Hi Bink-
35mm film runs at 90 feet per minute, which works out to 18ips. IIRC the width of the optical track and limitations of the phototube and film grain led to a bandwidth spec of about 80Hz-3k.. The variable density soundtrack was a hissy beast, even with a 3k top end. I found a nitrate reel in storage at a theater I worked at while in highschool, and the head projectionist ran it for me... Noisy as it could be, and I got a demonstration of nitrate's combustion.
Magnetic tracks arrived in 1953 (CinemaScope 4 track stereo) and extended the bandwidth to 50Hz on the low end and 6k on the top end IIRC...
Magnetic heads wore quickly, and many smaller exhibitors went back to the variable area optical tracks rather than spend the money to relap or replace the mag heads.
Reproduction was also limited by the A-7s behind the screen and the 20-30 watt Altec tube amps that warmed the booth (along with the arc lamps). I'd imagine that any contemporary low end would send the amps well into clipping and blown rectifier tubes and launch cones as the required LF drops below resonance.
Nowadays the digital tracks are optical, too. Kids these days! For a close up look click here:
http://en.wikipedia.org/wiki/Image:35mm_film_audio_macro.jpgAudience expectations have changed, much has been done to meet those expectations with audio on silver-based imaging.
With the continual conversion to digital cinema, there are nagging questions about how to archive new digital content, and how to deal with "remastering" archived movies that are sitting down in a salt mine 40 miles from me... Maybe silver ain't so bad after all? Probably best left to a Basement discussion.
Thanks for the memory jog, Bink!
Tim Mc