Spanish composer, educator, teacher and music critic who used the pseudonyms "Clivis" and "Juan del Brezo".

Born on 29 July 1895 in Vigo (Pontevedra), and passed away on 24 March 1964 in Madrid. His parents were Marcos Mantecón Gómez, who worked for the Spanish treasury, and Rita Molins.

When Juan José was quite young, his family moved to Madrid. There he studied Teaching, and later Law and Philosophy and Letters at the Universidad Central, where he received his doctorate. Starting in 1912, he worked as a civil servant for the ministries of Public Education, Public Works and Finance.

Mantecón self-taught music himself, through treatises on harmony, counterpoint, fugue and musical analysis. He also received advice from Joaquín Turina, Bartolomé Pérez Casas and Manuel de Falla, with whom he established a close personal and professional relationship. As a critic, he considered Falla the most influential figure of the day, by virtue of his work and style.

In 1914 Mantecón was secretary of the music section of the Ateneo de Madrid, where he gave his first lecture on teaching. Starting in 1917, his articles -signed "Clovis"- were published in "España Nueva", "El Parlamentario" and "El Pensamiento Español"; and from 1920 to 1934, he wrote for "La Voz" using another pen name, "Juan del Brezo". In 1925 he collaborated with Unión Radio and "Ondas" magazine. The following year he married Carmen Marín Ocón. He was a forerunner of the radio serial, broadcasting shows like "Una aventurilla sin aventura" and "El rubí negro o el corazón de la Diosa Yogowla" in 1931-1932.

The Spanish Civil War forced him to stop working. After the conflict, he stayed in Madrid and focused on teaching. He was a critic for "Santo y Seña" from 1941 to 1943, and the daily "El Alcázar" from 1953 to 1954.

In 1945, Mantecón began giving radio talks on Radio Madrid and Radio Nacional de España. In 1952 he was promoted to senior supervisor of the General Corps of Civil Servants of the Public Treasury. He enjoyed teaching singing, and worked as director of musical studies at the Teatro de la Zarzuela in 1960.

His activity as a critic was linked to the musicians of the Generation of '27, and Adolfo Salazar was his contemporary. As a composer he experimented with different trends, from impressionism, neoclassicism and irony, to late nationalism. Some of his best-known works are "Sonatina", "Dos poemas líricos" (1918) for piano, "Quinteto No. 1" (1923) for strings and piano, "Circo" (1923) for piano, "Parada"(1928) for orchestra, "Danza del atardecer" (1930) for orchestra, "Tres nocturnos" (1930) for small orchestra, "Minueto" (1932) for pulse and plectrum orchestra, "Con qué la lavaré" (1935) for strings and piano, "Una copla de Mingo Revulgo" and "Canción del marqués de Santillana" (1935) for soprano and orchestra.

El fondo personal de Juan José Mantecón se conserva en la Fundación Juan March, ubicada en Madrid. Contiene 188 partituras manuscritas e impresas, recortes de prensa, cartas, escritos y programas de mano de conciertos.