Tuesday, 4 April 2017

Tech Review: The Importance of Microphone Frequency Response

Talk of microphones usually revolves around the type (condenser or dynamic) and the polar pattern (cardioid, omni-directional, etc.), but there is more to a microphone. 

The “more” is the microphone’s Frequency Response.

Microphones differ in the way in which they respond to different frequencies. They might boost a frequency or reduce it depending on the purpose for which the microphone was designed. (Also depending on the ideas the designers had in mind!) They might not alter the frequency at all, in which case the microphone has a flat response to that frequency. 

A flat response microphone is one that is equally sensitive to all frequencies.

What Does This Matter?

There are hundreds (maybe thousands) of microphones on the market. There are vocal mic’s, guitar mic’s, drum mic’s, and even different microphones for the different components of a drum kit. One of the reasons for this is that microphones are designed for a purpose and when used correctly, you get the best sound possible. 

For example, a response pattern emphasising the frequencies in a human voice would be well suited to picking up speech in an environment with lots of low-frequency background noise.

Let’s go even further and dissect the response chart for the Shure SM57.*The chart is from 20 Hz to 20 kHz, the range of human hearing. 

The horizontal numbers represent frequency and the vertical numbers represent relative response in dB (Decibels). The SM57 Microphone Frequency Chart shows the SM57 response is fairly flat in the 150 to 1200 range. Anything below 150 is rolled off (cut). There is also a boost (or “bump”) starting around the 2 kHz – 3 kHz mark. Finally, it shows no response below 40 Hz or above 15 kHz.

What instrument would benefit from a Shure SM57? 

The snare drum is a perfect pairing for the SM57. The fundamental frequencies for the snare occur in the 150-250 Hz range. Therefore, the SM57 would capture these key frequencies as they are; without boosting or cutting them. The “snap” sound of a snare drum occurs in the higher frequency range in which the SM57 provides via the boost. Finally, because of the location of the snare drum to the kick drum, the microphone is prone to pick up the low frequencies of the kick drum. The SM57 provides roll off of frequencies in that low range. 

Therefore, the SM57 is capturing the true sound of the snare, accentuating the “snap,” and dropping out the low’s from the kick drum.Before you mic your next instrument, pull out the manual and check out the frequency chart. 

Then you’ll know if you are using the right microphone for the job.*Please note that microphone pairings used in the live environment are not necessarily the best for the recording environment.

Any additional inputs? Kindly plug them into the available comment channels below. 

Thanks Guys and always remember to keep the creativity perfected

Steve Aluko

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