Myths And Misconceptions About CD Players And DACs
Article By Liudas Motekaitis
In the 1980's, people spoke of experiencing "no air" and "aggression" while listening to digital recordings. Today we understand the principles which are fundamental to this phenomenon, we name it Jitter, we test it, calculate it and dress it with numbers, systemize it and describe it entirely. Jitter has always been and still is the worst enemy of the digital audio format. And today it is understood.
Fact: Digital audio data is 'just' 0's and 1's. There may be many formats (.wav, .aif, CD-audio) but the information is still digital. There is no loss during format conversion, provided the formats don't utilize compression.
Fact: Copying CD's (if they aren't damaged physically) is a lossless procedure. You can extract CD-audio with your computer and generate a file on your hard disk. Compare this file with the file created when you extract the same audio using a $30,000 player, the resulting two files are identical.
The question which naturally arises out of this paradox is: why does the $30,000 player sound better?
Before we answer that question, let us first understand that at the Digital Out of a $100 CD-player we have the same 1's and 0's as we do in the $30,000 player. The only difference is in the Jitter content. Jitter only means that the data (the 1's and the 0's) is not perfectly time-aligned, but is transmitted either slightly earlier or later than it should be in the ideal case. However, this time flaw is not as great as to cause a digital error (data fallout).
Now if you know that, then you must ask: so why does one CD-transport cost much more than another? Ah, Jitter. The cheap ones shake and the expensive ones don't.
Well, that's true. The entire audio business of CD transports and DACs is built on the totally backward setup of the CD player containing the Master Clock and the DAC being the Slave. This results in the entire
palette of innovations to lessen Jitter, starting from air drives to expensive digital cable technologies with complex math to reduce line-induced Jitter, to very carefully filtered power supplies, to all sorts of very necessary things when you want to achieve the least possible Jitter. So we have the worst possible digital scenario bringing in the most possible amount of money, because it is extremely difficult to annihilate Jitter when the CD player is the Master Clock. If you're looking for quality, this is stupid, to say the least!
The whole setup should be different. As is the standard case in any pro-audio studio, it is always the playing device, the DAC, which is the Master Clock. The clock is located right next to the converter chips. That way, no line induced Jitter can appear. This clock signal is then taken from the DAC device and is used as the clock input of the signal source device, say the computer, the DAT player, or the CD player. Yes, in that setup, the CD player is receiving a more jittered clock than the DAC is, but that doesn't matter, because the DAC is doing the audio playing. When the Jittered audio signal arrives at the DAC, it is quantized into place temporally and is then played, in perfect synch with the clock oscillator, which is right next to it.
But oh! In that case, you can use a $100 CD-player with a very poor power supply, a digital cable made from your average household extension cord, and still get a better sound than you'd be getting if you spent $30,000 on the best transport and digital cable! Yes, ladies and gentlemen, this is the naked, uncensored, plain truth about CD players and DACs. Their Master/Slave relationship is BACKWARDS and their prices therefore HIGH.
If you don't believe this, then all you need to do is record digitally your favorite tune from a $100 CD player into your computer (provided you have a soundcard and software that doesn't add yet more lies into the equation, which is often the case, so beware!) Then borrow the most expensive CD transport you can get your hands on and repeat the experiment. The resulting
sound files aren't just similar, they are identical!
But the $30,000 player sounds better! How do you get them to sound the same? You only need to slave the transports to a DAC in Digital Master Mode. That's it. Identical sound, guaranteed. The least possible Jitter. The least loss.
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