Free with admission, you do not need to be a member.
You are invited to attend a free lecture/performance about how Christian Frederick Martin created a uniquely American form of the guitar and, through the company he founded, influenced 180 years of American music. With performances by Douglas Back and others on historic and modern Martin guitars. The lecture/performance starts at 2:30 PM and will likely go for about an hour and a half.
The museum closes at 5 PM on Sundays and sometimes lectures run a bit longer than they're meant to. So, those who'd like to get drinks and snacks, meet beforehand at 1:00 PM at the gilded Diana statue in the middle of the Charles Engelhard Court (aka gallery 700), and go to the American Wing Cafe at 1:10 PM.
Then at 2:10 PM head over to get seats. It would be nice if someone waited outside the auditorium until 2:50 PM for anyone that can only make the lecture.