To help you select a pair of wireless speakers, I will clarify the term “signal-to-noise ratio” that is frequently used in order to describe the performance of cordless loudspeakers.
Whilst looking for a couple of cordless speakers, you first are going to check the price, power amid other fundamental criteria. Nonetheless, after this initial choice, you will still have quite a few types to choose from. Now you are going to concentrate more on a few of the technical specifications, including signal-to-noise ratio and harmonic distortion. The signal-to-noise ratio is a fairly key parameter and describes how much noise or hiss the wireless loudspeaker makes.
Comparing the noise level of different sets of cordless speakers may be done quite easily. Simply get together a couple of versions that you wish to compare and short circuit the transmitter audio inputs. Then put the wireless loudspeaker gain to maximum and check the amount of hiss by 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 cordless loudspeaker itself. After that compare different sets of wireless speakers according to the following rule: the lower the level of static, the better the noise performance of the cordless loudspeaker. On the other hand, keep in mind that you must set all sets of cordless speakers to amplify by the same level to evaluate different models.
In order to help you evaluate the noise performance, wireless speaker manufacturers show the signal-to-noise ratio in their cordless loudspeaker specification sheets. Simply put, the larger the signal-to-noise ratio, the lower the level of noise the cordless loudspeaker generates. There are numerous reasons why cordless speakers will add some form of noise or other unwanted signal. Transistors and resistors that are part of each modern cordless speaker by nature create noise. Generally the components that are located at the input stage of the built-in power amplifier are going to contribute most to the overall noise. Thus manufacturers generally are going to choose low-noise elements whilst developing the wireless loudspeaker amplifier input stage.
A further cause of hiss is the cordless music transmission itself. Generally types that employ FM style broadcast at 900 MHz will have a comparatively large level of static. The level of noise is also dependent upon the amount of wireless interference from other transmitters. Newer models are going to generally employ digital music broadcast at 2.4 GHz or 5.8 GHz. This type of audio transmission provides higher signal-to-noise ratio than analog style transmitters. The level of hiss depends on the resolution of the analog-to-digital converters and also the quality of other components.
Many today’s wireless speakers have built-in power amplifiers that include a wattage switching stage that switches at a frequency around 500 kHz. This switching frequency is also hiss which is part of the amplified signal. However, today’s cordless speakerspecifications typically only consider the noise between 20 Hz and 20 kHz.
The signal-to-noise ratio is measured by feeding a 1 kHz test tone 60 dB underneath the full scale and measuring the noise floor of the signal generated by the built-in amplifier. The gain of the cordless loudspeaker is pair such that the full output wattage of the built-in amplifier can be realized. After that, only the hiss between 20 Hz and 20 kHz is considered. The noise at different frequencies is removed via a filter. Then the amount of the noise energy in relation to the full-scale output wattage is calculated and shown in db.
Frequently you are going to find the term “dBA” or “a-weighted” in your cordless loudspeaker parameter sheet. A weighting is a technique of expressing the noise floor in a more subjective fashion. This method tries to evaluate in how far the wireless speaker noise is perceived by human hearing which is most perceptive to signals at frequencies at 1 kHz. The A-weighted signal-to-noise ratio is frequently larger than the unweighted ratio and is published in a lot of cordless loudspeaker specification sheets.