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Re: pressure build-up ring

Subject: Re: pressure build-up ring
From: "Walter Knapp" waltknapp
Date: Tue Nov 11, 2008 12:13 pm ((PST))
Posted by: "David Kuhn"

> I perceive no difference between with and without the PB Rings--good 
> data up to over 40 KHz. To apply them I pushed the mic's forward from 
> the SASS body about 1.5 inches, then slipped the rings on. All 
> recordings were with the SASS tripod mounted with 15 foot extension--
> the bats came very close to check it out.

Just a note, some random thoughts:

When you move the mics forward of the SASS boundary you will remove the 
acoustic coupling between the diaphragm of the mic and the boundary of 
the SASS housing.

The pressure ring is just a small boundary you substitute. The SASS 
housing boundary works the same but is larger.

I would think that this would make a difference only at low frequencies. 
But the repositioning of the mics that far forward will change the 
barrier characteristics and thus what you will have is no longer the 
SASS as designed. It is something else experimental.

As you already discovered the bored hole does allow the mics to be moved 
forward.  You should limit how far forward so the small screw near the 
connector end of the mic does not chew up the back o-ring. I'm pretty 
sure I told everyone I made a SASS for about this screw.


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