Program Tree Elements

The Program Tree shows all elements that make up the program that is selected in the Slot Rack.

Programs and Layers

Programs are the top-level elements in the Program Tree. Only one program is displayed at a time.

Programs are complex instruments or sounds that combine layers, zones, busses, MIDI modules, and FX modules. Often, a program contains a single layer that already comes with all necessary components such as the synthesis part or insert effects. This is because a layer already is a complete sound structure on its own. Layers can be used to structure programs, for example, by grouping a number of zones. This is useful if you want to apply the same settings to a number of zones in one go. Programs add the possibility of combining different layers to build up more complex sounds or to create combinations of sounds that you want to load as a unit. A typical example is a bass/piano split sound or a piano/string layer sound.


Zones are the elements that create the sounds in HALion. In the Program Tree, the zone is the element on the lowest level.

Different types of zones are available: synth, sample, granular, organ, and wavetable. The zone types differ in their basic sound source.

  • Synth zones provide an oscillator section with three main oscillators, a sub oscillator, a noise generator, and a ring modulation stage.

  • Sample zones load a specific sample.

  • Granular zones offer a sophisticated grain oscillator section that contains a page for the grain-specific parameters and another page for the sample-related parameters.

  • Organ zones produce the sound of classic drawbar organs with up to nine drawbars.

  • Wavetable zones allow you to create your own wavetables by extracting single-cycle waves from samples.

The numbers below the Program Tree indicate how many zones are selected, how many zones are contained in the focused layer, and how many zones are contained in the program. This is useful when you are editing or deleting zones.


For example, if you use a piano sound that was recorded with several velocity layers per note, each velocity layer has 88 sample zones. If you want to edit or delete an entire velocity layer, the numbers allow you to verify whether you selected the correct amount of zones before you edit or delete them.


Busses allow you to set up the audio routing in HALion and add audio effects.

MIDI Modules

MIDI modules process the stream of MIDI events inside a program. They can produce monophonic modulation signals, which can be used as sources in the modulation matrix. MIDI modules can be assigned to an entire program or to a single layer.

Audio Effects

Audio effects can be added for busses.