Amplifiers
An amplifier is an electronic device that boosts an incoming signal so that the
signal can be sent further over a cable.
Generally, amplifiers are used when you have to run an abnormally long cable from
the video source to the display. For composite and S-video cables, it is rare
since these signals have been known to travel up to 100 feet or more without
needing to be boosted. Component signals (using three cables) usually aren't
boosted because they are not typically run over 50 feet.
Usually it's an RGB signal using a monitor cable that is most often in need of
help. Running a monitor cable over 35 feet is usually not recommended. RGB
amplifiers — called line drivers — are inexpensive and small, although they do
require power.
Digital signals are another type of signal that usually must be amplified.
Typically a DVI type cable can be run no more than 15 feet before amplification.
This can be problematic for home theaters using front projectors. Although
digital amplifiers are coming down in price, they typically run in the
neighborhood of $300.
The other type of amplifier commonly used is called a distribution amplifier.
Distribution amplifiers split one signal into two or more signals, and then
amplify all signals. They are commonly used if you have one video source that
must be outputed to multiple displays.
Switchers
Video switchers enable more than one video signal source to be selected for one,
or sometimes two, video displays. Let's say you want to hook up three different
computers to your projector or plasma display, but the display only has one
computer input; then a switcher is needed. Simple switchers are relatively
inexpensive.
Switchers can get pricey when they get more complicated. Let's say you have
multiple video sources, like a VCR, DVD player, video game console, cable box
and an older laser disc player. Each source might output different types of
signals, but you want to input them into your video display only using its
single component video input.
First you'll need to convert the VCR's composite signal to a component signal.
(A device called a signal processor is used to do this). Then you'll need to
convert the laser disc's and video game's consoles S-video signals to component.
Next, you'll need a switcher to tie them all together and input into that
single component input.
There are switchers that are also signal converters, but with the added
functionality of a switcher, the price usually doubles.
Signal Processor
A signal processor converts one signal into something else. For example, it
would convert a composite signal into a Y/C type signal or component signal.
Do not confuse a signal processor with a switcher or vice versa. Although the
two can be combined into the one device, this is the exception, not the rule.
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