Im using adam hall sled1 ultra bnc gooseneck
It utilizes 4 cob leds and the area directly lit (width) is from the left side of the mixer to the masterfader on the right in horizontal direction on a 32SX, and from the bottom to the scribble-strips on the top vertically. Difusion of light reaches of corse further so channels 17-24 are lit too, but not directly.
The lamp does not disturb visibility of the scribble strips, while sitting in front of the desk.
And it has an on/off switch.