The two measurements show very different frequency responses, one with a rising response from low frequency to high, the other with a low frequency peak and upper response falling at approximately the inverse of the first response.
Attributing the decay at a single frequency (108Hz) to the taper alone in two completely different designs seems a stretch.
Attributing the decay at a single frequency (108Hz) to the taper alone in two completely different designs seems a stretch.
The ringing(108hz high ‘Q’?) measurement is in the parallel pipe(drawn) . It’s 240cm and 80cm (like a paraflex)
The other measurement is the folded tapered thing.
(Sorry the pics got out of order)
Do the straight and parallel pipes inherently want to do that?
The other measurement is the folded tapered thing.
(Sorry the pics got out of order)
Do the straight and parallel pipes inherently want to do that?
No idea how those two lengths are like or unlike a paraflex (Paragon + FlexTech?).
The difference in frequency response and design of the folded reverse tapered thing and the parallel pipe make it impossible to attribute inherent properties to a single specific design aspect.
That said, certain combinations of wavelength and length of a closed end pipe will result in a standing wave or resonance.
https://calculator.academy/closed-pipe-resonance-calculator/
Damping out unwanted resonances without removing the desired resonances requires finding their origin, which likely would be in the 80cm stub.
Since that portion also contains two drivers, the pipe is not "straight or parallel" in that section 😉 .
Patrick Sander (Ballfred 1) posted some graphs of a C2E- GF ("Golden Formula"..) with 50-80% damping material in the stubs to avoid a ringing tone at 97Hz.
It probably has 90cm stubs..
Art