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DSD to PCM


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#1 of 42 Mike Garofano

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Posted January 26 2004 - 05:11 PM

Is it true that most DVD players that support SACD actually convert the DSD signal to PCM before going through D/A? If so, aren't these players bstardizing the SACD format?

Is there a list of players that do not do this conversion (has Sony allowed any chipsets but its own to support or are they pulling another "we're Sony...we do it the proprietary way...everyone else can go screw!")?

#2 of 42 BrianWoerndle

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Posted January 27 2004 - 04:40 AM

I know the Denon 5900, 2900 and 2200 retain the DSD signal. I am sure others do, but I do not know off the top of my head.
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#3 of 42 John Kotches

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Posted January 27 2004 - 05:25 AM

Brian,

This is only true on the 5900 if you use the Direct option, anything else converts to PCM.

I can't comment on the other Denon players, as I haven't worked with them.

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#4 of 42 chung_sotheby

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Posted January 27 2004 - 07:09 AM

John,

I believe that the Denon 5900 and 2900 do not turn the DSD signal into PCM when crossover, balance, and time alignment settings are engaged. I remember reading somewhere in a thread on this forum that a Denon representative stated that all the above functions are done without changing the signal to PCM. I am not exactly sure which thread it is on, but I am sure I read it in this forum. Try doing a search and maybe you can find it

#5 of 42 John Kotches

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Posted January 27 2004 - 01:32 PM

Chung,

If you engage Bass Management, Time Alignment or Channel Trim, you convert DSD to PCM. If you run direct, without any of these you don't.

Check the specs page on the web site.

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#6 of 42 Estevan

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Posted January 27 2004 - 02:43 PM

all the Pioneer players following the DV-AX10 do not convert to PCM unless you are using bass management features...

#7 of 42 chung_sotheby

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Posted January 28 2004 - 08:27 AM

John,
I think you may be confused. The website says that there is full digital bass management for SACD, NOT that the bass management is done by converting the DSD stream to PCM. See the link here:

Denon DVD players

I think that the Denon is unable to do time alignment without converting the DSD signal to PCM, but IS able to do bass management and channel balance without convering DSD to PCM. Here is a post by DenonJeff, who works at Denon and has said repeatedly that the DSD bass management is done in the DSD domain:

Denon BM

If there are any links or posts that have definitive information that state that the BM is done by converting DSD to PCM, please let me know, as I am very interested in this subject, in case you haven't judged this alreadyPosted Image

#8 of 42 Kevin C Brown

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Posted January 28 2004 - 12:46 PM

The Pioneer 45a and 47ai do not convert DSD to PCM for any bass management. I think only the 563 does.


Chung- I was also under the impression that the 5900 converts to PCM for BM of SACD.

From your 1st link:

Quote:
Full Digital Bass Management for DVD-Audio/SACD (optional), featuring dual Analog Devices Melody 100 'HammerHead' processors • 40/60/80/100/120Hz crossover points with 12dB high and 24dB low pass slopes; Adjustable delay time and Channel Levels (DSD signals are converted to PCM for this feature) • Source Direct Mode for SACD allowing no conversion to PCM

I am taking "feature" as being the entire text between the bullets, and not just the preceeding time delay and levels (which means that if you simply change levels in the player, bingo DSD to PCM?).

From the 2nd link, Denon Jeff only comments about the 2900, which I already knew that didn't do any conversion:

Quote:
The 2900 will treat PCM as PCM and DSD as DSD all the way through. This was a design priority as we know what was being done in the marketplace and did not want to follow that path.

That's why, for example, the 5900 allows all the different crossover points for SACD, but the 2900, Pioneers, etc, don't. I.e., you get that flexibility if you convert to PCM, but remember all the S&V reviews where they complain about the different slopes and crossover points for SACD vs DVD-A, CD, DD/DTS *because* the intrinsic BM of the Sony DSD chip was being used.

??
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#9 of 42 Chris_C

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Posted January 28 2004 - 05:45 PM

There have been several discussions on this subject at audioasylum. Since I'm still a noobie here I can't post links but sony players dont do any conversion to PCM and if you search for posts by Allen Wright he states that PCM conversion generally doesn't occur. Allen modifies players btw. I quote one of his posts below.


"Every "new design" player I have inspected recently use PCM DACs that use seperate SACD inputs that feed an internal "side path" that utilises the DAC's internal low pass filter to process the bitstream signal direct to audio. No format conversion is needed - or wanted. The Burr Browm range, including the often used PCM1730 DAC does this, as does the CS4397 used in the marantz SA-14.

I suspect this idea that DSD/SACD signals get converted to PCM is someone's misunderstanding of some manufacturer's promotion piece. I don't know for sure but I've yet to see it."

#10 of 42 Kevin C Brown

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Posted January 28 2004 - 06:48 PM

Chris - That is actually similar to my understanding. Any player that uses a Sony DSD chip does not (have to) do DSD to PCM conversion.

The exclusions that I know of are the Pioneer AX-10 (model number?), the 563, and the 5900 (depending on config). I'm not even 100% sure of the 563, but the AX-10 and the 5900 are "for sures." Posted Image

Allen's site, btw, is www.modwright.com .
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#11 of 42 John Kotches

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Posted January 29 2004 - 12:45 AM

chung,

Wrong.

Quote:
Adjustable delay time and Channel Levels (DSD signals are converted to PCM for this feature)

What's not said about Sony's DSD bass management, is that internally it does not maintain DSD. Instead, it is converted to PCM for bass management, then back to DSD for D/A conversion.

So DSD In --> Internal Conversion --> Bass Management --> Internal Conversion --> DSD Out.

I've gone over the mathematics of this topic with a couple of people who do DSP engineering for a living. Both hold advanced degrees on the topic and don't earn their living in the consumer electronics field Posted Image So they've nothing to gain or lose by the discussion.

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#12 of 42 Lewis Besze

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Posted January 29 2004 - 06:10 AM

Chung,
Kevin is right the 5900 does convert to PCM[when BM is engaged] but the 2900 doesn't.

#13 of 42 chung_sotheby

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Posted January 29 2004 - 06:43 AM

John,
You're right, the 5900 does go DSD->PCM when doing BM. I thought you were talking about the 2900. But what is troubling is that you said the new Sony DSD engine, which does BM by itself, does not keep the signal as DSD all the way through. Therefore, it seems as though there is no way possible in any machine to do BM while keeping a DSD signal all the way through. Am I correct in assuming this?

#14 of 42 John Kotches

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Posted January 29 2004 - 07:08 AM

Chung,

Aside from propoganda, everything I've read, and everyone with an extensive background on the topic says "Nope".

If you're going to process a 1-bit signal, everything is an overflow or underflow Posted Image

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#15 of 42 Peter Ping

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Posted January 29 2004 - 02:31 PM

Does this mean that even 2900 or 2200 converts DSD to PCM for BM purpose?

#16 of 42 Kevin C Brown

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Posted January 29 2004 - 06:20 PM

John- If that's true, why not do time alignment too?

That would also mean that most (if not all) SACD players that do BM, convert to PCM and then back to DSD.

But I do distinctly remember seeing reviews that specifically mentioned how the AX-10 did it vs Pioneer's later players.

??
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#17 of 42 John Kotches

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Posted January 30 2004 - 01:15 AM

Kevin,

Time alignment can be accomplished with a simple buffer circuit.

As far as why not do time alignment... apparently most manufacturers don't think it's needed.

Welcome to the hell that is DSD "processing".

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#18 of 42 Lewis Besze

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Posted January 30 2004 - 03:12 PM

Quote:
Does this mean that even 2900 or 2200 converts DSD to PCM for BM purpose?
Nope.

#19 of 42 Peter Ping

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Posted January 30 2004 - 05:09 PM

After more reading about this, I have noticed a subtle distinction. 5900 does not have to convert DSD to PCM; it does convert only when it performs the full BM functions (e.g,. 40/60/80/100/120Hz crossover points for different channels, adjustable delay time and channel levels). However, if it performs the limited BM functions (e.g., the option of Source Direct Digital BM for SACD, fixed 80Hz crossover for all channels, and adjustable channel levels), there will be NO DSD->PCM conversion.

The reason for 2900 or 2200 not having to convert DSD to PCM for SACD is simply because they have limited BM functions (e.g., the fixed 80Hz crossover for all channels).

Am I right here?

#20 of 42 Kevin C Brown

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Posted January 30 2004 - 07:12 PM

Peter- According to John, almost any player that does any kind of BM for SACD converts to PCM and then back to DSD.

If this is true, just seems like a "dirty little secret" that obviously most of us didn't know.

I'm still not sure I 100% (want to) believe it, because if true, why not just leave it as PCM and then to analog? Why go to the trouble of converting back to DSD?

John- Why do time alignment for SACD? Marketing! Posted Image
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