Pass had this patent since expired and copied and changed by others..only 25 years have pass-ed.Active low frequency acoustic resonance suppressor. www.google.com/patents/US4899387 Filed 1988 granted 1990
Also change the 90 degree angles all around especially those overhead on and around a soffit. Think aerodynamic flow, rather than crashing head on into a 90 degree brick wall. Not only will they sound better they look better. Ask a wife.
Also change the 90 degree angles all around especially those overhead on and around a soffit. Think aerodynamic flow, rather than crashing head on into a 90 degree brick wall. Not only will they sound better they look better. Ask a wife.