What you need to know about understanding frequency response curves of loudspeakers.

Here’s an essential archival article from Paul Diacomo, a brilliant writer and longtime Polk Audio executive who published many classic articles on hi-fi throughout the years. We are publishing it again here in the hope that a new generation of readers finds great value in his writing.

The Secret Behind The Industry’s Most-Cited Spec.

Here’s a quick quiz: which of these two speakers sounds better: Speaker A with a frequency response range of 45Hz to 18kHz or, Speaker B with a range of 20Hz to 25kHz? The truth is there’s simply not enough data in these numbers to know anything of value. Taken out of context and without other data, a simple set of numbers don’t tell you much about real world sound quality. But people make audio buying decisions based on published specifications, such as the frequency response spec, everyday. I’d like to demystify the process for you; let you in on a little industry secret about “The Frequency Response Spec.”

My Frequency Response

The Frequency Response specification attempts to describe the range of frequencies or musical tones a speaker can reproduce, measured in Hertz (known to old-timers as “Cycles per Second”). The range of human hearing is generally regarded as being from 20Hz, very low bass tones, through 20kHz (20,000Hz), the very highest treble. Presumably a speaker that could reproduce that range would sound lifelike. Alas, it is no guarantee. The most important determinant of a speaker’s frequency performance is not its width or range, but whether it’s capable of reproducing all the audible frequencies at the same volume at which they were recorded.

You don’t want the speaker to change the “mix” of tones; that would ruin the timbre of voices and instruments, making them sound unnatural. Ideally, you want the sounds that are on the recording to be reproduced as they were recorded, without the speaker changing the sound. To say it another way: if you made a recording of all the audible tones at the same volume and played that recording through a speaker, you’d want all the audible tones to come out at the same volume. In fact, that’s one way of measuring speakers. A signal that’s comprised of all frequencies at equal volume is fed into a speaker that sits in a room with no reflective surfaces. A calibrated microphone is placed in front of the speaker and feeds the speaker’s output into a machine that plots the frequency vs. amplitude as shown in Figure A.

This article originally appeared at ecoustics.com and an intro has been published here with permission.

Read the full article: https://www.ecoustics.com/articles/understanding-speaker-frequency-response/