Until the advent of digital audio, sound was recorded, transmitted and modified with analogue tools.  The first representations weremechanical;  changes in air pressure modified the motion of a stylus which carved the analogue of the sound wave into wax or some other soft substance. Playback was the reverse: a stylus transmitted the wax etchings to a diaphragm and amplifying horn. Soon after elctromechanical systems were used. Primary among these was the use of magnetism to store and playback signals from metal wire and later, magnetic tape. Still found today in audio and video cassette machines, DAT recorders, data recorders, etc.
All analogue systems, as exemplified in these early devices face similar problems: 

 - noise inherent in the recording medium
- difficulties with capturing high frequency signals
(due to inertia, mass, etc.)
- noise which occurs during duplication or transmission
- storage systems prone to deterioration
- limits to dynamic range
-recording and playback dependent upon mechanical
systems and in particular, signal reflects speed fluctuations 
in thos systems

Advantages included:
- no loss of information due to to sampling
- damaged media can still reproduce signal;
albeit in a degraded form
- robust and more easily repaired in the field
- may or may not sound better