Sound Spec Symbol KeyEasyStagecraft Course · Tier 1B · Module 5 (Reading a Sound Spec) · v1.0 · the icons + symbols on a sound block diagram

Why this matters. Sound specifications are usually a mix of: input lists (table format), output lists (table format), and block diagrams (visual flow). The block diagrams use standard symbols. After this sheet, you'll be able to identify what every icon on the spec means + follow the signal path from a mic to a speaker.

Microphones + sources

Symbol	What it is	How it appears
	Microphone (generic)	Round head + stick body. Sometimes labelled with mic type (SM58, etc).
	Condenser mic	Dashed circle or shaded; needs phantom power.
	Wireless receiver	Box with "RX" label. Output to console via XLR.
	DI box	Rectangle labelled "DI". Converts instrument signal to balanced mic-level.
	Playback laptop / QLab source	Rectangle with disc icon. Pre-recorded audio source.

Processing + routing

Symbol	What it is	How it appears
	Mixing console	Large rectangle with internal divisions. Sometimes labelled with model.
	Stage box (multi-channel)	Rectangle with dots = input jacks. Often labelled "32-ch stage box".
	EQ unit	Rectangle labelled "EQ". Often outboard for FOH tuning.
	FX processor	Rectangle labelled "FX". Reverb / delay outboard or built-in to console.
	Amplifier	Triangle (right-pointing). Either separate amp or built into active speaker.

Speakers

Symbol	What it is	How it appears
	Loudspeaker (generic top)	Pentagon/trapezoid pointing forward + small driver rectangle.
	Subwoofer	Rectangle with circle (driver). Often labelled "SUB" + frequency below 80Hz.
	Monitor wedge	Triangular wedge shape, angled. On stage, aimed at performer.
	Sidefill	Larger speaker aimed across stage. Sometimes labelled "SIDE" or "FILL".
	Line array (per box)	Long box with internal dividers. Often stacked vertically (per-box symbol).

Cables + connections

Symbol	What it is
Solid line	Analogue audio cable (XLR or TRS).
Solid line, thick	Multicore cable (multiple audio channels in one cable).
Dashed line	Network / Ethernet (Dante, Cobranet, AVB).
Dotted line	Power cable (mains).
Diagonal slash through line	Cable is unplugged / not connected (mid-design).
Numbered tag on line	Channel number assignment.

Other annotations on the spec

What you see	What it means
Number + dB next to a line (e.g. +24dB)	Gain target for that signal at the input.
Number + Hz next to a speaker (e.g. 80Hz xover)	Crossover frequency between top + sub.
Number in parentheses (e.g. (4))	Quantity of that item.
Symbol with "P" or "+48V"	Phantom power required.
Symbol with "RF" + a frequency (e.g. RF 614.0)	Wireless channel + assigned frequency.
Symbol with a position label (e.g. SR ext)	Where on stage the item lives — stage-right external.

Standard layout of a sound spec block diagram

Left side: sources (mics, instruments, playback).
Middle-left: stage box + multicore to FOH.
Middle: mixing console (the big rectangle).
Middle-right: FX rack, EQ outboard.
Right side: speakers (FOH tops + subs at top of right column; monitors lower; sidefills if applicable).

Follow signal left-to-right. Start at any mic + trace through to the speakers. If you can't follow the path = there's a missing connection in the spec.