Wayne Parham Messages: 18789 Registered: January 2001
Illuminati (33rd Degree)
1/3λ is a fairly safe cutoff frequency estimate. 1/4λ would be a drop dead value, one that I would not expect any acoustic loading below. 1/2λ is where efficiency gains are seen, with the highest efficiency range above that frequency. Between 1/4λ and 1/2λ, there are usually some ripples in response, sometimes mitigated by other horn features like flare profile and rear chamber size.