Since our industry is fairly young (saying it started in the late 60's-for large scale shows)-there are people still alive who can contribute.
For the young guys-it was A LOT HARDER back then. With power transfer (not voltage transfer like now)-termination of inputs/outputs-mostly unbalanced lines-low power-lots of electronic failures (a lot of shows had a repairman on site with a bench to fix the gear that broke during the show), lack of standard connectors (although we are headed that way again in the digital relm) and so forth and so on.
When you look at some of the major acts and what type/size systems they used-it is quite small by todays standards. For example Cream toured with a 500 watt system-Woodstock used a 10Kw system-Deep Purple used a 10Kw system-Grand Funk used a 14Kw system and so forth. Now those wattages are barely a decent monitor rig-let alone a PA for a large crowd. And lots of medium sized acts used 1 or 2 Shure Vocal Masters-with 100 watts each!
Thank you for starting this-it should be quite interesting.
Things were harder, but there was less complaining about how tough it was, that was just the way it was.
On my first show as a partner with a "professional" sound company, Eclipse Concert Systems (AKA "Collapse Concert Systems"), I was instructed the first thing out of the truck was the tool box, and I should plug in the soldering iron so it would be ready for immediate use..
While my partners and stagehands assembled the system, I was busy using various spare parts and cutting up short XLR cords to make several microphone "Y" cords needed to cover Taj Mahal's input list, many channels more than our console.
After a few years, I struck out on my own starting a company called Southern Thunder Sound, and built a system that falls just on the tail end of Doug's 1979 cut off, pictured below with the “Enterprise”, a 24’ straight truck that was owned by Jefferson Starship, then the band Heartsfeild, then myself.
Many of the components from that system are still in use in various places around the upper mid west.
Most of the major systems at that time were DIY, note the Terry Hanley intercom in the ”Road System Inventory”.
The end of the 1970’s heralded a change from large, ultra efficient horn systems to more dense pack systems that used double (or more) the amplifier power but only required half the truck space.
Still using horn loaded cabinets, the STS/Welter Systems of 1981 were equal in output to the 1979 system using half the space. By 1987, speaker size was 1/3, which left more room for (relatively) light weight lighting equipment. This helped, as the weight density of speaker systems was now enough to make any truck legally overweight if completely filled with sound only.
The Enterprise on occasion was almost double legal capacity, we learned the routes required to avoid weigh stations.
Now my 2005 system can fit in a 5x8 trailer and equal the output (except in the mid bass/low mid frequencies) of the 1979 24' truck filling system.
Of course, people are used to systems much louder than in the "olden days", car subs have more power than concert systems used back then.