In Ardour terminology, a processor is anything which treats the signal in some way and gets plugged into a mixer strip. Ardour provides several builtin processors such as the fader or panners. Processors can also be plugins used for effects or as instruments, as well as sends or inserts which are affect signal routing.
The arrangement of processors is arbitrary, and there is no limit to how many there can be.

The main box in the top half of a mixer strip shows the processor box. Processors are shown as coloured rectangles, with a small "LED" beside them that lights up when the processor is enabled. The colour of the processor depends on its location in the sequence; processors that are pre-fader are coloured in red, and post-fader processors are coloured green (in the default theme).

The processor box will always contain a blue Fader processor. This indicates where in the processor chain the main channel fader is located — this is the fader shown in the lower half of the strip.

Adding Processors

Processors can be added to the chain by Right-clicking in the processor list, This does three things:

• A gap is opened up to indicate the location of the click. The gap shows where any new processors will be inserted.
• The processor under the click is selected.
• An options menu is presented.

From the menu, new processors can be inserted.

To Reorder (Move) Processors

Processors can be re-ordered using drag-and-drop. Dragging a processor allows it to be moved around within the chain, or copied to another processor list on another track or bus.

To Enable/Disable a Processor

To the left of the name of each processor is a small LED symbol; if this is lit-up, the processor is active. Clicking on it will deactivate the processor and effectively bypass it.

Removing Processors

Context-click on the processor you want to remove, and select Delete, or Right-click on it.