The rise of iPod docks, Bluetooth speakers, and soundbars has made it easier than ever to get great sound with minimal effort. But when it comes to recreating a truly exceptional movie or concert experience in your own home, it’s best to invest in a more traditional audio system comprised of separate speakers and equipment. So when shopping for speakers, what should you look for? Are there certain features that make one speaker better than another? What about all of those specifications—watts, amps, and ohms? Do they matter and, if so, which ones should you pay close attention to? Here’s a breakdown of the important speaker specs.
Recommended Amplifier Power Rating
One of the biggest misconceptions people have about speakers is that they are going to overpower them. This is a valid concern, but one that needs to be put into context. Every speaker has a Recommended Amplifier Power Rating. Speaker manufacturers provide this spec, so you know how much power the speaker is able to handle. This helps you choose an appropriate amplifier to pair with the speakers. It sounds pretty straightforward, but this doesn’t mean you have to use an amplifier in the recommended range. You can always use an amplifier that produces more than the recommended power rating. The reason for this is that most amplifiers rated at 200 watts per channel aren’t going to be delivering this amount of power all the time. In fact, most likely they will produce much less during normal listening —more along the lines of a couple of watts at most. In most cases, the only time an amplifier uses its full power rating is during dynamic swings in the soundtrack or song, such as an explosion in a movie or the crash of a cymbal.
You might be asking, “Why have more power than recommended?” When an amplifier exceeds its normal operating range (power capabilities), it is unable to deliver undistorted signals to the speakers; this phenomenon is known as “clipping,” and running an amp in this manner can damage it and the speakers. Moreover, if the electrical current is interrupted, the distorted signals can cause the speakers’ voice coils to heat up and the speaker drivers to move erratically, which can cause damage. The benefit of extra power is that it allows for the amplifier to have a sweet spot. The sweet spot is the optimum range of operation where it will have the lowest distortion levels. This usually translates to a cleaner signal being transmitted to the speaker, thus improving sound quality. A speaker that is recommended to handle 30W–100W will match really well with a 200W amplifier, because from 1W to 100W, the amplifier will be cruising along without even breaking a sweat. Warning:You do still need to be careful about how much power you provide your speakers. Cranking it up to obscene decibel levels can deliver too much electrical current, and this, again, can cause clipping. The best choice is to power your speakers with a little more power than needed.
Sensitivity
When selecting a speaker it is important to know its sensitivity level. We’re not talking about the speaker’s feelings, here, but instead how easy it is to make the speaker play. You will commonly see sensitivity listed as something like, “84dB SPL (2.83V, 1M).” This isn’t as complex as it looks when you break it down. 84dB SPL = 84 decibels (sound pressure level). 2.83V = 1 watt at 8 ohms, 2 watts at 4 ohms. 1M = 1 meter distance the decibel level was measured. 84db SPL (2.83V, 1M) is basically saying that this speaker will produce 84 decibels with 1 watt of power, measured 1 meter in front of the speaker. It’s fair to say that this speaker sensitivity is low. A speaker that has a lower sensitivity rating (84dB) means that it will take more power to make it sound loud. Conversely, a higher sensitivity rating (for example, 95dB SPL) will sound loud with less power. You will want to invest in a more powerful amplifier for a speaker with low sensitivity, but for high sensitivity speakers, the power rating is less of a factor.
Nominal Impedance (8, 6, & 4 ohms)
Knowing your speakers’ nominal impedance is important because it tells you how resistant your speakers are to the flow of electricity (current) from the amplifier. This is measured in ohms (ÃŽ:©). This spec can help prevent you from destroying your amplifier, over time. I say this not to worry you, but to make sure you know that an amplifier designed to handle only 8 ohm speakers shouldn’t be used with 4 ohm speakers. Speakers that have a lower ohm specification are less resistant to the flow of power being fed to them from the amplifier. This can be more taxing on an amplifier’s power supply, causing them to overheat and even fail. As the ohms gets lower, you want a more robust amplifier to be able to handle the increase in current.
Frequency Response
When you are looking for speakers, it’s important to know the range of frequencies they can reproduce. This will help you determine how much of the sound spectrum the speakers can replicate. It’s widely believed that the human ear can perceive sound from 20Hz to 20kHz. There is some debate, but for our purposes let’s assume this statement is correct. In an ideal world, you want your speakers to produce the whole 20Hz to 20kHz. This would make them full-range speakers, and they can duplicate all the sounds the human ear can perceive. However, achieving full-range sound is easier said than done. The majority of decent quality speakers can handle the treble (20 kHz) portion with little problem. It’s the bass (20Hz) side that is much more difficult to reproduce. Deep bass usually requires either a very advanced and/or large speaker or a powered subwoofer that is designed to reproduce sound to 20Hz. There is a wide variety of stand-alone speakers that are full-range, but in general they are very expensive and require high-powered amplifiers to run at their optimum performance level. Most people choose to include a subwoofer in their home theater or stereo system to help boost bass performance. A subwoofer can pick up the frequencies that your main speakers are unable to reproduce.
Speaker manufacturers provide customers with many different technical specs about their products, but these four speaker specs are the most important to consider. Getting your sound system right the first time is very important and will save you money and a lot of headaches. EH
Kevin Gallucci is a freelance A/V writer and self-admitting electronics junkie. He has written for various publications such as Electronic House, Hi-Fi Choice, ToneAudio, SoundStage, HiFi News, and Home Cinema Choice. Kevin’s goal is to make hi-fi/home cinema interesting for all ages and debunk the myth that you need to spend a fortune to get a great sounding system.
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