[Niteshade]

To my knowledge there are four optical disk mediums:
1) CD
2) SACD
3) DVD
4) Blue-Ray DVD

Each one of these have a response that's 20-20,000hz or greater. Mostly greater. What makes the sound that we hear out of any one of these different in technical terms? I'm betting that it's dynamic range from what I have read. CD's start around 90db. Music doesn't seem to go much over 15db. Would you say a CD is actually overkill for most music? Are there differences other than frequency response and dynamic range?

Just after high school I purchased a HiFi VCR to transfer songs I had on cassette and reel to reel. It worked GREAT! I also tried transferring CD music to it and the results were perfect- no sound degradation. The HiFi tracks record in analog FM and the response was at least 20-20k. Barring possible tracking errors, what's the difference between a standard CD and a HiFi VCR? I never could hear one.

[opaqueice]

I don't know much about DVD or Blu-Ray audio, but a study was published in the Journal of the Audio Engineering Society recently http://www.aes.org/e-lib/browse.cfm?elib=14195 .  It found that not one of hundreds of listeners across years and several different high-end systems could distinguish between SACD and a 16 bit/44.1 kHz re-sampled version of SACD on music.  The only exception was a particular SACD which had a noise floor below -96dB (which apparently is rare) - on that one if you took a silent part of a track and cranked the volume you could hear the quantization noise of the 16/44 A to D. 

So that more or less settles the issue of whether SACD is audibly superior to CD as a standard (as opposed to whether studios mix SACDs better or differently than the CD versions, which they sometimes do). 

[ctviggen]

This is what that study says:

"The systems included expensive professional monitors and one high-end system with electrostatic loudspeakers and expensive components and cables."

They used a single high end system.  That's a completely useless study and doesn't "prove" anything (one must remember that studies -- no matter how good they are  -- don't prove anything).

[Niteshade]

I've seen CD players with tube preamps installed. Do the manufacturers install the tube preamp directly in back of the D-A converter with nothing in between? Seems to me that would be a way to get the shortest signal path and higher music quality.

Even $10.00 portable CD players don't produce quantization errors- so their sampling rate must be more than adequate. What they lack is a good preamp/amplifier system.

Hybrid amplification systems always intrigued me. Letting each technology do what it does best in a well unified architecture can't be a bad thing. 

[opaqueice]

They used a single high end system.

"High-end" is not very well-defined.  They used four systems, all with very good quality components.  IIRC three were professional monitoring systems (which are probably best suited for hearing these kinds of differences) and one was an "audiophile" system.

  That's a completely useless study and doesn't "prove" anything (one must remember that studies -- no matter how good they are  -- don't prove anything).

"Completely useless".  Wow - that's a peculiar thing to say. 

It's impossible to prove anything outside of pure mathematics, so of course it didn't prove anything (and no one said it did).  What it is possible to do is provide strong evidence for something.  For example, if you correctly identify a difference 10/10 times, it provides strong evidence for the hypothesis that you can hear it and weren't guessing.  If you correctly identify it 5/10 times, it provides strong evidence against the hypothesis that you can hear it.  That's it.

Anyway, I don't want to get into this argument, so this will be my last post on this.

[JoshK]

I've seen CD players with tube preamps installed. Do the manufacturers install the tube preamp directly in back of the D-A converter with nothing in between? Seems to me that would be a way to get the shortest signal path and higher music quality.

Even $10.00 portable CD players don't produce quantization errors- so their sampling rate must be more than adequate. What they lack is a good preamp/amplifier system.

Hybrid amplification systems always intrigued me. Letting each technology do what it does best in a well unified architecture can't be a bad thing. 

There are numerous ways in which this is done from what I've seen.  One common way to do the tube dac is the use the tube as the analog output stage of the DAC.  Take for example a sigma-delta dac, which are the majority case, it puts out a very small voltage output.  The tube stage acts to increase the gain and provide low impedance output.  So it really isn't a true line stage/preamp in the traditional sense although it isn't much different that one except for the amount of gain.

My non-scientific observations on SACD vs. CD was that not many SACDs were that superior sounding to a well mastered CD.  That mastering trumped format almost always.  However, I did have disks like Beck - Sea Changes where I feel the SACD provided a much quieter background and spacious feel than the CD of the same album.  I have it on both formats.  Could I correctly identify it in a double blind test?  Maybe, maybe not.  The effect is subtle. 

[BobM]

DAC's these days are all implemented fairly well, once you get past the NOS vs oversampling vs individual chip's. What I mean is, they are built and implemented good and usually, as a DAC board, leave little to be desired. The real changes involve algorythms.

What can be improved is the power supply and the analogue stage. That's where many DAC's show their differences and add their value IMHO.

Enjoy,
Bob