I was going through my souvenirs and scrapbook last night and found some pictures of me in 1969 running the general session sound for NAVA- The National Audio Visual Association. That group morphed into INFOCOMM of today.
In the general session I was using a Bell and Howell reversing reel to reel tape deck for playback of 2 channel stereo for the opening ceremony and an Ampex AG600 R-R for recording.
For those who have not heard of Ampex R-R machines, they were famous for the lowest noise floor (a brand new term then) on wide open, unterminated mic inputs. You could hear no hiss or noise of any kind. These were tube amps.
We also used four Altec Voice of the Theater cabinets with external HF horns and they were not bi amped.
The amp I used was actually 2 -150 watt RCA tube style PA amplifiers wired together at the input with a balance control of my design.
We used this system to play the National Anthem by the US Marine Band. About a 1/3 of the way through the song, the live US Marine band began playing along side the recording and then marched through the ribbon projection screen into the room to thunderous applause. There was not a dry eye anywhere.
It's amazing what us old boys did with so little.