Have you ever asked what some of the technical language means that producers use in order to show the quality of cordless loudspeakers? In this article, I will explain a commonly used term: THD or “total harmonic distortion”.
It is often complicated to select a suitable pair of wireless speakers manufactured by Amphony Corp. given the great number of products. Aside from looks, you will often be faced with having to consider a few of the technical specs. THD is usually not as easily understood as several other commonly utilized terms including “signal-to-noise ratio” or “frequency response”.

In a nutshell, THD shows the difference between the audio which is produced by the loudspeaker versus the audio signal with which the loudspeaker is driven. The most widespread ways to show distortion are percent in addition to decibel. These two conventions can be translated into one another. The percentage shown as THD shows which amount of energy which is radiated by the speaker are higher harmonics versus the original signal. 10% would mean that one 10th is distortion. 1% would mean one hundredth and so on. 10% equals -20 dB whilst 1% is equal to -40 dB.
Harmonic distortion in a cordless loudspeaker is actually the consequence of a number of elements, including the power amp which is built into the speaker in order to drive the loudspeaker element. Amp distortion usually is dependent on the amplifier output power and is from time to time specified for a few power levels.

Having amplifier distortion specs for a few output power levels offers a better picture of the amplifier distortion performance.In addition, please understand that distortion normally is measured for a certain test tone frequency. Generally a 1 kHz sine wave tone is utilized during the measurement. Nevertheless, amplifier distortion will usually increase with increasing frequency, especially in digital class-D types. Distortion is additionally induced via the loudspeaker driver itself. Most loudspeakers use a driver which carries a voicecoil. This voicecoil is located in a magnetic field. The magnetic field is excited by the music signal. The change in magnetic flux, however, is not perfectly in sync with the audio signal resulting from core losses as well as other factors. In addition, the kind of suspension of the diaphragm will create nonlinear motion. As such the result is distortion brought about by the speaker element. Many producers are going to show harmonic distortion depending on the power level as frequently the higher the loudspeaker is driven the higher the level of distortion.

The overall distortion of the speaker therefore is the sum of the amp distortion along with the speaker element distortion. Furthermore, there are other contributing factors. The loudspeaker enclose is going to vibrate to some extent and consequently add to the distortion.

Total distortion is best determined via measurement. A signal generator is used that provides a highly linear sine tone to the speaker. The sound is recorded by a measurement microphone. The microphone signal is subsequently analyzed by an audio analyzer. The audio analyzer will calculate the level of higher harmonics or distortion. However, pure sine signals hardly give an accurate picture of the distortion of the wireless loudspeaker with real-world signals. A better distortion analysis is the so-called intermodulation distortion analysis in which a test tone that consists of a number of sine waves is used. Then the level of harmonics at different frequencies is measured.
One more factor contributing to distortion is the audio transmission of cordless loudspeakers, particularly with products that transmit an analog signal at 900 MHz. More advanced models utilize digital audio transmission. Generally these transmitters work at 2.4 GHz or 5.8 GHz.