Axiom Home Page Forums General Discussion Stereo How much difference does a good CD player make ??

Saturn,

Again - we know that any laser/transport can communicate a CD bitstream to a receiver (as I mentioned before - even the $30 CD-ROM drive in a computer is bit-perfect, if it wasn't - data would be corrupted).

So (1) any CD-P is capable of sending a perfect (or very nearly so) bitstream to a receiver. That's a given based on how well even cheap CD-ROM drives can deliver perfect data (even at 16x the speed of redbook audio CDs), which, mystique or no, is all that happens during a read of a CD and output to a digital out (TOS or SPDIF).

If your gear sounds different than these cheap CD-Ps, your gear must be sending a different bitstream than the cheap CD-P (which under (1) above, we proved was a perfect or near perfect signal).

Therefore, if your signal differs from the perfect signal, your equipment must be coloured.

Bren R.

I haven't made any further replies here because it's nearly impossible to intelligently discuss an audio topic with those who ignore well-established principles of audio engineering science and instead mindlessly repeat the mantra "Just trust your ears". However, an interesting side issue is the use of guitar amps to intentionally distort the sound and here engineer and physicist John Murphy discusses amps in general and in particular how a solid state device can be used to emulate more simply the "sound" desired with guitar amps.

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Personally, I wouldn't call NAD or Rotel mass market gear.

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I like them both (I actually like them both a lot!) but I would call them mass market also. Heck a lot of Rotels DVD players are nothing more then re-branded JVC's. NAD and Rotel make some very nice stuff and I don't think calling it mass market is a negative when put into the right perspective.

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I haven't made any further replies here because it's nearly impossible to intelligently discuss an audio topic with those who ignore well-established principles of audio engineering science

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Ah yes we all ignore science and the science types hide behind it. Anytime anybody disagrees with science, we get it force fed to us with nothing but contempt. Which of us is worse? Those that don't feel the need to scientifically justify what we are hearing or those that do? If it sounds good, it's all good regrdless of what science tells me.

There is an interesting point coming out in this thread :

Cheap CD players may be able to sound very good (drive mech notwithstanding) since all they are supposed to do is pass along a bitstream... but of course this only works if you are connected digitally.

If your cheap CD player has an analog feed to the receiver (hmmm, wondered what that connector on the back was for) then all bets are off -- although I guess one could argue that it's harder to cut corners and screw up the relatively simple CD electronics than it is to mess up the processing required on a DVD player.

I can see how the next argument in here is going to go, which is better for critical listening digital or analog?

Simple... Use digital if your DACs are better in your receiver (or seperate DAC if you have one) and analog if the CDP has better DACs. With digital, though, you have the added advantage of leaving it in digital format as long as possible, minimizing noise.

Dam, that was easy!.....and I think I even agree with you!

There are several unintended and problematic problems that occur in the conversion of digital data to analog signal. One is called "jitter" and remains a difficulty to this day. Jitter is measured in picoseconds, or trillionths of a second...yes, trillionths! Jitter occurs "when the distance between digital information, in time, is incorrect" (from Secrets of Home Theater and High Fidelity). When an "off" bit is followed by an "on" bit, and the "off" bit is read for even a tad too long a period of time, it crowds on to the time that the "on" bit would be normally read and confuses the interpretation.
This is a simplification of a very complicated factor, but regardless it is the timing of the data stream that is involved where jitter is concerned.
Many audio engineers feel jitter is not really an audible problem and dismiss it as unimportant. However, most new machines are being designed with low jitter in mind. A very common technique to reduce jitter is to store the digital data from the CD in a memory buffer where it can be reclocked and fed to the DAC in precise sequence. Vibration can also adversely affect CD player performance by causing jitter. To help eliminate vibration, use a quality damped housing.
The other big issue is the fact that it's difficult to accurately portray a complex audio signal in just 44,100 samples of 16-bits per second. DVDs we use today for video use 192,000 samples per second and produce 24-bit words of data! This is dramatically more data being recorded than that used in CDs. As such, the quality of the data is substantially better, which translates into noticeably better sound. DVD-A and SACD have up to 24 bit words collected at 192kHz to begin with, and the sound quality is spectacular.
Its very common in todays CD players to use something called "upsampling." Because modern DACs can handle the higher sampling rates and longer word lengths, some players have a chip that "upsamples" the data to higher rates. The upsampler tries to "interpolate" what the samples would have been if the original music had been sampled at the higher rate. The results are often quite good, but of course, nothing is better than having the actual music samples. Regardless of the tools used to defeat jitter or lack of samples, sound quality is the ultimate basis for a final decision on whether to purchase a particular CD player.
If you can ask for the specification on this if it is available when considering your purchase, do so. Seek the player with the lowest jitter. Jitter rates of 30 picoseconds or less are found in top quality CD players. CD players with high jitter can sound harsh and also lose fine detail, including the upper natural harmonics.

Oops... jitter. Again, a minor problem for almost all players... going back to a computer CD-ROM being the worst possible permutation of a laser and transport - does anyone here "rip" wav files from CDs?

I've done a lot of it, and received maybe 3 jitter warnings in the last 6 years... that's 3 samples (1/15,000 of a second total) in over 60 hours worth of music.

Hmm... I guess it's a bigger deal if, say, your CD-P is on top of your sub maybe?

Bren R.