Burn speed??? Does it matter?

 

Drew wrote: When Itunes asks you what speed you want to create an audio CD- does it matter what speed you choose? Will maximum speed vs. say, 8x speed create a slight difference in sound? Why does part of me feel that the slower you choose, the better the CD may sound? This probably sounds ludicrous.

Burn speed in itself cannot affect audio quality because the quality of the audio in the encoded files remains unchanged. What you get is difficulty in reading the digital data, causing the post-processing software/hardware to interpolate more of the missing data until such a point is reached that the data cannot be reconstructed and you get a drop-out. While this is annoying and can result in the disc skipping, glitching or sticking - the sound quality remains unchanged.

 

Faster burn speeds require the transport to spin the disc faster and the laser to switch on and off faster - this can cause the pits (digital "zeros") in the dye surface to become less well defined, resulting in difficulty in reading or misreading of the data. (for example a 1100011 code could be seen as either 1110011 or 1000011). However, manufactures of both the transport and the media would not specify either of them as being capable of achieving those speeds if they resulted in unreadable data.

 

mystic fred wrote: It is true - slower burn speeds are better for audio files, but picture files are unaffected - i have heard this from a number of IT technicians, though burning audio files onto a CD can eventually become unstable however slowly you burn them, recently i took my collection of 500 burned CD's to the dump as they were becoming unstable after about 8 or 10 years .

Degradation of CDRs is a known problem and they should not be used for archiving -  degradation of the aluminium coating due to chemical reaction with the bonding agents, UV degradation of the dyes used (the old "green" cyanine ones are particularly bad), attack of the polycarbonate layer due to stick-on labels and marker-pens, attack of the lacquer layer due to ingress of oxygen and air-borne polutants and micro-scratches on the surface diffusing the read-laser all result in giving CDRs a limited life-span. Glass pressed CDs and DVDs are less prone to this (but not immune) and are more reliable in the long term, but they also have limited life.

 

(see: http://www.clir.org/pubs/reports/pub121/sec4.html)

@mystic fred: If you say CDs become unstable after eight to ten years, does this happen just after they've been in use for that time, or does it also happen if they're just stored? Probably after use, but you never know?