Thread: Groundbreaking DXD recording for SACD

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Post by Myrtone October 27, 2007 (31 of 36)
Well, I have read before that DXD is a 5 bit PWM format that requires *half* the amount of noise shaping compared to DSD according to http://www.soundfountain.com/amb/noisesheng.html . Another thing that site claims, which is yet to be explained to me, 1 bit resolution gives a high average amount of noise, and the noise shaping ensures that the noise is highest outside the audio band, and extremely low in the audio band (the dynamic range is 120dB within the human hearing limits). If the noise is nearly all outside the audio band how does it *interfere* with the music and cause audible distortion? I know that some SACD players have low pass filters set at 30 kHz, and that amplifiers can introduce in band artifacts as a result of this noise, I myself have figured out that the low pass filter's frequency response should idealy roll off at the same rate as the noise floor increases.

Post by gfresh October 29, 2007 (32 of 36)
Myrtone said:

Well, I have read before that DXD is a 5 bit PWM format that requires *half* the amount of noise shaping compared to DSD according to http://www.soundfountain.com/amb/noisesheng.html . Another thing that site claims, which is yet to be explained to me, 1 bit resolution gives a high average amount of noise, and the noise shaping ensures that the noise is highest outside the audio band, and extremely low in the audio band (the dynamic range is 120dB within the human hearing limits). If the noise is nearly all outside the audio band how does it *interfere* with the music and cause audible distortion? I know that some SACD players have low pass filters set at 30 kHz, and that amplifiers can introduce in band artifacts as a result of this noise, I myself have figured out that the low pass filter's frequency response should idealy roll off at the same rate as the noise floor increases.

Well, first it can make make processing in both analog and digital realms very difficult. When you are mixing DSD and you have multiple channels of hf noise pilling up your equipment starts to run into problems and this can effect the quality of the sound. Even if you can't hear the noise it still has to pass through your gear. Also, I believe all that noise messes with AD,DD (especially), and DA conversions, not to mention floating point processing.

That, and if you aren't using a low pass filter you can almost sense the presence of the noise. I'm not sure how to describe it, but there is like some invisible fatigue.

Post by Myrtone November 29, 2007 (33 of 36)
Karlosak said:

The "flatness" of PCM at lower sampling rates is due to the steep filters used. They are needed to preserve as much of high frequencies as possible, unfortunately at the expense of some ringing introduced.

Isn't this more of a problem with analogue filters, digital filters probably perform better here, right? I certainly know this is the case when it comes to phase response. Modern PCM implementations (nearly) all use digital filters, right?

Post by hanser April 23, 2008 (34 of 36)
If Lindberg reads this:

Can you tell us anything about the upcoming SACD/BD COmbi Release "Divertimento"? Why did you chose this project for BD music? What is the microphone layout? etc.

Thanks a lot!

Post by Lindberg April 23, 2008 (35 of 36)
hanser said:

If Lindberg reads this:

Can you tell us anything about the upcoming SACD/BD COmbi Release "Divertimento"? Why did you chose this project for BD music? What is the microphone layout? etc.

Thanks a lot!

I have added some information about microphones and the production to the discussion directly related to the album: /showthread/28253

Post by RWetmore August 30, 2008 (36 of 36)
IT seems to me that a simple 441khz/24bit system would be ideal, though I'm glad to hear that DXD does not require the use of an anti-aliasing filter. I've long had a suspicion that the key to a truly transparent audio system is one that requires no filtering or processing whatsoever.

Too bad we'll probably never see DXD in a consumer format.:(

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