The present invention provides a gas delivery device and system and methods for delivering humidified pressurised gas through a conduit to a subject. The configuration of the elements of the gas delivery device enable the device to be conveniently oriented from a horizontal to vertical position to suit the needs of a user. The gas delivery device may incorporate a Helmholtz resonator for dampening sound of the motor. The conduit may incorporate concentric tubes to allow it to conveniently engage the humidifier at a single aperture. The invention includes a method of operating a blower motor for a gas delivery device using a single Hall sensor. The gas delivery device may be disposed in a sound housing for dampening the sound of the motor. The gas delivery device may include a valve chamber allowing the blower to rapidly change gas pressure or flow rate. The invention also includes a method of operating a blower motor by adjusting the timing of winding excitations depending on the rotational position or velocity of the impeller.