Combined resonator and air filter

The air filter has an air filter (13) arranged between an inlet (11) and an outlet (12). A connecting collar (15) for a resonator tube (16) is ranged on the air filter housing (14a,14b). At least part of the connecting collar forms at least part of the external wall of a resonant acoustic damper. Independent claims are included for a modular system for constructing an air filter, and for a method of manufacturing an air filter.