However, I've found in practice that the opposite is true, and that HF transmission through a rounded bend is enhanced as the radii of the bend, particularly the inner radius, is made larger. Thus,while the longest wavelengths require neither reflectors nor radiused bends, as the wavelength is decreased the inner bend radius required for its passage intact though the bend must be increased. As an example, my DR250a loaded with a PAudio SN10 has a HF limit of 4kHz, with an inner bend radius at 2-1/4". The same driver in a larger cabinet of the same basic design with an inner bend radius of 3-1/4" runs to 5kHz. Conventional wisdom says it should be the other way around.So far as I know Sheerin is the only one who's done extensive theoretical work on what happens in round bends. In truth I've done very little, my route being to build the box first and then try to figure out why it works as well as it does. Either way we both end up in Rome.