Trying to stay abreast of today's modern technology, I am reading this book. In chapter VIII, the author covers the improvements in recordings made on vinylite records, with increased frequency ranges - and corresponding improvements in phonograph pickups.
The linked article states, "High fidelity is the faithful electromechanical reproduction of an original musical performance. Among the necessary ingredients of high fidelity are wide frequency response (the ability to capture and recreate tones from deep bass notes to high treble) and wide dynamic range (a breadth of sound levels from thunderous fortissimos to hushed pianissimos). Noise that is not part of the music, such as the hiss endemic in traditional analog tape recording, must be kept to a minimum, and distortion—inaccuracy that changes the shape of musical wave forms and consequently their sound—must be restricted to near inaudibility."
Back to the book - and the records themselves, the book says - there are about 100 groves per inch on a standard 78 RPM record and 325 groves per inch on microgroove 33 1/3 RPM records. Fascinating stuff, huh?