A Look At The Cordless Performance Of Wireless Speakers
It is easy to be perplexed by the terminology that cordless speaker manufacturers utilize in order to describe the performance of their products. I am going to clarify the meaning of a commonly used parameter: "signal-to-noise ratio" to help you make an informed decision when buying a brand new a pair of wireless speakers.
Once you have narrowed down your search by taking a look at some key criteria, such as the level of output power, the size of the loudspeakers plus the cost, you are going to still have quite a few models to choose from. Now it is time to look at some of the technical specs in more detail. An important criterion of wireless speakers is the signal-to-noise ratio. To put it simply, the signal-to-noise ratio describes how much hum or hiss the loudspeakers will add to the audio signal. This ratio is customarily described in decibel or "db" for short.
Comparing the noise level of different sets of wireless speakers can be accomplished fairly easily. Simply get together several versions which you want to compare and short circuit the transmitter audio inputs. Next set the cordless loudspeaker volume to maximum and verify the amount of hiss by listening to the speaker. Generally you will hear 2 components. The first is hissing. In addition, you will regularly hear a hum at 50 or 60 Hz. Both of these are components which are produced by the cordless speaker itself. Ensure that the gain of each set of cordless loudspeakers is pair to the same level. Otherwise you will not be able to objectively compare the amount of hiss between several models. The general rule is: the lower the level of noise which you hear the higher the noise performance.
To help you evaluate the noise performance, wireless speaker producers show the signal-to-noise ratio in their cordless speaker specification sheets. Simply put, the higher the signal-to-noise ratio, the lower the amount of noise the cordless speaker creates. One of the reasons why wireless speakers generate noise is the fact that they use elements including transistors and resistors which by nature generate noise. The overall noise is dependent on how much hiss each component creates. However, the position of those elements is also essential. Elements that are part of the speaker built-in amp input stage will in general contribute the majority of the noise.
Another cause of static is the cordless music transmission itself. Typically models which employ FM style broadcast at 900 MHz will have a rather large level of static. Other wireless transmitters are going to interfer with FM type transmitters and result in additional noise. As a result the signal-to-noise ratio of FM type cordless speakers changes depending on the distance of the speakers from the transmitter and the amount of interference. To avoid these problems, modern transmitters make use of digital music broadcast and typically transmit at 2.4 GHz or 5.8 GHz. The signal-to-noise ratio of digital transmitters depends by and large on the type of analog-to-digital converters and other parts that are utilized and also the resolution of the cordless protocol.
Most of today's cordless speaker use amps which are based on a digital switching topology. These amplifiers are named "class-D" or "class-T" amps. Switching amplifiers incorporate a power stage that is always switched at a frequency of around 400 kHz. This switching noise may cause a certain level of speaker distortion yet is frequently not included in the signal-to-noise ratio which only considers noise between 20 Hz and 20 kHz.
The signal-to-noise ratio is measured by feeding a 1 kHz test tone 60 dB below the full scale and measuring the noise floor of the signal generated by the built-in amp. The amplification of the wireless speaker is set such that the full output power of the built-in amp can be realized. Then the noise-floor energy is calculated in the frequency range between 20 Hz and 20 kHz and compared with the full scale signal energy.
One more convention to state the signal-to-noise ratio makes use of more subjective terms. These terms are "dBA" or "A weighted". You will find these terms in a lot of wireless speaker parameter sheets. This technique was developed with the knowledge that human hearing perceives noise at different frequencies differently. Human hearing is most sensitive to signals around 1 kHz. On the other hand, signals below 50 Hz and higher than 13 kHz are hardly heard. The A-weighted signal-to-noise ratio is frequently larger than the unweighted ratio and is published in most cordless loudspeaker spec sheets.
Once you have narrowed down your search by taking a look at some key criteria, such as the level of output power, the size of the loudspeakers plus the cost, you are going to still have quite a few models to choose from. Now it is time to look at some of the technical specs in more detail. An important criterion of wireless speakers is the signal-to-noise ratio. To put it simply, the signal-to-noise ratio describes how much hum or hiss the loudspeakers will add to the audio signal. This ratio is customarily described in decibel or "db" for short.
Comparing the noise level of different sets of wireless speakers can be accomplished fairly easily. Simply get together several versions which you want to compare and short circuit the transmitter audio inputs. Next set the cordless loudspeaker volume to maximum and verify the amount of hiss by listening to the speaker. Generally you will hear 2 components. The first is hissing. In addition, you will regularly hear a hum at 50 or 60 Hz. Both of these are components which are produced by the cordless speaker itself. Ensure that the gain of each set of cordless loudspeakers is pair to the same level. Otherwise you will not be able to objectively compare the amount of hiss between several models. The general rule is: the lower the level of noise which you hear the higher the noise performance.
To help you evaluate the noise performance, wireless speaker producers show the signal-to-noise ratio in their cordless speaker specification sheets. Simply put, the higher the signal-to-noise ratio, the lower the amount of noise the cordless speaker creates. One of the reasons why wireless speakers generate noise is the fact that they use elements including transistors and resistors which by nature generate noise. The overall noise is dependent on how much hiss each component creates. However, the position of those elements is also essential. Elements that are part of the speaker built-in amp input stage will in general contribute the majority of the noise.
Another cause of static is the cordless music transmission itself. Typically models which employ FM style broadcast at 900 MHz will have a rather large level of static. Other wireless transmitters are going to interfer with FM type transmitters and result in additional noise. As a result the signal-to-noise ratio of FM type cordless speakers changes depending on the distance of the speakers from the transmitter and the amount of interference. To avoid these problems, modern transmitters make use of digital music broadcast and typically transmit at 2.4 GHz or 5.8 GHz. The signal-to-noise ratio of digital transmitters depends by and large on the type of analog-to-digital converters and other parts that are utilized and also the resolution of the cordless protocol.
Most of today's cordless speaker use amps which are based on a digital switching topology. These amplifiers are named "class-D" or "class-T" amps. Switching amplifiers incorporate a power stage that is always switched at a frequency of around 400 kHz. This switching noise may cause a certain level of speaker distortion yet is frequently not included in the signal-to-noise ratio which only considers noise between 20 Hz and 20 kHz.
The signal-to-noise ratio is measured by feeding a 1 kHz test tone 60 dB below the full scale and measuring the noise floor of the signal generated by the built-in amp. The amplification of the wireless speaker is set such that the full output power of the built-in amp can be realized. Then the noise-floor energy is calculated in the frequency range between 20 Hz and 20 kHz and compared with the full scale signal energy.
One more convention to state the signal-to-noise ratio makes use of more subjective terms. These terms are "dBA" or "A weighted". You will find these terms in a lot of wireless speaker parameter sheets. This technique was developed with the knowledge that human hearing perceives noise at different frequencies differently. Human hearing is most sensitive to signals around 1 kHz. On the other hand, signals below 50 Hz and higher than 13 kHz are hardly heard. The A-weighted signal-to-noise ratio is frequently larger than the unweighted ratio and is published in most cordless loudspeaker spec sheets.
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