Shure Beta 58
The SM58's hotter, tighter sibling - a supercardioid built on neodymium, and the first time Shure asked a stage vocal mic to do more than just survive.
Overview
Shure's own period advertising framed the new mic as coming "from the engineering team that brought you the SM58," announcing an "improved version" that shared the older mic's low-frequency warmth while adding a "unique supercardioid construction" for a more open, natural sound. That's marketing copy, but it describes what the Beta 58 is: a deliberate second take on the most familiar dynamic vocal mic on earth, not a replacement for it.
The headline change is the capsule. The Beta 58 was the first microphone to pair neodymium magnet material with a true supercardioid pattern, a combination Shure billed as delivering "extra-hot output" alongside the tighter pickup. A supercardioid pattern, as opposed to the SM58's cardioid, has a narrower rear null and a lobe of sensitivity directly behind the mic. For a vocalist standing in front of a wedge, that geometry is the whole ballgame. The Beta 58 rejects more of what's coming from the sides and front of the stage, which is why Shure's own literature emphasizes "exceptional gain-before-feedback." The company claims the pattern stays uniform across the frequency range. That matters, because a supercardioid that narrows at the top and widens at the bottom is worse than a cardioid. It changes the feedback frequency as the singer moves.
The neodymium magnet is what makes the output hot. A stronger magnet in the same gap produces more signal for a given diaphragm movement, so the Beta 58 puts out more level than a standard dynamic vocal mic. That helps when you're fighting a loud stage and want headroom before the preamp, and again when the singer is whispering and you'd rather not crank the gain. Shure's ad copy for the Beta line leaned on this duality, with endorsing engineer Paul Dalen quoted in Recording-Engineer (January 1991, p.15) describing the Beta 58's sensitivity and resistance to feedback as making it the perfect fit for the groups he worked with. That's an endorser's line, not a lab measurement. The design intent is a dynamic mic with the output of something hotter, without the fragility of a condenser.
Shure also built in a pneumatic shockmount system, which the company said minimizes handling and stand noise. This kind of feature never shows up on a spec sheet and shows up constantly in the real world: finger taps on the body, bumps of the mic stand, cable thumps traveling up the boom. A dynamic vocal mic that transmits all of that into the house is a mic the engineer stops trusting. The Beta's shockmount lets a sound tech hand one to a singer who grips the grille without spending the rest of the set chasing thumps.
The three-stage directional tuning network is the other piece of internal engineering Shure advertised. The company claimed it eliminates the irregular off-axis response that plagues other supercardioid designs. Off-axis response is what you hear when the singer turns their head, when a monitor bleeds in from the side, or when the drum kit leaks into the vocal mic from an angle. A mic that sounds one way on-axis and completely different off-axis makes the vocal disappear the moment the performer moves. Shure's claim is that the tuning network keeps the off-axis tone consistent. That's a design goal rather than a measured guarantee.
Shure's period advertising for the Beta line also stated a user net price of $258 for either the Beta 58 or the Beta 57, the instrument-oriented sibling. That figure comes from the company's own promotional material, not an independent review, and it puts the Beta 58 well above the SM58 in the lineup. The premium bought the neodymium capsule, the supercardioid pattern, and the shockmount. Whether it was worth it depended on the stage. For a quiet acoustic act in a small room, the SM58 is fine. For a loud band with wedges screaming back at the vocalist, the Beta 58's tighter pattern and hotter output are the difference between a vocal that sits on top of the mix and one that fights it.
The Beta 58 also found its way into wireless systems. Shure's own advertising for the L2/Beta 58 wireless system claimed the radio version preserved "the same crisp, clear sound and gain-before-feedback as its cabled counterpart," and Recording-Engineer (January 1991, p.15) carried an endorser's quote describing the Beta 58 Wireless as the first radio mic system that didn't sacrifice sound quality for freedom of movement. That's an endorsement, not a measurement. It does confirm that the Beta 58 capsule was considered good enough to be the flagship element in Shure's wireless line.
By 1996, the Beta line had moved on. Mix-Magazine (July 1996, p.174) reviewed the Beta 57A and 58A, noting that the updated 58A had less energy in the low mids - from roughly 250 to 800 Hz - compared to the SM58, and that the older Beta had 2 dB less at 8 kHz than the SM58, traded for a couple of dB more at 6 kHz. That's a snapshot of how the Beta's voicing differed from the SM58's: leaner in the boxy low-mid region, with a presence lift shifted slightly downward from the SM58's upper-mid peak. Whether that reads as "more natural" or "less warm" depends on the voice in front of it.
Collectors and working engineers tend to treat the original Beta 58 as a known quantity rather than a collectible. It's a stage tool, and it was built to be used hard. The pneumatic shockmount and the supercardioid capsule are the reasons to seek one out over an SM58. The reason not to is that the SM58 is cheaper, more forgiving of bad monitor placement, and so common that every venue on earth has a spare.
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