The JBL OnBeat dock's output is created by two little transducers, each powered by 7.5W of power. These are full range drivers, so unlike larger docks there's no separation between the speakers that supply bass and high-end detail. The two little silver cones hanging out behind the front grille have to do all the work.
As long as you keep the volume at a fairly low level, they perform extremely well, supplying plenty of detail and an unusually punchy, exciting sound. However, once you push the dock up to the levels needed to fill large rooms, the limitations of a small device like this become apparent. It can't produce enough bass at higher volumes to match rest of the sound, giving the OnBeat an incomplete, slightly strained sound.
This is symptomatic of the dock's design as well as the teensy drivers. Separates speakers and larger docks tend to factor-in a significant internal cavity and bass outlet for their woofers, but there's no outlet here - and precious little room for much space inside at any rate.
If you want to use the JBL OnBeat as a kitchen or bedroom unit, for relaxed listening, it produces the refined sound we'd expect from a weighty speaker name like JBL. If you want a dock to fill the floor at parties though, you'd be much better off spending your £150 on something more substantial, like the Philips DS8500 or the Roth Charlie wireless system, which is now available for peanuts from some retailers.
Even at lower volumes, if you like your music filled with powerful beats - whether they come from a rock drummer's footpedal or a prod at a TR-808 drum machine - you may be better off with one of Klipsch's iGroove models. They use larger drivers and therefore tend to struggle less with lower frequencies.
There's still a lot to admire about the JBL OnBeat though. Its design is bold and well-executed, it's small and the sound offers good clarity and balance at lower volumes.
Small and well-built, the JBL OnBeat offers quality at a price competitive with its rivals. However, its diddy drivers struggle to dole out enough low end at high volumes, meaning they're only suitable for relaxed listening, not for powering a party or rocking out in front of a mirror to, hairbrush in hand.