Just as the heartbroken see happy couples everywhere, people in my part of the Great Lakes see signs of spring all around them. This week, as the sun shines and the temperatures warm, it feels real. That’s a good reason to get out and sample what looks like a pretty good week for music in northwest PA. Among the events in the lct field of vision, I’m most excited about the recital at Allegheny College by the San Francisco-based Alexander String Quartet, who will present a typically brainy program of the birthday boys, Mozart and Shostakovich. I’ve been spending a lot of time with Dmitri Dmitrievich lately, and he has proven an apt companion. Miss this one at your peril. Not terribly far away from him musically and geographically are the Duquesne University Tamburitzans, who will be at Mercyhurst on Friday evening. For 25 years, my father presented this folk music and dance troupe, and they are probably the inspiration for my interest in exotic music. On Saturday, my favorite local band, Joseph Allen Popp’s Weirdo Theatre will bring the curtain down on the shooting-star phenomenon that was Moonsense CafÃ©. Don’t forget that this is an all-ages show (I’m bringing my daughter) and that the age that matters most is 65. That’s how old John Vahanian will be on that day (“My birthday is four-one, four-one,” the April Fool is fond of reminding people). While his presence is, like everything else in Vahan’s life, subject to impulse and whimsy, you can be there. And you should be.