What the maker puts in writing
- “Featured with clear QAM tuner built in for decoding certain unencrypted clear QAM channels or private QAM channels generated by modulators”
- “Simultaneous HD out, component YPbPr out, composite RCA and RF A/V output for connection with all TVs. Maximum HD output resolution up to 1080p”
- “Supports instant recording and scheduled recording… Supports time-shift function so users will never miss any part of the TV shows and easily skip the commercials. Maximum USB external drive support up to 4 TB”
- “Large LED digit panel for visual indication of current TV channel number. Supports EPG (Electronic Program Guide) for program information and closed captioning”
- “Supports timer function for auto start and auto shutdown. Supports last channel memory after power-off or power outage… Compact size with metal enclosure and full-function IR remote controller included”
- Description: “Both stereo and digital coax S/PDIF audio output available”
Four video outputs, working at the same time
Simultaneous HD out, component YPbPr out, composite RCA and RF A/V output.
No other box on this shelf publishes more than two, and the $159.99 ADTH has HDMI only.
What the four are for:
HDMI — a modern television.
RF — a television with nothing but an antenna input. A small modulator generates an analog channel on coax.
Composite RCA — the yellow, red and white sockets, which almost every television made between 1990 and 2015 has.
Component YPbPr — three cables splitting the picture into luminance and two color-difference signals. It was the best analog connection ever made, it carries full high definition, and a great many plasma and early LCD televisions and projectors have it but no HDMI.
And simultaneous means two displays at once: the main television on HDMI, a portable in the kitchen on RF, from one box.
Plus the only digital audio output here
Both stereo and digital coax S/PDIF audio output available for hookup with receiver or stereo amp.
S/PDIF carries a digital audio bitstream on one coaxial cable — so the box can feed an AV receiver or amplifier directly, and the receiver does the decoding. Broadcast television carries Dolby Digital on many channels, and that is the way to get it to an amplifier intact.
Mediasonic publishes Dolby Digital support without naming a digital output. Nobody else on this shelf mentions either.
The private QAM use, which nobody else names
Clear QAM tuner built in for decoding certain unencrypted clear QAM channels or private QAM channels generated by modulators.
Hotels, hospitals, schools, gyms, apartment blocks and corporate campuses frequently run their own small television network. A QAM modulator takes a source — a welcome channel, a notice board, a camera feed, a satellite receiver — and puts it onto the building’s coaxial as a digital channel that every television can tune.
A Clear QAM tuner receives those.
Six of the ten boxes here have the tuner, and five describe it only in terms of cable companies — where, as Mediasonic notes honestly, “the channel must be un-encrypted signal”, and American operators now encrypt nearly everything. So this is the one listing that names the use where Clear QAM still earns its place.
Time shift, which is more than recording
Supports time-shift function… easily skip the commercials.
The box writes the live stream continuously to the USB drive as a rolling buffer. So pausing does not lose the broadcast — it keeps being captured, and you resume where you left off. And because the buffer runs ahead of where you are watching, you can fast-forward through an advertisement break already recorded.
Two boxes here publish it: this, and Mediasonic as “Record and Pause Live TV”.
The caution belongs to Mediasonic too: use an external hard drive, not a flash drive. Continuous writing is exactly what a flash drive handles worst — poor sustained write speed, limited write endurance.
And four small features that show somebody used it
A large LED digit panel showing the channel, so you do not have to turn the television on to see where the box is. Only Mediasonic also has a front display — and its version shows the sub-channel too, which matters because United States digital channels are numbered 7.1, 7.2, 7.3.
An EPG — the program guide, so you can see what is on without hunting.
Auto start and auto shutdown timers.
Last channel memory after a power cut, which sounds trivial until a box resets to channel 2 every time the power flickers.
A metal enclosure, which both runs cooler and screens the tuner from interference better than plastic. Mediasonic also publishes a metal case.
What is not published
No ATSC version. “ATSC” without a number means ATSC 1.0, the standard since 1998 — and ATSC 3.0 (“NextGen TV”) is replacing it station by station, so a 1.0 box loses channels as broadcasters move. Only the ADTH at $159.99 does both; only the Mediasonic at $39.99 warns it does not.
No filesystem for the 4 TB claim. The ZJBOX names FAT32, which caps any single file at 4 GB — roughly two hours of HD. Whether that applies here is not stated.
No warranty — ZJBOX alone publishes a term. No antenna, which every box here requires and only the Tablo supplies. No cables stated beyond the remote, where Mediasonic supplies a 5 ft HDMI and ZJBOX supplies HDMI and composite.
340 g is published.
Prices quoted in this text were read on October 4, 2026. The live price is at the top of the page.
