Determining Suitability: Comparing A Host Of Measurement Microphones

The Results

Even inexpensive omni condenser mics are quite flat at bass frequencies – what separates them is how high their response extends, and how flat they are above 1 kHz. We tested to only 20 kHz, though I imagine some of these units are useful to even higher frequencies.

The Nady and Behringer mics are visually identical except for the name printed on the side. However, I didn’t take them apart to examine the capsule or electronics, so it’s possible only the cases are the same. I also noticed that the Behringer output was about 3 dB higher than the Nady.

All of the data is shown below in Figure 1. It’s difficult to show 11 test subjects all on one graph, so they’re divided into groups.

The top two graphs show the four “high-end” mics, averaged into third octaves. Raw response data is more accurate at low frequencies, but shows too much detail above 1 kHz; therefore, the graphs are all smoothed, using the Earthworks mic as an arbitrary reference for each graph, plus four other microphones.

All of the tests were done using the fabulous freeware program Room EQ Wizard, and the graph line heights were adjusted vertically to compensate for varying mic output levels. As you can see, most of them match very closely at low frequencies, deviating mainly above 1 to 2 kHz. In the bottom graph we can see how the response of the Radio Shack digital SPL meter is much more extended when aimed at the loudspeaker source.

From this data it appears that for measuring loudspeaker setup and room treatments, the Nady or Behringer models are quite adequate — within a few dB of the most expensive options – and significantly better than the Radio Shack SPL meter, which is often recommended. Additionally, we’re comparing the microphones’ responses 90 degrees off-axis, so it’s likely that their on-axis responses would match even more closely.

Thanks to Grekim Jennings and also to Mike Barney and Pete Basel of the Connecticut Audio Society for their participation, and special thanks to Mercenary Audio for supplying the Josephson/Gefell mic.

Graphs of the results, divided into groups, with the Earthworks mic serving as an arbitrary reference.