Despite the presence of Martin Siewert’s and Burkhard Stangl’s guitars plus Boris Hauf’s saxophones, the defining textures of this Vienna-based quintet arise from the wave forms manipulated through those three musicians’ electronic add-ons as well as additional pitches created by Billy Roisz’s computer and oddly-named dieb 13’s turntables.

Steadfastly wedded to lower-case improvising – note the non-capitalization in the band’s name and the CD title – krom’s four tracks impress by subtly mixing pure acoustic instrumental impulses with electronic vibrations, crackles and static.

While triggered drones and meditative circular timbres predominate, none of the instant compositions goes too far without the interjection of a folksy guitar lick, melodic finger picking, low-frequency reed-biting slur or saxophone body tube resonation. Impressively, almost as speedily as they appear, these interjections are then subsumed into the unfolding band sequences.

Equally fading in-and-out of aural focus around these often-single-note-acoustic interpolations are the crunch and crackle of a vacant, rotating turntable; band-saw-like-buzzing from Hauf’s synthesizer; and computer-triggered approximations of grinding rotor blades, Game Boy wiggles and rocket launching.

With undulating warbles defined as layered, mechanized sound colors during the nearly-16½ minute final track, krom is confirmed as paramountly group music. Mesmerizing, although miniaturized, the echoes from reed flattement and slurred string fingering fill in those tinctures absent from Morse code-like vibrations and stuttering drones. Although using only a limited spectrum of the aural color wheel, efzeg still manages to paint a vibrant and perceptive modern sound portrait.