Abstract: A marine seismic source comprises a housing having a central axis, an open end, and a closed end opposite the open end. In addition, the source comprises a piston coaxially disposed within the housing. In addition, the source comprises a flywheel disposed within the housing and axially positioned between the closed end and the piston. The flywheel is configured to rotate about a rotational axis. Further, the source comprises a connecting rod moveably coupling the piston to the flywheel. The connecting rod has a first end pivotally coupled to the piston and a second end pivotally coupled to the flywheel. The second end of the connecting rod has a first position at a first distance measured radially from the rotational axis, and a second position at a second distance measured radially from the rotational axis. The first distance is less than the second distance.