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RE: Re: Basic Electricity

Subject: RE: Re: Basic Electricity
From: "Alt, Mark" <>
Date: Thu, 20 Jan 2005 14:53:37 -0600
I would like very much if you would consider doing this presentation as
part of the MOU Youth Mentorship Program. We track who we present to and
there is money available to build kits for such presentations.

Mark Alt
MOU President

C/O J. F. Bell Museum of Natural History
University of Minnesota
10 Church Street SE
Minneapolis, MN 55455-0104
MOU.mn.org



-----Original Message-----
From: Rich Peet 
Sent: Thursday, January 20, 2005 2:19 PM
To: 
Subject: [Nature Recordists] Re: Basic Electricity



Clearly I am having trouble understanding and belief of why star would
have a ten fold reduction or 20db over an equiv. shielded 2 wire.  And
I appreciate your attempt as well as Walts in explaining it to me.

In further thought it makes no sense for me to buy the 2 wire version
when I like the 4 wire because of possible breaks, and maybe even the
"magic" that accounts for a noise reduction.

Right now I am preparing a parabolic presentation for a large group of
K to 12 science students.  I am sure they all will have fun and
education with a group of 32" dishes and Randys math for a hands on
learning experience.

Rich

--- In  "kennjava" <> wrote:
>
> --- In  "Rich Peet" <>
> wrote:
> >
> > --- In  "kennjava" <>
wrote:
> > >
> > > The 4 conductors in the twisted "star" pattern provides more
physical
> > > symmetry of the signal-carrying conductors; this symmetry means
that
> > > signals induced along the cable are more completely cancelled
out by a
> > > differential input.
> >
> > Of course you understand that there would be much more symmetry if
> > there was only two wires running directly next to each other.
> >
>
> I don't see how that could be so... (otherwise normal mic cable would
> be less prone to noise than star-quad, right?)
>
> If you consider a pair in cross-section (A and B) and noise source (N)
> like so:
>
> 1)               AB          N
>
> 2)               A           N=20
> 2)               B
>
>
> Then in 2) A and B are receiving the same signal from N, but in 1) B
> is closer therefore recieving more signal from N.
>
> Isn't that the whole point of pair twist - so that over a length of
> cable the distance  A to N and B to N average out to be equal... which
> means equal amounts of induced noise, which means better cancellation.
>
> And star-quad improves upon that, because it's cross-section is never
> as asymetrical as 1).






"Microphones are not ears,
Loudspeakers are not birds,
A listening room is not nature."
Klas Strandberg
Yahoo! Groups Links













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