Are you considering to choose a couple of wireless speakers (Read more on the subject of indoor outdoor speakers)? You might be baffled by all of the technical language utilized by manufacturers in order to describe the performance of their models. I am going to explain one normally utilized term that, though, ist often misunderstood: “total harmonic distortion” or “THD”.
It is often tough to choose a suitable set of cordless loudspeakers due to the huge amount of products. Aside from looks, you will often be confronted with having to study a few of the technical specs. Total harmonic distortion is generally not very well understood. On the other hand, this term is nonetheless essential regarding determining the performance of a particular type. Other specs, just like “output power” or “frequency response” are generally easier understood.
In a nutshell, THD describes the difference between the sound which is produced by the loudspeaker versus the audio signal with which the loudspeaker is driven. The most common ways to express distortion are percent along with decibel. These 2 conventions can be translated into one another. If a loudspeaker states a distortion of 10% as an example then one tenth of the energy radiated by the loudspeaker is distortion. A distortion of 10% can also be shown as -20 dB. 1% distortion is equal to -40dB. A cordless loudspeaker really has a number of components which add to harmonic distortion. One of these is the built-in power amp. This amplifier is driving the loudspeaker element. Amplifier distortion generally is dependent on the amp output power and is sometimes given for a few output power levels.
Distortion ratings for different output power levels are normally provided for a few power levels or as a chart listing distortion versus output power. Both of these methods allow to better evaluate the quality of the amplifier.Harmonic distortion measurements are regularly done via feeding a test tone into the speaker. This signal is a pure sine wave signal with minimum distortion. The frequency of this test tone is typically 1 kHz. Distortion, though, is generally dependent on the signal frequency. Many amps are going to have increasing distortion with increasing frequency. Particularly digital class-D amplifiers will have fairly high distortion at frequencies above 5 kHz.
Another element producing distortion is the speaker element which typically works with a diaphragm that carries a coil that is suspended in a magnetic field. The coil is going to follow the magnetic field which is controlled by the music signal in order to move the diaphragm. Nonetheless, this movement is not perfectly linear. As such there will be speaker element distortion which also is dependent on the amount of power with which the speaker is driven. As such both the amp in addition to the speaker element itself add to distortion. Besides, there are other factors that also contribute to distortion. The whole level of distortion is the sum 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 are going to also be non-linear in nature and add to distortion. In order to find out the total distortion of a loudspeaker, a signal generator is used that provides an ultra-linear signal to the speaker along with a measurement microphone that is connected to an audio analyzer in order to calculate the level of harmonics radiated by the speaker. Though, pure sine signals barely give an accurate picture of the distortion of the cordless speaker with real-world signals. A better distortion analysis is the so-called intermodulation distortion analysis where a test tone which consists of several sine waves is used. Next the number of harmonics at other frequencies is calculated.
In addition, please understand that the majority of cordless loudspeakers will experience audio distortion during the audio transmission itself. This is for the most part the case for transmitters that use analog or FM type transmission. Improved types are going to utilize digital transmission and transmit at 2.4 GHz or 5.8 GHz to minimize audio distortion. On top of that, check out http://www.digitaltrends.com/opinion/looking-ahead-to-ces-the-show-i-love-to-hate/ for more facts.
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