Tips Intended For Reducing The Static Inside Outdoor Audio Speakers

By Linda Cullmann


To help you decide on a pair of wireless loudspeakers, I will clarify the expression "signal-to-noise ratio" that is frequently utilized to explain the performance of wireless loudspeakers.

Once you have selected a number of cordless loudspeakers, it's time to investigate a few of the specs in more detail in order to help you narrow down your search to one model. Every wireless speaker will create a certain level of hiss as well as hum. The signal-to-noise ratio is going to help compute the level of static created by the speaker.

Comparing the noise level of several sets of cordless loudspeakers may be done fairly easily. Simply collect a number of products that you wish to evaluate and short circuit the transmitter audio inputs. Then set the cordless loudspeaker volume to maximum and verify the level of noise by listening to the speaker. You will hear some amount of hissing and/or hum coming from the speaker. This noise is produced by the wireless speaker itself. Then compare several sets of wireless speakers according to the next rule: the smaller the level of hiss, the higher the noise performance of the wireless speaker. Yet, bear in mind that you should set all sets of wireless loudspeakers to amplify by the same amount in order to compare different models.

If you prefer a pair of wireless speakers with a small amount of hissing, you may look at the signal-to-noise ratio figure of the spec sheet. Many producers are going to publish this number. wireless loudspeakers with a high signal-to-noise ratio are going to output a low amount of noise. There are a number of reasons why cordless speakers are going to add some form of noise or other unwanted signal. Transistors and resistors that are part of every modern wireless loudspeaker by nature create noise. The overall noise depends on how much hiss each element produces. Nonetheless, the position of these components is also vital. Components that are part of the loudspeaker built-in amp input stage will generally contribute the majority of the noise.

Noise is also caused by the wireless broadcast. Different types of transmitters are available that work at different frequencies. The cheapest sort of transmitters uses FM transmission and typically broadcasts at 900 MHz. Other wireless transmitters are going to interfer with FM type transmitters and cause further hiss. Therefore the signal-to-noise ratio of FM style wireless speakers changes depending on the distance of the speakers from the transmitter in addition to the level of interference. To avoid these problems, newer transmitters use digital audio broadcast and usually transmit at 2.4 GHz or 5.8 GHz. This kind of audio broadcast offers better signal-to-noise ratio than analog type transmitters. The level of noise depends on the resolution of the analog-to-digital converters as well as the quality of other components.

Most recent wireless loudspeakers have built-in power amplifiers that include a wattage switching stage that switches at a frequency around 500 kHz. Consequently, the output signal of wireless speaker switching amps have a moderately big amount of switching noise. This noise component, though, is usually inaudible since it is well above 20 kHz. However, it can still contribute to speaker distortion. Signal-to-noise ratio is typically only shown within the range of 20 Hz to 20 kHz. For that reason, a lowpass filter is used when measuring cordless loudspeaker amplifiers in order to remove the switching noise.

The signal-to-noise ratio is measured by inputting a 1 kHz test signal 60 dB below the full scale and measuring the noise floor of the signal generated by the built-in amp. The volume of the wireless loudspeaker is set such that the full output power of the built-in amp can be achieved. Next, the noise floor between 20 Hz and 20 kHz is calculated and the ratio to the full-scale signal calculated. The noise signal at different frequencies is eliminated via a bandpass filter during this measurement.

An additional convention in order to state the signal-to-noise ratio employs more subjective terms. These terms are "dBA" or "A weighted". You are going to spot these terms in the majority of wireless speaker spec sheets. In other words, this technique attempts to state how the noise is perceived by a person. Human hearing is most sensitive to signals around 1 kHz while signals below 50 Hz and higher than 14 kHz are hardly noticed. An A-weighted signal-to-noise ratio weighs the noise floor in accordance to the human hearing and is typically higher than the unweighted signal-to-noise ratio.




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