Thread: How To: SACD Dynamic Range (DR)?

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Post by onenairb April 29, 2014 (11 of 23)
zeus said:

This is a review site, not a database of numbers for people without ears. It now has over 10,000 reviews (thanks hugely to those who have contributed their time/effort ... yourself included). If the dynamic range was compressed and this had a deleterious effect on the sound quality, surely this would be brought up in the review.

Hi Zues.
There have been a number of reviews and comments (quiet recently of note) on the forum about remastered recordings released on SACD format that have trashed them for poor DR values.

I have contributed a positive review only to have a subsequent review trash the release on the basis of its DR values. As I don’t have the “nudge, nudge, wink, wink, say no more” capability to obtain this data, I'm just interested in how this is done and if the process involved has potentially any technical affect on the reported DR values. Hence is the reported DR value truly correct to justify the review.

As you rightly point out at the end of the day I have my ears. :D

Post by AmonRa April 29, 2014 (12 of 23)
There is no technical reason to have different DR for stereo layers, as long as DR is less than 98 dB, and it always is by wide margin.

That (pop/rock) reissues tend have more compression than the originals is an unfortunate result of prevalent mastering fashion of those genres. Producers of the said reissues do not seem to understand that people buying those SACD want more DR then less, and they are unlikely to listen to them in their cars or from smartphones or whatever.

DSD to PCM conversion and back does not include any kind of DR change in itself. Only if the original format has more DR than than the target format some loss is inevitable. In practice it never happens.

Post by DSD_Mastering April 29, 2014 (13 of 23)
zeus said:

This is a review site, not a database of numbers for people without ears.

I thought you knew about the audiophiles that can listen with their eyes and determine how something sounds by looking at graphs!! :o)

Post by DSD_Mastering April 29, 2014 (14 of 23)
AmonRa said:
DSD to PCM conversion and back does not include any kind of DR change in itself. Only if the original format has more DR than than the target format some loss is inevitable. In practice it never happens.

Then why do you need to attenuate DSD>PCM conversions on SACD's that have more than 50% modulation? This can surely change peak/DR values.

Post by AmonRa April 29, 2014 (15 of 23)
DSD_Mastering said:

Then why do you need to attenuate DSD>PCM conversions on SACD's that have more than 50% modulation? This can surely change peak/DR values.

50% modulation is an "agreed upon" kind of peak standard on DSD, not technical maximum. On PCM, on the other hand, 0 dBFS level is the technical maximum. In standard DSD to PCM conversion 50% modulation is aligned with 0 dBFS. If DSD file is over modulated, it needs to attenuated accordingly to align the peak value to 0 dBFS. This does not affect the dynamic range, just prevents clipping. It does not necessarily even change the peak values coming out of the player/DAC, because 0 dBFS from PCM and 50% modulation form DSD were unlikely to be at the exactly same output level in the first place. That is just something the listener fixes with the volume control. DR is the difference between the highest sample value/modulation and the lowest one, the absolute values do not really matter.

Post by DSD_Mastering April 29, 2014 (16 of 23)
AmonRa said:

50% modulation is an "agreed upon" kind of peak standard on DSD, not technical maximum. On PCM, on the other hand, 0 dBFS level is the technical maximum. In standard DSD to PCM conversion 50% modulation is aligned with 0 dBFS. If DSD file is over modulated, it needs to attenuated accordingly to align the peak value to 0 dBFS. This does not affect the dynamic range, just prevents clipping. It does not necessarily even change the peak values coming out of the player/DAC, because 0 dBFS from PCM and 50% modulation form DSD were unlikely to be at the exactly same output level in the first place. That is just something the listener fixes with the volume control. DR is the difference between the highest sample value/modulation and the lowest one, the absolute values do not really matter.

That's right.... the DSD data stream and PCM data stream are not exactly the same output level, especially when the discs are not within the "agreed upon" standard. "Most" of the time, the DSD file will have a greater DR or lower RMS than its equivalent PCM file.

Post by AmonRa April 29, 2014 (17 of 23)
I see no reason why DSD file would have greater DR than PCM file. Maximum DR in 64DSD is about 120 dB while the theoretical DR for 24 PCM is 146 dB and the best converters give about 128 dB. When the real DR of just about any real audio signal is less than 80 dB this is a moot point.

What peak value the DAC puts out from DSD and PCM has really no bearing on DR, it can be adjusted at will at the the design stage. Certainly the aim is to place the peaks to the standard maximum input voltages of preamps receiving the signal, to maximize the real world

Post by Claude April 30, 2014 (18 of 23)
Minimal differences in dynamic range are not important. The DR concept was introduced to detect heavily compressed releases. Before the loudness war, nobody worried about that stuff.

If an album is being mastered differently, once resulting in DR11 and once in DR12, the release with DR12 will not necessarily sound better, because both are on the safe side in terms of dynamic range.

So don't worry about what DSD-PCM conversion can do to the dynamic range. Analyzing a SACD rip converted to PCM is a very reliable indication of the dynamic range of the DSD layer.

Post by Iain April 30, 2014 (19 of 23)
AmonRa said:

I see no reason why DSD file would have greater DR than PCM file. Maximum DR in 64DSD is about 120 dB while the theoretical DR for 24 PCM is 146 dB and the best converters give about 128 dB. When the real DR of just about any real audio signal is less than 80 dB this is a moot point.

...

For the record:
http://en.wikipedia.org/wiki/Super_Audio_CD

" ... The SACD format is capable of delivering a dynamic range of 120 dB from 20 Hz to 20 kHz and an extended frequency response up to 100 kHz, although ... "

Post by AmonRa April 30, 2014 (20 of 23)
What the theoretical dynamic ranges are and what the real life converters can deliver is not the same thing. If I remember correctly the best DSD converters give about 110 dB of DR and best 24 bit PCM converters about 128 dB. It is very difficult to better this without cooling the electronics with liquid helium, or raising the voltages to dangerous levels.

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