What's the Difference: LCD vs. DLP Pt. 3

Image courtesy of Christie Digital

Image courtesy of Christie Digital

Today we’ll get to our final installment of LCD vs. DLP. We’ve covered some basic design differences, discussed the pros and cons of LCD, so today we’ll tackle the pros and cons of DLP. And I’ll tell you which one you should buy (spoiler alert, I’m not really going to do that; it’s not nearly that clear cut). But first, DLP; what’s good, and what’s not.

DLP Pros

  • High reliability. Because of their sealed optic engine and lack of organic or inorganic panels, they tend to last for a long time and look the same throughout the life span. 
  • No convergence issues. It’s a single chip, so you don’t have to worry about images not lining up. Of course, when you start looking at 3 DLP projectors, convergence becomes a factor again. 
  • No real screen door effect. At a given resolution, the pixel pitch tends to be tighter on a DLP than LCD. Thus, you are less likely to see the pixels. The image tends to look more homogenous. Again, at 1920x1080, these differences are shrinking a lot.
  • Higher apparent output. DLPs have a while slot on the color wheel to boost brightness. Thus, the image may look brighter than an LCD. This is deceptive, however. I’ve seen shootouts of projectors where a 5000 lumen LCD is clearly brighter than a 7000 lumen DLP. I suspect this has more to do with how “lumens” are calculated, however. 

DLP Cons

  • The rainbow effect. I mentioned this last time. Because of the color cycling that happens when the image is produced, some people can see a rainbow of color on the screen. 
  • Color saturation might not be as good as LCD. Again, this has to do with the way the colors are reproduced. There are some DLPs with exceptional color saturation, but they tend to be expensive. Lower cost units are often a little washed out. 
  • No grey. A DLP micro-mirror is either on or off, black or white. There is no grey. To produce a grey, the pixel as to be flashed on and off between black and white many times per second, and this can produce some artifacts. Whether this is a problem or not will depend on your content. 

Does It Matter?

Maybe, maybe not. Again, for many applications, either a DLP or LCD projector could be perfectly acceptable. As I said, I’ve seen some LCD models that look so much better than DLPs it’s not funny. At the same time, I’ve seen some DLPs that are gorgeous. Like many things, it’s more about the price point than the technology. Once you start comparing projectors of comparable (and sufficient) price, the differences become more subtle. 

That’s not to say there aren’t choices to be made. It all depends on the application. For something like environmental projection, you can easily get away with an inexpensive LCD projector. When you start talking about IMAG in a large room, you have to start choosing more carefully. I’m not convinced it’s the underlying technology that has to be the key factor, though. I’ve been to enough NAB’s and InfoComm’s and seen enough LCD and DLP projectors to know either can look great. Often, it comes down to availability, price, suitability, lenses, service and what your dealer carries. The good news is, either technology can be more than good enough. And they keep getting better

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What's the Difference: LCD vs. DLP Pt. 2

Image courtesy of Christie Digital

Image courtesy of Christie Digital

Last time, we touched on the basic, underlying technology of LCD and DLP imaging systems. Today, we’ll look at some of the pros and cons. As I said last time, much has been written on this subject and I’m not going to exhaustive here. If you want a very thorough look at this, albeit from a home theater projector perspective, check out this article at Projector Central

LCD Pros

  • LCD projectors are generally less expensive than 1-DLP units at a given brightness. This is a general rule, and there are plenty of exceptions. But if budget is a big concern, look to LCD.
  • LCD generally has better contrast. This is relative, however. Keep in mind, you’re shooting the image onto a white screen. So the blackest the image will ever get is as black as the white screen ever gets. 
  • No rainbow effect. I sometimes notice a slight jitter in DLP images. It’s not always readily apparent, and I’m a trained observer. But LCD images tend to be pretty rock-solid. 
  • Better apparent resolution. Because the pixels are very clearly defined, graphics tend to look sharper on LCD projectors. To some extent, this is academic now that we’re getting up to 1920x1080 chipsets in both technologies, and given the average viewing distances. But there is a difference. 
  • Better color saturation. Because a DLP color wheel typically has a white slot in it to boost brightness, the color saturation can be lower. LCDs behave more like LED lights; the brighter they are the more saturated they get. 

LCD Cons

  • Lifespan of panels. We don’t really know how long the LCD panels will last before they start breaking down. We do know they break down and the colors start to shift. Newer inorganic panels seem to hold up better than older organic designs, but some are projecting the life of an LCD panel to be between 4,000-10,000 hours. That could be 1-3 bulb changes. Of course, a lot of those tests are being done by DLP makers, so… If you are using your projector for a few hours on the weekend, and occasionally during the week, this is probably not an issue. In a big command center where projectors are on 24/7 for years, this is a problem.
  • Dust. The LCD engine is not sealed, so it’s possible dust can get in there. This is less of a problem with pro-grade projectors that have good filtration systems. Still, if you have a dusty environment, be aware of this. 
  • Screen door effect. Because the edges of the pixels are so well defined, you can sometimes see the spaces between them. It looks a bit like viewing the image through a screen door. Again, with higher resolution and tighter pixel pitch, this is less of a problem than it used to be. 
  • Mis-convergence. Because an LCD image is made up of three images of different colors, they have to be lined up perfectly. If they are not, you’ll see fringing of color on vertical or horizontal lines. Again, with newer, pro-level projectors this is less of a problem. But it does show up on budget models.

There’s a look at the LCD. On Friday, we’ll wrap this up with a look at DLP pros and cons, and some concluding thoughts on which one is better.

“Gear

Today's post is brought to you by DiGiCo. DiGiCo audio mixing consoles deliver solutions that provide extreme flexibility, are easy to use and have an expandable infrastructure, while still providing the best possible audio quality. Visit their website to learn more.

What's the Difference: LCD vs. DLP Pt. 1

LCD or DLP? This is a great debate that has raged on for years. Some of the debate is fueled by technology, much more is fueled by marketing. Thankfully, manufacturers in both camps have been steadily improving their respective technologies over the years, and the difference is now smaller than ever. I believe for most applications, the technology inside the projector is now less important than the service, support, price and brightness; and the suitability for the application. But we’ll get to that shortly.

Much has been written about this subject, and rather than attempt to rehash all of that, I’m going to give you an overview of the two technologies along with some links to learn more. Let’s start off with a basic overview of how the two methods produce a picture. In reverse alpha order, LCD first. 

All LCD Projectors are 3 Chip Designs

LCD stands for Liquid Crystal Display. You may see some projectors labeled 3LCD or being touted as having three chips as opposed to 1. The marketing difference compares not to single-chip LCD projectors (there are none), but to single-chip DLPs—the primary competitor to LCDs. Below is an example, albeit a highly simplified one, of how an LCD projector produces an image. 

Image courtesy of Christie Digital

Image courtesy of Christie Digital

The light from the bulb(s) is split into three parts. It passes through three LCD panels (red, green & blue), and then re-combined. The result is a color image. The LCD panel has millions of pixels that can be open, closed or partially open. When open, light passes through and a color (or white if they’re all open) is produced. 

DLP is all Smoke and Mirrors

Well, technically no smoke. Unless you count the magic smoke that all electronics run on. Let the magic smoke out, and they stop working. But I digress. Below you’ll see an image of a typical single-chip DLP engine. As you can see, it’s a bit more complex. DLP stands for Digital Light Projection, and was developed by Texas Instruments. It’s essentially a chip full of thousands of little mirrors. The mirrors tilt either toward or away from the lens producing light or not. Because it’s a single chip, there is a color wheel in the system to produce the various colors.

Image courtesy of Christie Digital

Image courtesy of Christie Digital

The technology takes advantage of a phenomenon in our vision called persistence of vision. Our eyes see relatively slowly. And what we see tends to stay there for a little bit. The DLP engine will flash the red portion of the image on the screen and sometime between 1/60th and 1/240th of a second later will then flash the green portion. Then the blue, then back to red. Some projectors event throw in yellow, magenta and cyan for good measure. In that short time frame, the red doesn’t full fade away—at least in our eyes. So when the green and blue parts pop up, we see it as one color. It’s crazy, but it works.

The downside is that some people have faster vision than others and can actually see each color individually. This is called the rainbow effect. It’s less of a problem now than it used to be; companies have sped up the rotation of the wheel to mitigate the effect. But if you can see it, you can’t un-see it, so to speak. 

3-Chip DLP is the Same, Only More

A 3-chip DLP projector is very similar to a single-chip, only there are three; one for red, green and blue. The rainbow effect doesn’t come into play in a 3 DLP design because there is no spinning color wheel. When you look at the above diagram, you can see why 3 DLP designs are so expensive; there’s a lot of stuff going on in there. You do get a good-looking image out of all the complexity, however. 

Does It Matter?

One of the questions I always ask when evaluating competing technologies is, “Does it matter?” When it comes to LCD vs. DLP, for the me the answer is yes. And no. The technology has advanced to a point where at a given price point, either will produce an acceptable image. So to some extent, the answer is no, it doesn't matter. However, there are pros and cons for each technology, and one may be better suited for your application than the other. We’ll talk about that next time.

Roland

Today's post is brought to you by CCI Solutions. With a reputation for excellence, technical expertise and competitive pricing, CCI Solutions has served churches across the US in their media, equipment, design and installation needs for over 35 years.

Cool New(ish) DiGiCo Features

I totally forgot I wanted to write a post about this. These aren’t necessarily the newest features of the DiGiCo SD series of consoles, but they are some pretty cool ones that I wanted to point out. The first one makes doing things like virtual soundcheck and personal mixing a lot easier. The second makes it easier to conserve faders on the surface during a big event. Both make a great console platform even better.

The Copy Audio Matrix

When it came to virtual soundcheck recording, one of the challenges we had with previous versions of the software was what to do with local inputs. The way we normally set things up was to copy MADI 1 to MADI 2. That essentially takes the inputs from MADI 1 and writes them directly out to MADI 2 without any processing. When we play back, we simply press “Listen to Copied Audio” and the inputs from the rack are replaced with the recorded copies. It worked great. Except for local inputs. 

Local inputs are on their own MADI bus. And you can’t copy two busses to the same destination. So we had to get creative and use Insert A out to write directly to MADI 2 so we could record those channels. But playback was a problem as we didn’t have gain tracking, and we had to re-patch the inputs. 

Enter the Copy Audio Matrix. With the Matrix, it’s now possible to copy any input to any other MADI bus. Take a look.

Copy 1.jpg

It looks unassuming enough, but when you start opening up the matrix, it gets interesting. For example, below you can see that for the most part, the copy is set up 1:1. That is MADI 1 (the Rack) is being copied to MADI 2. But look at Rack Input 16. There is no red square there. 

Copy 2.jpg

That simply means that channel is not copied over to MADI 2. In that case, we were doing some M+S mic’ing of the guitar cab, and I didn’t want the second mic in the IEMs. But I did want to record it. So I copied it to MADI 2:62. 

I set Reaper up to record both tracks, and when we played back, the console did all the work of re-assigning the inputs to the right channels. And how about those local inputs. We wanted to record all the tracks coming from ProPresenter. Those come in on local AES inputs on the back of the surface. Copy Audio to the rescue. 

I didn’t really care about the click, so I didn’t bother to copy it. But the rest of the channels would get recorded to Reaper and would be available for Virtual Soundcheck. Another note on this. If you’re familiar with DiGiCo, you’ll know they use a 56-channel MADI mode. Generally, you can’t use anything above 56 for anything. But in this same version of the software, they created a virtual 64-channel MADI device that you can “assign” to a MADI bus. In this case, I configured MADI 2 as a 64-channel device, which allows me to use all 64 channels in the RME MADIFace interface we use to record. So I can capture all 56 channels from the stage rack plus another 8 channels of local inputs. Cool.

Know When to Fold ‘Em

Another challenge to mixing large events is managing all the faders. The SD8 has 36 faders on the surface (plus master), which is quite a few. But on a big event, they go quickly. Now, I can use VCAs to group channels together for a reduced fader count, and I do that sometimes. But when you want to condense a group of channels down to a single fader, but still have rapid access to all the channels in that group, you need a Multi. 

A Multi is just that, a group of multiple channels on one fader. You can select up to 11 channels (any or all of which can be mono or stereo) for a Multi. Why 11? I have no idea. Maybe they wanted to do 10, but decided it should go to 11. Anyway, those 11 channels get “Folded” into a single fader. When you move the fader, all the channels move relative to the level of the fader. So if you have 1 channel set at −10 and another set at unity, if you move the Multi fader up by 5 dB, your first channel is now at −5 and the second one is at +5. It’s like a VCA in that way, only the faders move.

But if you want to get in and change the levels, just press the Unfold button and the channels spill out on the surface. You now have complete access to all the channels. In this way, a Multi behaves sort of like a POP group in Midas land. Here is an example of a Multi folded, and unfolded.

Multi 2.jpg

I like to use them for things like Video because I’m often using different channels for different songs. Its easy to adjust the levels, set up a baseline, snapshot those levels then mix them all one fader. 

So those are some cool things DiGiCo is doing with their consoles. There’s a new software update with a few other features, but that will have to wait for another day.

Roland

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