My studio space sounds pretty good. I have worked toward a balanced listening experience by utilizing space-specific sound treatments such as absorption and diffusion, keeping my monitors decoupled from my desk and their stands, and following all the usual recommendations for treating a room for recording and mixing. I have, however, never tuned my room or calibrated my listening environment using a reference mic and calibration software. When the opportunity arose to use the new second-generation measurement microphones from Earthworks Audio, I figured it’d be a good exercise and something I should have probably done years ago.
The new M23 G2 and M30 G2 omnidirectional microphones are the latest iterations of Earthworks’ well-loved and widely used reference microphones. Engineers use them to tune concert halls and mixing and mastering rooms, for capturing SPLs, in car stereo installation scenarios, and for recording audio that is essentially color-free and as accurate as possible. The M23 G2’s spec sheet shows the mic’s claimed frequency response as essentially flat from 5 Hz to 23 kHz, a low frequency cutoff of -3 dB below 3 Hz, and a high frequency cutoff of -3 dB above 30 kHz. It also shows a max SPL of 140 dB with +48V or 133 dB with +12V phantom power. The main difference between the two mics is the high frequency extension on the M30 G2, which has a -3 dB cutoff above 40 kHz. I really wish I could hear 40 kHz! Both mics come with a case, mic stand thread adapter, mic clip, foam windscreen, calibrator adapter, and calibration chart. The M23 G2 has a slightly shorter tip than the M30 G2, but both have that familiar, tapered alien probe look we’ve come to love from Earthworks. The metalwork on both mics lives up to the fine craftsmanship that Earthworks has built their name on, and the connections are snug. You certainly get the feeling that these mics will be in operation long after you are a pile of dust.
I went into this calibration/room tuning process with a little hesitation. I thought it might be a bit laborious, and I was mildly terrified about what the results would be. I installed a version of Sonarworks Sound ID software and followed the steps to create a profile for my room and listening spot. This involved pointing the mic at each speaker and following a series of prompts to move the mic to a bunch of different places around the listening area while the program played a series of frequency sweeps. It took about 20 minutes to complete the process.
The results were interesting, and I guess not really surprising. It showed about a +4 dB bump around 100 Hz and a few other little overs and unders across the frequency spectrum, but overall, it wasn’t nearly as bad as I expected! I did a few different calibrations using a couple of different preamps. The results were ever so slightly varied, but ultimately similar enough that I could flip between the created sound profiles without too much variation. I used both mics for different profile creations, and they performed almost identically. As far as room calibration goes, it is a process worth going through. I am certain my mixes will benefit, and there will be less of a need to check them in multiple locations (like the car).
Is there a reason I should not use a measurement mic to record music? They sure look like they’d be great room mics… and they are. I have been using a matched pair of Earthworks QTC40 mics in the drum room for years, and I love them. With that in mind, for a drum session I tried the M23 G2 pointed straight up at the ceiling in the corner and the M30 G2 at about the height of the drummer’s head when seated, where I thought the kit sounded best when standing in front of it. Both sounded excellent! I smashed the room mic with a Universal Audio 1176 and compressed the kit mic a little less with an Empirical Labs Distressor [Tape Op #32]. Blended in with the close mics of the Earthworks DK6 drum kit package [#165], the drums had power, definition, and some excitement from the room at Avast! Recording Co. So, use the M23 G2 or M30 G2 to tune your room, but know that you have an excellent microphone for all sorts of applications, especially acoustic instrument recording.
In general, I like my mics to sound like something. I want some color. I want some vibe. But I am impressed (again) by this line of mics from Earthworks, and I acknowledge the need to get my listening space dialed in with as flat a frequency response as possible so that I can actually work effectively with the tone and magic that my favorite microphones, preamps, and outboard gear are imparting to the sound. The process of room calibration was not nearly as daunting as I expected, and the results are welcome! You can’t go wrong with either of these beautifully crafted microphones.