What's the Difference Between the SM58 and the Beta58A?

Our technical team here at Shure are regularly asked to describe the difference between our classic SM58 and its closely related cousin, the Beta 58A. Firstly, let's be clear: this is not a question of better or worse – both microphones are characterized by outstanding sound and performance. However, each model has key fundamental strengths suitable for different applications. Here are some of the key differences to bear in mind...

Polar Pattern:

Perhaps the most obvious difference is the microphone polar pattern. The SM58 has a cardioid polar pickup pattern, while the Beta 58A is a supercardioid. The polar pattern subsequently affects how you should use the microphone and where it would be most appropriate.

A cardioid microphone will reject best from the back while a supercardioid microphone will reject better from the sides. Both microphones pick up sound best from the front, but a supercardioid polar pattern has the added advantage of being more directional and therefore less susceptible to feedback when using correctly placed stage monitors.

Output Level:

Due to its neodymium magnet, the Beta 58A has greater sensitivity and a 4dB hotter output than the SM58.

Frequency Response:

The Beta58 has an extended low-end and high-end compared to the SM58. This does not necessarily mean the Beta58 is better, and depending on the style/tonal characteristic of your voice, you may or may not benefit from the extended frequency response.

Handling Noise:

The Beta 58A is quieter than the SM58 due to its advanced pneumatic shock mount system.

Grille:

The Beta 58A has a hardened grille, which makes it more difficult to dent.

Summary

Which Should I Choose?

Choose the SM58 if you want a proven vocal microphone with a cardioid pickup pattern, classic tone, and forgiving performance in a wide range of live settings. It is a strong fit when you value familiarity, durability, and straightforward monitor placement.

Choose the Beta 58A if you want more output, a tighter supercardioid pickup pattern, reduced handling noise, and a more extended sound. It is a strong fit when you need added clarity and feedback rejection on louder stages, provided your monitors are positioned for a supercardioid microphone.

The Beta 58A is no doubt an upgrade for many applications, but in some scenarios, these upgrades can also be a hindrance. For example, if you're performing in a heavy-metal band, and you typically shout or scream into your mic - you may not want the extra sensitivity and detail of the Beta58. At the end of the day, it's all a matter of application and taste!

For further information on choosing the right microphone, take a look at our post on "How to Choose the Best Microphone for Vocals."