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?
I can't answer your specific question. I have a Naim CD555. It will play the Redbook layer of SACD. Tho, when I play a HDCD the display lights up "HDCD".
HDCD is recorded with least significant bit switching dynamics of remaining 15 bits. Standard CDP will read only 15 bits with noise on bit 16 plus weird dynamics - am I missing something?
Your post raises some interesting concerns. I never knew about the attenuation. Always wanted a HDCD player for those Live Dead discs. Hope someone with tech knowledge will chime in on the facts here.
Live Dead is an oxymoron. I had to ad that observation and realize that is of no help.
I still use my HDCD Adcom DA700 and have no idea about wht if any bad things it 'could' do to non HDCD discs.
I CAN say it equaled a new Bryston DAC and I returned the Wonder (Rave reviews)Bryston DAC as it's $2,200 cost for doing nothing better than my old DAC??
So clearly my Adcom DAc playing normal CDs was doing NOTHING different to ordinary non=HDCD discs.. As the two DACs sounded identical to me even with many attempts to find some differences.

So for me, and my Adcom HDCD capable DAC, there was NO differnces comparedto a 10 year newer, more than twice the price rave review DAC.

(Used with Bryston BP-26 pre, Bryston 4B-SST2 amp, Magnepan 3.6 speakers..)

So.. i have to question the 'theory' aspect of the op comments. As in practice NO attenuation is apparent with the employment of a HDCD chip (even on non-HDCD CDs.)

((Maybe he read it someplace??)) Did the op actually HEAR this and thus can comment, or is this just somme sort of "I read this once and..."?
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.
HDCD has belonged to Microsoft for a while now. Have no idea what they're up to with the technology. Maybe just chucked it in the back room. Why they bought it I don't know.
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.
For those who are going to PC audio, there is software, such as dBpoweramp, that will do the 16 bit to 20 bit conversion for HDCDs. It then pads it with zeros to 24 bits. You just check a box when you do the rip.
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?
Interesting post Elizabeth. I use an EAD 7000Mk3 DAC which decodes HDCD. I think it still competes well with the newer DAC's of today. Recently did an AB with the new Benchmark DAC...EAD was FAR more analog sounding. When I play any of the Ref Recordings HDCD's on the EAD, it's still up there with some of the best I have heard.
The biggest problem with HDCD enabled DAC's and CDP's is that the the PM chips are not that great sonically (sorry Poetcatullus) so much so that Mark Levinson (the brand) got special permission from PM to manufacture their own HDCD chips to incorporate in their players.

One non-PM solution for great sound from both Redbook and HDCD disks is (are) Wadia equipment. The reason is that Wadia's D to A processing is based on software decoding rather than 'brick-wall' filter chips. Therefore, all the information on a HDCD disk is read and fully processed (doesn't require the special PM chip) and HDCD's sound fantastic on Wadia equipment. Of course you don't get the little 'HDCD' indicator light on the front panel, but you can sure hear the difference!

So I was interested to hear about the 'attenuation' issue, because on my Wadia equipment, HDCD's sound louder if anything -- although that might just be a subjective response on my part to the improved quality of HDCD disks. I don't go out of my way to collect them, but I'm always thrilled when an artist/performer I like chooses to release their music on HDCD's. And some have been doing it for a long time (Chris Isaak comes to mind.) I know this is a bit off topic, but speaking of artists who seek to use interesting or sophisticated technology, I just discovered that quite a few of Lou Reed's earlier albums were recorded binaurally! The joke was definitely on me, because I've had those albums since they were released, and it never dawned on me until I was searching eBay for binaural recordings and they all came up!~
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?
HDCD was developed by PM. The initial PMD100 decoder/digital filter chip was certainly one of the best at that time. PMD200 was the successor and based on Motorola 24bit DSP, so it was superior to anything else available. Then when more and more audio manufacturers started using powerful 24 and 32 bit DSPs from Motorola, Analog Devices, TI, Cirrus Logic, etc. to use in their products, the HDCD algorithm was something already available as a programming software to existing DSPs used for audio, so if a certain manufacturers like to offer such feature, they simply pay the licensing fees.
Bottom line, if you see "HDCD" light on a recent digital player, it means that it has a powerful DSP inside that takes care of it, usually in 32 bit precision. So it is the best HDCD processing you can get.

Hope this helps!
Alex Peychev
One reason for reducing the volume on non HDCD tracks was to deal with CDs that contained both HDCD and regular CD tracks.

The Oppo players implement HDCD and actually allow you to turn it on and off. Their HDCD implementation used to use a customized version of a Mediatek chip. I believe they are still using Mediatek for HDCD with the 103/105, but I have not seen anything that confirms that.

It is my understanding that the Oppo does not change the volume for regular CDs, but I have not tried it.

You might check with Oppo on the details. They are usually pretty good about answering this type of question.
I've played HDCD recordings, especially the Reference recordings Stravinsky and Big Band Basie, many time with my Oppo 95 and noticed no loudness difference compared to CDs. Those two recordings are superb. On a good setup, Big Band Basie has a great sense of air and openness. At one point I thought I'd simplify by replacing a Proceed PAV and Amp 2 with a Sony AVR. That sense of air when I played Big Band Basie deflated. The Sony AVR was gone soon thereafter.

You mention that you have a few hundred albums. If you are judging only by the HDCD logo showing on the packaging that's one thing. But in reality, I would be surprised if you only had 6 cd's with HDCD encoding. I myself have a surprising number where there is no logo at all, but the ''light'' confirming HDCD status does come on. Neil Young is pretty well-known to have HDCD encoding.
Sorry, meaning cd's not albums of course !
Sonic, I know this isn't scientific, but what percentage of disks that indicate HDCD when played, would you say are unmarked 'HDCD' on the disk itself, or the case?

It's interesting to speculate why a performer would keep it a secret (especially Neil Young!) unless MS wanted an exorbitant fee to use the logo, and the performer figured 'screw you', my fans will find out on their own ;~)
There is some good information on HDCD on Goodwin's website, including links to original papers on the subject.

Information on HDCD

There is a also a very comprehensive list of HDCD CDs there.


According to the FAQ on that site the reason some HDCDs do not have the HDCD label on the case was that the artwork was completely prior to the mastering process.

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!
Oppo customer service is truly outstanding.
I got into cd's a little late but eventually discovered HDCD
more or less by accident...I noticed Joni Mitchell,Blue I
think,sounded pretty good by comparison to most other cd's in my small collection,and noticed also the HDCD logo on the back.This led me to look for that logo when I bought cd's,
as someone else mentioned ..Grateful Dead/Dicks Picks,other
Joni Mitchel,etc..So I replaced my pretty much brand new Yamaha cdp with a Harman kardon 8380/HDCD.Not hi-end but an
upgrade to my ears.I have an older Leonard Cohen cd,Songs of
Leonard Cohen,not HDCD, that was pretty rough on the Yamaha but really smoothed out on the HK so its positive affect on non-HDCD
cd's was a little gravy.Anyway I eventually hooked a Micromega Mydac into the system and didn't
really think of the HDCD one way or the other until somewhere along the
line I wondered if it was being passed along.Did alot of digging
and the consensus,though not unanimous,was that unless the external dac was HDCD,then the HDCD from the Harman -Kardon was
negated.At first I was bummed but the Mydac was a clear
improvement to my ears so I got over it.But no, the story is not over..I saw a Heed Obelisk DT transport here on Agon which reads HDCD,so it
caught my eye,but I am now confused again about HDCD and how and
where it gets de-coded.I just emailed Heed Audio to see if they could
clear this up for me.I came across this thread while looking up
HDCD and because it was the most recent posting I figured I'd wake
up ala RIP Van Winkle and see if anyone is still interested.
And apologies for the long wind of this but I tried to keep it as
short as possible.The long version is available upon request.