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 Easy testing of Class-D Amplifiers
Class-D (or switching) amplifiers are popular, not only because of their light weight, but mainly because they are highly efficient, with less power distributed as heat. Their audio parameters, however, can be difficult to measure because of high-frequency noise produced at the output stage. NTi Audio solves this by filtering out these unwanted noise components with the FX100 Audio Analyzer plug-in module filter, providing reliable test measurement of class-D amplifiers.
Class-D amplifiers work by rapidly switching the output voltage on and off, thus creating a pulse waveform. The width of the pulses are made proportional to the input signal's instantaneous level. The power delivered to the loudspeaker, averaged over time, is the same as if the input signal had been amplified in the conventional way.
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Low Frequency Noise – the XL2 now offers a valuable Toolbox for effective Assessment
The Data Explorer PC software for the XL2 Sound Level Meter now includes a series of professional tools for detailed analysis of low-frequency noise (LFN). The graphical representation of time varying frequency components offers an efficient process for identifying the presence and level of LFN. Also the associated high quality audio recording supports further correlation with the objective measurement data.
The new features are particularly useful in the calculation of immission levels which is defined as the cumulative noise energy to which an individual is exposed over time. Exposure to low-frequency noise over extended periods can lead to a range of health problems including cardio vascular disease, insomnia and depression. The sources of low frequency noise can often be attributed to electricity sub stations, chiller plants and incinerators with continuous noise at frequencies below 200 Hz.
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