What Is a Rack Diagram? How to Draw One for an Audio or IEM Rack

A rack diagram is a to-scale drawing of the equipment mounted in a rack: what each unit is, how tall it is, and where it sits from top to bottom. For an audio or in-ear monitor rig, it is the drawing you check before you buy a case, load a truck or hand the rig to someone else.

The short answer

• What it is: a front view of the rack, drawn in rack units, with every unit in its real slot.
• Why it matters: it shows whether the gear fits the case, where the weight and heat go, and what plugs into what.
• How to make one: list the gear, find each unit’s height and depth, place it top to bottom, then draw the rear and the cables.

What goes in an audio rack diagram

An IT rack diagram is servers, switches and patch panels. An audio rack has its own cast. These are the parts you will draw most often in an in-ear or playback rack:

• Mixer or audio interface: the unit that makes the mixes, such as a 3U Behringer X32 Rack.
• Wireless transmitters and receivers: often half rack wide, like the Shure P3T, so two share one rack space.
• Antenna combiner or distribution: a 1U box such as the Shure PA421B that joins several transmitters to one antenna.
• Power: a power conditioner such as the Furman PL-Plus DMC, and a UPS if the show can’t survive a dropout.
• Stage box or splitter: when the preamps live in the rack instead of on stage.
• Computer: a laptop on a shelf or a rack-mounted Mac for playback.
• Fillers: blank panels, vent panels and drawers. They take space, so draw them.

Rack units and rack sizes explained

Audio racks use the same 19-inch standard as IT racks, EIA-310. Height is counted in rack units: one rack unit, 1U, is 1.75 inches (44.45 mm). A 3U mixer is 5.25 inches tall. Front panels are 19 inches wide, which is why gear from any brand fits any case.

Road cases for audio are much shorter than data center racks. Molded and roto-molded cases commonly come in 2U to 12U. The standard doesn’t set depth, so each case and each unit has its own. A rack diagram should note the depth of the deepest unit, because a case can have the spaces and still be too shallow. See IEM rack case sizes for the numbers to check.

Draw the front and the rear

Most rack diagrams only show the front. For audio, the rear matters as much: it is where the XLR, network, antenna and power connectors are, and where the cables have to fit. A useful audio rack diagram has two views of the same rack, the front for layout and the rear for wiring.

Why draw a rack diagram

• It fits before you buy: count the units and check the depth against the case on paper, not in the venue.
• Faster load-in: the crew knows where everything goes and what plugs into what.
• Faster troubleshooting: when a mix goes silent, you can trace it on the drawing.
• Weight and heat: heavy power gear low, warm gear with a vent panel above it.
• Handoff: a rental house, a venue or a new engineer can rebuild the rig from it.

How to draw a rack diagram, step by step

1. List the gear. Every unit that goes in the case, including power, fillers and shelves.
2. Find each unit’s height and depth. Use the manufacturer’s spec sheet. Note which units are half rack.
3. Add it up. Total the rack units, add a space for power and two spares, and pick a case that holds that many with enough depth.
4. Place it top to bottom. Heavy power gear low, the mixer in the middle, wireless near the top close to the antennas.
5. Turn it around. Draw the rear panels and label every connector you will use.
6. Draw the cables. Every mix from its output to its transmitter, every antenna lead, every power cord.
7. Total the power and weight. Check the draw against one circuit and the weight against one person.
8. Share it. Print it, tape it inside the case lid, and send it to whoever runs the rig next.

You can do all of this with a pencil and a spec sheet. In IEM Rig, steps two to seven happen as you drag gear into the rack: each unit is drawn at its real size from front and rear, you wire the actual jacks, and the power and weight totals update as you go. For other tools, see audio rack design software compared.

Rack diagram examples

Three worked examples, each drawn as a rack and explained from mic to ear, are in IEM rig diagrams for a duo, a four-piece and a worship team. For how the gear stacks and why, see how to build an IEM rack.

Rack diagram vs signal flow diagram

A rack diagram is physical: where the boxes sit and which cables run between them. A signal flow diagram is logical: which sources feed which mixes and where each mix ends up, regardless of where the boxes are. You want both. The rack diagram gets the rig built. The signal flow diagram tells you why someone can’t hear the click. See how audio flows through an IEM rack for the signal side.

Frequently asked questions

What is a rack unit (U)?

The height step of a 19-inch rack. 1U is 1.75 inches, or 44.45 mm, set by the EIA-310 standard.

How do I draw half-rack gear?

Draw two half-rack units side by side in one rack space, on a shelf or a joining kit. Many wireless transmitters are half rack.

Does a rack diagram need depth?

For a road case, yes. EIA-310 doesn’t set depth, so note the deepest unit and the case’s rail-to-rail depth on the drawing.

Can I make a rack diagram for free?

Yes. Paper and spec sheets work, and so do free tools. IEM Rig can be tried free in the browser.

Is a rack diagram the same as a network diagram?

No. A rack diagram shows physical layout. A network or signal flow diagram shows how signals connect, whatever rack they are in.

Sources

• RackSolutions, What is EIA-310: 1U is 1.75 in (44.45 mm), 19 in panels, depth not set by the standard
• SKB rSeries rack range: roto-molded rack cases from 2U to 12U
• Microsoft Support, Create a rack diagram: rack equipment shapes sized to industry-standard measurements
• Behringer X32 Rack listing: 3U, 132 mm tall
• Shure P3T listing: half-rack transmitter
• Shure PSM1000 spec sheet: PA421B 4-to-1 combiner
• Furman PL-PLUS DMC product page: 1U power conditioner