Sony - PCM-501es DSP - digital sound processor

The incoming audio is digitized into a 14- or 16-bit code, depending on the user's requirements. Although the 16-bit version offers better sound quality in terms of noise, dynamic range, and distortion, there is an industry standard that operates on a 14-bit system, hence the option to choose. In addition, the error-correction system is more effective in 14-bit format, but we’ll discuss that later.
Converting an analog signal to digital involves sampling, and the 501 uses a sampling frequency of 44.1 kHz, which provides a frequency response from 5 to 20,000 Hz. Combined with a 16-bit sampling resolution, this means that, at least in theory, it is possible to match the quality of CD recordings, but with an even better frequency response. As with CDs, noise and distortion are very low, and speed-related effects such as wow and flutter are virtually imperceptible. Since the sampling is linear (the input is sampled in equal increments), high-frequency pre-emphasis and de-emphasis are used to further improve noise performance. This involves boosting the level of the high frequencies during recording and reducing them by the corresponding amount during playback, returning the sound to its original level while reducing high-frequency noise caused by quantization. Quantization noise is caused by differences between the input and output waveforms, because the digitized waveform consists of a finite number of steps. Each point on the analog waveform is digitized to the nearest step and, although these errors are small in a 16-bit system, they are still present and appear at the output as noise. Some pre-recorded material may not have been recorded using pre-emphasis; in this case, the 501 has a system to detect this condition and automatically disable de-emphasis during playback. A status indicator shows whether the function is on or off.