High Definition CD or HDCD - What is it exactly?

HDCD is a brilliant scheme which encodes extra audio information in the dithering signal present on all Redbook CDs.

The dither is put there to increase the number of bits in the lowest-level signals and thus improve resolution. On normal CDs it contains no signal information. The HDCD dither looks the same as the regular kind to a normal CD player. However to one equipped with a decoding chip, it delivers its information. This information can improve dynamic range, HF resolution and more.

The HDCD decoder chip must include very precise filters. These filters are sometimes better than those found on ordinary Redbook players. Consequently a CD player equipped with an HDCD chip may do a better job than a standard player on normal, non-HDCD-encoded CDs.

The only downside to playing a non-HDCD disc on a player with an HDCD chip is a slightly reduced volume level. Compensate by turning the volume up about 6 dB.

I own no stock in Microsoft, now the owner of HDCD. I just think the system, created by Pflash Pflaumer and Keith O. Johnson, is very elegant. It really can improve CD sound, too. Just too bad it's not in wider use for Redbook material. However if you have an HDCD-equipped player, you may get a surprise sometimes. With the occasional disc, the HDCD light comes on to show the extra info is there, even when there is no mention of HDCD on the disc wrapper.

The HDCD encoding is embedded in the audio data on the disc (low order bit modulation) and should survive a disc copy. If the CEC player failed to recognize the copy as an HDCD it means that your copy software did not make a bit-for-bit copy of the original disc.

Microsoft seems to have dropped this, but many performers insist of recording in HDCD. I have had two universal players that decode it properly. The first was the Lindemann 680D. I was shocked at the improved performance. My Exemplar/Denons also show a light with HDCD, but the performance jump is not as great.

If you can get the capability to play such disks as HDCD, go for it.

I have made copies of HDCD that do play as HDCDs.

Well thank God for Tobias (especially), Ghost, and Tbg -- y'all saved me from a lot of typing ;--) So I'll just add a couple of things:

First, I highly recommend Keith Johnson's newly ressurected Reference Recordings site: www.referencerecordings.com for both incredible HDCD recordings and info/links. As most of you know he co-invented HDCD.

Second, regarding HDCD decoding: The new(er) Levinson DACs and CDPs use a proprietary Levinson HDCD decoding chip, not the ones normally provided as OEM parts to most manufacturers. However, software-based DACs, such as my Wadia 27 and some others, do a perfectly marvelous job of decoding HDCDs. And even though you don't get the HDCD indicator light, some folks (like Steve Huntley @ GNSC) feel the Wadias do a better job than the HDCD implemented DACs.

I'll say one thing, I can usually tell (blind) if an unfamiliar disc is an HDCD or an XRCD (but not which is which ;--) Let's not do it here, but I'm going to start a thread for listing favorite HDCD/XRCD titles (if no one's done it yet ;--)

BTW, I agree that any bit-for-bit burner should copy an HDCD or an XRCD faithfully.

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I think Dusty Vawter of Channel Islands Audio eschews HDCD decoding in his DACS because the HDCD D-A chips don't sound as good as he wants them too.
I don't think I'm mis-paraphrasing him - Just another side of the coin to consider.
My HDCDs are the best sounding ones I have, on my compatable player.