1. May I ask what tool you used?
2. Interesting that there are ~5 peaks, and ~5 big bends in the horn.
3. Would it be correct to say that the F3 is ~40hz?
4. How do you like them?
Scott, many thanks. Would it be too simplistic to think that each peak/dip roughly corresponds to the QW resonance of a manifold (not that it necessarily matters in the larger picture)?
I was interested by the peaks as well. That's what prompted my post. I don't understand their significance, but I'm trying to wrap my brain around what Scott said. I've measured the impedance curve for a typical ported (bass reflex) enclosure. You get two peaks, presumably one from the woofer and one from the port.
Horns are basically impedance matching devices, viz. matching the high impedance of the diaphram to the low impedance of the air, and thereby improving efficiency as the driver is 'seeing' a constant resistive load at all frequencies in its functional BW.