In this piece of writing, I will highlight the specification “total harmonic distortion”, often also called “THD” which is frequently used to describe the quality of wireless outdoor speakers sold by Amphony.
Cordless speakers are available in all different shapes and sizes. Deciding on the correct model may frequently be tough. I am going to shed some light on a frequently utilized spec which is used to describe the technical performance of the speaker: “total harmonic distortion” or “THD”. Total harmonic distortion is typically not very well understood. Nevertheless, this term is still vital by way of determining the performance of a particular model. Different specs, like “output power” or “frequency response” are generally easier understood.
THD is expressed either in percent or in decibel and shows how much the signal that the speaker outputs deviates from the music signal that is fed into the speaker. The percentage shown as THD describes which amount of energy that is radiated by the loudspeaker are higher harmonics versus the original audio. 10% would mean that one 10th is distortion. 1% would mean one 100th and so forth. 10% equals -20 dB as 1% equals -40 dB. A wireless loudspeaker really has numerous components that add to harmonic distortion. One of those is the built-in power amp. This audio amplifier is driving the loudspeaker element. Generally the higher the amplifier is driven the higher the amount of amplifier distortion. For this reason, a few manufacturers will state amp distortion based on amp power. Having amp distortion specifications for a few output power levels gives a better picture of the amp distortion performance.In addition, please understand that distortion generally is measured for a certain test tone frequency. Normally a 1 kHz sine wave tone is utilized during the measurement. However, amplifier distortion will commonly increase with rising frequency, particularly in digital class-D types.
The next contributing factor is the loudspeaker element itself. The majority of speakers employ a diaphragm type driver which is driven by a voicecoil which is suspended in a magnetic field. The magnetic field is excited by the audio signal. The change in magnetic flux, though, is not completely in sync with the audio signal resulting from core losses and other factors. Also, the type of suspension of the diaphragm will bring about nonlinear motion. As such there will be speaker element distortion that furthermore is dependent on the amount of power with which the speaker is driven.
The total distortion of the loudspeaker therefore is the sum of the amp distortion and the speaker element distortion. Moreover, there are other contributing factors. Depending on the material used to construct the speaker housing, there will be vibrations or box resonances. These generally depend on the sound pressure level, the enclosure shape, the housing fabric as well as audio frequency. Consequently extra sound distortion is going to be brought about by the enclosure itself. To find out the total distortion of a loudspeaker, a signal generator is used which supplies an ultra-linear signal to the speaker as well as a measurement microphone that is connected to an audio analyzer to determine the level of harmonics emitted by the speaker. Intermodulation distortion analysis is an additional technique which offers a better picture of the loudspeaker distortion performance with real-world signals by utilizing a test signal with two harmonics and measuring how many harmonics at other frequencies are generated by the speaker. Furthermore, please understand that the majority of cordless speakers will experience signal distortion during the audio transmission itself. This is for the most part the case for transmitters that employ analog or FM type transmission. Digital audio transmission on the other hand provides the lowest amount of signal distortion. The music is sampled inside the transmitter and not affected throughout the transmission itself. Digital cordless audio transmitters are available at 2.4 GHz as well as 5.8 GHz.