It is easy to be baffled by the terminology that cordless loudspeaker producers employ in order to depict the performance of their products. I am going to explain the meaning of one regularly used spec: "signal-to-noise ratio" to help you make an informed decision when purchasing a new a pair of cordless speakers.
As soon as you have narrowed down your search by taking a look at a few basic criteria, such as the level of output wattage, the size of the speakers in addition to the price, you will still have quite a few models to choose from. Now it is time to take a look at some of the technical specifications in more detail. Every wireless speaker will make a certain level of hiss and hum. The signal-to-noise ratio is going to help calculate the level of static created by the speaker.
You can make a straightforward comparison of the cordless loudspeaker hiss by short circuiting the transmitter input, setting the speaker gain to maximum and listening to the speaker. You are going to hear some amount of hissing and/or hum coming from the speaker. This noise is produced by the wireless loudspeaker itself. Next compare several sets of wireless loudspeakers according to the next rule: the smaller the level of static, the better the noise performance of the cordless loudspeaker. However, bear in mind that you must set all sets of wireless speakers to amplify by the same amount to evaluate different models.
When glancing at the wireless loudspeaker specification sheet, you want to look for a set of wireless speaker with a large signal-to-noise ratio figure which indicates that the wireless speakers output a low amount of noise. There are numerous reasons why wireless loudspeakers are going to add some form of hiss or other unwanted signal. Transistors and resistors that are part of every modern cordless speaker by nature produce noise. As the built-in power amplifier overall noise performance is mostly determined by the performance of components situated at the amp input, makers are going to try to pick low-noise elements while designing the amp input stage of their cordless loudspeakers.
Noise is also caused by the cordless broadcast. Different kinds of transmitters are available that work at different frequencies. The most inexpensive type of transmitters utilizes FM transmission and usually broadcasts at 900 MHz. Other cordless transmitters are going to interfer with FM type transmitters and create further hiss. Consequently the signal-to-noise ratio of FM type cordless loudspeakers changes depending on the distance of the loudspeakers from the transmitter in addition to the level of interference. To avoid these problems, newer transmitters use digital music transmission and generally broadcast at 2.4 GHz or 5.8 GHz. The signal-to-noise ratio of digital transmitters is independent from the distance of the cordless speakers. It is determined by how the music signal is sampled. In addition, the quality of parts inside the transmitter are going to influence the signal-to-noise ratio.
The majority of of recent cordless speaker use amplifiers which are based on a digital switching architecture. These amplifiers are referred to as "class-D" or "class-T" amps. Switching amps include a power stage that is continuously switched at a frequency of around 400 kHz. Consequently, the output signal of cordless loudspeaker switching amps exhibit a fairly big level of switching noise. This noise component, however, is generally impossible to hear since it is well above 20 kHz. Yet, it can still contribute to speaker distortion. Signal-to-noise ratio is usually only shown within the range of 20 Hz to 20 kHz. For that reason, a lowpass filter is utilized while measuring wireless speaker amps to remove the switching noise.
Manufacturers measure the signal-to-noise ratio by means of setting the built-in amplifier such that the full output swing can be achieved and by inputting a test tone to the transmitter which is usually 60 dB below the full scale of the loudspeaker amplifier. Then, the noise floor between 20 Hz and 20 kHz is calculated and the ratio to the full-scale signal computed. The noise signal at different frequencies is removed through a bandpass filter during this measurement.
Time and again the signal-to-noise ratio is shown in a more subjective way as "dbA" or "A weighted". This technique tries to evaluate in how far the cordless loudspeaker noise is perceived by human hearing which is most responsive to signals at frequencies at 1 kHz. Thus an A-weighting filter is going to amplify the noise floor for frequencies that are easily perceived and suppress the noise floor at frequencies that are barely heard. The majority of wireless loudspeaker will have a higher A-weighted signal-to-noise ratio than the un-weighted ratio.
As soon as you have narrowed down your search by taking a look at a few basic criteria, such as the level of output wattage, the size of the speakers in addition to the price, you will still have quite a few models to choose from. Now it is time to take a look at some of the technical specifications in more detail. Every wireless speaker will make a certain level of hiss and hum. The signal-to-noise ratio is going to help calculate the level of static created by the speaker.
You can make a straightforward comparison of the cordless loudspeaker hiss by short circuiting the transmitter input, setting the speaker gain to maximum and listening to the speaker. You are going to hear some amount of hissing and/or hum coming from the speaker. This noise is produced by the wireless loudspeaker itself. Next compare several sets of wireless loudspeakers according to the next rule: the smaller the level of static, the better the noise performance of the cordless loudspeaker. However, bear in mind that you must set all sets of wireless speakers to amplify by the same amount to evaluate different models.
When glancing at the wireless loudspeaker specification sheet, you want to look for a set of wireless speaker with a large signal-to-noise ratio figure which indicates that the wireless speakers output a low amount of noise. There are numerous reasons why wireless loudspeakers are going to add some form of hiss or other unwanted signal. Transistors and resistors that are part of every modern cordless speaker by nature produce noise. As the built-in power amplifier overall noise performance is mostly determined by the performance of components situated at the amp input, makers are going to try to pick low-noise elements while designing the amp input stage of their cordless loudspeakers.
Noise is also caused by the cordless broadcast. Different kinds of transmitters are available that work at different frequencies. The most inexpensive type of transmitters utilizes FM transmission and usually broadcasts at 900 MHz. Other cordless transmitters are going to interfer with FM type transmitters and create further hiss. Consequently the signal-to-noise ratio of FM type cordless loudspeakers changes depending on the distance of the loudspeakers from the transmitter in addition to the level of interference. To avoid these problems, newer transmitters use digital music transmission and generally broadcast at 2.4 GHz or 5.8 GHz. The signal-to-noise ratio of digital transmitters is independent from the distance of the cordless speakers. It is determined by how the music signal is sampled. In addition, the quality of parts inside the transmitter are going to influence the signal-to-noise ratio.
The majority of of recent cordless speaker use amplifiers which are based on a digital switching architecture. These amplifiers are referred to as "class-D" or "class-T" amps. Switching amps include a power stage that is continuously switched at a frequency of around 400 kHz. Consequently, the output signal of cordless loudspeaker switching amps exhibit a fairly big level of switching noise. This noise component, however, is generally impossible to hear since it is well above 20 kHz. Yet, it can still contribute to speaker distortion. Signal-to-noise ratio is usually only shown within the range of 20 Hz to 20 kHz. For that reason, a lowpass filter is utilized while measuring wireless speaker amps to remove the switching noise.
Manufacturers measure the signal-to-noise ratio by means of setting the built-in amplifier such that the full output swing can be achieved and by inputting a test tone to the transmitter which is usually 60 dB below the full scale of the loudspeaker amplifier. Then, the noise floor between 20 Hz and 20 kHz is calculated and the ratio to the full-scale signal computed. The noise signal at different frequencies is removed through a bandpass filter during this measurement.
Time and again the signal-to-noise ratio is shown in a more subjective way as "dbA" or "A weighted". This technique tries to evaluate in how far the cordless loudspeaker noise is perceived by human hearing which is most responsive to signals at frequencies at 1 kHz. Thus an A-weighting filter is going to amplify the noise floor for frequencies that are easily perceived and suppress the noise floor at frequencies that are barely heard. The majority of wireless loudspeaker will have a higher A-weighted signal-to-noise ratio than the un-weighted ratio.
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