!8: Jbl Outdoor Speakers Right Now: October 2011

!±8± Understanding The Frequency Response Of Today's Wireless Speakers

Wireless speaker suppliers normally publish the frequency response of their products which, however, doesn't automatically explain to you a great deal about the sound quality. I am going to make clear the meaning of this term and additionally give some recommendations on how to interpret it while looking for a set of wireless loudspeakers.

Wireless speakers are meant to transmit and the reproduce a sound signal to moderate or high volume level. Suppliers normally show the frequency range over which the wireless speakers function. This range is specified by listing two frequencies: a lower as well as upper frequency. By way of example, the lower frequency might be 20 Hz and the upper frequency 20 kHz. From this specification it seems like the wireless speakers would be able to operate as a set of HIFI loudspeakers. However, there is certainly a lot more to understanding the wireless speaker's functionality than simply taking a look at these figures.

It seems like there are numerous techniques which manufacturers employ while specifying the frequency response. Typically, the frequency response shows the normal working range of the wireless loudspeakers. Within this range, the sound pressure level is essentially constant. At the lower and upper cutoff frequencies the gain will decrease by no more than 3 decibels.

However, several producers push this standard to the limit and often will show a maximum frequency where the wireless loudspeakers will barely produce a sound anymore. Additionally, just considering these 2 figures does not say much about the linearity of the frequency response. Consequently it is best to have a complete frequency response chart. This kind of chart is going to show whether or not there are any sort of considerable peaks or valleys inside the operating frequency range. Peaks and valleys might result in colorization of the audio. Ideally the sound pressure level of the wireless speakers should be linear throughout the entire working range.

The circumstances under which the frequency response was measured may also be necessary to fully understand. In fact the internal amplifiers might have different frequency responses depending on the speaker driver element that is built in.

This change is most apparent with a lot of wireless speakers that use digital amps, otherwise known as Class-D amplifiers. Class-D amplifiers use a lowpass filter inside their output as a way to reduce the switching components which are generated by the internal power FETs. Then again, the frequency response of the amp now is dependent upon the loudspeaker driver load since the behavior of this lowpass filter is influenced by the load impedance. Typically the lower the loudspeaker driver load impedance the lower the upper cut-off frequency of the amplifier

Some amplifiers incorporate feedback to be able to compensate for changes in gain caused by different connected loads. Another approach makes use of audio transformers between the power stage of the amp and various outputs. Every output was designed to connect a different speaker load. This method makes sure that the amplifier will be loaded equally and also improves amplifier power efficiency.