Yesterday seemed kind of a dud. Mostly just writing up various things discernable and claimed about HDCD. Was it a breakthrough, or a scam? Well, I still don't know, probably a bit of both I'll concede, but I've discovered some amazing things.
For one thing, and here I may have the smallest scoop of all time, but it is actually most likely a scoop because I doubt anyone has reported this before:
The Denon DVD-9000, when used as a SPDIF DAC, has an HDCD bug.
If I play any track from Mephisto and Co., one of the most justifiably praised HDCD's ever, and something I've long used as demos and tests, while using the DVD-9000 as a DAC to decode it, which it seems to do better than any other DAC I've experienced, it apparently sets the Peak Expand state of HDCD, which is used throughout this disc according to ffmpeg.
THEN, if I play anything else, even if not using HDCD, it gets peak expanded also. The peak expand mode stays set (or, perhaps it was because I didn't play Mephisto all the way through...not yet tested, just a few seconds is apparently sufficient to enable the peak expand bug I am describing).
So it's a bug in general, if you happen to be using the DVD-9000 as a DAC, which is probably a significant fraction of the small number of DVD-9000's still being used, and playing some fraction of HDCD's. In that case you, as I once did, might consider the DVD-9000 one of the best DAC's ever, because it's cheating, applying peak expand to everything.
BUT, it's also a feature! I can now apply peak expansion to basically anything. It's like having Carver's famous (or infamous) Peak Unlimiter on tap.
And, I can tell you, it sometimes really ups the ante. It really adds a lot to other albums, especially it seems, HDCD albums which don't actually use the Peak Expand feature. Such as Mannheim Steamroller Fresh Aire II. Or even non-HDCD albums, like Pancho Sanchez' Out of Sight.
This is a Damn Good peak expander function. We can already hear how fine it sounds on Mephisto. If you listen to that HDCD disc on a non-HDCD enabled player, it sounds perfectly fine and wonderful. You would just never know you are listening to a disk with at least 4dB of compression. Then, when you listen to it on an HDCD player, it knocks socks off.
But that's exactly how a GOOD compression scheme should work. You don't want your socks knocked off while your driving down the freeway or on your bicycle. You want your socks knocked off when you're seriously listening to your big rig, with the HDCD equipped player.
As I started to say in the last post, this is exactly how it should be, or should have been, to end the loudness wars. FM stations and car drivers can play the compressed version, but turned up to a higher average level.
But if you want to turn the Peak Expand state off, you can simply turn the Source switch on the DVD-9000 back to Disc for a few seconds, and then back to Coaxial. And by the same token, the bug does not appear to be triggered by playing the Mephisto disc, and then any other disc. It seems to only occur if you are using the DVD-9000 as a SPDIF DAC.
Anyway, the story of how I discovered this and many things, was like falling down the Rabbit Hole.
It started with the delight of getting my Denon DVD-9000 back online as a DAC, so I can play HDCD albums on my hard drive through Roon with actual HDCD decoding, from the very best HDCD decoder I have ever experienced, the Denon DVD-9000.
The DVD-9000 is not just a 40 pound monster Statement Piece by Denon as the first foray into serious competitive DVD-Audio (this player DOES NOT support SACD, though some had believed a PCM conversion would be permitted, Sony was never willing to license it for this player, which has a the last and best PCM DAC chip, the Burr Brown 1704, used in it's best dual differential mode, much like the top Mark Levinson 360S DAC did for 10 years afterwards, and many other famous DACs of note).
It is also apparently the first generation HDCD product to not include a PMI digital filter chip. It uses the second generation HDCD specification, which was never made into a chip, within a 32 bit digital filter system, which Denon called AL24. And, the development of all this probably occurred before, or contemporanously with, Microsoft's purchase of HDCD from PMI.
If any DAC has the "transient filter" feature enabled, this might well be it. Maybe it doesn't, maybe no HDMI players did, but I can state that this HDCD DAC sounds better to me than any other HDCD DAC I've ever heard, by a large measure, and it could be because of a Transient Filter feature, which I had always believed existed.
******
Just after setting up the Denon DVD-9000 with SPDIF input through a Roon enabled Sonos ZP80 Zoneplayer, I wanted to be sure this was actually working to correctly decode HDCD albums in my library (if not others).
It's damning that the DVD-9000 does not (usually) light the HDCD light when playing HDCD albums through the SPDIF input. That bug had been observed by others. It appears to only do so if you are playing an HDCD disc. But it also appears, I have confirmed, to do the HDCD decoding for 16/44.1 SPDIF signals as well, if they are HDCD titles. It just doesn't light the HDCD light. (And, yet, sometimes it does light the HDCD light, but I have not been able to duplicate this occurance, a peculiar series of albums might cause it, or perhaps I incorrectly observed this when an HDCD disc was loaded.)
So, how does one confirm that the HDCD decoding is actually being done, in the absense of a reliable luminous HDCD indicator?
Well, before I knew of anything better, I could measure the output of the DVD-9000. I do that automatically when I listen to the analog outputs, which are buffered and level adjusted transparently by my Emotiva XSP-1 preamp, and thence fed in balanced form to my Lavry AD10 analog to digital converter. The resulting digital signal then feeds my digital crossovers and equalizers.
The Lavry has a wonderful array of LED's, with Peak Hold that stays held until you flip the reset switch. Which means I can measure and/or compare any level within 1dB.
I've known for some time that HDCD's put out higher levels than regular CD's on the DVD-9000. This was what the original HDCD license required, and the DVD-9000 implements it. Later HDCD players tended to drop this feature, which reviewers and fans of other equipment (especially Sony equipment) tended to depricate. Justifiably, non-fans of HDCD thought this was an unfair trick, and indeed, it was.
Many falsely claim that CD players were supposed to put out only 1V maximum for CD's, and 2V peak extended maximum for HDCD's.
What the Denon does is put out 2V for regular CD's, and up to 4V for HDCD's. It's easy to see this difference on the Lavry LED's.
I generally try to adjust the gain on the Emotiva preamp so that the peak signal is -1dB on the Lavry indicator. That way I'm sure there was no clipping.
However, as I was playing various HDCD and other files from my library on the DVD-9000 through SPDIF, it seemed I kept having to turn the level down on the Emotiva to stay away from the 0dB light. Ultimately, it seemed, that if I set the Emotiva gain control to -5dB, I could do this effectively. Playing regular CD's on the Oppo UDP 205 and other players, I can do this with the gain control set to -1dB or so. So we can see there's at least 4dB difference in peak levels. When I play LP's, I have to set the gain to +4dB to +7dB.
(I have set the Lavry input maximum input level to 3.88V, but the Emotiva automatically doubles the output voltage from the single ended Denon to the balanced outputs feeding the Emotiva. So a single ended output reaching 2V would require a gain setting of about -1dB, as also with the Oppo balanced outputs reaching 4V.)
Anyway, I thought I could verify that the DVD-9000 was properly decoding the HDCD sent over SPDIF by playing an HDCD, and a CD, and comparing their levels shown on the Lavry.
I started with Mephisto and Co. I couldn't actually remember the gain setting required for HDCD's with this setup, I remembered it seeming to differ from disc to disc, so I started with a gain setting of -3dB. That didn't work, so I tried -4dB, and ultimately -5dB gain setting. That eliminated hitting the 0dB indicator LED on the Lavry with this disc.
Wanting to be sure I had found the maximum, I also tried Fresh Aire II, and it was also hitting the -1dB LED more consistently.
I was sure a regular CD would not reach higher than -4dB or so, because of the level settings I've just described. I was sure that I had already proven the Denon was playing HDCD's at an elevated output level. So I didn't bother to compare the levels of regular CD's, so much as CD's I had always wondered might really be HDCD's, whose potential might previously have been untapped.
I somehow had this idea that Poncho Sanchez' Out of Nowhere might have been mastered in HDCD. (Actually, I was confusing it with Arturo Sandoval's Hot House, I remembered later). So I tested that, and it was hitting the -1dB Lavry LED even more frequently than the previous two discs. So this had to also be an HDCD, despite not being marked as such.
This was a shock. I knew that not all HDCD's were labeled as such, but exactly how many of my CD's are really HDCD's that haven't had their full potential revealed, I wondered.
I decided it was high time I use one of these programs, like Foobar2000, to test my files and see if they have HDCD features enabled.
That was a long trip into computer frustration. The initial (and perhaps ultimately fatal) problem is that I use a Mac mostly, and Foobar2000 is solely a Windows program. Well, I'll try it under the Wine emulator.
I was pleased that I managed to get Foobar2000 running. And then I downloaded the HDCD plugin, and installed it, which required learning a lot about Foobar2000 and even a bit more about Wine.
Loading the HDCD plugin probably didn't work completely. Either that, or it is broken on the current release. It seemed to be installed, it shows up in black in the list of available plugins. And I was able to add the HDCD reporting to the default display, as described on websites (the actual HDCD plugin has no documentation itself).
But every HDCD I played showed no HDCD features enabled. I edited the default display so the contents of the HDCD variables are ALWAYS being shown, and they always show as ?.
It might have been that this was caused by an incomplete installation of the plugin. When I pressed the INSTALL button, Foobar2000 was supposed to reboot itself with the new plugin. It did not reboot, I had to restart it manually. It's possible that Foobar2000 missed picking up the last bit of the HDCD plugin installation process.
Well, I figured, I'll just have to wait until tomorrow (it was already past my getting ready for bedtime time) and install it on my actual PC. But this didn't keep me from another futile hour of futile fiddling with Foobar2000 on my Mac, all of which failed to reveal anything about any HDCD.
By the next morning, I decided to take a different path. I happened to stumble upon the other recommended way of dealing with HDCD, ffmpeg.
Now, ffmpeg is definitely more of my kind of program! For one thing, it runs natively on Mac (and many other systems!). It does all sorts of conversion tricks. And there's no need to fiddle with plugins or recompiling (which I was afraid of at first) because HDCD is included in the standard Mac binary distribution! (And if that isn't good enough, one can download the source code.)
And it runs from the command line also, another thing that I, a retired Unix programmer, really and truly like and appreciate. That means I can easily roll shell wrappers and things (which I have already done--I created a script which simply examines files for their HDCD flags, deleting the pesky output files I don't want yet).
And, the results of ffmpeg were quite shocking. I was shocked to see that neither Fresh Aire II, which is clearly marked HDCD and which I always believed was so much better on HDCD players as to not be worth playing on any other kind, uses no HDCD peak expansion or gain adjustment features! It is fully embedded with the HDCD Transient Filter flags, which some claim to be ineffective, and that is all!
Out of Sight, a more recent addition to my library, showed no HDCD flags at all! So how it the world was it reaching the nearly 4V output level when being played on my Denon DVD-9000 ???
Eventually, the theory I described at the top became clear to me. The Denon must have a bug, I concluded. And only then I set about systematically to prove it, as I shall show in the next post, with pictures!
For one thing, and here I may have the smallest scoop of all time, but it is actually most likely a scoop because I doubt anyone has reported this before:
The Denon DVD-9000, when used as a SPDIF DAC, has an HDCD bug.
If I play any track from Mephisto and Co., one of the most justifiably praised HDCD's ever, and something I've long used as demos and tests, while using the DVD-9000 as a DAC to decode it, which it seems to do better than any other DAC I've experienced, it apparently sets the Peak Expand state of HDCD, which is used throughout this disc according to ffmpeg.
THEN, if I play anything else, even if not using HDCD, it gets peak expanded also. The peak expand mode stays set (or, perhaps it was because I didn't play Mephisto all the way through...not yet tested, just a few seconds is apparently sufficient to enable the peak expand bug I am describing).
So it's a bug in general, if you happen to be using the DVD-9000 as a DAC, which is probably a significant fraction of the small number of DVD-9000's still being used, and playing some fraction of HDCD's. In that case you, as I once did, might consider the DVD-9000 one of the best DAC's ever, because it's cheating, applying peak expand to everything.
BUT, it's also a feature! I can now apply peak expansion to basically anything. It's like having Carver's famous (or infamous) Peak Unlimiter on tap.
And, I can tell you, it sometimes really ups the ante. It really adds a lot to other albums, especially it seems, HDCD albums which don't actually use the Peak Expand feature. Such as Mannheim Steamroller Fresh Aire II. Or even non-HDCD albums, like Pancho Sanchez' Out of Sight.
This is a Damn Good peak expander function. We can already hear how fine it sounds on Mephisto. If you listen to that HDCD disc on a non-HDCD enabled player, it sounds perfectly fine and wonderful. You would just never know you are listening to a disk with at least 4dB of compression. Then, when you listen to it on an HDCD player, it knocks socks off.
But that's exactly how a GOOD compression scheme should work. You don't want your socks knocked off while your driving down the freeway or on your bicycle. You want your socks knocked off when you're seriously listening to your big rig, with the HDCD equipped player.
As I started to say in the last post, this is exactly how it should be, or should have been, to end the loudness wars. FM stations and car drivers can play the compressed version, but turned up to a higher average level.
But if you want to turn the Peak Expand state off, you can simply turn the Source switch on the DVD-9000 back to Disc for a few seconds, and then back to Coaxial. And by the same token, the bug does not appear to be triggered by playing the Mephisto disc, and then any other disc. It seems to only occur if you are using the DVD-9000 as a SPDIF DAC.
Anyway, the story of how I discovered this and many things, was like falling down the Rabbit Hole.
It started with the delight of getting my Denon DVD-9000 back online as a DAC, so I can play HDCD albums on my hard drive through Roon with actual HDCD decoding, from the very best HDCD decoder I have ever experienced, the Denon DVD-9000.
The DVD-9000 is not just a 40 pound monster Statement Piece by Denon as the first foray into serious competitive DVD-Audio (this player DOES NOT support SACD, though some had believed a PCM conversion would be permitted, Sony was never willing to license it for this player, which has a the last and best PCM DAC chip, the Burr Brown 1704, used in it's best dual differential mode, much like the top Mark Levinson 360S DAC did for 10 years afterwards, and many other famous DACs of note).
It is also apparently the first generation HDCD product to not include a PMI digital filter chip. It uses the second generation HDCD specification, which was never made into a chip, within a 32 bit digital filter system, which Denon called AL24. And, the development of all this probably occurred before, or contemporanously with, Microsoft's purchase of HDCD from PMI.
If any DAC has the "transient filter" feature enabled, this might well be it. Maybe it doesn't, maybe no HDMI players did, but I can state that this HDCD DAC sounds better to me than any other HDCD DAC I've ever heard, by a large measure, and it could be because of a Transient Filter feature, which I had always believed existed.
******
Just after setting up the Denon DVD-9000 with SPDIF input through a Roon enabled Sonos ZP80 Zoneplayer, I wanted to be sure this was actually working to correctly decode HDCD albums in my library (if not others).
It's damning that the DVD-9000 does not (usually) light the HDCD light when playing HDCD albums through the SPDIF input. That bug had been observed by others. It appears to only do so if you are playing an HDCD disc. But it also appears, I have confirmed, to do the HDCD decoding for 16/44.1 SPDIF signals as well, if they are HDCD titles. It just doesn't light the HDCD light. (And, yet, sometimes it does light the HDCD light, but I have not been able to duplicate this occurance, a peculiar series of albums might cause it, or perhaps I incorrectly observed this when an HDCD disc was loaded.)
So, how does one confirm that the HDCD decoding is actually being done, in the absense of a reliable luminous HDCD indicator?
Well, before I knew of anything better, I could measure the output of the DVD-9000. I do that automatically when I listen to the analog outputs, which are buffered and level adjusted transparently by my Emotiva XSP-1 preamp, and thence fed in balanced form to my Lavry AD10 analog to digital converter. The resulting digital signal then feeds my digital crossovers and equalizers.
The Lavry has a wonderful array of LED's, with Peak Hold that stays held until you flip the reset switch. Which means I can measure and/or compare any level within 1dB.
I've known for some time that HDCD's put out higher levels than regular CD's on the DVD-9000. This was what the original HDCD license required, and the DVD-9000 implements it. Later HDCD players tended to drop this feature, which reviewers and fans of other equipment (especially Sony equipment) tended to depricate. Justifiably, non-fans of HDCD thought this was an unfair trick, and indeed, it was.
Many falsely claim that CD players were supposed to put out only 1V maximum for CD's, and 2V peak extended maximum for HDCD's.
What the Denon does is put out 2V for regular CD's, and up to 4V for HDCD's. It's easy to see this difference on the Lavry LED's.
I generally try to adjust the gain on the Emotiva preamp so that the peak signal is -1dB on the Lavry indicator. That way I'm sure there was no clipping.
However, as I was playing various HDCD and other files from my library on the DVD-9000 through SPDIF, it seemed I kept having to turn the level down on the Emotiva to stay away from the 0dB light. Ultimately, it seemed, that if I set the Emotiva gain control to -5dB, I could do this effectively. Playing regular CD's on the Oppo UDP 205 and other players, I can do this with the gain control set to -1dB or so. So we can see there's at least 4dB difference in peak levels. When I play LP's, I have to set the gain to +4dB to +7dB.
(I have set the Lavry input maximum input level to 3.88V, but the Emotiva automatically doubles the output voltage from the single ended Denon to the balanced outputs feeding the Emotiva. So a single ended output reaching 2V would require a gain setting of about -1dB, as also with the Oppo balanced outputs reaching 4V.)
Anyway, I thought I could verify that the DVD-9000 was properly decoding the HDCD sent over SPDIF by playing an HDCD, and a CD, and comparing their levels shown on the Lavry.
I started with Mephisto and Co. I couldn't actually remember the gain setting required for HDCD's with this setup, I remembered it seeming to differ from disc to disc, so I started with a gain setting of -3dB. That didn't work, so I tried -4dB, and ultimately -5dB gain setting. That eliminated hitting the 0dB indicator LED on the Lavry with this disc.
Wanting to be sure I had found the maximum, I also tried Fresh Aire II, and it was also hitting the -1dB LED more consistently.
I was sure a regular CD would not reach higher than -4dB or so, because of the level settings I've just described. I was sure that I had already proven the Denon was playing HDCD's at an elevated output level. So I didn't bother to compare the levels of regular CD's, so much as CD's I had always wondered might really be HDCD's, whose potential might previously have been untapped.
I somehow had this idea that Poncho Sanchez' Out of Nowhere might have been mastered in HDCD. (Actually, I was confusing it with Arturo Sandoval's Hot House, I remembered later). So I tested that, and it was hitting the -1dB Lavry LED even more frequently than the previous two discs. So this had to also be an HDCD, despite not being marked as such.
This was a shock. I knew that not all HDCD's were labeled as such, but exactly how many of my CD's are really HDCD's that haven't had their full potential revealed, I wondered.
I decided it was high time I use one of these programs, like Foobar2000, to test my files and see if they have HDCD features enabled.
That was a long trip into computer frustration. The initial (and perhaps ultimately fatal) problem is that I use a Mac mostly, and Foobar2000 is solely a Windows program. Well, I'll try it under the Wine emulator.
I was pleased that I managed to get Foobar2000 running. And then I downloaded the HDCD plugin, and installed it, which required learning a lot about Foobar2000 and even a bit more about Wine.
Loading the HDCD plugin probably didn't work completely. Either that, or it is broken on the current release. It seemed to be installed, it shows up in black in the list of available plugins. And I was able to add the HDCD reporting to the default display, as described on websites (the actual HDCD plugin has no documentation itself).
But every HDCD I played showed no HDCD features enabled. I edited the default display so the contents of the HDCD variables are ALWAYS being shown, and they always show as ?.
It might have been that this was caused by an incomplete installation of the plugin. When I pressed the INSTALL button, Foobar2000 was supposed to reboot itself with the new plugin. It did not reboot, I had to restart it manually. It's possible that Foobar2000 missed picking up the last bit of the HDCD plugin installation process.
Well, I figured, I'll just have to wait until tomorrow (it was already past my getting ready for bedtime time) and install it on my actual PC. But this didn't keep me from another futile hour of futile fiddling with Foobar2000 on my Mac, all of which failed to reveal anything about any HDCD.
By the next morning, I decided to take a different path. I happened to stumble upon the other recommended way of dealing with HDCD, ffmpeg.
Now, ffmpeg is definitely more of my kind of program! For one thing, it runs natively on Mac (and many other systems!). It does all sorts of conversion tricks. And there's no need to fiddle with plugins or recompiling (which I was afraid of at first) because HDCD is included in the standard Mac binary distribution! (And if that isn't good enough, one can download the source code.)
And it runs from the command line also, another thing that I, a retired Unix programmer, really and truly like and appreciate. That means I can easily roll shell wrappers and things (which I have already done--I created a script which simply examines files for their HDCD flags, deleting the pesky output files I don't want yet).
And, the results of ffmpeg were quite shocking. I was shocked to see that neither Fresh Aire II, which is clearly marked HDCD and which I always believed was so much better on HDCD players as to not be worth playing on any other kind, uses no HDCD peak expansion or gain adjustment features! It is fully embedded with the HDCD Transient Filter flags, which some claim to be ineffective, and that is all!
Out of Sight, a more recent addition to my library, showed no HDCD flags at all! So how it the world was it reaching the nearly 4V output level when being played on my Denon DVD-9000 ???
Eventually, the theory I described at the top became clear to me. The Denon must have a bug, I concluded. And only then I set about systematically to prove it, as I shall show in the next post, with pictures!
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