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In Reply to: RE: Read my lips. posted by The Sound Guy on August 19, 2009 at 07:14:31:
>> At least one DVD-A (Pet Sounds) was supposedly mastered with the HDCD flag! <<
That's because ANY signal coming out of the HDCD encoder box had the flag encoded. It was just a way of advertising their process.
>> So if dynamic filtering was never implemented, was HDCD for hirez audio/DVD-A just BS? <<
The biggest problem was that there were two distinct parts to Pacific Microsonics -- a crack team of brilliant engineers, and then a sleazy marketing team full of scammers. So you had some great products with a lot of misinformation and marketing bull spread around.
For example, they had an HDCD sampler disc that was give away to thousands of people at one CES. There were some "comparison" tracks that were supposed to let you hear how good HDCD was. But it wasn't a fair comparison at all. They could have done that by using their A/D converter and then recording two otherwise identical tracks, one with the HDCD features turned on and the other with the HDCD features turned off.
But instead, they cheated.
The "non-HDCD" tracks were made with a Sony 1630 A/D converter (I think that was the model number). For many years it was the only converter available to studios. It sounded like garbage and was one of the reasons that CD had such a bad sonic reputation in the early years. Then they compared that to the "HDCD" tracks that were made with a Keith Johnson-designed converter with ultra-low jitter clocks, all discrete analog circuitry, super high quality components, et cetera, et cetera.
Well of course the "HDCD" tracks sounded miles better. That's like saying that an Audio Rsearch Ref 3 preamp and Ref 110 power amp sounds better than a Sony receiver! But that had nothing to do with the actual HDCD scheme of compansion, which is mostly what HDCD was.
Then there was the whole "gain scaling" scam whereby an HDCD disc was played 6 dB louder than a normal disc. Everyone caught on to that one quickly and most of the manufacturers include easy ways for the end-user to defeat the "gain scaling" feature that Pacific Microsonics mandated.
Back to your question. Is there any reason to perform compansion when you have 24 bits? I don't think so!
The first thing to remember is that ANY signal sent through their machine will have the LSB's altered so that the HDCD light comes on. Basically this is just an advertisement and not an indication that anything needs to be decoded. In fact in the Operator's Manual for the Model Two encoder (the last one ever made), it specifically says that low-level extension and peak extend ONLY apply to 16-bit signals. So that doesn't leave much for the machine to do on a high-res release...
The A/D converter was better than anything else available at the time. It took nearly ten years for there to be a lot of other A/D converters that sounded really good (Apogee, Lavry, et cetera). And they *did* have the two dynamic filters during record, at least at 44.1 kHz. But there was no reason to use two filters for high sample rates.
They also applied proper dithering to their signals. Again, this is important for 16-bit data, but pretty meaningless for 24-bit data, as the noise from the analog circuits are far greater than any dither would be.
The bottom line is that a high-res "HDCD" recording would sound good (and turn on the HDCD light!) simply because the encoder was a good one, but not because of any specific HDCD features.
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Follow Ups
- More Pacific Microsonics marketing bull - Charles Hansen 19:50:32 08/19/09 (2)
- RE: More Pacific Microsonics marketing bull - The Sound Guy 11:38:58 08/21/09 (1)
- Your linked post is excellent - Charles Hansen 21:53:26 08/21/09 (0)
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