Earthworks TC40K Review

Originally published here:; rescued from Internet obscurity 2010-05-17.

By Jim Miller

This omni condenser mic delivers stellar accuracy, imaging, and detail.

I have been a big fan of Earthworks’ condenser mics ever since I reviewed the OM1 and TC30K for EM last year (see the November 1996 issue). I was convinced that no other mic in their price range could be as accurate. But now I have changed my mind; my new favorite mic under $1,000 is Earthworks’ TC40KEarthworks Precision Audio TC40K.

The TC40K, like the TC30K and now-discontinued OM1, is a small-diaphragm, omnidirectional condenser mic with a brushed stainless steel body. It has an on axis frequency response of 9 Hz to 40 kHz, which is impressive by any standard. The mic requires 48V phantom power and will tolerate sound pressure levels of 150 dB — higher than what our ears can handle. (The threshold of pain for most folks is about 130 dB. As a reference, a full symphony orchestra playing fff would deliver somewhere around 110 dB.)

Matched sets are available at no extra charge, and the company says matched mics typically vary by no more than 0.25 dB at any point across the 20 Hz to 20 kHz frequency range. The mics ship in an attractive, solid cherry-wood case.

The TC40K works fine with the transformer-coupled inputs found on high end consoles from companies such as Neve, Summit, and Focusrite as well as with electronically balanced inputs such as those found on Mackie, Soundcraft, and TASCAM boards.

Oram MWS Microphone WorkstationTo audition a mic with specs like the TC40K’s, I wanted a mic preamp with similar performance. So I made a few calls, did a little begging, and borrowed an Oram Microphone Workstation (MWS) mic preamp (which lists for $2,195), designed by John Oram, who is acknowledged as "the father of British EQ." The MWS has a frequency response that’s down only 3 dB at 40 kHz, which assured me I’d be getting the best recordings these mics had to offer. But you don’t need a high-end preamp to appreciate the sound of these exceptional performers. After grudgingly returning the MWS to its rightful owners, I did a number of additional sessions with the TC40Ks and my Mackie 1604VLZ board. I used the Mackie’s onboard solid-state preamps as well as an Aphex Model 107 Tubessence preamp, and the mics delivered consistently excellent recordings.


My first test was with two acoustic 12 string guitars: a relatively inexpensive Ibanez and a pricey vintage Gibson B45-12. Starting with the Ibanez, I placed the TC40Ks about six inches away from the body, pointed at neck and bridge; slipped on a set of AKG headphones; and started to play. The sound was simply glorious, with tons of upper harmonics that gave the budget 12-string an almost otherworldly top-end sparkle but with plenty of body and richness. I spent nearly two hours sampling this guitar and ended up with a most impressive 12 MB multisample.

Wondering how the Gibson would fare if the Ibanez sounded so good, I carefully removed the guitar from its plush-lined case and started to play. Indeed the sound was absolutely wonderful, but I was surprised to discover that there wasn’t as huge a sonic difference between the Gibson and the Ibanez as I expected. True, the Ibanez is an inexpensive instrument, and its construction quality and action don’t compare to the Gibson. But its sound is impressive, and the TC40Ks captured it beautifully. My initial conclusion: the TC40Ks, when set up properly, deliver excellent sound with even a modestly priced instrument and accurately capture the superb sonics of a finely crafted instrument like the Gibson.

Like all omnidirectional the TC40Ks work best in closer proximity to the sound source than you might ordinarily place a cardioid or hypercardioid condenser. In addition, you can work just about as close as you like without any of the nasty boominess typically caused by the bass proximity effect of cardioids. This makes it particularly useful when sampling or recording relatively quiet instruments such as dulcimers, clavichords, or harpsichords.

This doesn’t mean you can’t move the mics a bit farther away. I tried recording some “Pinball Wizard”-style acoustic guitar to DAT with the mics placed about two feet away. As you might guess, because these are omnidirectional mics, I got a lot of room sound. The recording sounded like a real acoustic guitar being played live in a real acoustic space: very spacious, but with a nice, tightly focused stereo image.


I had been working with the TC40Ks for a few days when I had the pleasant surprise of getting access to a beautifully crafted William Dowd harpsichord, built in Boston in 1975, which now resides at Florida State University. This particular instrument is in great demand and had just been tuned, so I had no choice but to rush down to the campus with my DAT recorder, Oram MWS, and the matched set of TC40Ks.

I set the mics up just four inches above the instrument’s strings, about two feet apart. Then, listening through the headphones, I adjusted them slightly until I had a well-balanced sound across the full 5-octave keyboard.

Considering how close the TC40Ks were to the strings, I was surprised to hear almost no perceptible volume difference when playing notes at the far ends of the keyboard compared to those right below the mics.

Halfway through my allotted 2-hour recording session, a jazz quartet began rehearsing in the next room. The piano player was loud enough, but the drummer pounded his set unmercifully. I sensed disaster, but knowing I’d not likely get another opportunity to rerecord this instrument anytime soon, I just pressed on, stopping only when the jazz cats hit some of the bigger crescendos.

When I finished the last note on the Dowd, I rewound the DAT to see just how noticeable the sonic damage was. Despite some audible snare and kick transients in spots, I heard almost none of the ensemble on the tape, and when I did, it was always at the points where I had stopped playing anyway. Returning home, I was still concerned and ran the last half of the DAT through my studio monitors, but this only confirmed what I’d heard in the headphones: the Earthworks mics, having been placed so close to the strings and behind the harpsichord’s lid, were able to adequately reject the unwanted music from my recording.


Heavy metal, that is. To test the TC40K’s ability to stand up to ridiculous SPLs, I stuck my Peavey Classic 50 amp in a closet, turned up its volume, shoved a TC40K right up to the front of the speaker, covered the whole thing with two thick blankets, and then shut the door. I plugged in my Les Paul with Zoom Driver set to Metal mode and made all sorts of ungodly racket, running the signal directly into my Kurzweil K2500.

Nothing seemed to daunt the mic: not hammering out power fifths, not scraping my pick along the low E string, not even tapping the strings right against the pickup magnets (ouch!). All were captured cleanly — if you can use that term to describe what I was doing. Back when I test drove the OM1 and TC30K, I found them easily able to handle even the most explosive popped bass notes, and the TC40K was just as capable of ignoring such hot, spiky transients, though my amp levels were even higher this time around.

Next I hauled out an old Ludwig snare I had purchased at a garage sale, stuck the TC40K right up close to the head, and began beating the drum with superheavy sticks. Again, no distortion. Ditto on a 21-inch Zildjian crash/ride cymbal I had inherited. All of which means that these might be the perfect mics to use for that 747 takeoff recording you’ve always wanted to do.

I also took these mics to a recording session where I was laying down some guitar tracks. After the session was over, I set the TC40Ks up and had the drummer pound away at his set with the mics in various positions (close-in, across the room, and overhead). The best sound was with the mics just three feet away from the drum kit. More distant miking, as you might expect with omnidirectionals, picked up just a little too much room sound, giving the drums a bit less presence.

I compared the TC40K tracks with some previous recordings of a different drummer miked with TC30Ks. My impression is that the TC40Ks have a bit more punch and just a tiny bit more air at the top end. Both recordings were great, but I definitely preferred those made with the TC40Ks.


All of the previous tests indicated that these mics were capable of delivering accurate, detailed recordings of close-miked solo instruments. Where many microphones fail, despite excellent frequency-response curves, is in time coherence. This means that many mics actually smear the time domain, with certain frequencies being transduced sooner or later than others or with some amount of ringing or resonance after the fact, resulting in a loss of much of the information that tells us exactly what kind of environment we’re hearing the music in. Is it a bathroom, or a medium-sized room, or a jazz club? Essentially, time-domain accuracy equals realism, the sense of actually being there for the performance.

To test this mic, I initially was going to record a live rock band. But then a better opportunity presented itself. Some friends who play in a local Irish folk band, the Long-Forgotten String Band, invited me over to hear them practice some new tunes. They were only too happy to allow me to do a live recording of the session. The group has two guitars, a mandolin, bass, two flutes, banjo, fiddle, and pennywhistle. The complex sound of all these instruments playing together would offer the mics a nice workout.

I had the musicians form a semicircle and placed the TC40Ks about eight feet away from the back of the circle so that the closest players were only about four feet away. Despite the fact that this session took place in a medium-sized living room (about 16 by 22 feet), the hardwood floors and lack of heavy drapes and other sound-absorbing furniture meant I’d have a rather live recording environment. I placed the Earthworks mics about a foot apart right at the spot that my ears told me the sound was the sweetest.

The mics performed incredibly well with this material; nobody would ever guess that this session didn’t take place in a studio. The sound was absolutely stunning, with every detail of every note from each instrument captured flawlessly. The left-to-right spatial imaging was amazingly realistic. Had the group been a little quieter (less coughs, foot taps, etc.) and more familiar with the material, I believe this tape would have been good enough to consider releasing commercially.

I added just a tiny bit of high-end EQ on the Oram preamp (about 4 dB) at 12 kHz, which added just the right amount of sparkle to the upper harmonics to please my ears, though there are those who would undoubtedly prefer the accuracy of the unequalized signal. In any case, the individual members of the group listened to our recording, and all agreed that it sounded great. Several even commented that the recording made them sound better than they actually do in “real life.”

Creating a recording that accurately captures the energy of a live performance is no easy task, but these mics, when matched with a quality preamp, could easily make an engineer’s life much simpler. Toward the end of the rehearsal, I purposely moved the mics around to different positions and still got recordings I felt were quite satisfying, though not as accurate as with the mics in their original position.


By now, you’re probably tired of hearing me praise these mics. You’re wondering if there’s a down side to these things. Admittedly, one area that the TC40Ks didn’t knock me out in was when recording lead vocals. Aside from the fact that they just didn’t quite have the sizzle I prefer on such tracks, they also captured a lot of performance noise when the singer was breathing or licking her lips, even when a windscreen was used. In addition, there was just too much ambient noise, particularly when I engaged my compressor.

When I did my review of the OMls and TC30Ks, I noted that they were both quite sensitive to extraneous noise. The TC40K is very similar in this respect. Earthworks states that these mics are indeed about 10 dB hotter (more sensitive) than most other condensers. Because of this sensitivity, there may be a perception that the mics are inherently noisy.

Though the TC40K specs list the self-noise level as 26 dB, this is actually a bit misleading. The typical ambient sound level in a broadcast studio runs about 20 dB, while your average suburban living room would have around 45 dB of ambient noise. Only in the most highly controlled acoustic environment would the TC40Ks even begin to exhibit noise beyond that of the surrounding room. As a comparison, AKG lists the noise level of its C 414 B/ULS at 14 dB, Neumann’s U 87 is also rated at 14 dB, and Audio Technica’s popular AT4050/CM5 weighs in at 17 dB. (These figures are all A-weighted.)

Specs aside, the TC40K does indeed tend to pick up more ambient noise than, say, an AKG C 414 or Neumann U87, at least partly due to its omnidirectional design. Set up a pair of TC40Ks in your studio, slip on a pair of headphones, turn up the volume on your preamp, and you’ll be surprised at how noisy the room sounds. You’ll hear cars driving up and down the street, jets flying overhead, and the neighbor’s kids fighting. Take off the headphones, and you’ll really have to listen carefully to hear all this.

This doesn’t mean there’s anything wrong with the design of the TC40K; it’s merely that they are extremely sensitive to sounds we don’t necessarily want in our recordings. But it’s this same sensitivity that allows the mics to capture all the expressiveness and detail of solo or ensemble instruments. To balance this sensitivity, you can confidently use the Earthworks mics much closer to the sound source, thus creating a situation .where overall volume levels on your mic preamp could be lowered. This would, in most cases, effectively offset any sensitivity issues.

Still, if you can’t move in close to your source and you are recording in an environment where noise could be a problem, you might want to choose another mic. A good example would be recording a pipe organ, because you can’t usually get the mics close enough to the pipes (which are typically well off the ground and spread across the entire width of a hall or church).


Are these the best mics at this price range? Well, yes and no. If you want incredibly accurate recordings with plenty of detail and can live with the few limitations inherent when using omni-directionals, the answer is definitely yes. If you need mics that can be placed inches from your sound source without sounding tubby, then again yes.

However, not everyone wants or needs a truly accurate mic. In truth, some of the most popular mics are not the most accurate. Modern recordings sometimes require mics with a certain high-end emphasis or glossiness (particularly on lead vocals), and that’s certainly not what these mics do best. If you need a mic that can be set to a cardioid or even hypercardioid pattern, the Earthworks mics aren’t what you’re looking for.

But other than the TC40Ks’ tendency to sometimes pick up a bit of unwanted noise, working with these mics has been a real pleasure. In my opinion, every studio owner, pro or semipro, should take a close look at these superb performers. With their 33-day money-back guarantee, you can’t go wrong. But I’m willing to bet that once you plug in a pair and use them for a while, sending them back will be the furthest thing from your mind.

Jim Miller is a freelance sound designer, sometime session guitarist, and frequent contributor to EM. Special thanks to Sweetwater Sound for use of the Oram MWS mic preamp.

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