Rode K2 Valve Microphone reviewed by Glenn Bucci

October 2005

Rode K2 Valve Microphone
Continuously-variable, multi-pattern tube mic
reviewed by Glenn Bucci

Most high-end studios have wonderful tube mics that are the envy of every project studio owner. The good news is due to newer technology, lower-cost tube mics are coming out of China by many companies that included Rode. With cheap labor in China, companies are able to manufacture good sounding mics at low costs. Rode, in wanting to be more competitive — and to stand out from the pack — decided to move their manufacturing back to their home base in Australia.

Rode bought expensive high-precision finishing machines and computer-controlled metal lathes. Most of the mics are put together by automated machines, though some parts still need to be done by hand. Each mic is tested and has a 24-hour burn before it leaves the factory. With this format, they have much better quality control, and with manufacturing a thousand at a time, they are able to keep their costs down.

Rode previously released two low-cost tube mics: the NTV and NTK. In wanting to improve on the NTK (which is still a decent mic in its own right) they used an improved capsule. To design a good capacitor capsule is extremely complex and very expensive. Many parameters are needed to consider from the diaphragm material, shape, thickness and tension. There is also spacing on the back plate, signal connection, isolation dielectrics, polarizing voltage and damping arrangement. I must say that new capsule design which is now also included in some of their newer mics like the NT2-A is a solid, very well-built capsule. Other factors that come into play that affect the sound of the mic include the rear chamber labyrinth, which affects the linearity of the off-axis frequency response.

Once the capsule has been designed, it has to be mounted to a mic body. The grill size and shape all come into play on the tonality of the capsule. Then as my friend Hugh Robjohns (of Sound on Sound magazine) advised, there is the impedance converter circuitry, powering circuitry, and output circuitry — all of which affect the sound of the mic further.

The K2 circuitry includes the use of a 6922 dual triode tube, with a Class A configuration, and holds the tube with a porcelain sockets with a plastic tube clip. A double-layer, stainless-steel grille mesh is then installed on to the mic, which helps block radio frequencies while giving a attractiv matte nickel plated finish. As always, a good pop filter is highly recommended when recording vocals.

Another improvement over the NTK is having a variable modes from Omni, figure-8 and caridiod, all which are controlled on the external power supply. The frequency range is 20Hz-20 kHz, with no real peaks with the exception of one at 5 kHz in cardioid mode and a more subtle peak at 12 kHz in Omni mode. The signal-to-noise ratio is 81 dB, which is lower than many solid state mics.

Rode's founder, Peter Freedman, found the rejection rate of capsules is way down since the manufacturing days in China. The consistency between two mics are now so close, which can not be said about Chinese mics. A six-micron, gold-evaporated Mylar diaphragm are used as well as a secret process to age the mic to improve the precision.

K2 is very well made for a mic in its price range, well thought-out, and has high quality control. But how does it sound? I compared the K2 against the AKG Solid Tube, Audio Technia 4060, and Rode NTK, all which are under $1,000. In comparison with the NTK, both give the subtle tube sound with the K2 having a slightly smoother top end. It also had a little less sibilance compared to the NTK. With a good shockmount included and not being a fixed cardioid-pattern as the other mic¹s, I found the K2 to be a real winner. It does not have a dark tube sound, or a tubby sound as with some inexpensive tube mics. Since it has more of an open and less colored sound, this mic can sound great on both male and female voices as well as other applications, including acoustic guitar and wind instruments.

I found it gave a gentle smoothness to vocal and acoustic guitar tracks that my Blue Blueberry could not give. The Solid Tube and 4060 both had a darker sound over the K2 though both had a nice sound; I feel their use would be more limited due to the stronger color character of both.

I had my eye on the Audio Technica 4060 for quite some time and really like the sound of the mic. However after several comparisons with the K2, I found the sound of the K2 along with the flexibility the continuously-variable patterns, and costing hundreds less, made it easy for me to choose the K2. Though it will not give you the sound of a high-priced Neumann or Rode Classic II, the K2 is a mic to use successfully in many situations. The only thing I could find fault with is that the mic did not come in a nice wood box. But in order to keep costs down they put the mic in a hard-plastic case that included a cable (to connect from the transformer to mic), transformer, shock mount and mic. If you are looking for a nice sounding tube mic with quality that won't break the wallet, I recommend checking out the K2.

For more info on the Rode K2 mic and other Rode products visit www.rodemic.com

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Glenn Bucci is a musician and received the same degree in recording as Rupert Neve, which Rupert calls QBE: Qualified by Experience. He owns Revelation Sound Studio, where he engineers and produces for clients and works on his own original blues/ jazz material.