Mike Andrews

An Engineer Buys a Television

In the Spring of 1999, I started to look for a new 32" television. I figured I'd visit a couple of stores, make my decision, and buy. After all, I'm hip to all the audio lingo, how different can this video stuff be?

Boy, was I wrong.

The stores were confusing as hell. All kinds of different options, with accompanying wide variations in price. All the posts on the TV-related USENET groups I searched through with dejanews were littered with unfamiliar model numbers - and EVERYBODY referred to their TVs by the model numbers.

Here's what you need to know

  • Digital comb filter: To minimize bandwidth usage, the NTSC broadcast TV standard has the chroma and luma signals packed into the same frequency range. If you were to scan across the frequency axis in the band of a particular channel, you'd see that the signals were alternated (chroma luma chroma luma...) Engineers knew wayyy back that applying a comb filter was the best way to extract these guys out. But, we've been using a freaking LOW PASS FILTER for ever, and it's only recently that comb filters could be made cheap enough. So, you'll see "analog comb filter", "digital comb filter", and maybe "3D Y/C comb filter" or something. In this case, digital is better, and the better the comb filter, the higher the contrast and resolution. BUT, the comb filter is only applied on inputs which need to separate the chroma and luma signals. If you're using S-video or component inputs, the signals are already separated, and no comb filter is used. So, if you watch DVD all the time, it doesn't matter what kind of comb filter you have.
  • Component inputs: Instead of S-video, new stuff is appearing which has three RCA jacks, one for luma and two chroma signals (the chroma "C" above was really the sum of two seperate "color" signals Pb and Pr, C = Pb + Pr.) Component inputs are said to give a marginal improvement in picture quality over S-video inputs, but not nearly as dramatic as the improvement gained by going S-video over composite.
  • Scan velocity modulation (SVM): (or velocity scan modulation, depending on who you ask) is evil. SVM is a means of increasing the APPARENT resolution of the image, but really ends up introducing funny artifacts at areas of discontinuity in the image. You can tell if SVM is operating by examining white text on a dark background - if it appears thinned or has a black shadow around it, then you've got SVM. Many televisions allow you to shut this off now.
  • Picture mode: Almost every television has menu options which enable the user to select from among a number of "picture modes": movie, theater, vivid, and sports are a few examples. TVs in a store will typically be set to "vivid," exhibiting very saturated colors. Try setting them to either "movie" or "theater" mode. The colors in those modes will be more subdued, but they are usually fairly accurate.
  • Color temperature: NTSC standard is 6,500 Kelvin. You'll probably be able to select from three: 10,000K, 8000K, and 6500K. 10,000K is the "coldest", in which whites take on a markedly blue cast. 6,500K is the warmest, and really what the set should be tuned to. Usually, if you change to "movie" picture mode, the set turns to 6,500K, but you might want to check.

What I finally did

I bought a Toshiba CX32H60 from Best Buy when they were getting rid of them. At the time, it was their 32" TV that sat just below the "Cinema Series" in the model line. This thing shared the same picture tube as the Cinema Series stuff, but they cut corners on the speakers and audio electronics. Who cares? I bought the thing to look at, not listen to! I have the set tuned to the "movie" mode. Colors are film-like, but someday I'd like to run a test disc on this thing. It has S-Video, component and RCA composite video inputs, and two antenna inputs.

The Best Buy purchasing experience was almost mind altering. The "Best Buy guy", lets call him him "Bob", made it very clear to me that they didn't work on commission at Best Buy. Bob mentioned a service plan while we were out on the floor, and I shrugged it off. Everything seemed to be going fine, until Bob went to ring in my service plan. "Wait," I stopped him, "I don't need the service plan."

"But just a minute ago you said you wanted it."

"Well, I don't think I really need it."

"What, do you have buyer's remorse now?"

"Uhh... no. I really don't need the service plan."

We went back and forth like that, and somewhere in there I said: "I'd really like to buy this TV, but if you can't sell it to me, I'll go buy it somewhere else."

Bob responds, "We don't work off of commission here! Go ahead." [This is, I think, why they don't work off of commission. They get all the fun of a high-pressure sales tactic, but with none of the responsibility]

Bob continues, "You know, this TV has two tuners in it. Those tuners are sensitive... and with these new fiber optic cables they're installing everywhere, if lightning strikes one of those - light follows light, you know, and it's going to take out one of those tuners and THEN you'll wish you bought the service plan!"

He may have continued, but half of my brain shut down to protect myself. I managed to get out that I had a Master's in electrical engineering, and that I felt I was aware of the risks inherent in owning a TV connected to a modern cable TV system. Bob completed the sale by saying, "You freaking guys never listen to me."

I wonder why!

Information updated on Tuesday, 2 May 2000.