Preamp Powerhouse: Inside the SM7dB Microphone

Want that legendary SM7B tone but don’t have an interface with enough power? Or perhaps you’re looking to simplify your audio chain while traveling?

Well, Shure has an addition to the SM7 family that is certain to pique your interest: The SM7dB is packing an extra +28dB of clean gain inside, making it perfect for nearly any recording setup.

But what exactly makes this microphone different from the SM7B that we all know and love? 

In this LOUDER article, we’re going to get deep into the tech specs of this engineering wonder.

The SM7dB:

• delivers the same legendary broadcast sound as the SM7B
• has a Shure-designed onboard preamp providing +18dB or +28dB
• can be used in Bypass mode as a regular SM7B  
• is slightly longer and comes in a sleek black finish

At its heart, this mic was designed to sound just like an SM7B. In fact, you can operate it in Bypass mode and for all intents and purposes that’s exactly what you’ll have. The SM7dB delivers the familiar warm tone adored by podcasters, musicians and content creators alike. Shure engineers have painstakingly ensured that it has the same sound signature as the original SM7B.

The key difference, therefore, is the active preamp designed by Shure inside, giving each SM7dB enough output level to work with any XLR interface. Providing up to +28 dB of low-noise, flat, transparent gain, the onboard preamp preserves the mic’s frequency response for a clean, classic sound. All you need is an interface or mixer offering +48V phantom power* to operate the preamp.

Speaking of which, the preamp has been custom made from scratch by the Shure engineering skunkworks in Niles, Illinois. It has been optimized for the microphone from start to finish, providing extra gain tailored to get the best results from what has become an audio icon.

If you look at the back panel of the SM7dB, you’ll see the bass roll-off and mid-range presence boost controls shifted slightly upwards compared to an SM7B. This is to make space for the two-step switch giving you either +18dB or +28dB of extra gain, as well as the Bypass mode switch to deactivate the preamp entirely.

Why the two different levels of extra gain or none at all? Well, I’m glad you asked that. When miking loud sound sources like a guitar cab or snare drum,you’ll likely want to use +18dB or bypass the preamp for the original SM7B output level. But if you’re podcasting or recording quiet vocals select the full built-in boost of +28dB. The SM7dB offers you unprecedented freedom to tailor the mic to your specific recording needs.

Whether you’ve activated the preamp or not, you’ll get the same great detail in your recordings from a proven dynamic cartridge and frequency range of 50 to 20,000Hz. You’ll hear all the highs and lows for truly natural sounding audio.

GET YOUR VERY OWN SM7dB HERE.

So where does that famous ‘radio voice’ come from? Good question! The dynamic cartridge and voice coil in both versions of the SM7 are optimized to deliver an extended low frequency response, a flatter response curve overall, and a polar pattern that is especially tight at the higher frequencies. They’re also transformerless for the cleanest possible signal path.

Speaking of polar patterns, the SM7dB, of course, also utilizes a cardioid pickup pattern to help isolate your voice (or other sound source) from any background noise. This makes it great for capturing warm, crisp audio in less-than-ideal podcasting or streaming spaces.

Another important feature preserved from the SM7B is the highly effective pop filter that eliminates the need for any add-on protection against explosive breath sounds, even for close-up vocals or narration. It’s just another reason this mic has come to dominate podcasting.

Physically, you’ll notice the SM7dB is ever so slightly longer than the original. How much longer? About 1 centimeter to accommodate the preamp inside. The silhouette is still very much unmistakably part of the SM7 family. Shure also gave the SM7dB its own special black finish.

For anyone interested in using the new mic to simplify their audio chain while on the road, you’ll be pleased to hear that it weighs 837 grams (1.875lbs) – which is almost exactly the same as an SM7B. More importantly, you’ll save the added bulk of lugging around an external in-line preamp.

In the box, you’ll also get a bigger, close-talk windscreen, as well as a 3/8” thread stand adapter.

Still not sure whether to get the SM7dB or SM7B? Check out this article to help you decide!

SM7dB SPECIFICATIONS 

Type                                        Dynamic (moving coil)

Polar Pattern                          Cardioid

Frequency Response              50 Hz to 20 kHz

Output Impendance               150 Ω in Bypass Mode 27 Ω in Preamp Mode

Sensitivity(at 1 kHz,               -59 dBV/Pa[1] (1.12 mV) Flat Response Bypass Mode
open circuit voltage)               -41 dBV/Pa[1] (1.12 mV) Flat Response +18 Preamp Mode

[1] 1 Pa=94 dB SPL                  -31 dBV/Pa[1] (1.12 mV) Flat Response +28 Preamp Mode

Polarity relative to Pin 3         Positive pressure on diaphragm produces positive voltage on Pin 2 

Net Weight                             837 g (1.875 lbs)

Housing                                   Black enamel aluminum and steel case with black foam windscreen

*Learn more about phantom power here.