Sony - PCM-501es DSP - digital sound processor

Input audio is digitized into a 14- or 16-bit code depending on user needs. 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 the 14-bit system, hence the option to choose. Moreover, the error correction system is more effective in the 14-bit format, but we will discuss that later.

Converting an analog signal to digital involves sampling, and the 501 uses a 44.1 kHz sampling rate, which provides a frequency response of 5 to 20,000 Hz. This, combined with 16-bit sampling resolution, means that, at least in theory, one can match the quality of CD recordings, but with an even better frequency response. As with CDs, noise and distortion are very low, and fast-motion effects like wow and flutter are practically imperceptible. Because sampling is linear (the input is sampled in equal-step increments), high-frequency pre-emphasis and de-emphasis are used to further improve noise performance. This results in increasing the level of high frequencies during recording and reducing the corresponding amount during playback, bringing the sound back to its original level but reducing high-frequency noise due to quantization. Quantization noise is caused by differences between the input and output waveforms, due to the digitized waveform consisting of a finite number of steps. Each point of the analog waveform is digitized at the nearest step, and although these errors are small in a 16-bit system, they are still present and manifest as noise at the output. Some prerecorded materials may not have been recorded using pre-emphasis, and in this case the 501 is equipped with a system to detect this condition and automatically disable de-emphasis during playback. A status indicator shows whether the function is active or inactive.