12/28/2013

A Look At The Frequency Response Spec Of The Latest Cordless Loudspeakers

By Michelle Finger


The frequency response is by far the most frequently found parameter to characterize cordless speakers. Nonetheless, it may regularly be confusing and may not really provide a good indication of the audio quality. You may not understand fully how the frequency response is measured. I'm going to explain what precisely this specific expression means. Hopefully you'll be able to make a more informed purchasing decision.

A set of wireless speakers are transmit and the reproduce a sound signal which is within the frequency response range. If the frequency range is 20 Hz to 20 kHz for example, the cordless loudspeakers could transmit all signals with a frequency higher than 20 Hz and lower than 20 kHz. You may be tempted to decide on a set ofwireless loudspeakers that gives the largest frequency response. Then again, there is a lot more to comprehending a cordless speakers's performance than simply realizing this simple range.

Then again, a number of makers push this standard to the limit and will list a maximum frequency where the cordless loudspeakers are going to hardly generate a beep anymore. Also, simply taking a look at these 2 figures won't say much about the linearity of the frequency response. Hence it is ideal to have a complete frequency response chart. This kind of chart is going to reveal whether there are any sort of major peaks and / or valleys inside the operating frequency range. Peaks along with valleys could potentially cause colorization of the music. Preferably the wireless loudspeakers should have a constant sound pressure level within the complete frequency response with the exception of the drop off at the upper and lower limit. Apart from the frequency response, a phase response chart will also say a good deal about the functionality as well as quality of sound of the cordless speakers.

You also will want to look at the conditions under which the frequency response was calculated. You typically will not find any information about the measurement conditions, unfortunately, in the producer's data sheet. One condition which may affect the frequency response is the impedance of the speaker driver built into the wireless speakers. Normal speaker driver impedances range between 2 to 16 Ohms. The lower the speaker driver impedance the greater the burden for the internal amplifier.

Mostly current wireless loudspeakers which use digital or "Class-D" amps will show changes in the frequency response with different driver loads. The reason is the fact that Class-D amplifiers employ switching FETs as the power stage that produce a great deal of switching components. These components are eliminated by a filter which is part of the internal speaker amplifier. A varying speaker driver load will impact the filter response to some amount. Normally the lower the loudspeaker driver impedance the lower the highest frequency of the built-in amplifier. Also, the linearity of the amplifier gain will depend on the driver load.

Some amplifiers integrate feedback in order to compensate for changes in gain because of different attached loads. Other amps make use of transformers and provide outputs for various loudspeaker loads. Apart from enhancing the frequency response of the amp, this technique generally furthermore enhances the amplifier power efficiency.




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