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On 650 MB CDs  (February 2018)

 

Until about six or seven years ago, the only CD-Rs I had come across were 700 MB (80 minutes), and I naively assumed that this was the standard size.  But when purchasing gold archival CDs for the first time, I was somewhat surprised that they were only 650 MB (74 minutes).  As it turned out, both sizes worked fine for me as music CDs and for data storage, and I didn’t perseverate over the difference.

 

That changed when I gave a 700 MB music CD to a friend, and she reported that her CD player wouldn’t recognize it, though it worked fine in her car.  Since providing unplayable CDs would be bad for business and suspecting that CD capacity might be the underlying cause, I started digging into the issue.  Here’s what I found.

 

When music CDs were introduced in 1982, the published standard was 650 MB (which in my mind explained why the archival CDs I bought came only in that size).  However, the music industry drifted away from this standard within just a few years, using 700 MB CDs instead.  The extra capacity was gained by reducing the space between data tracks.  Modern players handle both types of discs by loosening tolerances for where to locate adjacent data tracks, but CD players manufactured before the mid-1980s (like my friend’s player) cannot read the narrower pitch data tracks of 700 MB CDs. 

 

The shift to 700 MB CDs has been so pervasive that 650 MB CDs have all but disappeared from the marketplace.  Occasionally, though rarely, vendor web sites may display a warning that a commercial music CD may not be readable by older players, albeit in small print and not particularly prominent in the web page layout.  When discussing CD options with customers.  I always ask the age of their CD player, and if it predates 1990, I’ll recommend 650 MB silver or gold archival CDs.  If questions remain, we’ll test the player with a 700 MB commercial music CD to ensure that the player can read it.

CD roll call.JPG

Left to right:  700 MB commercial-grade, 650 MB gold archival, and 650 MB silver CD-Rs

 

Update:  Since this article was written and posted close to four years ago, 650 MB CD-Rs have come closer to disappearing from the marketplace altogether, and the manufacturer and supplier I have trusted and used for the past five years is no longer making them.  Although they’re not commonly requested, I have burned over 100 gold archival CDs for customers, so I want to continue offering them.  Fortunately, I found a comparable brand from a new source.

 

While 650 MB CDs are available, their prices have increased, due both to ever decreasing demand and the pandemic’s effect on availability of materials, labor, and shipping.  Since silver and gold archival CDs are available in the 700 MB size, are equivalent in quality to the 650 MB CDs, have 14% greater capacity, and are less expensive, my intent is to provide 700 MB CDs for most customers requesting archival CDs—those who do not need to worry about older CD players.  I will keep my remaining 650 MB CDs in reserve for customers who anticipate the possibility of playing them on a “legacy” CD player.

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