Audio Authority 1184 Ground Loop Isolator
Active Hum Eliminator / DC Blocker for RGB & Component Video
The Audio Authority 1184 HDTV Signal Hum Eliminator / DC Blocker can solve many hum and noise problems in HDTV video and/or audio signals. The 1184 is suitable for Y/Pb/Pr component video, as well as stereo audio. The unit can also handle RGB video in the R/G/B/H/V colorspace, by switching the unit into RGB mode, which configures the shared channels for H/V video mode. (Naturally, stereo audio filtering is not available when the 1184 is in RGB mode).
Like most Audio Authority products, the 1184 comes with a one year limited warranty from the manufacturer.
Please notice that Audio Authority has deleted the YPbPr / RGBHV mode switch. You will still find the switch described in the user manual, but it is no longer present on the device itself. With that said, the 1184 still works in both YPbPr and RGBHV modes.
Designed to solve the problem of rolling video hum bars caused by AC-line related noise due to ground loops in coaxial cabling. The 1184 also eliminates hum from low level stereo audio signals.
How it Works
Television displays and projectors usually have a hard connection between their inputs and chassis. Therefore, a ground loop may develop, leading to 60Hz current flowing in the input cable, which causes hum bars. Model 1184 uses active circuitry to isolate the input and output grounds. It also includes video input clamping to thoroughly eliminate artifacts caused by differences in electrical potential between the chassis of equipment connected to it. In addition, Model 1184 strips DC off sources of component or RGB video, and clamps the Y or RGB black level to 0 volts.
Passive devices, known as hum buckers or video transformers, can be effective in eliminating the effect of the difference in ground potential. The advantage of the 1184 is that its bandwidth is not limited by inductance, as is the case with the chokes used in hum buckers or transformers. Furthermore, as passive devices, humbuckers and transformers are inherently lossy–their gain is a little less than one–compared to the 1184, which has a gain of exactly one.
Model 1184 is designed to overcome hum bars on a Component or RGB display at the end of a long run of coaxial cable. In these cases, breaking the ground loop is best accomplished at the video input of an offending TV, projector, or video display. This situation could occur in a residence, but is more likely to occur in larger venues, such as clubs and churches.
For example, if four component video displays are fed by a component video distribution amplifier and ground current happens to circulate between any of the displays and/or their source, hum bars will appear on one or more of the displays. A Model 1184 can be added at the input of the offending display(s) to break the ground current path and eliminate the hum bars without sacrificing bandwidth or image quality.
User manual (in PDF format)
This photo shows the inputs on the back side of the 1184.
Here is another view of the output side.
The power connection is located on the left end of the 1184
Shown here are the contents of the box.
Audio Authority DC Blocker Focus Sheet
Here is the manual in PDF format.
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