The coupon just arrived and you're thinking about buying a converter, right?  Problem is, most stores only sell one or two models, and many don't have one hooked up for you to watch.  So how can you compare what's available to make the best decision for you?

For the next few posts we'll compare the most easily available converters and give the results.  If someone tells you they're all pretty much the same... wrong.  Each has strengths and weaknesses that you will want to know right up front.  Some differences are matters of preference: how you like the program guide to be set up, for instance.  Other things can be measured... like today's tests of picture quality.

We're looking at four different converters:

• Magnavox TB100MW9, available at WalMart
• Digital Stream DTX9900, available at Radio Shack
• Insignia NS-DXA1, availble at Best Buy
• Zenith DTT900, available at Circuit City and Radio Shack

The Insignia and Zenith boxes are virtually identical except for the front trim plate -- they're actually made by LG Electronics (which oddly enough doesn't market the device under their own brand).

Test 1:  How accurate is the picture?

Each box was connected to the professional-grade antenna at our studio and tuned to digital channel 9-2; its video output was connected to a Videotek test set.  We also connected the main studio feed for channel 9-2 to the test set so we could directly compare the converter box's picture against the original signal we transmit.

The Magnavox TB100MW9 fared the poorest in our tests:  it produced video that was somewhat darker overall than the original picture, and very light colors tended to be washed out, reproducing as white instead of the intended hue.  This was particularly apparent in facial highlights, where skin tone on cheekbones and foreheads tends to break into white.

We had better results with the Digital Stream DTX9900: highlights were reproduced properly, but the entire picture was slightly lightened.  Blacks, for instance, reproduced as very dark grey rather than pure black.

The best results came from the LG-made Insignia NS-DXA1 and Zenith DTT900 twins, which produced video levels almost exactly matching our studio feed.  (In fact, the accuracy of the LG boxes was slightly better than our professional Sencore receiver... but then, our Sencore is five years old.)

Test 2:  How detailed is the picture?

Using the same test setup, I inserted a test signal into our picture to see how well the converters could reproduce fine detail.  Naturally, a standard definition converter won't give you the performance of a high-definition display, but all of these converters produce a noticeably more detailed picture than you could get with regular analog reception.  Still, there were apparent differences between the boxes.

The Magnavox reproduced the test pulse fairly accurately; it was not quite as prominent as the original, but close -- about 92%.  Edge details are a bit exaggerated, apparently in an attempt to make the picture look sharper.  This isn't a problem most of the time, except when the original picture is noisy -- and it has the effect of slightly accentuating the noise.  Still, the picture is generally quite pleasing.

Digital Stream seems to have taken an opposite strategy, and has opted for producing a picture with noticeably less apparent noise.  While this gives the edges of text a nice smooth look, it also reduces actual picture details.  The test pulse was only about 65% of the original, and the whole picture has a distinctly soft look compared to what we transmitted.

Once again, the Insignia and Zenith came out on top, reproducing the test pulse at exactly the right level.  Moreover, there was no sign of either over-enhancement (as with the Magnavox) or over-filtering (as with the Digital Stream).

So... which one is right for me?

If you want a picture that most closely resembles what the station transmits, go for the Insignia or the Zenith.  Either one will cost you about $60, or $20 with the coupon.

If cost is most important, or if you prefer a picture that's a bit sharper than normal, go with the Magnavox.  It's just under $50, less than $10 with the coupon.

If you have a TV set that already makes noise too apparent and you want to tone it down, the Digital Stream would be the pick -- it's about $60, $20 after the coupon.

Hang on a bit before heading to the store... picture quality is only one difference.  Next time we'll take a look at how well the boxes handle less-than-deal signals.

-- Jeff