IRPA/Oktava MK13

The Oktava MK13 is a Soviet-made multi-pattern large diaphragm tube condenser microphone using a double-sided M7 style capsule and a 6S31B tube (also used in the LOMO 19a19). The microphone was developed by the IRPA in Leningrad in the 1960s, and was put into regular production at the Oktava plant in the early 70s although in very small numbers (less than 300 were made). IRPA designs that made it to regular production were manufactured by the Oktava plant (and KINAP/CKBK designs were manufactured by the LOMO plant), although many of their designs never made it that far and were limited to very small special-issue batches, such as the MK8, MK12, MK14, MK15 - I’ll be sharing those models soon.

The MK13 is an incredibly well-made microphone, the same build quality and sound as its LOMO cousins. Most of us are familiar with Oktava after they became popular by mass producing and exporting affordable high performance microphones in the 1990s, most notably the MC-012, the MK219, and the MK319. But in the Soviet era, the Oktava factory mostly specialized in moving coil dyamics and gorgeous ribbon microphones. They also made a few very high quality condensers like the MK13. As a tube condenser, it stands out from other Soviet (LOMO) tube mics in in that it is the only dual-diaphragm multi-pattern Soviet tube condensor produced with electronic pattern control (selected at the PSU). The LOMO 19a10 is a multi-pattern tube condensor, but it uses two fully polarized diaphragms, each with their own tube and an external switchbox that passively blends the signals and their polarity with a transformer matrix (another future post). 

The MK13 is one of my all-time favorite condenser microphones ever made, including the well-known classics but they are hard to come by, especially with good original diaphragms. You can see some corossion around the center terminal on this MK13, but thankfully this one sounds exactly as it should and matches our second fully original MK13. Of the dozen or so MK13s I’ve come across, I’ve only seen two with good original diaphragms. If properly reskinned, a serviced MK13 should sound just as good as an original.