Speaker Buyer's Guide

by Jim Warren on September 11, 2000 12:00 PM EST

Speaker Specifications: How to read between the lines

Before listening to any speaker system, the manufacturer’s specifications provide a basis for comparison.  Through a variety of tests to determine the sonic quality and electrical characteristics of the speakers, manufacturers determine the numbers intended to reveal the performance of their systems.  However, results can, and often are, presented in an ambiguous manner that appears to enhance the specs of a system.  In order to reveal these possibilities, careful examination of each specification is necessary.

·         Drivers:  The actual speakers used in the cabinet.  The physical components of a speaker are fairly simple.  The cabinet, or enclosure, is the wood or plastic box that contains the drivers, or speakers, and the electronics involved in making the sound, such as an amplifier and crossover networks.  This specification indicates the size and type of transducers (speakers) used.

The number of drivers is very revealing as to the nature of the speaker system.  When there are more speakers, they can be tailored to fit particular sound spectrums as each component handles just part of the frequency range. In a two way system, low and mid frequencies are reproduced by the woofer while a tweeter reproduces the highs.  A three way system is when a subwoofer reproduces the lowest frequencies, a mid range woofer powers the intermediate frequencies, and the tweeter provides the high frequencies.  When a transducer handles a smaller frequency band, it can handle higher levels of power; sound is energy and if they are reproducing a more limited range of energy, they can handle higher levels.

In these multi speaker units, a crossover network is used to split the sound spectrum and route the parts to the appropriate speaker.  The crossover can also control the relative output levels for the speakers, actually balancing the sound across the frequency spectrum.  Most importantly, they are set so as not to overwork the speakers and shorten their life spans by sending high energy frequencies to speakers not designed to handle them.

Here is a breakdown on the components often used in speaker systems.  Through a combination of these components, a speaker is able to reproduce the full (or almost full) spectrum of sound.

o Tweeters are used for high frequency sound, usually sounds over 1.5 kHz.  A smaller transducer can reproduce high frequency sound.  Compression drivers and piezoelectric transducers can also serve as tweeters in a speaker system.

o Woofers are used for low frequency sound reproduction up to around 1.5 kHz.  Because low frequencies have a longer wavelength, woofers must be larger in order to move the air volume necessary to reproduce these lower frequencies.  As a result, the larger a woofer, the more power it can carry, and the louder the bass will be.  In addition, for all the rumbling low frequency noise, the body senses the energy as much as feels it.  When used for both low and mid frequency sound, woofer will produce sounds up to around 1.5 kHz

o Sub woofers are use to reproduce the lowest frequencies, usually up to 500 Hz.  These provide the rumble element to the sound system as they move the most air and shake the body as much as the eardrums.  The larger the sub woofer driver, the more energy it can handle, and the more impressive it can be.

The Decibel Frequency Response
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