In this article, I will highlight the term “total harmonic distortion”, often also named “THD” which is frequently used in order to show the quality of cordless loudspeakers.
Looking for the perfect model from the enormous number of models, you might have a difficult time understanding a few of the technical language and terms which you are going to see in the specifications of today’s cordless speakers (Check out more information on waterproof wireless speakers from this website). Total harmonic distortion is typically not very well understood. Nonetheless, this term is nonetheless important by way of determining the performance of a specific type. Other specs, such as “output power” or “frequency response” are normally easier understood. THD is expressed either in percent or in decibel and indicates how much the signal that the loudspeaker outputs deviates from the audio signal that is input into the speaker. A -20 dB or 10% distortion means that one tenth of the radiated audio is a consequence of distortion while -40 dB or 1% would mean that one percent of the energy are harmonic products of the original audio. Nonetheless, be cautious because there are in reality a number of components which bring about harmonic distortion. Cordless loudspeakers as well as any type of active speaker or active subwoofer all have built-in power amps in order to drive the speaker element. Normally the larger the amplifier is driven the larger the level of amp distortion. For this reason, a number of suppliers will show amp distortion based on amp output power.
Distortion specifications for various power levels are generally shown for several output power levels or as a chart listing distortion versus output power. Both of these methods allow to better evaluate the quality of the amplifier.Also, please understand that distortion usually is measured for a specific test tone frequency. Commonly a 1 kHz sine wave tone is used during the measurement. Distortion, however, is usually dependent on the audio frequency. Many amps are going to have rising distortion with rising frequency. Particularly digital class-D amps are going to have rather high distortion at frequencies above 5 kHz.
Distortion is additionally caused by the loudspeaker driver itself. Most speakers use a driver which carries a voicecoil. This voicecoil is positioned in a magnetic field. The magnetic field is excited by the music signal. The variation in magnetic flux, though, is not completely in sync with the audio signal resulting from core losses in addition to other factors. Also, the kind of suspension of the diaphragm will cause nonlinear motion. This results in the audio being distorted by the loudspeaker element itself. Moreover, the bigger to power level with which the speaker is driven, the bigger the distortion. Frequently loudspeaker producers will publish distortion for small to moderate output power levels only.
As such both the amplifier and also the speaker element itself contribute to distortion. Additionally, there are other factors that also contribute to distortion. The whole amount of distortion is the total of all of these factors. The enclosure of the speaker is going to shake to some extent depending on the sound pressure level. These vibrations will also be non-linear in nature and add to distortion. Overall distortion is best determined via measurement. A signal generator is utilized which supplies a highly linear sine tone to the loudspeaker. The sound is received by a measurement microphone. The microphone signal is subsequently analyzed by an audio analyzer. The audio analyzer is going to calculate the amount of higher harmonics or distortion. Intermodulation distortion analysis is another method that gives a better picture of the loudspeaker distortion performance with real-world signals through using a test signal with 2 harmonics and measuring how many harmonics at other frequencies are generated by the speaker.
In addition, please note that the majority of wireless speakers are going to 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. Improved types will use digital transmission and transmit at 2.4 GHz or 5.8 GHz to reduce audio distortion. Moreover, go look at http://www.coroflot.com/indzyn/portfolio1.
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