As a welcome counterpoint to the procession of cardioid condensers that forms the staple of new studio microphones, DAVE FOISTER rigs a pair of American omnis with some serious performance figures. Do they measure up?

I'VE HEARD some bold claims in my time, but few bolder than Earthworks' declaration that one of its models is 'the most accurate recording microphone available'. Earthworks is a small. relatively new American company set up by David Blackmer, founder of dbx, and its catalogue to date consists entirely of a range of omnidirectional microphones. The similarities between models outnumber the differences; all share a distinctive styling strongly reminiscent of Bruel & Kjaer's measurement microphones, and all have impressive specifications, varying mainly in the extent of the frequency response outside the traditional audio range.

Another important common factor is the very small capsule, about half a centimetre across. It is the narrowness of the tube holding the capsule that dictates the shape, so that the practical reasons for the probe-like appearance are the same as in the B&K reference microphones; nevertheless, the effect of the subliminal link with the standard by which all others are measured cannot have been lost on the designers.

Image is clearly important to Earthworks. The microphone boxes are carved from solid pieces of wood, with slots routed out and fitted with felt pads to support the microphone-even the box maker gets a credit. Clips for stand mounting are supplied, but without the thread adaptors for European use, a cheapskate omission too common to many American manufacturers.

Earthworks began with the OM1, which only works into electronically balanced inputs, but features the winning spec that is the Earthworks trademark--a time-coherent response way beyond 20kHz. The TC30K makes this 30kHz bandwidth available to those with transformer inputs, and the TC40K extends the time-coherent response to 40kHz, with the same lower limit of 9Hz and lower self-noise. Self-noise is a parameter Earthworks is self-conscious about, as on paper it is higher than much of the competition; at the same time, the microphones' sensitivity is relatively high, which goes a long way towards compensating for it. Certainly, I didn't find it to be a problem, and the TC40K is, indeed, marginally quieter, or at least has less top in its noise. All also claim to be able to handle 151dB SPL without pads.

Earthworks has produced a demo CD featuring the OM1; they really shouldn't have, as it sounds like someone's garage recording. It could serve as a demonstration of how not to record a jazz quartet: how to choose the wrong room; the wrong mic placement; the wrong mix; and the comparisons with industry-standard microphones sometimes have the opposite effect to what Earthworks intended. I'm glad I listened to the microphones before the CD, because I realised immediately that the demo doesn't do them justice.

The use of omnis is a neglected art, and I'm as guilty as the next man, being a Blumlein enthusiast. Many omnis aren't truly omnis, and the clarity of image and stereo spread of a well-placed 90° pair of figure-of-eights takes some beating to my ears. Having said that, the flat response and lack of off-axis coloration of a good omni is well known, and its applications both close up and in a spaced pair configuration are familiar enough. To be fair, the area of rejection of even the most accurate cardioid is pretty small, and very often its advantages over a similarly specified omni microphone are minimal at best.

EARTHWORKS STAKES its reputation not on the specs of its microphones, but on their sound. The specs are extraordinary, and the sound more than vindicates them. The most immediately striking aspect is a kick in the teeth to those who believe that low frequencies can only be captured by large diaphragms, as the depth of bass in these microphones is phenomenal. Not disproportionate or tweaked in any way, just accurate and full to an extent that would strain many people's credulity in a capsule so small. This is not at the expense of the top end, which comes over as flat and clean in the same way, as indeed it should given the quoted response of the microphones. Earthworks sets much store by time coherence, a quality often lacking in a traditional cardioid design, and reckon that getting this right affects the slam of a kick drum at least as much as the ting of a triangle. Certainly, there is an openness about the sound which makes it hard to argue with Earthworks' claims to accuracy.

My experience with the TC30K and TC40K left me highly impressed. Omni enthusiasts will find these microphones right up there with the best of them, and those less used to omni working should try them anyway to see what they've been missing. There's a smoothness and a realism about a good omni that is rarely achieved by anything else, and the Earthworks models have this in abundance.

The final surprise is the price: the TC40K is well under $1,000; and the TC30K little more than half that, despite the esotLarry image that often borders on the pretentious. As both microphones stand comparison with models costing five times as much, or more, they are a serious bargain.