A mass port configured to tune a frequency response of an audio reproduction device is disclosed. The mass port includes a head portion and an insertion portion coupled to the head portion. The head portion includes a sealing structure on a rear side. The head portion is configured to attach to a rear plate of a driver at the sealing structure. The insertion portion is configured to be inserted into a speaker port on the rear plate of the driver. The head portion and the insertion portion include an air slot that runs through the head portion and the insertion portion.
