Figure F.6a illustrates a generic two-port description of the series adaptor.
As discussed in §7.2, a series connection is characterized by a common velocity and forces which sum to zero at the junction:
The derivation can proceed exactly as for the parallel junction in §F.2.1, but with force and velocity interchanged, i.e., , and with impedance and admittance interchanged, i.e., . In this way, we may take the dual of Eq. (F.11) to get
diagrammed in Fig.F.7. Converting back to force wave variables via and , and noting that , we obtain, finally,
as diagrammed in Fig.F.6b. The one-multiply form is now