60TECHNICALLY SPEAKING continued
the C 1 are used for connecting the C 1 to wired infrared repeater sensors or system controllers. Note that the main and remote zones each have their own IR input jacks.
The IR input jacks accept standard 1⁄8" (3.5 mm) two- conductor
Preventing or Minimizing Hum and Buzz
Audible hum and buzzing noises in a system are usually related to issues with the component grounds. Ground (sometimes called common) is a point of reference for voltages in virtually all audio and video components. Every component has its own ground reference, and the audio signal swings positive and negative in relation to that. Problems occur when components with slightly different grounds are connected together. Such “ground loops” allow unwanted voltages to flow between the components. This causes an audible hum at the fre- quency of the local power line (60 Hz in the U.S. and many other countries, 50 Hz in Europe and elsewhere). Harmonics of the
and 480 Hz in
Here are three tips to avoid hum and buzz:
1.Keep the components in your system close togeth- er, with their power cords plugged into a common AC outlet or power strip, to avoid problems created by resistance in the house’s wiring.
2.Use balanced input and output lines with your Parasound C 1. (See Balanced and Unbalanced Lines in this section).
3.When rack mounting, always use insulated “shoul- der” washers. These break the ground loops caused by
Headphone Circuit
The C 1 includes a
The headphone jack accepts a standard 1⁄8" (3.5 mm) stereo
Video Signal Formats
The C 1 can handle the three common video signal formats: composite video outputs,
Composite video combines all the components of the video signal and passes them through a
Component video, which requires three cables is capable of handling all current
The key to the high quality of component video con- nections are that they include separate links connec- tions for the video signal components of luminance
(Y)and color difference (Cb and Cr) rather than trans- mitting them mixed together and separating them out later. (Not every source component or video monitor labels its component video Y, Cb, and Cr; some may label their connections as be Y,
A growing number of video components, (including
C 1’s component video board is isolated from its other video circuitry.
In addition to these three jacks, which you’ll find on home theater components, and some professional video gear may have RGB connections, which use separate cables for red, green, and blue, plus external connections for horizontal and vertical sync signals (or, sometimes R, G and B plus a composite sync), as do the VGA video inputs and outputs on computers; the five jacks on the component video inputs and output of the C 1 can be connected to these components, too.