The Soviet Union issued this card in 1979, the hundred anniversary of the birth of composer Alfred Kalnins. Born in Lativa, the postcard hails Kalnins as a "people's composer of the Lavitan Socialist Republic." In addition to composing, Kalnins was an organist, teacher, conductor and music critic. His most enduring composition is his nationalistic opera Banuta. He spent most of his life in and around Lativa, except for a stint in New York City (1927-1933). He held organist and teaching position in Parnu, Leipjaj, and Tarnu, before settling near the end of his life in Riga, and serving as organist of the Riga Dom and rector of the Latvian Academy of Music.
The art on this postcard features a building facade, perhaps that of a music conservatory in one of the cities mentioned here. Also included is a page from a musical score, presumably an image of one of Kalnins' works.
The 4-kopek postage image includes a representation of Kalnins and the facade of an organ. I do not believe the organ is that in the Riga Dom, but that begs the question which organ is it? Two other instruments of some import are related to Kalnins, that in St Anna's Cathedral and Holy Trinity both in Leipaja. I have not been able to find images of those churches' interiors nor their instruments.