Tuner

The Tuner is a utility app that plays reference tones through the PortaPack's audio output to help tune musical instruments by ear.

This is an External-apps-informations (.ppma file on the SD card).

Controls

Field	Description
Instrument	Select the instrument preset: Guitar, Violin, or Pitch Fork.
Note	Select the string or note to tune to. Changes dynamically based on the selected instrument.
Note Frequency	Displays the frequency (Hz) that will be played.
Note Octave Shift	Displays the octave shift applied. A value of -1 means the PortaPack plays one octave lower than the actual target pitch (hardware limitation for very low frequencies).
Volume	Audio output volume (0–99).
Play / Stop	Large button at the bottom. Starts or stops the reference tone.

Instruments & Notes

Guitar (Folk Guitar)

String	Frequency played	Octave shift	Note
E2	165 Hz	-1	PortaPack plays E3; actual string is E2
A2	110 Hz	0	—
D3	147 Hz	0	—
G3	196 Hz	0	—
B3	247 Hz	0	—
E4	330 Hz	0	—

Violin (440 Standard, 12ET)

String	Frequency
G3	196 Hz
D4	294 Hz
A4	440 Hz
E5	659 Hz

Pitch Fork

Standard	Frequency
12ET A4	440 Hz
Sarti's A4	436 Hz
1858 A4	435 Hz
Verdi's A4	432 Hz

Octave Shift Indicator

When playing a note with a non-zero octave shift, the display shows:

• The played frequency (left, in red) — what the speaker actually outputs
• The real target frequency (right, in red) — what the actual string should sound like
• The shift value in octaves (e.g. -1 * 8ev)

When no shift is applied, these indicators are hidden.

Notes

• Audio output goes to the 3.5 mm headphone jack or the internal speaker.
• The tone plays continuously until the Stop button is pressed or the note is changed.
• Changing the note while a tone is playing immediately switches to the new frequency without stopping.
• Very low frequencies (e.g. guitar E2) are played one octave higher due to PortaPack hardware speaker limitations.