Shure Beta 57A vs Shure SM57
The Beta 57A takes the idea of the SM57, the go-to dynamic instrument mic, and adds a supercardioid pattern and a neodymium magnet.
Which one to choose
The Beta 57A has more output and presence, and its supercardioid pattern isolates each source better, which helps on snare and toms when the kit is full of mics. The cardioid SM57 sounds more neutral and is the standard on guitar amps, where almost every engineer knows by heart how to place it. For drums and stages with lots of bleed, the Beta 57A; for amps and as a general-purpose mic, the SM57.