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Re: Parabolic, Stereo and Mono

Subject: Re: Parabolic, Stereo and Mono
From: "Rich Peet" <>
Date: Thu, 06 Mar 2003 21:55:23 -0000
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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