The standard commercial record disc was 10 inches in size, made of shellac, and played at 78rpm (revolutions per minute) on a phonograph. Playing time was between three and four minutes per side, therefore each side contained one song. The materials caused limitations in fidelity (the accuracy with which the original sound is reproduced by recording and playback) which reduced the dynamic range, meaning bass instruments were hard to pick up. This was also the time of acoustical recording, in which sound is played into a large horn that is connected to a cutting stylus. This cuts grooves into the wax of a disc in response to the sound vibrations.
There are a number of “master pressings” in this collection. This refers to a pressing created from the master cut of a given recording directly from a microphone or recording horn. For collector’s these are extremely valuable, especially when considering the matrix and take numbers. A Matrix number is a combination of numbers and letters assigned by a record company to a master at the early stages of the recording process. It appears etched or stamped onto the disc near the label. Take numbers are of particular significance, since two or more versions of the same piece may have been recorded at the same session and may differ significantly.