So you’re sitting at home recording a vocal track and you think, “Gee, this vocal sounds kind of harsh.  And when I try to EQ it, it ends up sounding dull and unnatural.  I wonder if it’s this affordable Chinese-made microphone that I’m using that’s causing the problem.  Boy, I wish I had a [fill in the blank] microphone, which I can’t afford, to make it sound more balanced.”

Now, what if the conversation you had with yourself went like this instead?: “… I wonder if it’s this affordable Chinese-made microphone that I’m using that’s causing the problem.  Maybe I should send this mic to OktavaMod to have them modify it to create a killer mic that can hang with the best microphones on the planet!”

OktavaMod is a company that offers an aftermarket upgrade service for your cheap Chinese and Russian-made microphones, and they are a hit with top professionals and home recordists alike.  Michael Joly, President and Founder of OktavaMod, sent us one of his upgraded large diaphragm tube condenser mics to try out.  We shot it out against some of the greatest large diaphragm condensers of all time (including the untouchably expensive vintage Neumann U67 and U47 tube condensers) and it stood strong with the competition.  See and hear it for yourself by watching the video review here (link).  The upgraded mic that OktavaMod sent us was originally an ordinary MXL V69 tube mic, which retails for about $300, and the mod itself costs $359.  That’s amazingly cheap considering the quality of this mod.

OktavaMod Tube Mic Upgrade

The reason I used vocal tracking as an example in the conversation above and in the shootout is because large diaphragm tube mics are the go-to choice for vocals.  Condensers tend to be very detailed and articulate, but the mass of the large diaphragm slows the mic’s response slightly (only milliseconds) and gives it a smooth quality. In addition, using a tube condenser adds a wanted bit of warmth.

Now let’s get historical and technical.  Almost all Chinese-made large diaphragm capsules are modeled after the Neumann K67 capsule, which was used in the famous Neumann U67 microphone.  The K67 capsule has a slight presence push, giving it an unnaturally bright sound.  In order to compensate for this brightness, the engineers at Neumann designed the U67’s circuitry in such a way as to attenuate these high frequencies and make the output more flat and natural.  By contrast, the Neumann U47 (undisputedly the most famous and sought-after vocal mic in history) used a K47 capsule, which had a very flat EQ response.  Neumann matched this capsule with a flat output circuit design and the overall response of the mic is very balanced and natural.  Other things, like the specific tubes and transformers that Neumann used, gave each of those mics their unique sonic signature.  But the matching of capsule and circuit design is important in understanding what’s going wrong in your Chinese-made mics.

Almost all of the Chinese large diaphragm condensers employ a K67-type capsule matched with a U47-type circuit design.  This mismatch of the K67-type capsule’s high frequency emphasis with the flat response of the U47-type circuit gives these mics an unpleasantly harsh and unnatural quality.  This is the first major problem that OktavaMod addresses in this mod.  Michael Joly has combed the planet and found a manufacturer that makes his K47-type capsule that matches almost identically the original K47 within very strict tolerances.  Michael Joly’s K47-type capsule is a better match for the circuit in your mic – you not only get a mic that sounds more accurate but you also capture the timbre balance of a U47!

(See also my review of the MJE-K47H (link), which is a screw-on large diaphragm condenser headbasket for small diaphragm condensers that uses the same K47-type capsule.)

Other improvements in the mod include upgraded critical components in the circuit as well as the removal of layers of mesh from the headbasket to make your mic a single-layer headbasket.  This cuts down on resonant frequencies in the headbasket and gives the mic a more open sound.  Upon request you can also have a new-old-stock tube installed, which can give your mic that extra warm and full-bodied tone.

So before you go out and drop crazy money on your dream mic or even a hefty sum on a middle-of-the-road mic, check out the huge results you can get from OktavaMod for a very modest price.  Go to for more info, and check out all of their other cool products and solutions.

by Michael Vecchio