Sony - PCM-501es DSP - digital sound processor

The incoming audio is digitized in 14- or 16-bit code depending on the user's needs. Although the 16-bit version offers better sound quality in terms of noise, dynamic range, and distortion, there is an industrial standard that operates on the 14‑bit system, hence the option to choose. Additionally, the error correction system is more effective in the 14-bit format, but we will discuss this further.

Converting an analog signal to digital involves sampling, and the 501 uses a sampling frequency of 44.1 kHz, yielding a frequency response of 5 to 20,000 Hz. This, combined with 16-bit sampling resolution, means that, at least in theory, one has the ability 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. Because sampling is linear (the input is sampled in steps with equal increments), high-frequency pre-emphasis and de-emphasis are used to further improve noise performance. This results in raising the high-frequency levels during recording and reducing them by a corresponding amount during playback, returning the sound to its original level but reducing high-frequency noise due to quantization. Quantization noise is caused by the 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 to 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 pre-recorded 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 not.