Y Niwl or, "the world's highest altitude surf band," have to cruise down their mountainous habitat every couple of years to give everybody a wave and allay some twenty-first century Rock and Roll. Since the surprise success of their 2010 self-titled debut record, the Welsh outfit have basked in its plaudits. From touring the four corners of the United States to the rolling hills and smiling coasts of Wales, there are plenty of reasons why Y Niwl have taken their time on their sophomore effort, 4, the biggest being the aforementioned schedule.

4 is written in a similar vein to their past material; as close to band member Alun Evans' memory of "an old Shadows album on tape." So, if you crave slack guitar solos garnished with pastiche piano, and a rhythm section that won't quit, you won't be disappointed.

Opener 'Dauddegtri' is as surf a moment as the album has at its behest. Based on a classic 12-bar-blues chord motif, it throws curly fries and hamburgers in your face and, without even blowing a kiss, rockets by in 1:46 seconds. Track two 'Dauddegdau' arrives and we're dumped right into a similar sound; soon enough it becomes clear that the listing of this mini-record is fairly indistinguishable. Whilst there are differing melodic glimpses and changes in emphasis, stylistically, it's extremely self-perpetuating.

Y Niwl's musicianship is entertaining and fiery. Whether you look at the bouncing sixties' organ solo showcased at the midway point in 'Undegnaw', or the intelligent, subtle interactions on 'Dauddegpedwar' this is their strongest element. It's an obvious point to make; after all, they're an instrumental band – but I felt a dignified optimism when I discovered that their songs regularly emerge from 'jams'. At times, 4 sounds a little like Battles' Dross Glop,

There are glimpses of really interesting songwriting on 4 - 'Dauddegpedwar' and 'Dauddegtri' certainly contain the majority of the record's better moments. Whilst painting on the same canvas as one another, the two are very refined, interesting songs that juxtapose delicate moments with helter-skelter stomach turns. It doesn't really happen frequently, though. There's not enough charm on the record for it to go beyond than the initial, 'Ah, this is different' smile and, unfortunately, your reaction becomes more and more diluted as the album progresses.

Of course, Y Niwl define themselves with a really simple, vivid idea to direct the music they create but it feels like there's not enough thought or diversity to validate the time you spend listening to the album. With more care, they could be as exciting an act on record as I'm sure they are on stage, but 4 plunges them deeper into a wilderness of hefty promise which rarely fulfils.