Walt,
I'm afraid, that you can not compare the ability of small diaphragm
microphones to pick-up low frequencies with the physical effects,
that occur in a parabola. A small diaphragm microphone detects the
variations of air pressure only (it does not need to reflect
sounds). The size of the diaphragm has no impact on the lower cut-
off frequency (only on the sensitivity and on the upper corner
frequency, that is caused by undesired reflections of higher
frequencies). In contrast to such a pressure detector, a parabola
relies on the reflection of sound waves, which heavily depends on
the size of the reflector. This would be the theory.
However, there might be also other physical effects which lead to
some additional gain at lower frequecies, as you have experienced.
Perhaps, the air pressure field is influenced in some way.
Raimund
> Note that a lot of the bit about parabolics not reflecting low
> frequencies is flawed understanding of how sound travels through
air.
> Even the tiniest dish (or microphone diaphragm) reflects low
> frequencies. If this were not so, then microphones could not pick
up
> those frequencies. Think about a MKH-110-1 mic. It's diaphragm
picks up
> sounds down to 0.1Hz. But it's only about 1/2" in diameter.
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