What is All The Fuss About LED Walls?

One valuable benefit for LED screens is that they offer a much higher visible contrast ratio, versus projecting onto a white screen, as is done with projection.

LET'S BE HONEST HERE if you are reading this article, chances are you like new technology, and words like digital, line array and LED catch your eye

So what is the big deal about LED wall technology?

There are a few significant advantages that an LED wall has over a projector, and I'll highlight a few of them. At the same time, there are also a few issues to be aware of, if you are considering purchasing an LED wall.

The first things to remember about LED walls are that they are a bit different in terms of technology compared to projection. LED walls operate using an emissive versus reflective method when displaying an image.

So why does this matter? A projector works by using an extremely bright light source (lamp or laser) and an imaging panel that is typically .65- to 1-inch diagonal and consists of somewhere between 1 million and 2.3 million pixels jammed into that small area.

The projector is designed to shoot light through the imaging panel and a lens, and then onto a screen or wall. You then see the reflection of that image. One of the major issues with projection, though, is if you want a screen on stage you typically will have to account for a projector to screen light path where you don't want things in the way, since they can impede the image from getting to the screen. Think back to when you were young, and used a flashlight and your hand to "project" onto a wall

By comparison, an LED wall display is made up of multiple panels to assemble a desired screen size each comprised of thousands of multi-color LEDs. The LEDs directly emit light and generally are surrounded by black area.

There is no "light path" that could cause a shadow on the screen. Another benefit is that the LED screen offers a much higher visible contrast ratio versus projecting onto a white screen and expecting it to be "black." In a dark room, projectors do quite well, but in high ambient light situations, the LED wall will easily overcome the light and offer a brighter image with deeper blacks and contrast compared to projection. LED wall panels are defined and marketed by their pixel pitch. This is a measure of the distance between each individual LED installed on the panel.

The current pixel pitches for what you would normally find in a church today following a recent LED wall install, could range anywhere from 6mm down to 2.5mm. One of the critical issues but not the only one when choosing an LED panel is the pitch.

The closer the individual is viewing the screen, requires a tighter (lower numerically) spacing between each LED, to have a cohesive image versus what could be seen as a lot of bright little dots to the viewer, if the pixel pitch is too high. So let's quickly address cost pertaining to an LED wall, as it is a mystery to a lot of people.

For example, a typical single square LED panel can run anywhere from less than $1,000 to in some cases, to more than $2,000 per panel. A key point here is that the largest manufacturing factor in an LED wall is what pixel pitch you choose, since that directly is tied to the sheer number of diodes on each panel, thereby driving up the cost.

To get a sense of how the number of diodes can impact the cost per panel, an example of a single panel might have it be where it is a 3.91mm pixel pitch panel, with each panel measuring at 19.7 inches wide by 19.7 inches high.

Based on those measurements, it would mean that each panel would have 128 diodes across and 128 diodes down.

In all, each panel would then consist of 16,384 LEDs. Can you imagine being the engineer that designed the wall and is wiring it up to make that all work? Now let's put those panels together to make a screen.

And I know you are asking, what size and cost is that? If you are interested in having the LED wall be configured in a 16:9 widescreen aspect ratio, and you want to have the wall display at the same actual resolution as a 1080p HD projector, it would require you to design a wall made up of 15 panels across and more than 8 panels height-wise (8.4375 panels to be exact), using the same 3.91mm pixel pitch referenced earlier.

Whoops, I can't do that.

The designed wall has to be either 8 or 9 panels tall. With square panels, there is usually some give and take, but now there are also native 16:9 panels available on the market. With these special panels, you can use 1, 4, 9 or more panels to make a perfect ratio LED wall allowing for one to design a perfectly designed widescreen format, using the same number of vertical and horizontal tiles.

So now let's specifically look at the size and cost of a widescreen format LED wall. How big is 16-by-9 then, in terms of feet for an LED wall? One such configuration would be 26.2 feet wide by 14.7 feet tall.

That is huge.

When looking at the cost, if we were to figure that each panel would run at an average of $1,500, the overall cost of the panels would be north of $200,000. And that's just for the panels, which still require processing, rigging and power. A smaller 16-by-9 configuration (using 19.7-inch panels), would be made up of 60 panels priced at less than $100,000.

What are the other things to look out for when choosing a LED panel? I happen to be strongly opinionated about the quality of most of the LED panels on the market as they may create an image, but to get a real quality panel, there are certain things to watch out for.

Some of the most common issues with lower- grade LED panels include "moiré patterns" (rainbow or zebra stripe patterns as recorded by video cameras see the images included in the slideshow), reduced greyscale and color gamut at lower brightness levels, radio frequency, or RF, emissions that can mess up your wireless mic and IEM systems, and no long-term service and support by the panel's manufacturer.

So how do you choose a good quality panel? One of the simple tests I personally do is to record video with my iPhone in the slow motion mode, capturing content displaying on the LED wall. The recording could very well show issues that may pop up on your video camera system. Also, work with someone who is knowledgeable about LED walls, and is not just trying to sell you something.

Check for the UL listing, the FCC tests showing that they won't interfere with your wireless microphone system and lastly, seek out a company with a proven track record.

STEFAN SVARD is the CEO at Audio Video Electronics, a Minneapolis-based AVL systems integrator.

TAGS: Video Video
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