SARATOV, Russia — Mike Matthews, a sound-effects designer and one-time promoter of Jimi Hendrix, bought an unusual Russian factory making vacuum tubes for guitar amplifiers. Now he has encountered a problem increasingly common here: someone is trying to steal his company.

Sharp-elbowed personalities in Russia’s business world are threatening this factory in a case that features accusations of bribery and dark hints of involvement by the agency that used to be the K.G.B.

Though similar to hundreds of such disputes across Russia, this one is resonating around the world, particularly in circles of musicians and fans of high-end audio equipment.

“It’s rock ‘n’ roll versus the mob,” Mr. Matthews, 64, said in a telephone interview from New York, where he manages his business distributing the Russian vacuum tubes. “I will not give in to racketeers.”

While most of the Soviet electronics industry has disappeared, rendered obsolete by Japanese makers and Silicon Valley, ExpoPul, which opened in 1953, is thriving. It is a rare example of a Soviet-era factory that became a success without painful reforms. Hidden in this provincial town, its 1950′s vintage technology survived long enough to become a worldwide hit.

If the tube factory dies, so will the future of a rock ‘n’ roll sound dating back half a century, the rich grumble of a guitar tube amplifier — think of Jimi Hendrix’s version of “The Star-Spangled Banner” — that musicians say cannot be replicated with modern technology.

“It’s nice and sweet and just pleasing sounding,” Peter Stroud, the guitarist for Sheryl Crow, said in a telephone interview from Atlanta. “It’s a smooth, crunchy distortion that just sounds good. It just feels good to play on a tube amp.”

He added: “It would be a catastrophe for the music industry if something happened to that plant.”