before I get eaten alive on my second comment. I should say that I
understand that the minimum frequency to see gain will be the same
when a barrier is used, but the gain of the segment between minimum
and double that frequency is reduced. (if that makes the confusion
less or more confusion)
--- In "Rich Peet" <>
wrote:
> You have done well in identification of issues regarding dishes.
> I am not the dish expert here and can only state my decisions in a
> complex ongoing discussion.
>
> I run ME-62 pointed in for two reasons. Better wind resistance and
> because the 62 is not an omni at high freqs I figure I reduce out
of
> phase cancellation by pointing it in. Both ways are being done.
>
> I run without a barrier because I do not want to divide the dish in
> half and therefore double the minimum frequency at which the dish
> will generate gain. Obviously both are done.
>
> The pzm issue gets more complex and I am not the one to go there.
I
> like pzm for some things but do not use it within my dish. Anything
I
> volunteer here would be anecdotal at best as of right now.
>
> Rich Peet
>
> --- In "1gdw" <> wrote:
> > Members,
> >
> > I have no experience with building microphones but would like to
> > make a parabolic using the Telinga dish. I have been thinking
> about
> > both a Stereo and Mono design, following the previously posted
> > diagrams for a home made unit.
> > For the Mono setup;
> > If I use a mono mic such as a ME-62 ( I have a K-6 power unit),
> > would I be compromising the microphone efficiency if the mic was
> > orientated to point away from the dish? The reason for that
> > orientation would be to accommodate the K-6 element of the mic
and
> > keep the unit within the lip of the of the dish.
> > For the Stereo;
> > I will be using nosier lapel electric elements.
> > First idea: Would there be any benefit if I used a small 1 1/2
inch
> > boundary (mounted perpendicular to the dish axis ) and mount the
> > elements as a PZM.
> > Second idea, if the PZM idea has no merit: Would you expect the
> pick
> > up field of a cheaper omni to be uniform in shape? Should I
face
> > them into the dish or away from the dish .
> >
> > A second thought about the stereo parabolic. You folks have me
> > confused about using a barrier in the dish, is the barrier in
> Lang's
> > most recent photos acting as a PZM? Is the barrier simply
> > reflecting the wave to a new path and the mic diaphragm is large
> > enough to gather all the semi focused wave? Perhaps the setup is
> > relying on the efficiency of the mic to offset any loss of gain,
> > since the mic is not at the focus point. How far from the focal
> > point can you move the mic elements?
> >
> > 1GDW, Gerald White
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