river is critical to ensure that the different drivers in a speaker blend together seamlessly while faithfully reproducing the full audio spectrum.
Audio Specs Explained
- What is Nominal Impedance? Impedance is a measure of resistance. All electrical devices resist the flow of electricity to some degree. Because they resist at some frequencies more than at others, engineers thought they would confuse the layperson. Thus they chose the word impedance instead of resistance. But the concept is the same. The nominal impedance (resistance) means “the lowest the impedance (resistance) will be at any frequency is not much lower than the spec listed.” This spec is unrelated to the quality of speaker performance but it can effect how much power your speaker draws from your receiver. The lower the impedance, the more power the speaker will draw from your receiver with the “volume” knob at a given position. Therefore if your speaker has a low nominal impedance spec, typically 4 ohms or lower, you will need a higher powered amplifier to drive it.
- What is Efficiency (also known as SPL)? The efficiency of a speaker is how loud it will play, in dB, when fed one watt of power and measured from one meter away. If a speaker is 10dB higher in efficiency than another, it will play twice as loud with the same amount of power. An increase of 3 dB means it will play just as loud with half the power. Don’t mistake efficiency for quality. In fact, many good speakers, like high performance cars, are low in efficiency.
- What is Sensitivity? This takes efficiency and adds the effect of impedance. If two speakers are the same in efficiency but one as half the impedance (resistance), it will play 3dB louder since it’s drawing twice the power from your amp (and that’s without touching the volume knob).
- What is Frequency Response? This is usually the most reliable indicator of a speaker’s sound quality. Unfortunately, it’s also the easiest spec to manipulate given that it depends on microphone placement, room placement, how the graph of the response is scaled and smoothed, etc. If your speaker system really is +/- 3dB, that is only 3dB of deviation, from 300 Hz to 18,000 Hz in a lab condition and +/- 5 dB from 30 Hz to 500 Hz in your listening position it’s likely to be a fine sounding system indeed. If you choose to look at response graphs, keep in mind, rough peaks that are narrow in frequency range will not be as audible as graphs that have a wide frequency range that is low or elevated.
- What is Power Handling? Continuous power handling is only limited by how hot the voice coil can get before the glue that holds the wire begins to melt. Peak power handling refers to how big of a momentary burst (at the most troublesome bass frequency) a speaker can take. This is a somewhat tricky spec, because if a speaker is rated for 100 watts, we don’t know how long it can really sustain that power level. Also, just because a speaker can handle a large amount of power does not mean that it is better than a speaker with a lower power handling spec. Finally the power handling spec is only really important if you plan on playing your speakers at a loud volume for a long period of time.
- What is Recommended (amplifier) Power? This defines the manufacturer’s idea of a sensible range of amplifier (or receiver) power for their speaker. This specification is a helpful way of subjectively combining power handling and efficiency into one useful rating.
- What is Max SPL? This is a measure of how loud a speaker can play. It’s hard to make sense of this spec. This isn’t the most helpful specification because there isn’t a real standard in terms of the conditions that are used to test the maximum SPL of a speaker, so you may not be comparing apples to apples when looking at different speakers.
Hopefully this article helped demystify how speakers work and also will help you make an informed buying decision the next time you are shopping for speakers. Just remember, the most important thing is to trust your ears and as always, happy listening!
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