Understanding Speaker Specifications

There are a lot of specifications when it comes to loudspeakers, and understanding speaker specs can be a real pain if you’re sifting through data you don’t fully grasp. Still, the specifications game is one way you can at least whittle down your list to something more manageable—giving you a starting point and a shorter group of products from which to decide. In no particular order, here are some of the more common speaker specs you’ll want to understand when you’re shopping: 1. Sensitivity: Measured in dB (decibels), it is one of the most significant albeit ignored, speaker specifications. A speaker's sensitivity indicates the loudness of a speaker. The higher the sensitivity rating, the louder your speaker is. An average speaker comes with a sensitivity of around 87 dB to 88 dB. A speaker with a sensitivity rating over 90 dB is considered excellent. When you see a sensitivity rating, it is always written as a factor of SPL output from a particular distance.This is a rating that tells you what the output of a speaker is when fed a 1kHz signal (sine wave) at exactly 1 Watt (2.83V) and measured on-axis from 1 meter away. This is a great number because it tells you how “efficiently” the speaker uses amplifier power. In a sense, you could call this how “loud” the speaker is, but that’s not entirely true since a less efficient speaker might be able to take more power before distorting. To give you an idea of how much this matters, consider that the way we perceive something as being “twice as loud” means that it has increased by 10 dB SPL. If one speaker has a rating of 84 dB SPL @ 1W/m and another has a sensitivity of 94 dB SPL @ 1W/m then it will take twice the amplifier power to bring the first speaker to the same volume as the second. That’s an amazing difference that will mean a lot when you’re trying to fill a larger room or play back music at much louder volumes. 2. Impedance: Impedance = Resistance. Measured in ohms, this is another critical specification that you should take a note of. A speaker’s impedance rating is always given as a single number—which is a bit deceiving. Every loudspeaker’s impedance curve is just that—a curve. There are frequencies that drop the impedance down and require more power from an amplifier to power through. The bottom line is that impedance is the resistance or “load” the loudspeaker presents to the supplied power. A majority of speakers are rated at 8-ohms. That’s a nominal, or averaged, impedance specification and it means the speaker can be driven by just about anything more powerful than a 9V battery. It may not be loud or efficient, but it will work. 4-ohm speakers may require more power and a better quality amplifier if you intend to play them loudly or fill a large room with audio. There’s also the chance that playing a 4-ohm speaker on a lower-cost amplifier or receiver could, after a sustained period of time, actually ruin the amplifier. Think of it like this: How far would you get powering a laptop off a battery that had half the amount of voltage required? It may power up, but very quickly that power supply will start to smoke. Match the amp or receiver to the speaker and you’ll be much better off. 3. Frequency Response: It is sometimes mentioned as frequency range and is measured in Hertz (Hz). This specification in a speaker tells how low and high a speaker can play. It is mentioned as "XHz-XkHz" - where X is a number. Let's take a hypothetical figure: 65Hz-20kHz. The number at the lower end i.e.,"65Hz" here represents the bass output which means how low a speaker can play. The lower the number, the deeper the bass. And 20kHz (20,000 Hz) represents the highest treble. It is said that the human ear can hear between 20Hz and 20kHz. But, practically, bass frequencies below 30Hz are less heard and more felt. Therefore, any speaker that reaches 50 Hz or lower is considered good and is not required to be teamed with a subwoofer until you really want to hear the deepest bass. Make sure that there is always a "+/-" after the frequency response rating. If the "+/-" deviation is absent, then this spec doesn't reveal the true picture. Speakers usually come with a +/- 3 dB or +/- 4 dB rating after the frequency range. For example, A speaker has a frequency response of "40Hz-20kHz +/-3 dB". The "+/- 3 dB" indicates that every tone that the speaker produces will be within 3 dB of any other sound in the entire frequency range. Which means that your ears won't miss even the little sounds. 4. Power Handling: Specified in Watts (W), the power handling specification of a speaker indicates how much power a speaker can bear without causing any damage. This is often defined in either nominal or continuous power (Watts RMS), and short-term peak input power a loudspeaker can handle before destroying the loudspeaker. However, a speaker driver may be destroyed as a result of overheating even with a lot less power than its peak rating if its continuous power handling capability is exceeded for a sufficient length of time. Even driving an amplifier into clipping may destroy your speaker drivers, and especially the tweeters. In a similar manner, an amplifier struggling to drive a speaker may produce a high level of distortion which may also destroy your speakers. In either situation, more energy is passed onto the speaker especially at high frequencies which may easily damage a speaker driver unit. This implies that: More amplifier power is better than less, and the cleaner the better! 5. Signal-to-Noise Ratio (SNR): The sound that a speaker produces includes some level of noise. In other words, audio signals are sent to a speaker which are then converted into the sound (via internal driver movements) that we hear. But the sound that we hear are not purely audio signals that a speaker gets, in fact, it also includes some level of noise. This noise is added by internal components of the speaker/device. Therefore, this spec describes how much noise is there in the output (sound that we hear) of a device in relation to the signal level. It is also expressed in decibels (dB). So if a speaker has 120dB of Signal-to-Noise Ratio, it means that that the level of the audio signal is 120dB higher than the level of the noise. The higher the number, the better it is. Well, the specs of a speaker can give you more than an idea about its performance, but how well it performs in real world depends on the quality of its drivers, cabinets and other significant components. As always, choose your speakers wisely. Of all of your components, they really don’t ever go out of style and should last you a very long time. You can always upgrade them, but it won’t be because some newfangled technology came into play that stopped them from working or made them obsolete.