What Fidelity Is “Hidden” in a CD?
This past week I’ve been finishing up the CD production process for my advanced recording course at California State University, Dominguez Hills. The past few class meetings have detailed the electronic and physical aspects of the format as enshrined in the “Redbook” specification. My students now understand the essential parameters that affect and limit the fidelity of a compact disc. We’ve discussed the processes involved with converting analog signals to digital PCM encoded words and visa versa AND they know how each stage of the production process affects the ultimate fidelity of the end product.
But there are equipment manufacturers, audiophiles, writers and accessory suppliers that don’t understand the fidelity capabilities of the humble CD. From what I’ve been able to discover, the reason is the continued misconception of the difference between analog and digital storage methods. In Paul McGowan’s introductory video about their new DirectStream DAC, he pulls a CD off the shelf and ponders an experience that he has encountered numerous times. He revels in those moments when a new piece of playback equipment or hardware has delivered something from a familiar disc that he hadn’t heard before. It’s as if a new amplifier or speaker has removed or reduced some type of barrier between the “ultimate fidelity” that we all know is locked into the CD and us. He and others believe that we can continually improve the delivery hardware and thus continue to derive more and more fidelity from the same disc.
I call this the audiophile’s paradox.
This type of thinking is usually associated with analog advocates. If I just separate the drive motor from my spinning turntable platter, I’ll be able to reduce the rumble in my system OR if I put ruby guides in the tape path of my analog tape deck, the scrape flutter associated with analog tape machines will be reduced. These types of refinements DO improve the performance of analog audio systems. There are very real improvements that can be achieved with better electronics and electro-mechanical systems. But there are also very real limits to the performance enhancements that can be delivered through continued tweaking of these things…in the analog domain. There is a very real ceiling…and we reached it long ago. There is a ceiling in digital audio systems as well. But with high-resolution PCM at least the ceiling is much higher!
Contrary to my insistence that bogus audiophile accessories do nothing for spinning optical discs, there are indeed benefits to cleaning and demagnetizing the heads and tape path on your refurbished Technics 1500 iso loop tape deck. Keeping your machine in top condition will ensure that you get its optimum performance out of it. But you’re only getting back to the original specifications…you don’t get more than that. You never will.
So the question that Paul ponders in the opening minutes of his promotional video is just how much fidelity is “locked away” out of reach for mere mortal playback equipment in the spiral of bumps on a CD? He’s thinking in analog terms when analog thinking doesn’t apply. There is no special multiple upconversion of PCM to DSD scheme that is going to deliver more than 16-bits of potential dynamic range and frequencies up to around 20 kHz from a CD…ever.
The fact is that a good quality transport and DAC can deliver a completely accurate representation of the audio that was recorded, mixed and mastered by the production team responsible for the project. It may be possible to contour the fidelity with better clocks, higher grade preamp, amps and speakers but you’re only reshaping the essential audio fidelity that a compact disc can deliver and NOT finding additional “subtle cues” in the same original bits.
The level of over zealous hype and spewing of techno babble doesn’t benefit anyone that enjoys well-recorded music. It might however make you question the quality of your existing setup. And once you start doing that…there are lots of companies hoping you’ll open your wallet in their direction.
As I’ve said previously…the biggest improvement in the fidelity of your listening can be realized with the least expensive tweak. Just find better recordings and buy them. They’re out there.
I think you have got it right on this one. I think that Paul’s analog equipment is good. I like his phono preamp a lot. However, when he starts his sales pitch, I question his credibility not my system.
I’m going to write on their new DAC very soon. But I just can’t deal with unsubstantiated statements like, “The problem is the PCM decoding process itself: …most PCM playback processors mask some of the subtle cues in music.” If any format is masking the the subtle music cues in music, it’s DSD not PCM. He gives no evidence or justification for this false statement. There’s isn’t anything hidden in PCM…or covered up for that matter.
As a long time (1980s) audio nut and speaker building hobbyist I find it refreshing to read about reality versus the fiction that has spun long and hard in the audiophile world.
I have always been interested in remasters of the classics. Some of them really do sound better to me. Many have been compressed to meet the demands of the loudness war. Some seem just redone to death. I am surprised that the Beatles can have a “new” remaster of their entire catalogue every few years. Unfortunately, I think the sound quality of those reissues brick walled years ago. I just could not hear a qualitative difference in successive “remasters”. I would be the first to buy a 24/96 PCM flat master of Abbey Road – if only a modern recording system could be brought back in time…
Keep up the myth busting and showing the path to the future.
Actually, there is a process for getting more than 16 bits of dynamic range from a Redbook CD, called HDCD. Look for a very small, logo with those letters in a light, rounded, san serif font inside a rectangle with rounded corners.
The way I’ve seen it explained is that it repurposes a few of the least significant bits as flags to trigger dynamic range expansion in players that have the decoding logic for HDCD built in – like my Oppo BDP-93 and my old Denon 2910. It expands the dynamic range from 16 to 20 bits (in computer terms by half a byte, which I’ve seen called a “nibble.”) On players not equipped to decode it, it may add a bit of white noise, though I haven’t heard it.
Most of the HDCD disks I have are by Joni Mitchell, who applied that process to all of her CDs, and I have one by Denny Zeitlin and David Grisman called New River that bears no such labeling but does light up the HDCD indicator.
The increased dynamic range can be heard, and sounds very nice, enabling you to hear more layers in the music.
So you can get more than 16 bits of dynamic range on a CD, but not by using a Sharpie!
Phil, you’re right and I wrote about HDCD in a post many moons ago. Here’s the link: Article on HDCD
I thought if you wrote HDCD with Sharpie (has to be a green one of course) on the shiny side of the CD, it enhanced the dynamic range.
Also, I have my $2,000 copper wire demagnetizer that rids my system of time smear.
Thinking of opting in for the $6,000 one when it comes out because I hear it is supposed to be PCM.
Is this true?
Thanks in advance
I think you’re on to something.