Old timer at the shop in Boise showed me his spoke tension trick and it's just a guitar tuner app
I was building up a rear wheel last month and a guy who's been lacing for 30 years pulls out his phone and starts plucking spokes while watching a tuner app. He says he checks the note on each side and if they match he knows the tension is even before he ever touches a tensiometer. Tried it on my next build and the wheel came out dead straight on the first try, so now I'm wondering if I'm the last person to hear about this or if anyone else does it.