https://reverb.com/news/the-story-of...ang-evh-guitar

Chip had worked with Seymour Duncan for pickups on the EVH Frankenstein replica, so that was the obvious first stop. "They were dialed in to the sound Ed was looking for at that time, and we spent probably three months testing variations of custom pickups from them. I would receive a set, load up a few guitars so we could test 'em, go up to 5150, Ed would plug in, and we'd try them out."

Chip is referring to Ed's studio complex, known as 5150. "We could only go about an hour at a time testing pickups, because you tend to lose your ears at that point. Everything starts to sound the same."

They got close with the Seymour sets, but not quite. Same thing with DiMarzio. Finally, an engineer at Fender started making samples, and his second set made the grade. "Working in-house at Fender on the pickups helped," Chip says, "because we had the ability to do everything real-time, stand over the engineer, work with him, get a better understanding of what's going on."