If you’re an audio hardware geek and happen to be flying on United Airlines in or out of San Franciscio, allow a few extra minutes to see The History of Audio exhibit in the United concourse at SFO. I was shocked that I actually remembered so much of this gear and going back so far. The exhibit emphasizes sound for motion pictures and seems to have more than its share of gear from Dolby, but there are some real classics such as the Ampex 300 quarter-inch tape machine and the marvelous Nagra IV. (I used to own a III and  IV for location film work.) The exhibits at SFO are always fascinating and it almost seems like a waste to put them there since so few people have a chance to linger.