For metal fans, Dub Trio might be too arty; for fans of experimental music, the band is a little too hard-rock. In pushing these extremes further apart, IV won’t win new converts from either base. The fully instrumental album IV is Dub Trio’s heaviest collection yet, with a flurry of ideas eventually devolving into thudding sludge-rock. In terms of raw energy, the thrash-frenzy of “Noise” sets a high-water mark for the band, but IV still probably won’t satiate the head-banging crowd: The use of spaced-out dubstep hasn’t gone away, and bad-acid-trip soundtracks such as “Ends Justify The Means” would only confuse the mosh pit.

After recent collaborations and tours with Mike Patton and Matisyahu, Dub Trio’s versatility has only grown, and there’s a rarely a missed chance to showcase it. Ambient noise and stoner atmospherics wash the album in a chilling haze, sometimes to a tedious degree, on tracks such as “1:1.618.” By the closer, “Thousand Mile Stare,” which begins with toy piano and ends with stargazing static, the sledgehammer riffs have been broken down and rebuilt into an unpredictable patchwork of instruments and styles. IV is a little like Frankenstein’s monster: It’s a freak hybrid that takes unquestionable genius to assemble, but it’ll probably scare off the commoners.