12G-SDI distribution amplifiers: how to spec a DA.

What a distribution amplifier does

A distribution amplifier (DA) takes one SDI input and fans it out to multiple buffered outputs — so a single source can feed a switcher, a multiviewer, a recorder, and a monitor without daisy-chaining or splitting the signal. Every output is a clean, independent copy of the input.

At 12G data rates (12 Gbps for 4K/UHD single-link), that fan-out is harder than it sounds. The signal is fragile, cable losses are steep, and a cheap DA will happily pass a marginal signal that falls apart down the run.

The five things that actually matter

1. Reclocking

A reclocking DA regenerates the signal timing on each output, cleaning up jitter before it fans out. On 12G, this is not optional for anything beyond a very short run — a non-reclocking (buffer-only) DA will let jitter accumulate and you’ll chase intermittent sync faults on show day. Spec reclocking.

2. Cable equalization & auto input detection

12G loses signal fast over coax. A DA with automatic cable EQ compensates for the loss on the input side — critical if the source cable is long. Look for stated input EQ figures against a known cable (e.g. Belden 1694A). Auto input detection (12G/6G/3G/HD/SD) means the box adapts to whatever rate it’s fed without manual config.

3. Output count

Count your loads and add headroom. A 1×6 DA is the workhorse size; 1×4 if space is tight, more if you’re feeding a big monitor wall. Don’t spec exactly the number you need today — builds grow.

4. Form factor & power

Throw-down mini DAs are great for flypacks and tight racks but need clean power — plan your PDU and any power-supply redundancy. Rackmount frames (openGear, etc.) make sense when you’re running many cards and want card-level redundancy and remote control.

5. Reference / sync pass-through

Some DAs pass or regenerate reference. In a genlocked plant, make sure your distribution doesn’t break the reference chain. Small detail, big headache if missed.

A representative box: the AJA 12GDA

As an example of a DA that hits the marks above, the AJA 12GDA is a miniature 1×6 12G-SDI reclocking distribution amplifier for 4K/UHD single-link workflows — six separately buffered outputs identical to the recovered input, 12G/6G/3G/HD/SD-SDI auto-sensing, reclocking, and 12G cable equalization (rated against Belden 1694A). It’s a solid default for a throw-down 12G fan-out. It’s one of many we source — the right DA depends on your build.

Common mistakes we see

• Buying a buffer-only DA and fighting jitter faults later
• Under-counting outputs, then splitting a DA output (defeats the point)
• Ignoring input cable length — then blaming the DA for a cable-loss problem
• Mixing 12G and 3G expectations on the same box without checking auto-detection
• No power redundancy on a mission-critical distribution point

Need help speccing (or sourcing) a DA?

We’re a broadcast equipment supplier run by a working engineer — so we can both help you pick the right distribution amplifier and source it (single unit or full build) at distribution pricing, fast. Serving Los Angeles and Southern California.