At first glance, there should be no reason for loss of fidelity between an original disc and a CD-R copy. In practice, there are often reports of such degradation. For example, Philips reports at their WWW site in cddd3610e.pdf that you can expect the following differences at the analogue line output, with similar values for headphone.
| Line Out | On pressed CD | On recordable CD |
| Amplitude Linearity | 1.5 dB (20 Hz - 20 kHz) | 2.5 dB (20 Hz - 16 kHz) |
| S/N-ratio | 81 dB (84 dB A-wtg) | 80 dB (82 dB A-wtg) |
| Total Harmonic Distortion + Noise | 65 dB (1kHz) | 55 dB (1kHz) |
| Channel separation min. | 70 dB (20 kHz) min. | 65 dB (16 kHz) |
They also state - emphatically
Those numbers are pretty good, but why don't they match? Why is CD-R playback inferior to that from a pressed disc? I have no proof, but offer the following guess. If someone has information about it, please let me know.
The signal read from a CD-R is inferior to that from a pressed disc. Either the maximum brightness is less or the minimum blackness is brighter - or both. As we know, a layer of error correction is saved by using Mode 2 Form 2 for CD-DA. So we have a weaker signal and less correction, hence more errors. That means that the circuitry on the analogue side - the part that feeds line out and headphones - will be making more corrections. Those corrections will have exactly the kind of impact in the table. My guess is that Philips recognizes the losses and adjusts the circuitry so that it does not attempt to pass an inferior signal.
Regardless of why or how it happens, it's clear that Philips acknowledges that pressed discs deliver better performance on the analogue output - sound better - than recordables. Even though other manufacturers may not be explicit about it, you can bet that they, too, cannot deliver the same performance from recordable and pressed discs. Does that mean that the digital signal is better and that you will get better response from SPDIF or from DAE? Probably not; the cause is still there - errors in the read signal. The effects should be the same in the sense that there will be uncorrected extraction errors. It seems likely that some drives will have fewer than others, just as some do DAE faster or with fewer audible errors than others.
E-mail me at cdrecording@mrichter.com
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