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What’s with the Watts? (Part 2 Speakers)


Continued from part 1:

Now that I’ve covered a bit about power ratings of the amplifier, let’s move on the the loudspeaker.

Among other things, speakers are rated in Watts. This is again the subject of the most misunderstanding and abuse by marketing. Here I will attempt to break down what this all really means.

In a perfect world a speaker rated 1000 watts would handle a true 1000 watts all day long, and produce fairly accurate sound in the process. Unfortunatley, the world of retail/marketing is seldom perfect. I have seen many a “1000 watt” speaker tear apart or release smoke at 500 watts, and also seen quite a few “800 watt” speakers handle 1600 watts with no trouble and still sound great in the process.

As with Amplifiers there is a lot of misinformation and mythology surrounding power handling of speakers and unscrupulous manufacturers have been quick to take advantage of it by putting unrealistic numbers on inferior products to mislead the uninitiated. If you have ever smelled the unmistakable sweet and sour aroma of a speaker giving up the ghost, you know how awful it is to destroy a speaker. If you haven’t, hopefully the following will help you avoid ever having this experience.

In the real world, power handling of a speaker depends on how much the cone can physically move (xmax) and how much heat the coil can hold before melting. The most common causes of death for speakers actually have little to do with rated power handling whatsoever! Before I really break down rated power handling (which is more often than not a useless marketing tool), I will break down the most common causes of speaker failure and go over how to avoid some of them.

First, we will put to rest the most common myth surrounding speakers. Many people assert that “under powering” speakers can damage them. This is completely absurd. If a speaker could only be played safely at full power, we would not have volume controlls on our equipment, it would be either full blast, or damaged equipment. Even the most poorly made speakers should function (to some degree) at low power levels and up to it’s mechanical and thermal limitiations.

Actually this myth has it’s roots in reality to some degree. When someone claims to have blown up a 500 watt speaker on a 300 watt amp, what is usually happening is the amplifier is being pushed beyond it’s limitations and is in a state known as “clipping”. The lay-person would recognize this is distorted crunchy sound. I won’t get more technical than that for this discussion. Sufficed to say, if your amp is clipping, it is common to damage speakers at much lower power levels than they would normally handle with ease with a good clean signal. To prevent this, use your amplifier within it’s limitations. Put your ear right up to the speaker as you turn the music up and when things start to sound “distorted” or “dirty” BACK OFF. That’s problaby the limit of your equipment. This is one of the most common causes of speaker failure, and also a common killer of amplifiers.

A close second in why speakers fail also has little to do with rated power handling and more to do with frequency response. Though this is another spec that can be mostly ignored when printed on a product advertizement, we can save a lot of trouble with some common sense. Simply put, small speakers cannot handle low frequencies. This mostly comes into play with midrange speakers and tweeters, but can be a factor with subwoofers. Low notes involve the “cone” of the speaker moving much greater distances back and forth. Generally speaking the bigger the “motor structure” or magnet and suspension system of a speaker, the better it will handle the lower notes. Use speakers for what they are designed to do! A midrange speaker is designed for the middle ranged sounds (mostly vocals and instruments). Most midrange speakers should be “crossed over” at even modest power levels to avoid trying to make them produce low sounds that they are physically incapable of doing. If you plan to amplify speakers, you will most likely need to cross them over, fortunately almost every component these days comes with, or has crossovers built in. Even subwoofers should normally be run with a “subsonic filter”. This will keep the woofer from over extending itself trying to play ultra low frequencies. In almost all situations, running a subsonic filter is a good idea and will improve real world power handling, efficiency, and sound quality. Playing signals that are “too high” for a speaker will not harm them, but after a point, it will be very inefficient and sound quality will suffer.

The last major culprit in speaker destruction has to do with the speaker “enclosure”. Among other things a speaker enclosure (or box) creates a cushion of air to help controll the motion of the speakers moving parts. Almost all subwoofers will require a box of some sort to function properly. I will not go too deep into this topic here, but to say that any woofer (from 3.5″ to 18″) will benefit in real world performance and power handling from being in a tight, well made box. Many midrange woofers are designed to run “free air” in your doors, dash, or rear deck, but they will all benefit greatly if a small “box” can be manufactured in these locations to seal off the rear of the speaker from the front.

Now assuming you are running a good clean honestly rated amp, and your speakers are all in well made enclosures and properly crossed over, we can finally delve into the topic of watts.

The amount of power a speaker can handle is limited by mechanical factors and thermal factors. In theory the “max power” or “RMS power” rating on the speaker will be the least of the two. A speaker with a motor structure allowing 2 inches of motion peak to peak is pretty useless if the coil burns out at 500 watts. Conversely, a speaker than can handle 2000 watts worth of heat that is mechanically only able to move 1/2 inch before tearing itself apart is equally worthless. A good manufacturer will keep both mechanical and thermal power handling closely matched and be honest (or conservative) in their marketing. Companies that advertize with a “max power” rating 2 to 3 times the “RMS” or “continuous” rating are trying to impress with big unrealistic numbers. In my opinion this is dishonest and I would be leary of a company that is trying to be dishonest with me from the start. A good company does not need big numbers on the box to sell products. They advertize their speakers as able to handle power that under most circumstances they can do with ease, in the real world, and with good quality sound.

All things being equal you would think “the more the merrier” right? Not so. Along with high power handling will often come inefficiency. This is not necessarily the case with the premium products, but a good enough guidline for the average consumer. If you only plan on powering a speaker with 50 watts, getting a speaker rated to handle 300 watts may not be your best answer.

I generally try to get a speaker rated to handle at least 10 to 25% more power than the amp claims to deliver. If you think you may upgrade amps later, or just get a good deal on a high power rated speaker, go ahead and get whatever you like. Be very careful buying speakers rated for less power than your amp will produce. Many speakers (like amps) are conservatively rated, and depending on the other facotrs can be made to handle much more than rated power, but this should be done with extreme caution!

For most people 75 to 100 watt rated components or coaxials will be plenty, and there are many great offerings in the market. For subwoofers, 250 to 600 watts is enough for most.

If you are looking to put more than 200 watts into component speakers or 800 watts into a single subwoofer, be prepared to start spending money exponentially. Not many products on the market will handle that kind of power in the real world for more than a fraction of a second. Try to stick with the premium brands and the heavy duty build, large motors and attention to detail should jump out at you. Like when you handle a Rolex watch, you can just see and feel that it’s a superbly made product. Top end speakers will have that feeling about them.

When shopping, try to stick to reputable brands! Speakers are the most important link in your sound system and can make or break things. Get a brand that is known for honest ratings and quality build. Ask around locally and in online forums and if at all possible go and listen to some in person. At the end of the day, if it sounds good, it is good. Keep in mind when listening on the display board in a shop, the speakers are mounted in ideal locations and in sound enclosures. While actual in car performance may vary, you can test different models side by side and get a fair idea as to what kind of sound they’re capable of, and what kind of power they can really handle.

In general if you plan to buy amps and speakers of the same brand, you can safely expect the 200 watt amp to properly power their 200 watt speaker. When mix-matching brands, you’ll need to do a bit of homework to find out how accurate each is and match accordingly.

Today the cutting edge of high performance loudspeakers are still manufactured in the USA. Many of the best companies out there are virtually unknown to the average consumer and will not be found in the big box stores. Europe has some outstanding speaker manufacturers as well, and Israel has the well respected Morrel brand. Even many of the Aisian made products today are pretty good for the price and can often get people a lot of bang for the buck.

In summary, use your head and your ears when selecting speakers. As with amps, you usually don’t get something for nothing, and most of the numbers you’ll see thrown around are meaningless in the real world. If it sounds good, it probaly is good, and if you use your equipment properly and within it’s limitations you should never have that sinking feeling when the smoke comes rolling up from your doors or trunk.


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