The Zenith DTT901 Converter Box - A Review

In June, 2008, I bought a couple Zenith DTT901 converter boxes and installed them on my local TVs. These units were manufactured by LG Electronics and are sold under the Zenith name and other brandings. They convert over-the-air US digital transmissions (ATSC 8-VSB) to analog (NTSC), allowing conventional TVs to receive the new digital formats. In this whitepaper, I report on my experience with and my evaluation of these units.

My converters were purchased from HHGregg in Columbus. Back in June, 2008, when I purchased them, I spent a couple weeks looking for places -- then, towards the end, any place -- that had converter boxes in stock, and I must confess I was beginning to worry that my government coupons ( would expire before I located a box for sale.

I was specifically looking for either the Zenith DTT900 (aka Insignia NS-DXA1) or the RCA DTA800. The RCA is better priced ($50) at Walmart, but I could never find them in stock. The Zenith retails for $10 more. Both are eligible for the $40 government rebates. A helpful HHGregg employee told me to be at the store at a certain date and time, and he apparently knew what he was talking about -- they had just put a pile of units out on their shelves, and had a slew of customers, all with coupons in hand, ready to purchase them. But, hmm, what they had was the DTT901, not the DTT900 I had been looking for. A friendly customer, who said he had spent a good deal of time personally investigating the various converter boxes on the market, told me that, no, these were not cheapened-down units. The "1" meant that this converter had the desirable signal pass-thru, which the DTT900 lacked.

The checkout process was more like something you might expect if you were trying to acquire a high-schedule narcotic, and I understand it has been greatly streamlined since last June: For me, they required physical identification including a phone number. They asked for an email address, but accepted my declination. Then they used a separate computer linked to a government website to verify the rebate cards were good. Each card (most people had two) had to be processed individually, requiring that each box be purchased separately. Once the validation was taken care of, they transferred you to another station to complete the transaction. The whole process was taking perhaps 20 minutes per person. How the retailer makes any money on a $60 unit with all this overhead remains a mystery to me. By the way, the State of Ohio assessed tax on the full $60, making my final cost $24.02 each. I left with two units that could be exchanged if they turned out to be defective, but could not be returned for a refund.

My intent was to install these units on a small TV in the ham shack / computer room, and on a big screen TV in the family room. I don't watch much TV; rather, I tend to use it as a background activity when I'm preparing dinner or working on the computer (as I am doing now), so I felt I really did not need to replace these TVs with true high-def models.

Packaged with each converter box was the converter unit itself, an infrared handheld remote (battery included), a video and audio cable with RCA plugs on each end, and a coaxial cable, along with an instruction manual (English and Spanish).

The converter box is about 7" x 8" x 1" in size. It has a coaxial input for the antenna connection, a coaxial output supplying an RF modulated signal, and 3 RCA connectors for baseband video plus stereo audio. In addition, it has "Power" "Channel Up", and "Channel Down", buttons on the front. There is an LED lamp on the front of the unit that glows red when it is plugged in but turned off, and blue when it is on. Surprisingly for this day in age, the unit has an internal power supply instead of an external power brick.

The remote is small and lightweight, but full featured. It has no visual LED to confirm a button push, but never-the-less seems to work well and has adequate range. It is powered by a single AAA battery. The channel can be changed by using the Up/Down buttons, or by entering the station (not channel) number on a keypad. The unit also has its own Volume control which works by varying the level of the audio signal being offered to the TV (as opposed to varying the TV's own volume control). There is also a "TV Power" button that can be programmed to toggle most brands of TVs on and off.

The actual installation was uneventful: I simply disconnected the antenna from the TV, connected it to the converter box, and then used the included coax cable to connect the unit's RF output to the TV.

On initial powerup, the unit walks you through several initialization steps. It asks questions about your TV's aspect ratio, your time- zone, and then conducts an auto-search to find the digital channels, which takes perhaps 30 seconds. I was worried about how sensitive the unit would be, as I have only rabbit ears here, but with the exception of one channel, the initial scan found all of the local digital signals on the first scan. Re-orienting the antenna slightly and rerunning that sequence resolved this problem. There is also an option for rescanning for digital signals without removing any already existing ones, as well as a method for manually adding specific digital channel (not station) numbers to, and deleting them from, the scan sequence.

The picture is as good as anyone has a right to expect from a conventional TV, but obviously it is not Hi-Def. Sound is excellent. There is a handy "Signal" button on the remote which turns on a visual and audible signal strength indicator which really helps with positioning the antenna. The signal tends to vary from one reading to the next, but a signal strength consistently above about 50% generally provides excellent reception. Signals below that level are problematic.

Picking up good conventional analog (NTSC) signals required I adjust the antenna occasionally to get the best picture, and I found I have to occasionally do the same to get the best digital signals after changing channels. However, I am able to get a solid signal on all the local channels with just the rabbit ears. If anything, this unit seems as sensitive, if not more so, as my $160 LAN-based digital receiver, and is less demanding of antenna adjustment than the analog channels.

The unit also has a handy "Zoom" function. By default, it selects an aspect ratio that permits the entire picture to be seen on the screen. This usually results in letter-boxing (black bars at the top and bottom on the screen), which can prove vexing when the transmitted signal is itself a 16x9 retransmission of a 4x3 source, leaving a picture that looks like a shrunken picture-in-picture image centered in the screen. The "Cropped" Zoom option expands the picture to cover the entire screen, and is a setting which is, handily, remembered on a channel-by-channel basis. (There are also a few less useful Zoom options which tend to distort the image in various ways.)

The "Display" button identifies the station being watched by station number and callsign. It also gives the Program Name, Description, Program Start and End Times, and the Current Time. There is also a "Guide" button that reports on the current and next program for each channel.

By default, the unit powers itself down after 4 hours of inactivity (no buttons pushed on the front panel or the remote). It will flash a warning on the screen before doing this, and the feature can be disabled (or set to 1-3 hours) if desired.

As I mentioned previously, the unit seems quite sensitive. It does an excellent job of pulling in usable signals at my locale. And even when there is a signal drop-out, the glitch is handled with minimal interruption to the viewed signal and sound.

A Few Downsides:

I really like one aspect of my TV's design -- it turns on Closed Captioning automatically when the volume is muted. Although the converter box has a plethora of options pertaining to Closed Captioning, there appears to be no way to link Closed Captioning to its Mute function. However, the unit does insert the Closed Captioning digital information into the vertical retrace of the NTSC signal it produces, so Closed Captioning on mute still works on my TV if it is muted with the TV's remote.

The "Guide" button displays only the current and next offerings for the various channels the box knows about. I understand that some converter boxes have more sophisticated Guides that display a wider range of programming. However, this guide does allow you to see what's on while continuing to watch (or mainly listen) to the previously selected station. There are a few minor annoyances: Before it can be used, the Guide's information needs to be populated by manually tuning in the desired channel, and this must be done each time the box is turned on or after an extended interval. (If a channel is broadcasting multiple streams, tuning to any of them will load the Guide information for them all.) Also, the Guide may be exited either with or without changing channels, a plus, but it will not honor a channel change request if you are trying to change to the channel you are currently watching, a minor nit.

Miscellaneous Observations:

Overall Assessment:

I have to say after experimenting with these units, and using them on a day-to-day basis for the past eight months, I remain pleasantly surprised by the DTT901. It performs better than I expected it to with my internal rabbit-ears antenna, and it appears well designed both electrically and from a human factors perspective. I find myself prefering its digital over-the-air signals to the conventional analog transmissions, even before the switchover. I give the Zenith DTT901 a thumbs-up.

(This review was written in July, 2008, and updated in March, 2009.)