The OB1 splits the input instrument signal into two separate paths. One amplifies the clean signal, with all the clarity you would expect from Orange. The other adds stages of gain to the upper harmonics only, controllable via the amp’s Gain knob. These two elements are combined using the amplifier’s Blend control which adjusts the balance between clean and dirty. The Blend control can then be remotely engaged or defeated using the optional footswitch.
The gain and blend range allows for almost any tone, from a subtle level boost that cuts through the mix to added girth and presence at moderate settings that fattens up chorus passages, and fully saturated savagery at the extremes. However you dial it in, the OB1 always maintains critical low-end definition, right the way up to the most offensive settings.