To help you pick a set of cordless speakers, I am going to explain the expression "signal-to-noise ratio" that is commonly utilized to express the performance of wireless speakers.
As soon as you have narrowed down your search by taking a look at a few fundamental criteria, including the level of output wattage, the dimensions of the loudspeakers and the price, you will still have quite a few products to choose from. Now it is time to look at some of the technical specs in more detail. The signal-to-noise ratio is a fairly important spec and describes how much noise or hiss the cordless loudspeaker makes.
Evaluating the noise level of several sets of cordless speakers can be done fairly easily. Just get together a couple of versions which you wish to compare and short circuit the transmitter audio inputs. Then set the cordless loudspeaker volume to maximum and verify the level of noise by listening to the loudspeaker. You are going to hear some amount of hissing and/or hum coming from the speaker. This hiss is produced by the cordless speaker itself. Make certain that the gain of each set of cordless speakers is couple to the same level. Otherwise you will not be able to objectively compare the amount of static between several models. The general rule is: the smaller the level of noise that you hear the higher the noise performance.
In order to help you evaluate the noise performance, wireless loudspeaker manufacturers publish the signal-to-noise ratio in their wireless speaker specification sheets. Simply put, the larger the signal-to-noise ratio, the lower the amount of noise the wireless loudspeaker produces. One of the reasons why wireless speakers create noise is the fact that they use elements like transistors as well as resistors which by nature produce noise. As the built-in power amplifier overall noise performance is mostly determined by the performance of components situated at the amplifier input, producers are going to try to select low-noise parts whilst designing the amplifier input stage of their cordless loudspeakers.
The cordless transmission itself also creates static which is most noticable with types which employ FM transmission at 900 MHz. Other wireless transmitters will interfer with FM type transmitters and create further hiss. As a result the signal-to-noise ratio of FM type wireless speakers varies depending on the distance of the loudspeakers from the transmitter and the amount of interference. To avoid these problems, newer transmitters use digital music transmission and usually broadcast at 2.4 GHz or 5.8 GHz. The signal-to-noise ratio of digital transmitters is independent from the distance of the wireless speakers. It is determined by how the music signal is sampled. In addition, the quality of parts inside the transmitter will influence the signal-to-noise ratio.
Most today's wireless speakers have built-in power amps that include a power switching stage which switches at a frequency around 500 kHz. In consequence, the output signal of cordless loudspeaker switching amps contain a fairly large amount of switching noise. This noise component, however, is typically impossible to hear given that it is well above 20 kHz. Nonetheless, it may still contribute to speaker distortion. Signal-to-noise ratio is typically only shown within the range of 20 Hz to 20 kHz. As a result, a lowpass filter is used while measuring cordless loudspeaker amplifiers in order to eliminate the switching noise.
The most common technique for measuring the signal-to-noise ratio is to couple the wireless loudspeaker to a gain that permits the maximum output swing. Subsequently a test tone is fed into the transmitter. The frequency of this signal is usually 1 kHz. The amplitude of this signal is 60 dB below the full scale signal. After that, only the noise between 20 Hz and 20 kHz is considered. The noise at other frequencies is eliminated via a filter. Subsequently the level of the noise energy in relation to the full-scale output wattage is computed and shown in decibel.
Frequently the signal-to-noise ratio is expressed in a more subjective method as "dbA" or "A weighted". In other words, this method attempts to state how the noise is perceived by a human being. Human hearing is most perceptive to signals around 1 kHz whereas signals under 50 Hz and higher than 14 kHz are hardly heard. An A-weighted signal-to-noise ratio weighs the noise floor according to the human hearing and is usually larger than the unweighted signal-to-noise ratio.
As soon as you have narrowed down your search by taking a look at a few fundamental criteria, including the level of output wattage, the dimensions of the loudspeakers and the price, you will still have quite a few products to choose from. Now it is time to look at some of the technical specs in more detail. The signal-to-noise ratio is a fairly important spec and describes how much noise or hiss the cordless loudspeaker makes.
Evaluating the noise level of several sets of cordless speakers can be done fairly easily. Just get together a couple of versions which you wish to compare and short circuit the transmitter audio inputs. Then set the cordless loudspeaker volume to maximum and verify the level of noise by listening to the loudspeaker. You are going to hear some amount of hissing and/or hum coming from the speaker. This hiss is produced by the cordless speaker itself. Make certain that the gain of each set of cordless speakers is couple to the same level. Otherwise you will not be able to objectively compare the amount of static between several models. The general rule is: the smaller the level of noise that you hear the higher the noise performance.
In order to help you evaluate the noise performance, wireless loudspeaker manufacturers publish the signal-to-noise ratio in their wireless speaker specification sheets. Simply put, the larger the signal-to-noise ratio, the lower the amount of noise the wireless loudspeaker produces. One of the reasons why wireless speakers create noise is the fact that they use elements like transistors as well as resistors which by nature produce noise. As the built-in power amplifier overall noise performance is mostly determined by the performance of components situated at the amplifier input, producers are going to try to select low-noise parts whilst designing the amplifier input stage of their cordless loudspeakers.
The cordless transmission itself also creates static which is most noticable with types which employ FM transmission at 900 MHz. Other wireless transmitters will interfer with FM type transmitters and create further hiss. As a result the signal-to-noise ratio of FM type wireless speakers varies depending on the distance of the loudspeakers from the transmitter and the amount of interference. To avoid these problems, newer transmitters use digital music transmission and usually broadcast at 2.4 GHz or 5.8 GHz. The signal-to-noise ratio of digital transmitters is independent from the distance of the wireless speakers. It is determined by how the music signal is sampled. In addition, the quality of parts inside the transmitter will influence the signal-to-noise ratio.
Most today's wireless speakers have built-in power amps that include a power switching stage which switches at a frequency around 500 kHz. In consequence, the output signal of cordless loudspeaker switching amps contain a fairly large amount of switching noise. This noise component, however, is typically impossible to hear given that it is well above 20 kHz. Nonetheless, it may still contribute to speaker distortion. Signal-to-noise ratio is typically only shown within the range of 20 Hz to 20 kHz. As a result, a lowpass filter is used while measuring cordless loudspeaker amplifiers in order to eliminate the switching noise.
The most common technique for measuring the signal-to-noise ratio is to couple the wireless loudspeaker to a gain that permits the maximum output swing. Subsequently a test tone is fed into the transmitter. The frequency of this signal is usually 1 kHz. The amplitude of this signal is 60 dB below the full scale signal. After that, only the noise between 20 Hz and 20 kHz is considered. The noise at other frequencies is eliminated via a filter. Subsequently the level of the noise energy in relation to the full-scale output wattage is computed and shown in decibel.
Frequently the signal-to-noise ratio is expressed in a more subjective method as "dbA" or "A weighted". In other words, this method attempts to state how the noise is perceived by a human being. Human hearing is most perceptive to signals around 1 kHz whereas signals under 50 Hz and higher than 14 kHz are hardly heard. An A-weighted signal-to-noise ratio weighs the noise floor according to the human hearing and is usually larger than the unweighted signal-to-noise ratio.
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