TV Half-Life

Q. I read somewhere in your magazine that cathode-ray tube TVs have a half-life of 30,000 hours. At 6 hours a day, that's around 13 years. I'm about to make the HDTV plunge. What are the half-life specs for plasma, LCD, and DLP?
Jeff Dorscher
Glendale, AZ

A. Al Griffin says: Most plasmas are spec'd for a half-life (the amount of time it takes for the screen to drop to 50% of its original brightness) of 60,000 hours, or twice as long as CRTs. And the half-life spec for LCD TVs is around the same. Most DLP and LCoS (a.k.a. SXRD or D-ILA) TVs, on the other hand, use a replaceable lamp to project images. When the picture starts to look dimmer (usually after 5,000 to 8,000 hours), you simply pop in a new lamp to restore the TV to its original brightness. The exception: LED-driven DLP sets, which have no lamps to replace.

Loopy EQ

Q. I had my graphic equalizer connected to the "pre-main coupler" of my stereo receiver, but that circuit stopped working. Is there another way to hook up the equalizer?
Marc Protasel
Redondo Beach, CA

A. Ian G. Masters says: Many receivers offer "pre-out" and "main-in" jacks that let you interrupt the signal from the control section (preamplifier) to the power amp to connect equalizers and other components. If none is connected, the jacks are usually bridged by U-shaped metal jumpers. There's really nothing that can break in this arrangement, so your problem may be in the equalizer. Either way, an alternative is to hook up the equalizer to one of the tape monitor loops, and you'll find out quickly if the failure is in the EQ.

The Dish on Bandwidth

Q. I have an old HDTV with just a component-video input, and I want to buy a new receiver. When I look at receivers with component-video switching, different models have different input bandwidths. How high a bandwidth do I need to pass through a high-definition signal from my Dish HD receiver to the TV?
Scott Prokash
Pulaski, WI

A. Al Griffin says: Until recently, a receiver's component-video bandwidth spec needed to be looked at closely. But most new models have the bandwidth to pass high-def component-video unscathed. An HDTV signal of 720p — the highest-bandwidth signal you'll need to pass via a component-video connection — has a minimum requirement of 37 MHz, so make sure any receiver you buy meets that minimum.

Sub Matching

Q. When I'm in the process of choosing a subwoofer, do I have to take my present speakers into account for tonal balance?
Robert Brissard
Cornwall, Ontario

A. Ian G. Masters says: Virtually all subwoofers are designed to work with a wide variety of satellite speakers, so you're unlikely to find gross mismatches. Just make sure that you can adjust the crossover point of the sub to match your other speakers and avoid sonic gaps, as might happen, say, if your sub's highest crossover point is significantly lower than the lowest frequencies reproduced by your main speakers. Then follow the sub manufacturer's setup directions carefully, and be sure to take a lot of time to choose the proper location for the sub. That'll have the greatest effect on your overall tonal balance.

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