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RE: To Dither or Not to Dither? J. River/PonoMusic World

These ADCs output 24 bits as a result of signal processing. The DSP creates low order bits, and generally quality of DSP will suffer if there isn't at least 48 bits of resolution in the signal processing. In addition, most recordings go through additional DSP in post production. The same situation happens during playback if a digital volume control is used in playback, whether done in the computer or in the DAC.

If dither is not used when bit depth is reduced (e.g. 48 down to 24) the result is signal dependent distortion. This is true even if the original analog signal is noisy. For example, if the ADC is only "good" to 22 bits, it might have noise at the 22 bit level added into the output. Or, there might even be distortion generated by the analog equipment when handling high level signals resulting in even greater errors. However, none of these errors will necessarily hide the errors involved when dither is omitted.

If you look at signal numbers that are applied to manufacturers' spec sheets and not how the mechanisms actually work you will not get a complete picture. The limitation in one dimension (noise or analog distortion) does not justify a limitation in another dimension. Each type of distortion can and will be perceived separately by critical listeners. In the case of 24 bit dither, most people would consider the benefit small and might not be willing to pay a large amount to eliminate what is a low level distortion. However, the cost of doing things correctly is essentially zero, being just a few instructions added to software.



Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar


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