Analog Output In the digital realm - Need another lesson

[timetohunt]

I just want to point out that if you are indeed using DSD < Analog, you will have no bass management. Therefore, all 5 speakers should be identical and full-range. There will also be no time alignment (aka Distance), therefore, each speaker should be the same linear distance from the listening position.

I thought the time alignment and bass management would be set in the player. At least that is what my disc player supposedly does.

And here is a question that might help me understand what is going on my setup. When I play SACDs using Multi Channel Ins as source, it operates like I would expect relative to not being able to apply tone controls and so forth. Those audio options are not available when 'Multi Channel In' is the source similar to choosing 'Pure Direct' for example when playing CD through analog connects of my receiver. That makes sense.

I also thought that with 'Mult Channel In' as source you would not be able to control channel levels. On my receiver I have a couple different presets for various listening positions. The main reason for the presets is channel levels. For example one spot where my wife does some craft work is very close to the right front speaker. So, I have a preset that can be selected which raises the left front channel and lowers the right. OK, not to get too far off track here - I am still able to change/select these presets even when listening to SACD over multi channel. - I thought one litmus test for being able to tell if you are getting SACD direct to the speakers is that you will be unable to change anything. My receiver is a Pioneer VSX94 which is geared to please the audiophile, it was not a cheapy (MSRP $1800, paid $1350) - and I have to think that it would not convert to PCM. So what do you think about this?

 

[AcuDefTechGuy]

I thought the time alignment and bass management would be set in the player. At least that is what my disc player supposedly does.

And here is a question that might help me understand what is going on my setup. When I play SACDs using Multi Channel Ins as source, it operates like I would expect relative to not being able to apply tone controls and so forth. Those audio options are not available when 'Multi Channel In' is the source similar to choosing 'Pure Direct' for example when playing CD through analog connects of my receiver. That makes sense.

I also thought that with 'Mult Channel In' as source you would not be able to control channel levels. On my receiver I have a couple different presets for various listening positions. The main reason for the presets is channel levels. For example one spot where my wife does some craft work is very close to the right front speaker. So, I have a preset that can be selected which raises the left front channel and lowers the right. OK, not to get too far off track here - I am still able to change/select these presets even when listening to SACD over multi channel. - I thought one litmus test for being able to tell if you are getting SACD direct to the speakers is that you will be unable to change anything. My receiver is a Pioneer VSX94 which is geared to please the audiophile, it was not a cheapy (MSRP $1800, paid $1350) - and I have to think that it would not convert to PCM. So what do you think about this?

The main thing is Bass Managment, which has to be in PCM digital domain.

The Speaker Level Adjustment (+1dB, -1dB, etc.) is in the Analog domain, so DSD-direct is still good here.

I think you are good to go for DSD-direct.

But...you should NOT do bass management ANYWHERE -- not in the player either if you want DSD-direct. So absolutely no bass management anywhere in the food chain.

 

[gus6464]

I thought the time alignment and bass management would be set in the player. At least that is what my disc player supposedly does.

And here is a question that might help me understand what is going on my setup. When I play SACDs using Multi Channel Ins as source, it operates like I would expect relative to not being able to apply tone controls and so forth. Those audio options are not available when 'Multi Channel In' is the source similar to choosing 'Pure Direct' for example when playing CD through analog connects of my receiver. That makes sense.

I also thought that with 'Mult Channel In' as source you would not be able to control channel levels. On my receiver I have a couple different presets for various listening positions. The main reason for the presets is channel levels. For example one spot where my wife does some craft work is very close to the right front speaker. So, I have a preset that can be selected which raises the left front channel and lowers the right. OK, not to get too far off track here - I am still able to change/select these presets even when listening to SACD over multi channel. - I thought one litmus test for being able to tell if you are getting SACD direct to the speakers is that you will be unable to change anything. My receiver is a Pioneer VSX94 which is geared to please the audiophile, it was not a cheapy (MSRP $1800, paid $1350) - and I have to think that it would not convert to PCM. So what do you think about this?

I would say call Pioneer and ask them if the DACs on your receiver are DSD-Discrete. After doing some searches last night I found out that most Marantz and Yamaha receivers also have DSD-Discrete DACs as well. What you could do to test it out is to put your SACD player in direct mode and also put your receiver in pure direct mode with the analog multi-ch inputs. And for HDMI leave your player in direct mode and that should make it send a DSD bitstream. Do you know if your receiver turns off HDMI when using pure direct? I know mine turns off any kind of video processing through the HDMI when using pure direct but still sends audio.

 

[timetohunt]

I would say call Pioneer and ask them if the DACs on your receiver are DSD-Discrete. After doing some searches last night I found out that most Marantz and Yamaha receivers also have DSD-Discrete DACs as well. What you could do to test it out is to put your SACD player in direct mode and also put your receiver in pure direct mode with the analog multi-ch inputs. And for HDMI leave your player in direct mode and that should make it send a DSD bitstream. Do you know if your receiver turns off HDMI when using pure direct? I know mine turns off any kind of video processing through the HDMI when using pure direct but still sends audio.

Wow. Pretty crazy stuff here. You say you can apply Pure Direct when your source is Multi Channel In. Pure Direct is not applicable with Multi Ch In on the Pioneer. Even the pioneer tech folks said its already in a pure direct state. Which did make sense to me. But the fact that you are able to apply it, has me confused.

And, I'm not sure what you mean by using direct mode on the disc player. I read the Marantz manual front to back, and did not see anything about pure direct. Could have missed it though. If there is pure direct modes on any players I would think maybe it shuts down all video processing.

And yes, I believe Pure Direct with HDMI shuts down video on the Pioneer as well, but I'm not %100 certain.

 

[gus6464]

Wow. Pretty crazy stuff here. You say you can apply Pure Direct when your source is Multi Channel In. Pure Direct is not applicable with Multi Ch In on the Pioneer. Even the pioneer tech folks said its already in a pure direct state. Which did make sense to me. But the fact that you are able to apply it, has me confused.

And, I'm not sure what you mean by using direct mode on the disc player. I read the Marantz manual front to back, and did not see anything about pure direct. Could have missed it though. If there is pure direct modes on any players I would think maybe it shuts down all video processing.

And yes, I believe Pure Direct with HDMI shuts down video on the Pioneer as well, but I'm not %100 certain.

I know Denon players have a pure direct mode which in deed does shut down all video processing. I would guess Marantz might have the same since they do come from the same parent company. I've noticed that the newer Marantz stuff has a lot of the same features as the comparable Denon models.

 

[AcuDefTechGuy]

On my Denon SACD player, there is a Source Direct & a Pure Direct.

Just using Pure Direct alone turns off all video circuits, but it does not turn off bass management. Thus, DSD is still converted to PCM.

I have to turn Soure Direct on. Only then will it turn off bass management and use DSD-direct.

So naturally, I turn on both Source Direct and Pure Direct.

On my Integrated Amp, I also turn on Source Direct, which also bypasses all tone controls and balance control.

 

[tbewick]

Well, you need a SACD player to even playback the DSD.

And even then, most SACD players will automatically just convert DSD to PCM.

Theoretically, I think DSD is superior than PCM. But practically, I don't know.

My understanding is this.

If we look at the final audio sound as a SINE wave, we see this smooth looking sine-wave. The curved line is smooth as it oscillates up and down. That's what DSD is supposed to look like -- the final analog sine wave.

PCM is a representation of a sine-wave with PERPENDICULAR STRAIGHT lines. Imagine drawing a sine-wave with only 90 degrees perpendicular lines, instead of smooth curved lines. This is PCM.

View attachment 6053

In your diagram, I do not understand why you ignore the filter stages of a LPCM converter but include them with the DSD converter. If you ignore the low-pass filter stage of 1-bit DSD digital-to-analogue conversion, then a DSD-quantized sine wave would look jagged due to the presence of high-frequency ultrasonic quantization noise. The diagram below shows the noise introduced by a sigma-delta modulation ADC (as used in DSD) in quantizing a sine wave:



Page 31, 'Sigma Delta Modulation of A Chaotic Signal' Gary Ushaw PhD thesis, Edinburgh University.
http://www.era.lib.ed.ac.uk/retrieve/509/gu96.pdf

This quantization noise of a sine wave was generated in a simulation of a basic SDM ADC design. Different and more advanced SDM converter designs do exist, so the quantization noise shown here probably differs from that of a real-world SDM ADC.

Of course, once PCM is converted to Analog, you also get the smooth sine-wave. But theoretically, PCM has more distortion than DSD. But then again, the distortion is most likely insignificant. This brings us back to the practical vs theoretical DSD vs PCM.

DSD does not have a lower level of distortion than PCM. TPDF-dithered PCM has no distortion or modulation noise at all. Practical LPCM converters will still introduce errors of some kind. Please review Prof. Malcolm Hawksford's paper on LPCM versus DSD, Julian Dunn's description of dither, and this subjective double-blind study comparing LPCM and DSD:

Hawksford, M. (2001). "SDM versus LPCM: The Debate Continues", 110th AES Convention, paper 5397.
http://www.essex.ac.uk/ESE/research/audio_lab/malcolmspubdocs/C115 SDM versus LPCM.pdf

Dunn, J. (2003). "Measurement Techniques for Digital Audio", 'Dither Annex', p140-144. Audio Precision Application Note #5, Audio Precision, Inc. USA.
http://ap.com/library/technotes.htm

Blech, D. & Yang, M. (2004). "Perceptual Discrimination of Digital Coding Formats", Audio Engineering Society Convention Paper 6086, May 2004.
http://www.hfm-detmold.de/eti/projekte/diplomarbeiten/dsdvspcm/aes_paper_6086.pdf

A properly designed LPCM converter uses an analogue filter to remove unwanted high frequency/ultrasonic components from the output sine wave. With an oversampling LPCM converter, a digital and analogue filter would typically be used in combination.

The sinc function (the filters I mentioned approximate this function) allows perfect regeneration of the continuous form of the original bandlimited signal. This is the basis of the Nyquist-Shannon sampling theorem, which states that a signal can be regenerated with no loss of accuracy so long as the sample rate is twice that of the highest frequency components of the signal.

It is only necessary to use a higher sample rate if the filters of the PCM system are inadequate. This has not been demonstrated except in low quality designs, e.g., some computer sound cards, badly designed 'audiophile' DACs.

 

[AcuDefTechGuy]

In your diagram, I do not understand why you ignore the filter stages of a LPCM converter but include them with the DSD converter. If you ignore the low-pass filter stage of 1-bit DSD digital-to-analogue conversion, then a DSD-quantized sine wave would look jagged due to the presence of high-frequency ultrasonic quantization noise. The diagram below shows the noise introduced by a sigma-delta modulation ADC (as used in DSD) in quantizing a sine wave:



Page 31, 'Sigma Delta Modulation of A Chaotic Signal' Gary Ushaw PhD thesis, Edinburgh University.
http://www.era.lib.ed.ac.uk/retrieve/509/gu96.pdf

This quantization noise of a sine wave was generated in a simulation of a basic SDM ADC design. Different and more advanced SDM converter designs do exist, so the quantization noise shown here probably differs from that of a real-world SDM ADC.



DSD does not have a lower level of distortion than PCM. TPDF-dithered PCM has no distortion or modulation noise at all. Practical LPCM converters will still introduce errors of some kind. Please review Prof. Malcolm Hawksford's paper on LPCM versus DSD, Julian Dunn's description of dither, and this subjective double-blind study comparing LPCM and DSD:

Hawksford, M. (2001). "SDM versus LPCM: The Debate Continues", 110th AES Convention, paper 5397.
http://www.essex.ac.uk/ESE/research/audio_lab/malcolmspubdocs/C115 SDM versus LPCM.pdf

Dunn, J. (2003). "Measurement Techniques for Digital Audio", 'Dither Annex', p140-144. Audio Precision Application Note #5, Audio Precision, Inc. USA.
http://ap.com/library/technotes.htm

Blech, D. & Yang, M. (2004). "Perceptual Discrimination of Digital Coding Formats", Audio Engineering Society Convention Paper 6086, May 2004.
http://www.hfm-detmold.de/eti/projekte/diplomarbeiten/dsdvspcm/aes_paper_6086.pdf

A properly designed LPCM converter uses an analogue filter to remove unwanted high frequency/ultrasonic components from the output sine wave. With an oversampling LPCM converter, a digital and analogue filter would typically be used in combination.

The sinc function (the filters I mentioned approximate this function) allows perfect regeneration of the continuous form of the original bandlimited signal. This is the basis of the Nyquist-Shannon sampling theorem, which states that a signal can be regenerated with no loss of accuracy so long as the sample rate is twice that of the highest frequency components of the signal.

It is only necessary to use a higher sample rate if the filters of the PCM system are inadequate. This has not been demonstrated except in low quality designs, e.g., some computer sound cards, badly designed 'audiophile' DACs.

Well, apparently, "my understanding" is not less than yours.

Could you "break it down" for us in simple terms the pros and cons of DSD vs LPCM?

Obvisously there are 2 opposing sides, and each of them think they are better than the other. They both have supporting theories and documents.

I think both DVD-A (LPCM) and SACD (DSD) sound exacly the same.

 

[timetohunt]

The main thing is Bass Managment, which has to be in PCM digital domain.

The Speaker Level Adjustment (+1dB, -1dB, etc.) is in the Analog domain, so DSD-direct is still good here.

I think you are good to go for DSD-direct.

But...you should NOT do bass management ANYWHERE -- not in the player either if you want DSD-direct. So absolutely no bass management anywhere in the food chain.

No bass managment ANYWHERE? I mean, the only thing I can do on the Marantz Univ/SACD player as far as bass management is change speakers from Lg to Sm and have the subwoofer set to 'on' or 'none'. At which settings am I in trouble with converting DSD to PCM ? And sense I am using Multi Ch In as source I don't have bass managment available on the receiver. As we discussed before, using Multi Ch In as source is already a pure state with no digital manipuation available. So the only thing I would need to be wary of is the player settings. I'm not sure what would invoke digital processing. I think I still have to have the subwoofer set to 'on', on the player settings - there is at times (not always esp classical) a low freq channel available on SACD - with most of my SACDs there is something being sent over that 6th cable.

 

[AcuDefTechGuy]

No bass managment ANYWHERE? I mean, the only thing I can do on the Marantz Univ/SACD player as far as bass management is change speakers from Lg to Sm and have the subwoofer set to 'on' or 'none'. At which settings am I in trouble with converting DSD to PCM ?

On my Denon, I cannot even change the speakers from Lg to Sm. When I turn that Source Direct on, which is the only way to get DSD, the only thing I can change is the speaker volume level (+1dB, +2dB, -1dB, etc.). The speakers are automatically set to "Large" and the Subwoofer is automatically set to "Yes". The crossover is automatically set to full range (20Hz-20kHz) -- there is not a cutoff point like 40Hz, 60Hz, 80Hz, etc.

So I think you need to turn something on that will disable the speaker settings (Large vs Small, Sub Yes vs No, Crossover setting).

Try playing around with the Audio settings. Like turn PCM Downmix to OFF, etc.

 

[obscbyclouds]

No bass managment ANYWHERE? I mean, the only thing I can do on the Marantz Univ/SACD player as far as bass management is change speakers from Lg to Sm and have the subwoofer set to 'on' or 'none'. At which settings am I in trouble with converting DSD to PCM ? And sense I am using Multi Ch In as source I don't have bass managment available on the receiver. As we discussed before, using Multi Ch In as source is already a pure state with no digital manipuation available. So the only thing I would need to be wary of is the player settings. I'm not sure what would invoke digital processing. I think I still have to have the subwoofer set to 'on', on the player settings - there is at times (not always esp classical) a low freq channel available on SACD - with most of my SACDs there is something being sent over that 6th cable.

That's right, No bass managment, ANYWHERE! . If in doubt, set all speakers to "large" and subwoofer to "on". Audio Out should be set to "5.1". According to pg.43 of your manual, the distance and speaker size settings "do not apply to Super Audio CD playback". Digital Out should be set to "off". If you have these settings, you should be going from DSD--->Analog output to the reciever. Just make sure you are still using the multi-channel input on your reciever and not doing any conversions there. Then you should be getting straight DSD, without the PCM conversion process.


Simple enough? Anyone surprised why SACD didn't catch on?

As an aside, I've enjoyed SACD converted to PCM for years now without worrying. I like using PCM to get some bass management and time alignment. (I don't have 5 identical speakers, and it's not possible to have them all at the same distances in my room). I still think it sounds terrific.

Also IMO DVD-A sounds about just as good as SACD. Of course, much of that has to do with the mixing process as format. I think to some extent we're splitting hairs here. Hopefully moving forward, BR audio will get more market exposure and we can all enjoy our PCM, DTS-HD MA and TrueHD encodes with far less pain and frustration.

 

[timetohunt]

On my Denon, I cannot even change the speakers from Lg to Sm. When I turn that Source Direct on, which is the only way to get DSD, the only thing I can change is the speaker volume level (+1dB, +2dB, -1dB, etc.). The speakers are automatically set to "Large" and the Subwoofer is automatically set to "Yes". The crossover is automatically set to full range (20Hz-20kHz) -- there is not a cutoff point like 40Hz, 60Hz, 80Hz, etc.

So I think you need to turn something on that will disable the speaker settings (Large vs Small, Sub Yes vs No, Crossover setting).

Try playing around with the Audio settings. Like turn PCM Downmix to OFF, etc.

OK. PCM downmix would be the only one I could think of to play with.
But there is still a mystery afoot - as far as how your gear is handling vs. mine. Really has me wondering. Pioneer tech support (and Rotel for that matter on a different but related call) said that the channel level and crossover is in the Analog Domain. I thought the analog signal might have to be redigitized for some of that. So far all of the techs are saying no it is not. So Def, I still don't know.

EDIT: the rotel call, I asked if I was still getting the analog signal from my rotel CD player even if I was getting subwoofer output. They said yes. I was wondering if pure direct was the only way to absolutely get the player's analog output (and ofcourse that would be 2.0 only). They said the crossover on the receiver was still in the analog domain.

 

[timetohunt]

That's right, No bass managment, ANYWHERE! . If in doubt, set all speakers to "large" and subwoofer to "on". Audio Out should be set to "5.1". According to pg.43 of your manual, the distance and speaker size settings "do not apply to Super Audio CD playback". Digital Out should be set to "off". If you have these settings, you should be going from DSD--->Analog output to the reciever. Just make sure you are still using the multi-channel input on your reciever and not doing any conversions there. Then you should be getting straight DSD, without the PCM conversion process.


Simple enough? Anyone surprised why SACD didn't catch on?

As an aside, I've enjoyed SACD converted to PCM for years now without worrying. I like using PCM to get some bass management and time alignment. (I don't have 5 identical speakers, and it's not possible to have them all at the same distances in my room). I still think it sounds terrific.

Also IMO DVD-A sounds about just as good as SACD. Of course, much of that has to do with the mixing process as format. I think to some extent we're splitting hairs here. Hopefully moving forward, BR audio will get more market exposure and we can all enjoy our PCM, DTS-HD MA and TrueHD encodes with far less pain and frustration.

Wow thanks - I did not see that on page 43. And your right, it is splitting hairs. But I just wanted to get to the bottom of the truth. Your also right about it sounding good, even with an uneven setup. Due to room shape, furniture, and the woodstove, I don't have a perfect speaker arrangment as well. Yet, I find that many of my DVD-As and SACDs discs sound awsome.
Is the converted PCM still high resolution tho ?
Do you think BR will catch on with an audio disc anytime soon?

 

[obscbyclouds]

Wow thanks - I did not see that on page 43. And your right, it is splitting hairs. But I just wanted to get to the bottom of the truth. Your also right about it sounding good, even with an uneven setup. Due to room shape, furniture, and the woodstove, I don't have a perfect speaker arrangment as well. Yet, I find that many of my DVD-As and SACDs discs sound awsome.
Is the converted PCM still high resolution tho ?
Do you think BR will catch on with an audio disc anytime soon?

Yes, SACD converted to PCM is still "high resolution". Usually it's converted to 48Khz/24 bit PCM. In my Oppo (981) it's converted to 88.2khz/24bit PCM, and some can even convert to 176.4khz/24-bit.

There has been at least 1 BR audio release. I hope it catches on, but I'm not very optimistic given the hope I had already put into SACD and DVD-A. There's an audioholics article about it here: http://www.audioholics.com/news/industry-news/high-resolution-blu-ray-audio

My advice is don't get too caught up in the DSD vs. PCM nonsense. Well-mixed and mastered discs of either format will sound terrific. Even with all the money I've wasted on it, I'm still happy because it got me into new genres of music (Jazz and Classical) that I'd never really bothered with before.