We report here on the realization of a single-tube on-beam quartz-enhanced photoacoustic (QEPAS) spectroscopy sensor employing a custom-made quartz tuning fork (QTF) with a large prong spacing. The prongs of the QTF have been designed in order to provide a quality factor twice higher when the QTF operates in the first overtone flexural mode than in the fundamental mode. The influence of the microresonator tube on the main parameters characterizing the sensing performance of the QEPAS spectrophone, including the quality factor, the magnitude of the QEPAS signal and the associated background noise was investigated in detail.