We are asked this question all the time: “How much amplifier power do I need?” Simply put, the amount of amplifier power that you need will depend on what you are trying to do. Higher frequencies require less cone movement to reproduce, thus less power is required. A good amplifier for midrange and highs needs to be clean. The power needs to match up to the speakers well, and it needs to deliver enough output to balance the system overall. Usually it is the lower frequencies that dictate the power requirements for the system, as the subwoofer requires far more power for the bigger job of reproducing notes that require a large heavy cone and a lot of movement.
Peak Power – “If Lightning Strikes”
Many manufacturers will use a “peak” power rating for both the subwoofer and the amplifier. Many in the industry will refer to this rating on an amplifier as “ILS” power – because that amp is only going to produce that much power “If Lightning Strikes”. It would be the same as rating the top speed for your car as you pushed it off a very high cliff – maybe it did reach 200 MPH before it crashed at the bottom, but that isn’t a speed that you could get at the track every weekend. Consistent power is what counts.
In order to level the playing field the Federal Trade Commission has required amplifier manufacturers to use an industry standard RMS (root-mean-square) rating for amplifiers. You should completely ignore the big number plastered in neon all over the amplifier and box, and look for the real number which is the RMS rating. It is required to be there, and may be buried on a spec sheet in the box, but that is the only way to know what you are really buying.
Pair Up Your Speakers And Amp
Ideally you would need to make sure that the real continuous RMS power output of the amplifier matches up well with the rated continuous power handling of the woofer. Once again any “peak” power ratings should be ignored. It is worth mentioning that there is no FTC regulation for subwoofers to level the playing field. Most manufacturers will try to give you a rating that will help you avoid overpowering and damaging the woofer, but it is important to deal with a reputable manufacturer who is more likely to give accurate ratings. Only use manufacturers who will stand behind the product if there is a problem down the road. If the speaker seems light weight and of a cheaper build than other woofers of similar ratings, then it might be better to avoid it, no matter what the numbers say.
Once the decision is made on the subwoofer and sub amp, then it is a matter of matching up the mids and highs to keep up. Using the bottom-up approach will help you choose the right amplifiers and get the proper amount of power for a balanced system.
As always, it is best to consult an expert! If you a trying to figure out how much amplifier power you need and you are in the Richmond, VA area, we invite you to stop in at our facility. We will take the time to assess your situation and make a quality recommendation just for you. We look forward to meeting you!