ETC Source 4 Incandescent

After a three year development process by David Cunningham and Entertec, the ETC Source 4 ERS was introduced at LDI on 11/21/92.

Why 115v lamp versus 120v lamp? Because you don’t get 120v at the fixture

1v loss across the SCR
up to 7v loss across the inductor
line loss over the length of the cable
you could have as little as 104v at the lamp
115v lamps achieve about an 8% boost at the fixture compared to 120v lamps
Source 4 with a 575/115 lamp produces 17.7 LPW, which was 88% more efficient than the 360Q with a 1000 Watt FEL lamp, so a lot more ligtt with 45% less power consumption.

Dave Cunningham and the Magic of the Source Four

In February of 2021, Steve Terry spoke with Dave Cunningham about the invention of the Source Four, and how it made history to become the most successful spotlight of all time.

See the full interview here.