Apr 19, 2023
By Andrew Thompson
Now known perhaps as much for products targeted at broadcast applications as they are for studio microphones, in the early 2000s the Australian company RØDE Microphones’ burgeoning reputation rested largely on the NT1 and NT2. These mid-90s large-diaphragm studio condensers were reassuringly classicist in design and delivered a high level of performance, underpinned by a conscientious adherence to premium components which belied their then-disruptive pricing.
Released in 2001, the NTK and NT1000 were also aggressive value propositions, and also large diaphragm condensers, but they incorporated improved industrial design and a new proprietary edge-terminated capsule, and, perhaps surprisingly for the time, the NTK was a valve microphone. The paucity of affordable valve-based options in the professional and prosumer audio market of the day might have made that venture seem somewhat of a gamble, but the exclusivity of valve microphones and the enduring widespread reverence held amongst the audio community for the technology’s most celebrated examples – the Neumann U47 and U67, the Telefunken ELA-M 251, the AKG C12 – had certainly preserved their allure, and the NTK was well received.
The microphone is a traditional side-addressed fixed-pattern cardioid design with a 25mm capsule. The body is large, sturdy, simply designed and attractively if not opulently finished, with the address side of the microphone indicated by a gold dot just below the grille. The valve, a 6922 twin-triode provided stock, is easily accessed along with the head amplifier circuitry by unscrewing the threaded lower portion of the microphone body. Power is delivered from the included power supply unit by means of an included standard 7-pin XLR cable, which also carries audio back to the PSU unit. The power supply is a robust and utilitarian design and features an on/off switch and 7- and 3-pin XLR sockets. A simple stand mount is also provided.
The manufacturer claims an unusually wide useful frequency range of 20Hz-20kHz for the NTK, which may be in part attributable to the edge-terminated capsule, as well as 12dBA self noise – which for a valve microphone must be considered very competitive – and a relatively modest sensitivity of 12mV/Pa.
On-axis frequency response is essentially neutral between 50Hz and 2kHz, describing a steady and very gentle ramp from around -1dB at 50Hz to perhaps +0.25dB at around 1800Hz, where sensitivity begins to increase more emphatically. A subtle presence boost, generally around +2dB but with a +4dB peak at 5kHz, precedes a +6dB brilliance peak around about 13kHz. Sub bass frequencies are very slightly erratic but within -2dB of zero.
The cardioid pattern is quite pronounced, developing hypercardioid null points below 1kHz and becoming wider and gentler above 4kHz. Off-axis rejection is quite consistent at 90 degrees, purportedly -8dB at 1kHz and -6dB at 4kHz, and a hardly draconian but very steady -18 to -17dB at the rear.
Valve microphones owe a great deal of their considerable mystique to their reputation for lending a pleasing tone to vocal performances, being associated with some of the most celebrated vocal recordings of the mid-20th century. How much of this reputation is strictly deserved is up for debate, but lead vocals remain a popular application for valve microphones in the studio, and indeed they are stated by RØDE as a recommended application for the NTK. The microphone’s extended bass response certainly preserves the weight of closely mic’d vocals, and its slight presence lift and brilliance peak can add a welcome sense of intimacy. The 5kHz peak does tend to enhance sibilance and general mouth noise, however, which may be problematic on some voices. Likewise, the NTK’s slight midrange tilt toward the treble may tend to prefer those voices prone to overemphasis of the lower midrange and bass frequencies over naturally brighter voices.
Louder, closer performances may also benefit from the slight, pleasant distortion and naturally compressed dynamics associated with valve amplification, and indeed this principle may be extended to louder instrumental sources and amplified sources. That same compression, especially in a large diaphragm design, may not lend itself to fastidious accuracy in the representation of fast transients, so other options may be preferred where absolute fidelity to such material is deemed paramount. However the NTK’s low self-noise goes hand in hand with a relatively undistinguished specified sensitivity, and the small amount of extra headroom could in theory ameliorate this issue to some extent.
On the other hand, a hotter mic may be preferred when recording more distant sources, especially if possessed of a great dynamic range. The fairly tight cardioid pattern also suggests larger ensembles may not always find the NTK appropriate, despite its relatively benign off-axis colouration, while its relatively gentle degree of rear-rejection may lead to problems in complicated acoustic environments.
Although its construction is first-rate, and while certainly technically capable of being used as a jack-of-all-trades large condenser, the NTK gives the impression of having been intended for a single overriding purpose: to affordably and reliably deliver a pleasing but not overly confected version of the “valve sound” on smaller, relatively loud or close sources – lead vocals or lead instruments in a studio setting. When used in this capacity it’s hard to fault, and its extended frequency range may occasionally recommend it over some more famous models in such circumstances.
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