On Wed, 25 Oct 2006 17:35:54 -0700, DeserTBoB
wrote:

Just from those number you can see how prerecorded RTR tapes decreased
in quality from those high quality Westminster, Columbia and Omega 2
tracks of the mid-'50s to the comparaitvely lousy 3¾ IPS 4 track of
later days. This is why original 2 track dupes from the '50s, even
though they've suffered the vagaries of time (brittleness and
self-magnetization) are prized by collectors, while the big hub 3¾
dupes are pretty cheap. snip

But beware of 2 track RTRs from the '50s! Many were on acetate
backing and are VERY fragile when used on a "real" deck!