When you search for the K42 Russian PIO caps through google you can find results back a few years now. The tube guys have been onto Russian caps for a while, but surprisingly there is not a lot of information available on them; perhaps becuase all of the technical information is in Russian.

People have had good results with these in tube amps, power supplies and speaker crossovers. You can find a few comparisons to the brand name PIOs.

The K42y seems to be generally well regarded. The K40Y is considered to be almost identical in sound to the VitQ, but honestly in the Max I can't tell the difference between the K42y and the VitQ. And, the K40y is about as big as the VitQ, which is far less suitablefor those who want to stay under 1" for the Hammond case - the K42 is small and sounds great.

The ultimate is the K75, but these are very rare (those tube guys probably have them stashed), and I haven't seen any small k75s at all on ebay - only the really big ones.


Head-Fi user "Ferrari" used the K40y in his Max.

Here is a post from a Russian user over at diytube explaining the differences in the Russian caps: DIYtube.com on Russian caps


K15-4 Ceramic HV "doorknobs"
K15-5 Ceramic HV Disc

K31 Silver Mica "kidney bean" style cap

K40P-2B Paper in Oil, 5% tol.
K40U-9V Paper In Oil , Silver body, 10% tol.

K41-1A PIO, High Voltage "Pulse" caps

K42U-2 PIO, green painted body
K42Y-2 PIO, green painted body

K50 Aluminum Electrrolytic

K71-7V Polystyrol "High Tolerance" 1% or 2% tol.

K72P-6 Teflon Dielectric 5% tol.

K73-14 PETP High Voltage
K73-15 PETP / Dry Mylar
K73-16 PETP / Dry mylar
K73P-4 "tub " style AC capacitors (may be paper or mylar, still TBD)

K74 HV caps

K75-10 PIO, Green body
K75-15 PIO, High Voltage "tub"
K75-17 PIO High Voltage "tub"
K75-24 PIO Green body tubular
K75-28 PIO High Voltage "tub"

BMT-2 Paper In Oil

FGT High Voltage Teflon Dielectric, Ceramic body (almost beer can size)

KBG PIO

KBI HV "doorknob" RF / Transmitting cap

KSO Silver-Mica "precision" caps

MBG Paper-Aluminum "tub" AC caps



The letters OTK are initials for "Otdiel Technicheskovo Kontrolya" or Bureau of Technical Control which indicates that special mil-spec or industrial testing standards are applied. In other words, "Top Shelf."

- Rob Wills, from a forum post on Head-Fi.org.