Bill Sitler has been doing mods on these mics for a while. Here is his take.
Brand new 012 mics benefit just as much as older ones.
On searching the Internet I find a significant amount of confusion on this topic. Many speculate that brand new 012’s have all the improvements already incorporated, so the modification will have no effect on performance. This is simply not true. Here are the facts, based on years of experience working with these microphones. New mics have two basic changes in addition to serial numbers. (1) New mics are slightly longer to accommodate a new style XLR base. (2) Oktava no longer uses any wet-slug capacitors in the 012. Old mics typically used wet-slug caps for C3, C4, and C5, and sometimes even C2. These wet-slug caps are prone to leakage and can even damage the circuit board. Most new mics use BBC caps, like the ones in the kit, for C3, C4, and C5. But beware; even brand new mics can use different brands of lower quality and various values. The majority of the sound improvement comes from the changes on the front of the board, where Oktava has made no improvements. In fact I see more variation of factory parts than on older mics. So YES, the sound improvement from modification is just as evident on new mics as older ones!
The modification is only for true Russian made Oktava's. True Russian Oktava 012's came with the 10db pad and the metal mic clip and can be labeled MC or MK 012. Only newer ones (2002) have serial numbers. Click HERE for more info on fake Oktava 012's.
Good soldering skills are required to perform the modification. The Circuit board is small and delicate and can be easily damaged. If you do not feel comfortable doing the modification yourself, you should send your mic(s) in for modification.
A difference you can Hear!
"Greetings from Australia.Thought i'd drop you a line and confirm the 012 mod is a must for all 012's .It's cheeze & chalk difference!! .Amazing clarity compared to the original .I will not be parting with these mic's ever.Even the tech who did the mod was amazed!!In fact i might buy 2 more Oktava 012's and respective mod kits regards Robert b Dillon Aria Award winning Recording Engineer:Blues&Roots. Melbourne Australia"
Robert B. Dillon
"One thing is for certain, these little mics sound great now and are far more useful. In some cases, I might even go to them instead of my KM184s."
Joseph Bregande
The kit contains the following parts, individually packaged and labeled:
The kit includes all parts required for standard modification of the Oktava MC012 or MK012.
R1 - 1G Thick Film Resistor
R2 - 1G Thick Film Resistor
C1 - COG ceramic capacitor
C2 - Tantalum capacitor (optional C2 Film by-pass capacitor now also included!)
C3 - electrolytic capacitor
C4 - electrolytic capacitor
C5 - electrolytic capacitor
Q1 - Toshiba Audio FET
Q2 - Toshiba transistor (no longer using the Fairchild 2n5087, see notice below)
Complete Instructions