I spoke about the minimum proximity of a crossover point to the horn rate but there was one very fine point that I did not address and that I never have seen voiced. We have a horn and the driver of the horn is properly crossed, far enough to escape the horn choking and the “sonic boom”. There are many factors that would describe the reason of the minimum proximity (drivers type, horn curve type, crossover type and any other) but among all factors one is always overlooked – the reference volume.
It is paradoxical but with increase volume of signal the minimum proximity between crossover point and horn rate increases. I would hardly be able to put it in any kind of formulation but subjectively I feel that we lose 1/3 octave of proximity with each 6dB. I do not know what would be an explanation of the phenomena but the phenomenon is there.
"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche