Does a CD Transport need to be HDCD ALSO?

I could be wrong but I'm pretty sure it's the filter in the DAC that does it,so you should be ok....

It's all done with the DAC by employing a special decoder chip/filter. Pacific Microsonics makes one if not all of them. When HDCD's first came out the contract for HDCD playback required the DAC/CD player designer to attenuate the gain on normal CD's. It may still. This guarantees that HDCD's played on HDCD enabled units will always sound louder than normal ones. It's quite a gimmick.

My Theta Data Basic II transport sometimes has trouble initializing HDCD's on the first try, but always gets it on the second. If there's such a thing as a HDCD transport I've never run across one.

the transport just reads the bits, whether hdcd or not, and sends them off to the internal or external dac. if an hdcd code is present on the disc and the dac/filter is capable of recognizing the embedded hdcd code in the bit-stream, then the dac/filter will apply the appropriate noise-shaping.

there is more than one level of hdcd encodeing that the hdcd standard allows. there is a demo disc with the same music encoded with different levels of hdcd encoding.

in other words, all transports will read hdcd discs and send the bits containing the hdcd information, but only certain dac/filters can recognize the embedded signal.

i hope this helps

All of the "bit decoding" is done by the DAC. I use the ML 37 transport and 360S DAC, and the HDCD reading is done by the DAC alone. I've also used Sony and Pioneer CD players as transports for the 360S and it had no problem reading the HDCD info. Good Luck. Craig

This has caused some confusion, especially since some of the early Cal Audio Labs Delta Transports specifically stated HD-CD Transport right on the front of it. CAL meant that it was a "high definition" i.e. "high resolution" CD transport and not that it could specifically decode HDCD discs. When Pacific Microsonics came out with HDCD encoding, CAL was forced to remove this from their faceplates. That is how you can tell the age on some CAL Delta's.

If i remember correctly, i think that Microsoft bought the rights to the HDCD format. Does anybody know what they are doing or plan to do with this ? Sean
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One nice feature of the Levinson No.36 Dac is that you can defeat the attenuation of non-HDCD discs.
Great sounding DAC!!!

The one requirement on the transport is that the output bitstream be an exact copy of the data on the disc.

Some transports (Wadia 270, and at least one ML model I can't remember) perform resolution enhancement by dithering the orginal data on the disc to generate a new bitstream with more bits per sample (24 in the Wadia's case).

On these transports resolution enhancement must be switched off to retain the HDCD encoding in the output bitstream.

Similarly any resolution enhancing digital processor (Genesis Digital Lens, AA DTI Pro family, etc) in the signal chain must have enhancement turned off.

Good points Ghostrider. Thanks for taking ALL of the factors into consideration. Some of the "extra's" are sometimes easy to overlook. Sean
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I really appreciate the help you all have given me. I now THINK I understand what it all means. The main reason I was confused is I saw a transport somewhere that said HDCD.

Thanks again to everyone.
Tom

Don't forget that many discs are not identified as having HDCD encoding, but do have the sub-code embedded within.

HDCD is a marked improvement over non-encoded discs and forces me to use vinyl, when available, for the source material instead of non-encoded music.

Still staying away from DVD-A or SACD until they settle their production plans.