May 5 , 2005 - Podcast #6
Our email address is hdtvpodcast@mac.com
This weeks show
On
tap today we will cover the news. We'll talk about the best way to lay
out your home theater. We'll explain how plasmas work. We'll talk about
the state of HDTV in Canada. Finally, we'll see if any of our favorite
HD TV shows have "Jumped the Shark"
The Room
Unless a room is specifically designed and built for home theater,
trade offs must be made. Do you choose form over function or function
over form? In most cases compromises in sound quality are made in order
to make the equipment fit the room. Some have found that the only place
the new TV and home theater system will fit is in front of the
fireplace. In an ideal world the room will be rectangular with the TV
in the center at one end and speakers at the four corners. The sub
woofer can be placed along any wall anywhere in the room.
The TV
Try
not to place the television in a corner or to one side of the room. The
best location is the center of a wall with the left and right speakers
equidistant from it. This will provide the best viewing angle for the
most seats in the room. Windows opposite the TV will cause glare on the
screen. This will seriously detract from your viewing experience. If
there is no way around this and the glare bothers you consider
purchasing black out shades or curtains that fully cover the windows.
The Speakers
Speaker
placement is straightforward. As mentioned in the previous paragraph
the left and right speakers should be placed equidistant to the TV and,
with the center speaker, form a slight semi circle with the speakers
pointing at the listening area.
There are two schools of thought on the distance between the speakers.
One says to try and maximize the space between all the speakers, as
this will provide the greatest spatial imaging of the sound. The other
says don’t get too wide so that the sound and the image can feel
connected.
If you have the space, try different speaker placements to determine
what sounds best for you. I prefer the wide feeling I get from placing
my speakers as far apart as I can. Do not place the speakers on the
floor, as some sound will be absorbed by it. Place the speakers on a
stand or mount them on or into the wall.
Avoid placing the left, right, and center speakers together on top of
the TV. Why spend the money for a great home theater system if all you
are going to hear is monaural sound. The center speaker is where the
dialog comes from and should be placed directly above or below the TV.
Typically the center speaker is magnetically shielded to prevent
interference with the television. Be sure to point this speaker where
you will be sitting.
If possible rear (surround) speakers should be placed on the side
walls just above the head. Do not aim the surround speakers directly at
the sitting position. Surround speakers sound the best when the sound
is projected across the room giving it a feeling of airiness. If there
is nowhere to place them on the side walls, place them on the back
walls facing the front of the room.
The Audio Equipment
Equipment can really go anywhere you want. Two things you’ll want to
consider is that most electronic equipment needs a line of sight to
operate it via a remote control and placing the equipment close
together reduces the cable lengths required to connect everything. If
you are like us you will want to show off the electronics as much as
the picture and the sound. So display your home theater system proudly!
Plasma
- Plasma
TVs work by lighting up millions of tiny dots (or pixels) to create an
image. Every pixel is actually composed of three tiny florescent
lights, a red one, a green one and a blue one. The plasma screen varies
the intensity of each of the lights to create different colors.
- How
the pixels get lit up is what makes plasma technology unique. There is
a thin layer of xenon and neon gas sandwiched between two pieces of
glass. Under normal circumstances, the gasses are nothing special, but
when an electric current is run through them, they become what's
referred to as the "plasma" in a plasma screen.
- The
free electrons slam into unsuspecting atoms, causing them to release
electrons and end up as positively charged ions. All these electrons
and ions bouncing into each other excites then atoms and eventually
causes them to release photons of energy. Most of these photons are of
the ultraviolet (invisible) variety but they can be used to create
visible light photons.
- Every pixel in the plasma
TV actually has three of it's own little chambers or cells where this
gas charging takes place. The TV can charge each cell independently to
create different "situations" in each cell. By varying the pulses of
current applied to each cell, the TV varies the amount of ultraviolet
photons emitted in that cell.
- Each cell is
coated with a phosphor material that gives off light when it is exposed
to other light, visible or not. This is how the invisible, ultraviolet
photons are converted to visible light. The phosphor in a cell may glow
green, red or blue, so three cells are used to create one pixel.
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