Connections and sockets

A cable carries one kind of signal from an output socket to an input socket. Outputs sit on the right of a node and inputs on the left. Most surprises come from connecting two sockets of the same kind that mean different things, so this page starts with the canvas and ends with the reference tables.

Make a connection

• Socket to socket: drag from an output to an input and release over the input socket.
• Socket to empty canvas: drag from a socket and release over empty canvas. A menu lists only the nodes that can connect there. Choose one to add it already connected.
• Into an existing cable: zoom in until a + appears at the middle of a cable, then click it. Choose a node to insert between the two ends.
• One output, many inputs: an output can feed any number of inputs. Drag from it again to add another cable.

To remove a cable, click it and press Option+Shift+Delete (macOS) or Alt+Shift+Delete, or drag across it with the Cut tool (B). See Editing and navigation.

Read what a cable carries

Turn on Help at the bottom left of the editor, then point at a socket or cable. Its details appear above the Help button. For a cable it shows the kind, the range and both ends, for example Audio connection: Audio · Normalized · −1 to 1, Oscillator · Signal → VCA · Signal.

Three properties decide what a connection does:

• Kind is what flows: audio, control, gate, trigger, MIDI or a structured type such as Clock.
• Unit is what a number means: Hz, milliseconds, a MIDI note number or a 0–1 level.
• Range is the values the socket expects.

Look at Lesson 2 of Build a synth. ADSR Envelope and Filter Cutoff are both control sockets, but the envelope moves between 0 and 1 while Cutoff expects 20 Hz to 20 kHz. Map Range turns one range into the other, so the envelope sweeps a cutoff range you choose. When a connection works but sounds wrong, compare the two sockets' units and ranges first.

Parameter inputs

Many controls have a socket at the left end of their row. That socket is a parameter input: connect a cable to it and the cable sets the parameter.

• While a cable drives a parameter, its slider no longer responds to dragging. Remove the cable to set the value by hand again.
• A parameter has one driver at a time: its own control, one cable or one Macro. A parameter assigned to a Macro refuses a cable until you remove it from the Macro.

Refused connections

Throughline refuses a connection that cannot work and tells you why. A refused drag shows Invalid connection with the reason. Common reasons:

• Incompatible socket: the two kinds cannot connect, for example an audio output into a MIDI input.
• Choose an input socket as the target: both ends are outputs. Drag from an output to an input.
• Both sockets belong to the same node.
• Map Range is locked to …, but this target expects …: a Map Range that already drives one kind of target cannot drive a different one.
• Polyphony Zones don't take audio input: a Zone accepts notes, not audio. See Polyphony.
• … is controlled by a Macro: remove the Macro binding first.

For more fixes, see Cannot connect these sockets.

Warned connections

Some connections work but may not mean what you expect. Throughline accepts them and marks the cable with a small badge. Point at the badge to read the warning.

A gate driving a frequency input is an example: it works, because a gate is 0 or 1, but it is rarely musical. MIDI connected straight into a number input also works with a warning. Use MIDI Decode when you want pitch, gate and velocity as separate, clear signals.

Group boundaries

Inside a Group, the Group Input and Group Output nodes each have an add socket. Drag a cable to an add socket to expose that signal on the Group's node in the parent canvas. See Frames, Groups and Zones.

Socket shapes and colours

Each socket's shape and colour show its kind. The label always names the kind too, so you never have to rely on shape or colour alone.

Socket	Kind	Shape	Carries
	audio	Filled circle	Full-band audio signal
	control	Filled circle	Normalized control/CV signal for parameter modulation
	string	Tall rectangle	String-backed enum value
	gate	Filled circle	Gate signal (0/1)
	clock	Diamond	Musical phase clock signal
	timeSignature	Diamond	Musical meter carried as numerator and denominator
	trigger	Filled circle	Trigger pulse
	midi	Diamond	MIDI note/CC data
	scale	Diamond	Musical key and scale selection
	number	Filled circle	Control/parameter value
	event	Filled circle	Discrete pulse/clock/gate
	sequence	Diamond	Timed step sequence with values and durations
	bool	Hollow circle	Boolean/toggle
	bufferAudio	Filled circle	Audio buffer
	bufferFFT	Filled circle	FFT buffer
	unknown	Hollow circle	Unconnected wildcard input; adopts the connected signal type

Signal type reference

Every signal kind that can flow between sockets, with its normalized range and unit hint. This table comes from the same vocabulary as the editor's socket details.

Kind	Name	Meaning	Range	Unit
audio	Audio	Full-band audio signal	-1 to 1	float
control	Control	Normalized control/CV signal for parameter modulation	0 to 1 normalized	cv
string	String	String-backed enum value	catalog-defined	string
gate	Gate	Gate signal (0/1)	0 or 1	gate
clock	Clock	Musical phase clock signal	beats from clock origin	beats
timeSignature	Time Signature	Musical meter carried as numerator and denominator	positive numerator / power-of-two denominator	meter
trigger	Trigger	Trigger pulse	0 or 1	trigger
midi	MIDI	MIDI note/CC data	0-127	note numbers / CC
scale	Scale	Musical key and scale selection	catalog-defined	scale
number	Number	Control/parameter value	0-1 (unipolar)	number
event	Event	Discrete pulse/clock/gate	0 or 1	gate/trigger
sequence	Sequence	Timed step sequence with values and durations	varies	steps
bool	Boolean	Boolean/toggle	true/false	—
bufferAudio	Buffer Audio	Audio buffer	n samples	buffer
bufferFFT	Buffer FFT	FFT buffer	spectrum	buffer
unknown	Unknown	Unconnected wildcard input; adopts the connected signal type	varies	—

Units

Control signals share one kind but carry different meanings depending on their unit:

Unit	Name	Meaning
Hz	Hertz	Frequency in cycles per second
kHz	Kilohertz	Frequency in thousands of cycles per second
cents	Cents	Pitch offset — 100 cents per semitone
semitones	Semitones	Pitch offset in semitone steps
octaves	Octaves	Pitch offset in octaves
midiNote	MIDI Note	MIDI note number (0–127, 69 = A4)
midiVelocity	MIDI Velocity	MIDI note velocity (0–127)
midiChannel	MIDI Channel	MIDI channel number (1–16)
midiCC	MIDI CC	MIDI continuous-controller value (0–127)
v/oct	Volts per Octave	Pitch CV — one unit per octave
bpm	BPM	Tempo in beats per minute
beats	Beats	Musical position or offset measured in quarter-note beats
ms	Milliseconds	Time in thousandths of a second
s	Seconds	Time in seconds
samples	Samples	Time in audio samples
dB	Decibels	Level in decibels
normalized	Normalized	Unitless value in a shared normalized range
gain01	Gain (0–1)	Linear level from 0 (silent) to 1 (unity)
phase01	Phase (0–1)	Normalized phase across one cycle
pan	Pan	Stereo position from left (−1) to right (+1)
degrees	Degrees	Angle in degrees
Q	Q	Filter resonance / quality factor
ratio	Ratio	Dimensionless ratio between two quantities
percent	Percent	Proportion expressed from 0 to 100
mix01	Mix (0–1)	Dry/wet blend from 0 (dry) to 1 (wet)
bits	Bits	Resolution in bits
grainsPerSec	Grains per Second	Granular density in grains per second
count	Count	Integer count of discrete items
division	Division	Musical time division (e.g. 1/4, 1/8)

Conversion reference

How Throughline treats mismatched sockets

Each input declares how it accepts other kinds. A connection is one of:

• Direct: the kinds already match.
• Implicit: Throughline converts the signal on the cable. MIDI into a control, gate or trigger input works this way.
• Risky: allowed with a warning badge, because meaning may be lost.
• Forbidden: refused.

Some pitch and control conversions happen on the cable, so a direct connection can be enough. Add a conversion node when you want the conversion visible, reusable or shared by several destinations:

To do this	Use
Turn MIDI into pitch, gate, velocity, bend	MIDI Decode
Read a MIDI controller as a 0–1 value	CC Extractor
Switch between Note, Hz and V/Oct pitch	Convert
Turn pitch and gate back into MIDI	MIDI Encode
Move a signal into another range	Map Range, Clamp
Turn a continuous signal into a gate or event	Compare
Scale an audio level	Gain, VCA

A MIDI controller made audible: CC Extractor reads the controller as 0–1, and Map Range turns it into a pitch range.

Normalized ranges

A normalized range is a shared expected range: audio usually runs from −1 to +1, and modulation from 0 to 1 or −1 to +1. It is not a safety limit. A normalized signal still clips if you amplify it, and Mix adds signals without limiting the result.

Named modes

Some settings take named values rather than numbers, such as Oscillator Waveform and Filter Filter Type. Choose them on the node. Numbers and control signals do not convert into named modes.

Gates and triggers

A gate is a held on/off state, such as a held key. A trigger is a one-moment event, such as the Trigger output of MIDI Decode or the Reset input of a Clock. Use a gate for anything that lasts and a trigger for anything that happens once.