Categories: Blogs & Little Things

Little Things: HDMI Repeaters for Long HDMI Cables

If you are like many home theater enthusiasts, you probably have your high definition display, either a flat panel or projector, some distance from your equipment rack.

Since most audiophiles don’t believe expensive audio cables make a difference, why should expensive HDMI cables make a difference?

It turns out that cheap HDMI cables, even short ones, can produce sparkles or white horizontal lines flashing on the high def display.

This happened to me. My projector is in the back of the room, and my SSP is in the front. I have to run the HDMI cable 30 feet along the floor, wall, and ceiling, to reach the projector.

I pieced several cables together so that I wouldn’t have a long section of cable left over. Piecing several HDMI digital cables together is just asking for trouble.

As a result, I noticed a white line flashing at the top of the image on the projection screen. I knew immediately what it was and set out to cure the problem.

I Googled HDMI Repeaters and found many that are available. I found several on Amazon, and here is a photo of the one I selected.

This one is called the ELEGIANT HDMI Repeater, and it costs $12.95

Here is the link. (As this article passes time, the link will undoubtedly disappear, but if you Google HDMI repeaters, you will find others to choose from.)

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Now, this is called a passive repeater. It has a small transformer inside that increases the voltage (5 volts is the standard in HDMI cable transmission).

At your SSP’s HDMI output, the voltage is 5, but if the cable is long or not very well constructed, the voltage will drop. The repeater increases the voltage so that it is about 5 volts when it reaches the display.

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You will need one additional short HDMI cable. Plug one end into the input jack of the repeater and plug your existing HDMI cable into the output. It’s important to do this at the SSP end rather than at the display end. That is because the cable will pick up noise along the way, and if you use the repeater close to the display, the repeater will be amplifiying the noise along with the signal. The shorter the cable from your SSP to the repeater, the better. I used a 3 foot HDMI cable.

If you have a really long HDMI cable, then try an active repeater. This type has a wall wart to bring the power up to 5 volts.

Here is one I found on Amazon.

It’s called the Portta PETRT, and here is the link. It costs $17.88, but you will need to also purchase a 5 volt wall wart power supply. With this unit, you can adjust the amount of amplfication using the dial on the right side of the chassis. If I were installing a new home theater with HDMI splitters to send video to several rooms, I would definitely use something like the Portta PETRT.

The results are definitely visible. The images on the screen have no sparkles, and the white line that was flashing on my projector image disappeared.

It’s a cheap fix for a common problem. Try it if your display suffers from those sparkles or white lines.

John E. Johnson, Jr.

Editor-in-Chief Emeritus. John E. Johnson, Jr. founded Secrets of Home Theater and High Fidelity in 1994, shortly after publishing a hardcopy book of the same title. He served as Editor-in-Chief of Secrets of Home Theater and High Fidelity until 2022. John has been involved in audio and video for more than 50 years, having built radio transmitters, amplifiers, turntables, and speakers from scratch. He was also one of the founders of the Northern California Audio Video Association, now The Bay Area Audio Society. John holds four university degrees, including a Ph.D. in Neuroscience, and has published numerous scientific books, along with dozens of scientific articles on biomedical research topics as well as imaging technology. He was the founder and Editor-in-Chief of two medical/scientific journals for 20 years. John holds several patents, including one on high resolution image analysis and one on a surgical instrument. He has been affiliated with NASA, The National Institutes of Health, The Johns Hopkins University, Stanford Research Institute, and The University of California at Berkeley. He is President of the consulting firm Scientific Design and Information, Inc., which is based in Redwood City, California. John resides in the San Francisco Bay area with his wife and multiple kitties! His daughter, Cynthia, who was an integral part of SECRETS for many years, resides in San Francisco.