[quote name='project_c' timestamp='1457916414' post='3003060']
Why, do you have perfect pitch? You'd usually need reference for at least one of the strings to be in tune with everyone else. Plus have you tried tuning a bass in a sweaty rehearsal room full of musicians setting up and getting ready to play? Good luck hearing yourself amongst that car crash.
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I went decades without owning a tuner and in defence of the OP what has perfect pitch got to do with it? If it's just guitars, you tune to each other, you're probably all going to be in the general pitch ballpark anyway, so being slightly off isn't going to be an issue. If you have a fixed tuned instrument (keys), tune to that. Insofar as being in a noisy room, you set aside a few minutes to tune to each other. Band discipline.