Re: Beta 57a vs. Beta 58a for vocals
Tests are done with a noise source at a specified distance from the microphone.
Singing drummers may be classified as a "noise source", but human singers include lips, mouth and nasal cavities, and often reflective eyeglasses and hats, all of which have a completely different response curve than a simple noise source.
As has been mentioned before, the biggest difference between the microphones from a singing application is the distance from the capsule to lips, a Beta 57 is about 15 mm, the Beta 58 is 22 mm.
Halving the distance would be a 6 dB increase in signal to noise, the difference between the two is probably greater than 3 dB.
If you have a close look at vocal microphones noted for "rejection", one thing they all have in common is the diaphragm is located very close to the wind screen.
Prior to there being so many options for "hypercardioid" mics, Rocky Holman would "modify" SM 58s for his hard rock singers, using a brick to squash the grill flat to very near the capsule diaphragm.
Looked kind of like a Beyer M-88 if you did it right, and around an instant 6 dB of "rejection" compared to a normal SM-58.
Beta 58 screens are a much harder metal, they don't bend like the SM-58, one of the reasons they can break the element when thrown on a hard surface, while the deformed 58 screen absorbs the impact.
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