This is part of an interview in Guitar World Magazine with Phil Taylor, David Gilmour’s guitar tech.
GW: I notice David tends to use stomp boxes instead of rack-mounted effects. What is his reasoning?
PT: I think his general feeling is that while rack effects tend to cover a lot of areas, they don’t cover any of them particularly well. He feels that foot pedals such as a Big Muff tend to have more character.
GW: How does Dave achieve the classic sound that we hear on the solos of songs like “Comfortably Numb”?
PT: It think it’s just pretty much him. He is obviously using a couple of effects, like a Big Muff and a delay, but it really is just his fingers, his vibrato, his choice of notes and how he sets his effects.