If you came to E.S.T. through Esbjörn Svensson Trio albums like Tuesday Wonderland (2006) or Viaticum (2005), you probably remember the pianist first. That's natural — Esbjörn Svensson had the tunes and the name above the door. But spend time actually listening to those records and you start to clock how much Berglund is doing. He plays with a heaviness and a sense of forward motion that keeps the trio from floating off into prettiness. He anchors things when they need anchoring and then, without announcement, becomes the most disruptive voice in the room.

His sound on the bass is distinctly his own. It's not the walking bass of classic jazz, and it's not the in-the-pocket funk of fusion either. It sits somewhere in between, with a physicality that owes something to rock and a harmonic awareness that's purely jazz. He uses effects, loops, and extended techniques in ways that feel purposeful rather than decorative — tools to expand what a double bass can actually do in a live setting, not just studio tricks. In the E.S.T. context, that meant the trio could conjure textures that a conventional acoustic group simply couldn't reach.

After Esbjörn Svensson's sudden death in 2008, Berglund could have coasted on the reputation those years had built. Instead, he formed Tonbruket, a four-piece that leans harder into rock, electronics, and improvisation. The band is less refined than E.S.T. in the best possible sense — rougher at the edges, more willing to sit in noise or groove for longer than is strictly comfortable. It's a project that feels like Berglund finally making music entirely on his own terms, without any implicit brief to keep things accessible.

What makes Berglund genuinely interesting as a bassist is that he thinks like a composer. He doesn't just support the harmony — he's shaping the narrative of a piece, deciding when to push tension and when to let it breathe. That quality was essential to what made E.S.T. work as a trio rather than a piano-led group with accompanists. Magnus Öström, the drummer, had similar instincts, and the two of them together gave Svensson the freedom to take melodic risks because they were managing everything underneath.

He is not a household name outside of jazz circles, and that's partly because bassists rarely are. But among players who care about what the instrument can actually do in a modern context, Berglund is taken seriously. If you haven't started with the E.S.T. catalog, that's the place. Just make sure you're listening to the whole band, not just the piano.