It is easy to be puzzled by the terminology which wireless speaker manufacturers employ in order to depict the performance of their models. I will explain the meaning of a frequently used spec: “signal-to-noise ratio” to help you make an informed choice while buying a new a set of wireless speakers.

While trying to find a couple of cordless loudspeakers, you first are going to check the price, wattage amongst additional essential criteria. Nonetheless, after this initial choice, you are going to still have numerous types to choose from. Now you are going to concentrate more on several of the technical specifications, including signal-to-noise ratio as well as harmonic distortion. Each wireless speaker will create a certain level of hiss and hum. The signal-to-noise ratio will help quantify the amount of noise created by the loudspeaker.

Evaluating the noise level of several sets of wireless loudspeakers can be accomplished fairly simply. Simply gather a couple of versions that you wish to compare and short circuit the transmitter audio inputs. Next set the cordless speaker volume to maximum and check 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 generated by the cordless speaker itself. After that compare several sets of wireless speakers according to the following rule: the smaller the level of hiss, the higher the noise performance of the wireless speaker. However, bear in mind that you must put all sets of wireless loudspeakers to amplify by the same amount in order to compare different models.

To help you compare the noise performance, wireless speaker producers publish the signal-to-noise ratio in their cordless speaker specification sheets. Simply put, the larger the signal-to-noise ratio, the smaller the amount of noise the cordless speaker generates. One of the reasons why wireless speakers create noise is the fact that they utilize elements including transistors and resistors that by nature generate noise. The overall noise depends on how much hiss every element produces. Nonetheless, the location of these components is also essential. Elements which are part of the speaker built-in amp input stage are going to in general contribute most of the noise.

The cordless broadcast itself also will cause hiss which is most noticable with products which make use of FM transmission at 900 MHz. FM transmitters are extremely prone to wireless interference which is why newer models commonly use digital music transmission. This style of audio transmission provides higher signal-to-noise ratio than analog type transmitters. The amount of static is dependent on the resolution of the analog-to-digital converters and also the quality of other parts.

The majority of of recent cordless loudspeaker use amplifiers which are based on a digital switching topology. These amplifiers are called “class-D” or “class-T” amps. Switching amplifiers include a power stage that is continuously switched at a frequency of approximately 400 kHz. This switching frequency is also noise that is part of the amplified signal. However, recent wireless speakerspecifications typically only consider the hiss between 20 Hz and 20 kHz.

The most common method for measuring the signal-to-noise ratio is to set the cordless loudspeaker to a gain that permits the maximum output swing. After that a test signal is input into the transmitter. The frequency of this tone is usually 1 kHz. The amplitude of this signal is 60 dB below the full scale signal. Subsequently the noise-floor energy is measured in the frequency range between 20 Hz and 20 kHz and compared with the full scale signal energy.

Time and again the signal-to-noise ratio is expressed in a more subjective way as “dbA” or “A weighted”. This method was developed with the knowledge that human hearing perceives noise at different frequencies differently. Human hearing is most sensitive to signals around 1 kHz. Then again, signals under 50 Hz and above 13 kHz are barely heard. Therefore an A-weighting filter is going to magnify the noise floor for frequencies that are easily heard and suppress the noise floor at frequencies which are barely perceived. Many wireless loudspeaker are going to have a higher A-weighted signal-to-noise ratio than the un-weighted ratio.

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