“An Awesome Wave” is the debut by Alt-J, a quartet from Cambridge, UK. And, awesome surely is the word to describe outstanding tracks like “Tessellate.” “An Awesome Wave” is a calm, quiet album with strong folk overtones, sung in a voice sometimes breaking with emotion. Yet Alt-J are not lamenting and whining like so many singer-songwriters. Relaxed, light and easy-going numbers such as “Something Good,” “Dissolve Me” and the yearning “Matilda” are absolutely enthralling. The mean, gnarling synth bass on “Fitzpleasure” and Eastern influences on “Taro” add some variety to the indie songs. Alt-J have delivered an absolutely convincing debut that raises expectations for their sophomore album.