Analog was the only form of signal processing for many
years.
Several methods of analog recording have come and
passed
Wax cylinders and disks
Vinyl Records
Magnetic Tape
8 tracks
Cassettes
Analog typically involves some type of distortion. This is often considered as warmth by analog purists
RIAA preamp for records
Saturation of magnetic tape
The main problem is that analog is noisy (and distorted,
etc). A certain amount of this noise and distortion is added
with each additional
generation. Digital does not have this
problem.