Abstract: Disclosed is a passive noise cancelling assembly suitable for reducing exhaust drone from an exhaust system, whereby one or more tuning rods or tuning assemblies are disposed between two exhaust pipes of the system to cancel out or shift the target frequencies thereof. One or more elongated tuning rods are sandwiched between a first and second support plate, wherein a carrier rod extends through the assembly and connects to the exhaust pipes at its ends. An alternative embodiment contemplates smaller tuning rod subassemblies that include shorter tuning rods and a pair of support plates, whereby several subassemblies are supported along a single support rod. The modes of the assembly are controlled by the stiffness of the tuning rods, and its connection between the exhaust pipes attenuates exhaust modes creating audible drone.

Abstract: Disclosed is a passive noise cancelling assembly suitable for reducing exhaust drone from an exhaust system, whereby one or more tuning rods or tuning assemblies are disposed between two exhaust pipes of the system to cancel out or shift the target frequencies thereof. One or more elongated tuning rods are sandwiched between a first and second support plate, wherein a carrier rod extends through the assembly and connects to the exhaust pipes at its ends. An alternative embodiment contemplates smaller tuning rod subassemblies that include shorter tuning rods and a pair of support plates, whereby several subassemblies are supported along a single support rod. The modes of the assembly are controlled by the stiffness of the tuning rods, and its connection between the exhaust pipes attenuates exhaust modes creating audible drone.