In this article, we explain the most important speaker specs you need to look into when sourcing speakers, including rated power, impedance, frequency response and sensitivity. Here’s a quick guide to what the most mysterious terms mean.
1. Rated power
Rated power refers to the maximum input power allowed by the speaker within the rated distortion range.
Particular note
Speakers usually come with two power ratings – RMS or continuous, and Peak.
The RMS rating defines the continuous power a speaker can handle without getting destroyed. Whereas the Peak power rating implies the maximum amount of power a speaker can bear in an instant. This peak rating, however, is of no use in practical application.
Sourcing tip
Make sure that your speaker has power ratings mentioned in RMS to make a true comparison.
2. Impedance
Impedance refers to the resistance an amplifier will encounter when trying to drive a given speaker. Most speakers have an impedance rating that falls between 2Ω and 16Ω, with 4Ω and 8Ω impedance ratings being the most common.
Particular note
The impedance of a speaker is generally related to frequency. Without seeing the impedance “curve” you cannot know whether the speaker presents an amplifier with an easy or a difficult load.
Given this variability, one should not put too much emphasis on rated impedance and it should only be used to give you a general idea of how the speaker will load your amplifier.
Sourcing tip
Look for loud speakers with a “nominal” 8Ω impedance, though most amplifiers will easily handle a 6Ω load.
3. Frequency response
The frequency response is used to describe the audible frequency range that a speaker can reproduce.
Particular note
Consider an example where the frequency response of a speaker is noted in the specifications as “40 Hz to 22 kHz”. Note that the frequency response specification in our example does not include an amplitude tolerance.
But even when the frequency response is put into context with an amplitude tolerance the spec still does not give any real indication of how the speaker is measured, which can affect the response.
Sourcing tip
At best, the frequency response spec of a loudspeaker should only be used to give a general indication of how high the treble frequencies will reach and how low the bass notes will hit.
4. Sensitivity
Speaker sensitivity is the measurement of the amount of sound pressure that the loudspeaker will produce, at a distance of one meter, when only 1W of power is applied from an amplifier.
Particular note
The sensitivity spec of a speaker is one of the most useful specs. It will give you a general idea of how loud the speakers can play and how much power will be required to achieve desired listening levels.
Sourcing tip
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.
Finally…
Understanding how to read speak specs is important. While the specifications can give you some general ideas about the loud speaker, they alone cannot be used to gauge performance.
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