Instruments

As no samples are stored in instruments (except for the DPCM channel), a set of settings are available to customize the sound. These settings are defined through sequence-graphs. A sequence is a list of values that are applied to the channel at the same rate as the frame rate, shown in the main window. Default for NTSC is 60 FPS and PAL is 50 FPS.
The instrument editor - 2A03
Select a sequence in the Instrument settings list and use the Select next empty slot to get a free sequence slot. Check the checkbox to enable the sequence.
These effects are available (none of these apply to the DPCM channel)

Volume | Channel amplitude. is not possible to change triangle volume, but a zero will disable the channel and non-zero will enable it. Range: 0 to 15.
Arpeggio | Produces fast note-shifting, commonly used to simulate chords. Range: -79 to +79 +79
Pitch bend & High-speed pitch bend | Alters the pitch, Hi-pitch multiplies the value by 16. Range: -127 to 126
Duty cycle / noise mode | Sets the duty cycle and noise mode. Square: 0 = 12.5%, 1 = 25%, 2 = 50%, 3 = 75% Noise: 0 = 32k-bit mode, 1 = 93-bit mode

The sequence can be drawn in the sequence editor, left mouse button then changes single items and right button draws lines. You can set a loop point by clicking the Length-field.
The instrument editor - DPCM samples
The DPCM channel behaves different from the others in the way that samples are used, this tab is used to assign DPCM samples to instruments.
First load the samples, either directly from "Load sample" where the format must be 1-bit delta PCM, or "Import sample" to import wave-files. (The quality of wave files will decrease significantly when converted to DPCM.) The NES can handle a total of 16 kB DPCM samples.
Then select a key in "Assigned samples"-box and select the sample from the drop-down box below. The pitch box sets the pitch for the sample.
The "<-" can also be used to assign samples, and "->" to remove assigned samples.
More about importing DPCM samples.
Note: Playing a DPCM sample may decrease the volume level of triangle and noise. If full volume isn't regained after a sample is finished, use a note stop or the Z-effect in the DPCM channel to restore it.

VRC6 instruments

VRC6 are not compatible with 2A03 instruments. To create a VRC6 instrument, place cursor in a VRC6 channel and create a new instrument. The differences are no DPCM-support and 8 levels of the duty pulse setting.

MMC5 instruments

MMC5 is compatible with 2A03 instruments. The two square channels in MMC5 are identical to the 2A03 square channels, except for no hardware sweep function.