It is easy to be perplexed by the language which cordless speaker manufacturers employ to explain the performance of their products. I will explain the meaning of one usually utilized specification: “signal-to-noise ratio” in order to help you make an informed choice whilst purchasing a brand new a couple of cordless speakers.
While looking for a couple of cordless speakers, you initially are going to check the cost, power amid additional fundamental criteria. Yet, after this initial choice, you are going to still have a number of models to choose from. Next you are going to concentrate more on some of the technical specs, like signal-to-noise ratio in addition to harmonic distortion. The signal-to-noise ratio is a rather essential parameter and shows how much noise or hiss the cordless speaker creates.
One technique in order to perform a straightforward assessment of the noise performance of a couple of wireless outdoor speakers reviewed at amphony.com/products/wireless-speaker.htm is to short circuit the transmitter audio input and then to crank up the cordless loudspeaker to its utmost. Next listen to the speaker. The hiss which you hear is generated by the cordless loudspeaker itself. Next compare different sets of cordless speakers according to the next rule: the smaller the level of noise, the higher the noise performance of the cordless speaker. Though, keep in mind that you should set all sets of wireless loudspeakers to amplify by the same level in order to compare different models. To help you compare the noise performance, cordless loudspeaker makers publish the signal-to-noise ratio in their wireless speaker specification sheets. Simply put, the higher the signal-to-noise ratio, the smaller the amount of noise the wireless speaker generates. There are several reasons why wireless loudspeakers are going to add some form of hiss or other unwanted signal. Transistors and resistors that are part of each modern cordless loudspeaker by nature produce noise. Typically the elements that are situated at the input stage of the built-in power amplifier are going to contribute most to the overall hiss. Therefore makers typically are going to choose low-noise components whilst developing the cordless loudspeaker amplifier input stage.
The cordless broadcast itself also causes hiss which is most noticable with types that use FM transmission at 900 MHz. Other cordless transmitters will interfer with FM type transmitters and bring about additional hiss. Therefore the signal-to-noise ratio of FM type cordless speakers varies depending on the distance of the speakers from the transmitter in addition to the level of interference. To avoid these problems, newer transmitters employ digital audio broadcast and typically transmit at 2.4 GHz or 5.8 GHz. This kind of audio broadcast provides better signal-to-noise ratio than analog style transmitters. The level of noise is dependent on the resolution of the analog-to-digital converters as well as the quality of other components. Many latest wireless speakers have built-in power amps that incorporate a wattage switching stage that switches at a frequency around 500 kHz. This switching frequency is also hiss that is part of the amplified signal. On the other hand, recent wireless speakerspecifications normally only consider the noise between 20 Hz and 20 kHz. The most common technique for measuring the signal-to-noise ratio is to pair the wireless speaker to a gain which permits the maximum output swing. Next a test tone is input into the transmitter. The frequency of this tone is generally 1 kHz. The amplitude of this signal is 60 dB below the full scale signal. Then, only the noise in the range of 20 Hz and 20 kHz is considered. The noise at different frequencies is eliminated via a filter. Next the amount of the noise energy in relation to the full-scale output power is computed and shown in decibel. Time and again the signal-to-noise ratio is expressed in a more subjective method 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 perceptive to signals around 1 kHz. However, signals below 50 Hz and higher than 13 kHz are hardly noticed. The A-weighted signal-to-noise ratio is usually higher than the unweighted ratio and is shown in the majority of wireless speaker spec sheets.