In short: DMX512 sends up to 512 channels, each valued 0 to 255, down one cable. That block is a universe. A fixture's address is its first channel. The White Space has two universes, which is 1024 DMX channels, and 42 dimmer channels, so dimmer channels and DMX channels are different counts.
DMX512 is a control signal that sends up to 512 channels of data down one cable, and each channel holds a number from 0 to 255. A lighting desk writes those numbers, and every dimmer or fixture on the cable reads the channels it has been told to listen to.
That block of 512 channels is called a universe. A fixture's address is simply the first channel in the universe that it reads. Once you have those two ideas, the rest of DMX is bookkeeping.
Channels, values and universes
Each channel carries one number between 0 and 255, which is 256 steps. For a basic dimmer, 0 is off and 255 is full. For a fixture with colour, one channel might be red, the next green and so on, and 255 is full on for each.
A universe holds up to 512 channels. If you need more, you add another universe. Universe 2 can be thought of as channels 513 to 1024 when numbered continuously, and many desks also show it as channels 1 to 512 on a second output. Check which numbering your desk and fixtures use before you set anything.
The signal runs at a fixed 250 kbit/s over a balanced RS-485 link, according to ENTTEC's DMX basics page. You do not need to adjust that. It does explain why DMX needs proper cable and care with how you connect it.
What an address is
A fixture's DMX address is the number of its first channel. If a fixture uses several channels, it reads consecutive channels starting there. Fixtures with the same address respond identically, which is sometimes useful and often a mistake.
Worked example
You have a simple colour LED panel that uses 4 channels: red, green, blue and white. You have three of them.
| Fixture | Start address | Channels it uses |
|---|---|---|
| Panel 1 | 1 | 1 to 4 |
| Panel 2 | 5 | 5 to 8 |
| Panel 3 | 9 | 9 to 12 |
Panel 2 starts at 5 because panel 1 uses 1, 2, 3 and 4. If you set panel 2 to address 3, its channels would overlap with panel 1, and the two would fight over channels 3 and 4.
The rule is: next address = this address + the number of channels this fixture uses.
How many fixtures fit in a universe
Divide 512 by the channels per fixture, and round down. A fixture using 10 channels gives 51 per universe, since 51 × 10 = 510. A fixture that offers different modes uses a different number in each one, so read the mode on the fixture, not the label on the box. Many fixtures offer a basic mode with few channels and an extended mode with more, including finer control.
Dimmer channels and DMX channels are not the same thing
This is where people get confused about the White Space.
A dimmer pack is a box that takes a DMX signal in and turns lamps on and off at different levels at its output sockets. The Zero 88 Betapack 3 dimmers at the barn have six dimming channels each, with a DMX512 input on a 5-pin XLR with loop-through. Seven of them feed the main stage, and six channels times seven packs is 42 channels of dimming in the White Space. That is the figure on the rate card.
DMX is the control side. The White Space has two DMX universes, which is 1024 DMX channels. Controlling 42 dimmer channels takes 42 of those DMX channels, which leaves most of the 1024 free in principle for other fixtures you bring. Ask the studio what is already patched. The two numbers measure different things.
The studio also has a Zero 88 Fat Frog and a grandMA2 lighting console. The desk you use is a conversation to have with the studio when you book, as it affects how you patch.
A rack dimmer usually needs a start address, and its channels then follow in order from there. So six channels addressed from 1 occupy 1 to 6, and a pack addressed from 7 takes 7 to 12. The house patch, meaning which dimmer channel feeds which lamp on the grid, is what you need before you plan. Ask the studio for it, then plan your own fixtures' addresses around the dimmer channels already in use. The lighting plot planner for our stages is the place to draw it out.
Cabling and connection
DMX is simple until the cable is wrong. The points below are the ones that cause most faults.
- Use DMX cable. Data cable is a 120 ohm shielded twisted pair. Microphone cable is the wrong impedance and can cause flicker and drop-outs.
- Daisy-chain, do not Y-split. Run the desk to the first fixture, then on to the next in series. A Y-split reflects the signal and corrupts data. If you need to branch the line, use a splitter.
- Terminate the last fixture. Put a 120 ohm terminator, a small plug with a resistor, in the output of the last fixture. Without it, reflections can cause flicker. Some units terminate automatically, which the Betapack 3 does, but check your own kit.
- Watch the connectors. The standard connector is a 5-pin XLR. Many fixtures use 3-pin XLR instead, and the pins carry the same signal, but check that the pinouts match at both ends.
- Limit the run. A line is rated for 32 unit loads, and ENTTEC suggests about 16 devices per run for reliability. Add a splitter beyond that. Runs are typically limited to about 300 metres before a repeater helps.
Setting up, step by step
- List your fixtures with the channel count in the mode you will use.
- Allocate addresses one after another, with no overlap.
- Set each fixture to its address and mode. Label it.
- Connect in a chain from the desk, and terminate the last one.
- Patch the addresses in the desk so it knows what each one is.
- Test by bringing each fixture up at full and back down, one at a time.
Common mistakes
- Overlapping addresses. Two fixtures that share a channel move together or fight.
- Wrong mode. The fixture is on a 10-channel mode while the desk expects 6.
- Confusing dimmer channels with DMX channels. 42 and 1024 are different counts.
- Wrong cable. Microphone cable looks the same and behaves differently.
- Missing terminator. Flicker that comes and goes is a classic sign.
- Y-splitting the line. Use a splitter instead.
- Forgetting the second universe. Check the numbering on your desk and your fixtures.
The Green Space has six dimmer channels, so the 42-channel figure applies to the White Space only. For how lamps are used once the control side is sorted, see three-point lighting and beyond. A gaffer can set the addresses and patch for you: see gaffers and lighting crew.
Sources
- ENTTEC, What is DMX512, read 5 November 2026
Related guides
Questions we get asked
What is a DMX universe?
A DMX universe is one set of up to 512 channels carried on a single DMX512 data line. Each channel holds a value from 0 to 255. A bigger rig uses more than one universe, each on its own line or network connection.
What is a DMX address?
A DMX address is the first channel a fixture listens to. A fixture that needs several channels reads that channel and the ones after it, so the next fixture must start after the last channel the first one uses.
How many DMX channels does the White Space have?
The White Space has two DMX universes, which is 1024 DMX channels, and 42 channels of dimming for the house lighting on the 8-bar grid. Those are two different numbers: DMX channels carry control data, and dimmer channels are the outputs that power lamps.
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