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HDCD Decoding ?

Recently, I have noticed that the specifications for CD players sometimes mention that they are compatible with HDCD CDs. I thought that HDCD died about ten years ago. But HDCD CDs have always been playable on any CD players; albeit not all CD players would decode the HDCD formatting because that required a special digital filter from Pacific Microsonics.

Several years ago, when HDCD first appeared, Pacific Microsonics required that anyone licensed to use their HDCD filter had to install automatic attenuation in their players for ALL non-HDCD discs. This was not necessarily a good thing.

When a 21st century CD player will read HDCD discs, it may or may not perform the automatic change in volume as a result. The net impact in older HDCD players was that all normal (non-HDCD) discs were attenuated. I own a few hundred CDs and only about 6 of them are HDCD. I expect that now in the year 2013, this is no longer a problem regarding the Pacific Microsonics HDCD filter. My guess is that current players are not using a Pacific Microsonics filter.

Perhaps "compatible with" is simply a reminder that the CD player will play the older HDCDs as regular CDs?

What says the group mind?
poetcatullus

Showing 5 responses by poetcatullus

poetcatullus OP
53 posts
 
So, how are we to discover what HDCD means and how it is implemented in a 21st century CD player? I have emailed one manufacturer about this but have not heard back from them yet. They may need to consult one of their older engineers who was on the job when this all started. Was that sometime in the early 1990s?
poetcatullus OP
53 posts
 
This issue about which I raise concerns was well-known at the time and mentioned in Stereophile every time they reviewed a piece of equipment with HDCD capability. They generally made a point of praising the manufacturers who chose to implement the attenuation (required by the Pacific Microsonics HDCD license agreement) in the ANALOG domain rather than in the DIGITAL domain by simply cutting off a bit (thereby "punishing" all the normal CDs in ones collection for the benefit of the HDCDs).

There were certain pieces of gear where one could contact the manufacturer directly after purchase and they would accommodate the purchaser by telling them how to open up the unit and move a jumper, thereby undoing the compromise to their regular CD collection by reversing the attenuation and having all CDs play at their natural volume levels.
poetcatullus OP
53 posts
 
Excellent point, Rja!

I am seeing current models of CD (and DVD, etc.) players mentioning that they are compatible with HDCD CDs. This is what sparked my question(s) and caused me to start this thread. I only own a few HDCD CDs, but a few hundred regular CDs. I want to be certain that any player I purchase will not compromise the sound of my CD collection in favor of the HDCD discs.

Please allow me to emphasize the following: The aforementioned attenuation was never necessary to help HDCDs sound their best. The attenuation was done because HDCDs are naturally slightly lower in sound volume than standard CDs. So why not simply adjust the volume and leave the regular CDs alone?

Because: When Pacific Microsonics first implemented HDCD, they were afraid that the lower volume might cause a perceived (but imaginary) inferiority of HDCDs. So, they made it part of their license agreement that the devices using their HDCD digital filter (which was an excellent filter) would automatically lower the volume of all standard CDs as a means of leveling the playing field. This was often done by throwing away one of the bits of information from the standard CDs playback.
poetcatullus OP
53 posts
 
Yes indeed, Nsgarch!

I agree that the original PM chips were not necessarily all that wonderful after all. And I fully recognise that in the price/quality category of Levinson and Wadia, HDCD can be implemented without compromise, either to the HDCD discs or regular CDs.

This takes us back to the original issue. If I see a current mid-priced CD player that includes HDCD decoding and an HDCD indicator light, without knowing what process the manufaturer is using, how can I know that said player is not going to compromise my regular CDs (either intentionally or by default) with their particular HDCD implementation. Is the old attenuation practice from the 1990s even used today at all?
poetcatullus OP
53 posts
 

Good news!

I emailed Oppo directly and sent them the link to this thread. Here is their response (which was virtually instantaneous):

"There is no attenuation for Red Book CD. When playing a HDCD the player will decode the HDCD from 16-bit to 20-bit then expand to 24-bit word length. CD and HDCD is still processed at 0dB reference, with extended HDCD done at -6dB to allow for the expanded dynamic range."

In a follow-up email they verified that the concern that started this thread is obsolete and that current HDCD capable players no longer attenuate standard CDs as they had done back when it all started almost 20 years ago.

I am grateful that we can now all move on and enjoy the music!
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