Earthworks TC30K

Earthworks is not the first name that comes to mind when one thinks of microphones, but the man behind Earthworks might be more familiar. David Blackmer played an active role in console development at API and went on to be the founder of dbx. Now Blackmer has built a mic, the TC30K, with time-coherent response from 9 Hz up to 30 kHz. Earthworks feels that clean impulse response and time coherency (see sidebar) are crucial to a mic's ability to accurately reproduce sound. The design goal of the TC30K was to offer serious recordists a microphone with exceptional sound quality at an accessible price.

The TC30K microphone is an omnidirectional condenser housed in a slick-looking stainless steel body that makes it look like some kind of medical instrument or a laboratory measurement microphone. Earthworks supplies a clip-type holder, and if you purchase a pair of mics, the company will match them and supply a beautiful solid cherry presentation case at no extra charge.

The first mics we received came with clips that did not put quite enough pressure on the body of the mic, so the mics would slip out of position when held at certain angles. Earthworks has changed to a design that holds the mic much more securely. There are no external controls of any kind; a standard three-pin XLR cable carries audio and phantom power between the mic and your console.

Earthworks suggests muting the signal from the TC30K for the first minute while the mic powers up and becomes stable, but we never heard any coughs or strange noises. Our first session with the TC30K involved recording a nylon-string acoustic guitar. The guitarist played quite softly, and, as a result, the TC30K's self-noise became quite evident even when the mic was placed within inches of the instrument. Tonally the mic sounded very closely reproduced what the instrument was actually producing, but the noise factor was a problem. Our experience was verified by literature from Earthworks that explains that the TC30K was not designed for ambient recording or recording very quiet sources. Rather, the mic's strength is medium-to-high-SPL sources--so we decided to try miking live drums.

In our first drum session, we used a pair of TC30K's set up as an XY coincident pair. Omnis in X-Y configuration? I call this the Swedien technique because engineer-producer Bruce Swedien records omni/X-Y all the time with his Neumann M49's. The folks over at Earthworks also suggested this approach, and while we know it doesn't make classic sense, it works. The imaging was rock-solid, and, in this particular room, bringing in the kick and snare close-mics was totally unnecessary. Keep in mind that the room sound plays a big part since the mics are omnidirectional. In a different room with the mics set up in a similar fashion, the drums sounded good but not nearly as good as in the first room. It just proves the point that using omnis makes the sound more dependent on the acoustical environment.

We then proceeded to move the mics closer to the drums (still in X-Y), first at a distance of two feet above the kick and then one foot above. When we got to the one-foot range, the tone of the toms ruled. They had the round bottom and midrange tone of close-miked toms without the high-end choke. And there was still a sense of space and room sound. In this position, the floor tom sounded a bit distant compared to the rack toms and the sense of spaciousness definitely decreased from the more distant position.

The next logical thing to do was to close-mike drums with the TC30K's. Since the TC30K doesn't suffer from proximity effect, you can mic much closer-which somewhat counterbalances the omni pickup pattern (Earthworks recommends getting as close as you can). We miked an inch away from the top head on rack and floor toms, and the TC30K's really excelled in this application. Transient response on floor tom was excellent--the snap from the stick was right in your face and the big bottom of the drum was maintained without sounding sloppy. These mics are indeed capable of capturing very low frequencies. Although we couldn't actually hear it, closing the studio door clearly moved the woofers on our control-room monitors at a very low frequency.

Since TC30K's can be placed so close to an instrument, using a single TC30K on acoustic guitar was interesting. It's hard to describe, but we were able to get the mic an inch away without overblowing the bass-even with the mic near the sound hole. It was almost as if we could mic any area of the instrument and get a well-balanced tone as long as we kept the mic close to the guitar. Perhaps this naturalness of tone sounded unusual to us because it is rare that we can mic so closely without proximity effect dominating the sound.

TC30K's can on occasion act a bit "quirky." We used the mic with our Demeter VTMP-2a mic pre and got a strange pulsing click that almost sounded like a heartbeat, rendering the combination unusable. [Earthworks and Demeter have delved into this problem and come up with the solution. -HGL] Earthworks informed us that the TC30K also does not make a particularly good marriage with the Anthony DeMaria Labs mic preamp. David Blackmer explained to us that the feedback loop in the Demeter audio circuit operates at a frequency very near the critical frequency of the TC30K's electronics making the couple unhappy (he suspects that the situation is similar for the ADL preamp). In any case, we didn't have any problems with Mackie, ART, or Soundtracs mic preamps, but be aware that these mics may not be happy with every mic preamp.

Note that the TC30K's current drain is about 10 milliamps--rather high for a condenser microphone--so make sure your phantom power can supply 10 milliamps. If you are willing to throw some "classic" mic conventions out the window and try new ideas in miking techniques, the TC30K's will reward you with a very wide frequency range and time-coherent response.

--Steve La Cerra