Thursday, 5 December 2013

Guidelines For Making An Informed Decision While Searching For Wireless Speakers

By Michelle Finger


Cordless speaker vendors frequently show the frequency response of their products which, sadly, doesn't automatically tell you a lot regarding the sound quality. I will explain the meaning of this expression and also offer a few recommendations on how to interpret it while looking for a set of wireless speakers.

Wireless speakers are made to transmit and the reproduce an audio signal to medium or large sound level. Manufacturers typically present the frequency range over which the wireless speakers operate. If the frequency range is 20 Hz to 20 kHz for example, the wireless loudspeakers could transmit any signals with a frequency higher than 20 Hz and lower than 20 kHz. You could think the larger the frequency response the higher quality the wireless loudspeakers. That, on the other hand, may well not necessarily be. You ought to glance at the specs far more meticulously in order to adequately interpret them.

A large frequency response doesn't mean the cordless speakers provide excellent sound quality. For example a set of cordless loudspeakers with a frequency response between 30 Hz and 15 kHz may sound better than another set having a response between 10 Hz and 30 kHz. Furthermore, every maker, it appears, uses a different way of specifying the minimum and highest frequency of their cordless speakers. The most popular technique is to describe the frequency response as the frequency range within which the wireless speakers have rather constant sound pressure level having a highest drop of 3 decibel (dB). Commonly the drop in sound pressure level is highest at the upper and lower frequency. Nevertheless, numerous suppliers overlook this particular established practice. They push the lower frequency and upper frequency to where the wireless speakers rarely have any kind of sound response. What's more, these figures tell practically nothing about how linear the wireless speakers are working inside this range. Thus it is better to have a complete frequency response document. This kind of chart will reveal whether or not there are any sort of substantial peaks and valleys within the working frequency range. Peaks in addition to valleys could potentially cause colorization of the audio. Preferably the sound pressure level of the wireless loudspeakers ought to be linear throughout the entire working range.

Yet, many companies overlook this particular convention. They push the lower frequency and higher frequency to where the cordless speakers barely provide any kind of sound response. Moreover, these numbers tell almost nothing about precisely how linear the wireless speakers are functioning inside this range. A full frequency response graph, however, will show if there are any peaks and valleys and in addition show the way the frequency response is to be understood. Peaks as well as valleys might result in colorization of the sound. Ideally the sound pressure level of the wireless loudspeakers ought to be linear through the entire working range.

Primarily modern wireless loudspeakers which use digital or "Class-D" amplifiers can have changes in the frequency response with various driver loads. The reason is the fact that Class-D amplifiers make use of switching FETs as the power stage which generate lots of switching components. These components are removed by using a filter that is part of the internal speaker amplifier. The lowpass filter characteristic, however, greatly depends upon the connected speaker load.

Some amp topologies provide a mechanism to compensate for changes in the amplifier gain with various loudspeaker loads. One of those methods utilizes feedback. The amplifier output signal after the internal lowpass is input to the amplifier input for comparison. If not developed correctly, this method could cause instability of the amp though. Yet another technique is to offer specific outputs for different speaker driver impedances which are connected to the amp power phase via audio transformers.




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