SM57 and SM58 have the same innards, and only differ with regard to end cover (spherical vs. cylindrical)
True. 57 & 58 have identical capsules & transformers. 57 casing is designed for instruments and cabs, 58 for vocals. I've unscrewed the grille from a 58 and used it in place of a 57 more than once in a pinch!
It's usually easier to dial in a system and reduce feedback when all singers use the same model of mic.
+1! Regardless of which mic you go with, I can't recommend enough matching all your vocal mics. IME if you have 3+ singers this is an easy win that will improve your sound much more than the merits of one mic over another.
The thing about 58s is that they aren't actually designed to sound 'nice'. They're designed to work well live. The frequency response is lumpy, but it means that they cut through. Rock gig with a loud drummer and tons of backline, but stuck with a 400W crappy vocal-only PA? The 58 has more chance of being audible when many other mics will be drowned out in the sludge.
As PA systems have improved in fidelity over the years, the lumpiness of the 58 has become more & more apparent, and the mic has understandably lost some fans. But here's the thing. It'll always 'work'. I've had great experience with the Sennheiser mics
sometimes; but other times it's just been mud, mud and more mud. Especially the 835/845. I've had gigs where there have been better options than the 58 available, but I've never, ever found the 58 'unusable' in the way that I have with many other mics.
Also, you can throw a 58
down a lift shaft, drop it in a river and run it over with a dump truck and it'll still work. That's why it still has a place in many engineer's mic bags.
As for the Beta58, I've had mixed results. It's definitely a different beast to the SM58. It has a flatter response, and it sounds lovely in isolation, but, again, at tough gigs it just doesn't cut through as well, and it' harder to get a nice blend when there's a big frontline.
But the real question is, which mic is best for metal?
That one probably IS the 58, mostly because you can do
this with it...
