HI Lee,
I would guess the PV board is from about 1975 era..... Played in a group decades ago that had either that board or one very similar. From what I remember it pretty much sucked but was able to get much louder than most things of that vintage. Everyone would run away when it came time to find someone to carry it to the car! It was paired up with some much larger speakers that sounded about the same.
I think the control panel knobs are what sold it to many....
The Shure VocalMaster was a much nicer system
.
Robert