The first two full-lengths by 40 Watt Sun — essentially the solo vehicle of Patrick Walker, the U.K. singer-songwriter known previously for his work in the doom-metal band Warning — found the trappings of conventional heaviness gradually draining away. By the time of this third LP, the project bore little sonic resemblance to Walker’s prior outfit, beloved in the underground for the almost alarming despondency of its second album, 2006’s Watching From a Distance. But on a deeper level, there was a clear through-line from Warning’s bleak beauty and the patient, understated epics found on Perfect Light. Largely stripping away distortion in favor of acoustic guitar, piano and gentle drums, Walker puts the focus here on his lyrics — poetic, almost prayerful meditations on the bittersweetness of life and love — and, most prominently, his voice: an extraordinary instrument that can range from a gentle murmur to an arresting wail, bursting with yearning, regret and, at times, sheer desperation. In this stripped-down context, the slow-burning climaxes of songs like “Until” and “Raise Me Up” somehow take on an even greater intensity. Shot through with a timeless, unclassifiable beauty, this may be the definitive statement to date from one of the great musical melancholists of our time.