The arithmetic, shown.

Pitch is a distance, not a quality

Pixel pitch is the centre-to-centre spacing between adjacent pixels, in millimetres. It is not a measure of how good a wall is. It is a measure of how close you can stand before the image stops being an image and becomes a grid of dots.

The industry sells pitch as a quality ladder — finer is better, pay more. That is only true if somebody is standing close enough for it to matter. A P1.2 wall viewed at fifteen metres and a P4 wall viewed at fifteen metres look identical, because the eye cannot resolve either. One of them costs six times as much.

Specify pitch from the seating plan, not from the budget.

The one-arcminute rule

Human foveal acuity resolves detail down to about one minute of arc — one sixtieth of a degree. Below that, two adjacent points merge into one. This is the actual physical constraint underneath every viewing-distance rule of thumb in the industry, and it is worth stating plainly because the rules of thumb disagree with each other.

Set the angle to one arcminute and solve for distance: d = pitch / tan(1'). That gives a multiplier of 3.44 — so a 1.5 mm pitch merges completely at about 5.2 metres, and a 4 mm pitch at about 13.8 metres.

The common "pitch × 2 to × 3" rule is a design band inside that limit — close enough that the wall feels sharp, far enough that it is comfortable. We publish all three figures in the configurator rather than picking whichever one flatters the product.

d = pitch ÷ tan(1′) → ×3.44

COB and SMD are different objects

An SMD pixel is three discrete packages, each with a lens, soldered to the board. A COB pixel is bare die bonded straight to the board and flooded with resin, so the whole cabinet face is one continuous plane.

The consequences are physical, not marketing. COB has nothing standing proud, so it survives contact, cleaning and flight cases. Its tighter encapsulation absorbs more ambient light, which is why measured contrast under a real 100-lux ambient runs roughly 12,000:1 against 5,000:1 for equivalent SMD.

SMD gives up that robustness and buys peak brightness and lower cost per square metre. For a wall behind glass at eight metres, that is the correct trade. For a boardroom where people put their hands on it, it is not.

Contrast quoted at 100 lux ambient. A lab figure in a blacked-out room describes a room nobody works in.

Refresh rate is a camera specification

The human eye stops seeing flicker well below 1,000 Hz. Refresh rate above that exists entirely for cameras. A rolling bar across a shot is the LED driver being sampled by a shutter faster than it can complete a refresh cycle.

3,840 Hz is the industry floor and is fine for a lobby that will never be filmed. A broadcast set shooting at 1/2000 s needs roughly double that, which is why the Nano series runs at 7,680 Hz.

Watch for "refresh rate" quoted without saying whether it is the visual refresh or the driver clock. They differ by an order of magnitude and only one of them is on your camera.

Ask which number it is. A supplier who will not say is telling you which one it is.

Nobody runs a wall at 100%

Peak brightness is a nameplate figure measured on a full white field at full drive. Permanent installations run at 30–50% of it, because that roughly doubles LED half-life and because a 1,500-nit wall at full output is genuinely unpleasant to sit in front of.

So the number that matters is service brightness — peak multiplied by drive level. It is almost never published, and it is the figure that decides whether the wall greys out when the afternoon sun comes through the atrium.

The configurator shows service brightness, and warns when it is below the ambient requirement.

The specification nobody prints

Cabinet-to-cabinet flatness determines whether adjacent cabinets sit in the same plane. Out by a few tenths of a millimetre and each seam catches raking light differently, so the wall reads as a grid of slightly disagreeing rectangles rather than one surface.

It is measurable, every manufacturer measures it, and it is almost never on the datasheet — because it is the specification that most clearly separates a good cabinet from a cheap one.

Ours is ±0.1 mm and we ship the measurement report for your cabinets, not a representative sample from the line.

±0.1 mm, per cabinet, documented.