Quartet Diminished is an Iranian avant-prog and avant-jazz ensemble founded in Tehran in 2013 by guitarist and composer Ehsan Sadigh. The band operates at the intersection of progressive rock, contemporary jazz, Persian traditional rhythms, ethnic ritual music, and 20th-century avant-garde composition — building a language where structured writing and free improvisation carry equal weight.
The original lineup brought together four distinct voices: Ehsan Sadigh on guitar, Mazyar Younesi on piano and vocals, Peter Soleimanipour on clarinet and saxophone, and Rouzbeh Fadavi on drums. After Soleimanipour’s departure, woodwind duties passed to Soheil Peighambari, whose clarinet and saxophone work deepened the band’s textural range and pushed its improvisational edges further.
Ehsan Sadigh
is the founding force behind the group — a guitarist and composer whose writing draws from Persian modal traditions, progressive rock architecture, and modern classical forms. His compositions set the structural backbone: long-form pieces with shifting time signatures, layered harmonies, and space for collective improvisation.
Rouzbeh Fadavi
occupies the drum chair, anchoring the band’s complex rhythmic structures. His drumming navigates irregular meters and Persian percussion patterns while maintaining the fluid, conversational feel that improvisation demands.
Mazyar Younesi
handles piano and vocals, contributing harmonic color and melodic invention. His piano work bridges classical sensitivity and jazz spontaneity, while his vocal passages add an atmospheric, almost ritualistic dimension to the band’s sound.
Soheil Peighambari
plays woodwinds — clarinet and saxophone — bringing a reedy, exploratory voice that threads through the ensemble’s dense arrangements. His playing extends the band’s dialogue between Persian woodwind traditions and Western jazz phrasing.