Sergei Vladimirovich Protopopov (Russian: Серге́й Владимирович Протопопов; 2 April [O.S. 21 March] 1893, Moscow - 14 December 1954, Moscow) was a Russian avant-garde composer and music theorist.
Not much is known about his life. After studying medicine at the Moscow University, he attended the Kiev Conservatory where he pursued studies of music with theorist Boleslav Yavorsky. He graduated in 1921 and started working as a conductor. During 1938-43, he taught at the Moscow University.
He was associated, as many composers of the Russian avant-garde, with the Association for Contemporary Music. Due to the ideological incompatibility of avant-garde with the contemporary regime supporting socialist realism, his works were mostly unknown following 1931.
Protopopov's 2nd Sonata is a gargantuan work of incredible creativity and ingenuity, at times abyssal, profoundly dark, other times shimmering, celestial, blinding.
The work begins with a fast tremolo figuration of ecstatic major seventh chords in pppp, located in the low register. One important thing to note is that due to Protopopov's unique harmonic language, accidentals are valid only for the note of which they stand. Soon the mass of sound leads the listener to the Allegro, were some harsh, menacing chords are followed by a splendorous, forceful ascending cascade of fourths. The initial figuration appears again, marked "lontano, sgridando, sempre più perseveramente" (far away, scolding, more and more perseveringly). The piece uses basically the entire register of the keyboard at it's utter extremes. The development is characterized by a slow, funebre melodical section, where the cascade of fourths eventually reappears, at times marked "come una potente volata" (like a powerful sprint). The music grows gradually, getting denser and denser, to the point of being written on four staves... A more playful, scherzando theme is introduced, where a quite Moslolov-ian expression appears "acuto, col suono dell'acciaio" (sharp, like the sound of steel)... then, another indication "col suono leggerissimo di cristallo" (with the very light sound of crystal). At the end of the developement there are some mysterious, resonant arpeggios, "dolce, soave, come in una nuvola" (sweet and suave, as if in a cloud). The arpeggios eventually lead to some tenebrous chords, at first in fff, which "decease" into a ppp, which brings the colossal recapitulation: the tremolando figure is presented again, followed by the more ironic scherzando one, now with the expression marking "scintillando, galleggiando" (sparkling, floating) which eventually explodes into the grand, final, furious, Presto: a stormy sequence of tritones/fourths, marked "con una grande respirazione, con massima potenza" (with great breathing, with sheer power), which concludes this cosmic piece with extreme violence.