jcx
Headphoneus Supremus
- Joined
- Jul 24, 2002
- Posts
- 2,371
- Likes
- 371
look again?
Quote:
Dither is the recommended practice for digital audio any time wordlengths are reduced, which does happen in the consumer DAC end of the signal chain too.
There are (at least) three scenarios I can quickly come up with:
24 bit "hi rez" source meeting 16 or 20 bit R2R DAC chips, when these 24 bit digital audio streams reach a 16 or 20 bit R2R DAC chip the frimware in standalone DAC product should be dithering.
When the DAC itself applies digital processing, even starting from a 16 bit digital audio stream, which happens in every digitally filtered oversampling system including Schiit's R2R 16 and 20 bit DAC products.
Even with the "bit perfect dammit", "megaburitto" filter all of the n-1 interpolated samples' bit resolution are longer than DAC chip wordlengths - only the nth "original" samples can be "bit perfect" and only with 16 bit source will that fraction of the upsampled data fit the R2R DAC chip resolution.
And computer based digital source, streamers today do give the option apply digital volume and should be set to send out 24 bits, even from a 16/44 file to take full advantage of digital volume.
Mike's talk of rounding instead of truncating really sounds anachronistic to those familiar with recommended for the last few decades digital audio practice.
I believe that given the numbers and Psychoacoustics that listening to the conventional consumer audio DAC 2 Vrms fs output with sensitive iem, appropriate digital volume turn down for a unity gain amp/output, should make 16 bit rounding vs dither audible to some.
Bob Katz seems to me a credible source, does claim dither is an audible improvement over rounding, some commentary on his blog, more in his book http://www.amazon.com/Mastering-Audio-Science-Bob-Katz/dp/0240818962
Quote:
I have taken some heat from Mike for daring to discuss some dither theory with respect to DAC implementations when questions from other thread participants introduced the subject
I don't see how dither is relevant to DACs, as opposed to ADCs. When applied at the source, dither replaces artifacts by uncorrelated noise. Once the signal is encoded, its bits are the most one can now about the original signal, and additional dither at the DAC would only increase the noise level. If the source was not dithered, tough, but the DAC has no way of "knowing" that, as any pattern of LSBs could be the result of just a bunch of unlikely coin tosses while dithering the source.
Dither is the recommended practice for digital audio any time wordlengths are reduced, which does happen in the consumer DAC end of the signal chain too.
There are (at least) three scenarios I can quickly come up with:
24 bit "hi rez" source meeting 16 or 20 bit R2R DAC chips, when these 24 bit digital audio streams reach a 16 or 20 bit R2R DAC chip the frimware in standalone DAC product should be dithering.
When the DAC itself applies digital processing, even starting from a 16 bit digital audio stream, which happens in every digitally filtered oversampling system including Schiit's R2R 16 and 20 bit DAC products.
Even with the "bit perfect dammit", "megaburitto" filter all of the n-1 interpolated samples' bit resolution are longer than DAC chip wordlengths - only the nth "original" samples can be "bit perfect" and only with 16 bit source will that fraction of the upsampled data fit the R2R DAC chip resolution.
And computer based digital source, streamers today do give the option apply digital volume and should be set to send out 24 bits, even from a 16/44 file to take full advantage of digital volume.
Mike's talk of rounding instead of truncating really sounds anachronistic to those familiar with recommended for the last few decades digital audio practice.
I believe that given the numbers and Psychoacoustics that listening to the conventional consumer audio DAC 2 Vrms fs output with sensitive iem, appropriate digital volume turn down for a unity gain amp/output, should make 16 bit rounding vs dither audible to some.
Bob Katz seems to me a credible source, does claim dither is an audible improvement over rounding, some commentary on his blog, more in his book http://www.amazon.com/Mastering-Audio-Science-Bob-Katz/dp/0240818962