Thread: Groundbreaking DXD recording for SACD

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Post by DAD-Digital Audio De December 19, 2006 (1 of 36)
Dear everybody

I will like to recommend a groundbreaking DXD recording. To my knowledge this is the first SACD recorded and mixed in DXD.
More information can be found at our web site: www.digitalaudio.dk

The recordings and mixing has been done in DXD by Lindberg Lyd.
The main benefit of DXD is the much better impulse response which are capable of capture the ambience around the instruments.

These recordings are also quite remarkable in the minimal microphone approach.

The orchestra formed a circle around a core with microphones in order to optimize the recordings for the 5.1 mix.
For more details about the microphone setup please read this press release from DPA Microphones:
http://www.dpamicrophones.com/page.php?PID=1679&backid=110&LANG=3

Enjoy, these Mozart recordings are brilliant. From a technical point of view I think this SACD surround mix is one of the best ever made.

More information can also be found at:
http://www.lindberg.no/english/collection/007.htm

This SACD can be purchased at:
http://www.2l.musiconline.no/shop/displayAlbum.asp?id=31396

For more informations about DXD and impulse response please read:
http://www.digitalaudio.dk/technical_papers/axion/dxd%20Resolution%20v3.5.pdf

Interesting article about minimal microphone setup:
http://www.discmakers.com/music/pse/2005/jarvis.asp


Best regards,

Peter Scheelke

Digital Audio Denmark a/s
Gregersensvej 1A
Postbox 141, 2630 Tastrup
Denmark
Www: http://www.digitalaudio.dk
E-mail: ps@digitalaudio.dk
Phone: +45 7220 3555
Fax: +45 7220 3550
Skype: peter_scheelke

Post by Claude December 20, 2006 (2 of 36)
Hi Peter,

The recording was discussed previously here:

/showthread/17003/17003/y#17003

Post by DAD-Digital Audio De December 20, 2006 (3 of 36)
Dear Claude

Thanks for telling me. I was not aware of that, however the main reason for my Tread is not the Mozart recording itself. My issue is to bring some expert knowledge to this forum about the technology used for SACD production.

We are the manufacture and developer of the Sphynx 2 converter (and our own AX24 converter) used for the Mozart recording. Together with Merging Technologies we have developed a solution for DXD recordings.

As you can see I have recommended everybody to read:
http://www.digitalaudio.dk/technical_papers/axion/dxd%20Resolution%20v3.5.pdf

This article is explaining the benefits of DXD for SACD production.

Allow me a short and popular explanation of the reasons behind our technologies:

1. In a multi bit (PCM) A/D audio converter all frequencies is mirrored around half sampling rate.

2. As a consequence multi bit (PCM) audio sampling can not reproduce higher frequencies than half the sample rate.

3. The mirrored frequencies will loose their harmonic relationship to the original signal. Therefore and A/D converter has an Anti Aliasing Filter, typically a filter starting at 45 % of the sample rate with full attenuation at 55% of the sample rate.

4. A perfect square pulse has an unlimited frequency band, however with less amplitude of the higher frequencies. (A perfect square sound pulse do not exist in nature however many type of attacks will contain parts which is close to a square pulse when analyzed in the analog domain).

5. Many claims that a sampling rate at 192 kHz/24 bit should be enough (can reproduce frequencies up to 96 kHz), however at 192 kHz sampling rate an Anti Aliasing Filter is still needed.

6. At DXD 352.8 kHz/24 bit (or 384 kHz) an anti aliasing filter is not needed since the frequencies at more than 176.4 kHz are very weak by nature.

7. A downsides of the anti aliasing filter is that some energy is lost in pre/post ringing. A smooth filter will give a better impulse response a less ringing than a stiff filter.

8. When analyzing a 3us perfect pulse we can reproduce 49% of the amplitude at 192 kHz and 88 % of the amplitude at 352.8 kHz (due to the lack of anti aliasing filter and the wider frequency band).

9. The impulse response is very important, since the brain is using the small differences in time from one ear to the other ears in order to re-calculate an image of the room.

Therefore a digital recording at 352.8 kHz (DXD) is sounding real analog. You are able to capture the ambience around the instruments at 352.8 kHz.
192 kHz, 96 kHz and 44.1 kHz/24 bit are all sounding digital. Of course the higher resolution is better that the lower resolution, but these formats are all sounding digital.

10. DSD is a one bit format (SACD format) and do not have an anti aliasing filter. It has a band wide up to 1.3 MHz and can therefore reproduce the amplitude of a perfect pulse 100%.

11. The downsides of DSD is that the format can not be edited since it is a 1 bit format, and the quantizes noise of the format is significant (-80 dBfs without noise shapers)

12. With a noise shaper we have been able to move some of the noise to a higher frequency band; however the energy will always be there. We can keep the noise below -120dBfs up to 24 kHz but then the noise will increase. At 100 kHz we have -22dBfs noise in our DSD implementation.

13. If you need to edit a DSD file you have to convert it to some kind of multibit format.
When you then again want the DSD format you will ad quantizes noise once again.

14. Therefore DSD (SACD) is a consumer format. It is very good if you only ad quantizes noise once, due to the perfect impulse response, but it should not be used for production.

Best regards,

Peter

Post by DAD-Digital Audio De December 20, 2006 (4 of 36)
Dear Everybody

Hereby some measuring of the pheromones described above.

Best regards,

Peter

Post by Julien December 20, 2006 (5 of 36)
Thanks Peter for your explanations. I've read many of very specialized explanations about PCM, DSD and DXD, but your post is making some light in my brain! I'm still wondering why Sony and co didn't use this kind of sampling rate and without filter from the beginning, actually DXD and PCM are basically the same principle!

And also I would be grateful if you could take a little time to enlighten me on a few matters:

To begin with a cheap question: can you hear the difference between the basic DSD and DXD recordings before editing? I guess you need some good equipment for that. By the way many of us on this site would tend to believe that even after multi-bit conversion then re-conversion to DSD we wouldn't hear the difference with a DXD recording directly converted into DSD. I guess you hear it?
SACD purists would even prefer pure DSD recording without editing, which seems a little bit of an utopia in our world no? (A little bit like taking a picture like we used to do before the digital era, since you don't have Photoshop to edit your picture you have to get everything right from the beginning...). What do you think of that?
And do you think there will be players reading DXD directly? It should be easy to make, but what should be the spinning speed of the disc?

Thanks a lot.

Julien.

Post by DAD-Digital Audio De December 20, 2006 (6 of 36)
Dear Julien

Yes I can here the difference between DSD and DXD, and I prefer DXD, however the difference is small.
I think it is the energy from the noise that disturbing me. If we compare DXD with DSD 128 fs (5.6 MHz) the difference is nearly none existing.
However DSD 64 fs (2.8 MHz for SACD) are much more close to the original analog signal than 192 kHz/24 bit when using our DSD modulator.
When developing our DXD/DSD converters we did a lot of testing with different analog sources, mostly turn tables and analog ¼ inch tapes.
We used my Audio Note AN-E Lexus speakers and my Sudgen Class A amplifier in order to optimize our AX24/Axion converter.
Sometimes we were also testing with a friend who has better Audio Note speakers and better amplifiers.

I hope DXD will be a consumer format in the future, but at the moment know body is doing anything in that direction.

Best regards,

Peter

Post by brenda December 20, 2006 (7 of 36)
DAD-Digital Audio De said:

...At DXD 352.8 kHz/24 bit (or 384 kHz) an anti aliasing filter is not needed since the frequencies at more than 176.4 kHz are very weak by nature. ....
You are able to capture the ambience around the instruments at 352.8 kHz.
192 kHz, 96 kHz and 44.1 kHz/24 bit are all sounding digital. Of course the higher resolution is better that the lower resolution, but these formats are all sounding digital.

dear peter,
could you pls. tell me (as someone with no technical knowledge) why 24 bit is still used for DXD? I know that 32 bit PCM recording has been practised, - Sony developed a machine in the early 90's, - wouldnt that produce even better results? Or am i making a simplistic assumption and defying some audio law?
regards, B

Post by Julien December 20, 2006 (8 of 36)
I see. Do you also believe that DSD is only better than DXD for the storage of analogue recordings? Or is there soundwise anything better in pure DSD compared to pure DXD?

And also could you tell me anything about the spinning speed of the disc? Would direct DXD reading from a player require the same or even faster spinning speed or could it be slower? To me the speed is always a problem mechanically speaking because of the noise it generates (I don't know any cheap SACD player that doesn't have this problem).

Post by Lindberg December 20, 2006 (9 of 36)
All the points mentioned by Peter are the very reasons why we moved directly from 44.1/24BIT to DXD and never took DSD on as a production format. Lindberg Lyd and 2L has a minimalist approach to producing classical music, but dogmatically avoiding editing would be like shooting an 1-hour movie with a static panoramic view in real-time, not allowing for close-ups. As with the motion pictures there is a great advantage in intensifying the performance and perception of music.

Post by dvda-sacd December 20, 2006 (10 of 36)
DAD-Digital Audio De said:

I hope DXD will be a consumer format in the future,

I hope DSD 128 fs will be a consumer format in the future as well.

Cheers! ;-)

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