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Michaelz wrote:

Some drivers have a rising db curve from low to high frequencies.  The horn may help with flattening the FR.  If the FR of a given coaxial compression driver is flat, I would agree with your conclusion.

all cabperson drivers have rising db curve from low to high frequencies. The entire concept of compression driver (that is misleading name) is not that a diaphragm is loaded into a front chamber (actually in most case it is back chamber) but that the driver must use horn for external equalization. It is worthless to talks about frequency response of a compression driver without a horn and any rising of decaling db curve from low to high frequencies is juts improper selection of horn EQ for a given driver (or a defect of the gioven driver itself, which BTW is very common)

So, let see what the “bad” people do in the coaxial drivers. The LF part of the coaxial is presumably properly loaded but not the HF. In the BMS driver the HF kicks-in at 7KHz and for 7KHz the 300Hz horn is irrelevant- it is like the horn does not exist. So, the LF part of the coax is loaded but the HF part is shooting though with being loaded (or loaded with own small horn). However the 2” throat of the LF horn is VERY small opening and… this hole (though wish the HF driver shoots) is located… at the front of the mouth of the HF horn – this is VERY bad.

From my photography life I know that diffraction is a process of nonlinear bending of the source waves to the area of geometrical shadow. Interesting the diffraction become to be noticeable when the diameter of the hole is co-measurable with the length of the waves … It is exactly what should be doing on in the coaxial compression drivers.

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