Sound Advice: Speaker stats can help when comparing
- Article by: DON LINDICH
- Special to the Star Tribune
- August 17, 2012 - 3:54 PM
Q It seems that advertising the frequency response of audio equipment is no longer done. I would really prefer to have the report of an objective measurement to start with and then evaluate the speakers on subjective factors. Why is frequency response no longer advertised?
A I don't mention frequency response in my column. I prefer to stick to subjective impressions, understanding that most readers assume I have done my homework before I review and recommend a product.
But most manufacturers do provide frequency response specifications. The only company I know that makes it a point not to is Bose. I saw a test years ago of one of Bose's speaker systems, and it had about the worst tested specifications I had ever seen. That could be why it doesn't publicize the information. (Read more at www.intellexual.net/bose.html.)
Frequency response is the range of audio frequencies that an audio component can reproduce. Humans can hear 20 hertz (lowest bass) to 20,000 Hz (highest treble). You can feel frequencies below 20 Hz but not hear them. Women tend to hear high frequencies better than men, and men tend to hear low frequencies better than women.
In addition to the frequency response specification a +/- number is often given. A pair of speakers with a frequency response of 50-20,000 Hz +/- 3 dB means that the speakers can reproduce the audible range between 50 Hz and 20,000 Hz with a variation of no more than 3 decibels away from a perfectly even response throughout the entire range. Speakers will usually have a +/- 3 dB or +/- 4 dB rating.
Electronics such as high-quality amplifiers have much tighter specifications, often reproducing signals outside the audio range, for example 10-100,000 Hz +/- 0.1 dB. The thought behind such designs is that if an amplifier can handle extremes beyond the audible range, it will hand the audible range easily, the same way a car that can go 150 miles per hour feels relaxed and in control when going 60 mph on the interstate.
Pay most attention to frequency response when evaluating speakers and anything with an amplifier, such as an audio-video receiver. Looking at the lower end of a speaker's frequency response will give you an idea of how well it produces bass. Most bookshelf speakers are in the 50-60 Hz range and tower speakers under 40 Hz. If a speaker has a bottom end of 80 Hz, you will probably need a subwoofer to make the system sound full-range.
Many inexpensive receivers give their power rating at a single frequency, such as "100 watts at 1,000 Hz at 1 percent distortion" which tells you the real-world power between 20 and 20,000 Hz is likely to be significantly less. Try to find receivers with power rated between 20 and 20,000 Hz and below 0.1 percent distortion.
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