as a clean signal.  If the speakers receive this clean, unclipped signal, they will operate at their "full potential" no matter what the power ratings are.  The difference in SPL between 50 watts and 100 watts is 3db.  3db is about 1/3 louder.  It is not significant.  Most speakers can produce their "full potential" as far as frequency response with 2 watts input.  Many speakers can achieve their "full potential" of SPL with 10 watts input.

There are many misconceptions floating around concerning this topic..people pick up on them and believe them. That's why this topic is so misunderstood. If you're not 100% positive you know what you're doing...play it safe and match RMS ratings..less power is fine as well.

It controls the sensitivity.

That is such an awsome post Dyohn.  It's amazing how many people ignore our recommendation to them to run a 700-1000 watt amp and instead pick up a 1500 watt one because of the ratings on our subwoofers.  Heading up the warranty department, I see a lot of subs come back because of this.  In fact we are deflating our ratings a little bit on the new lines just to add a "dummy" factor into it.  Apparently using the pro sound standard for rating doesn't work in the car audio market.

I do want to make one small clarification though.  A speakers voice coil will blow with too much unclipped power as well.  The speaker doesn't care if the signal is clipped or not, if the power levels exceed it's thermal capabilities it will blow.  This is because to a speaker a clipped signal is no different than an audio signal.  It only cares about the power level of that signal.  There is of course a time factor involved as well.  Music is dynamic and it's peaks in power levels might not be long enough to heat up a coil beyond it's limits.  That's how SPL competitors can send 10 kilwatts into subs without blowing them.  One of our competitors (Scottie Johnson) does this in his vehicle and has never blown a voice coil.  But these people know what they are doing.  

Steven Kephart

Adire Audio