Pitch Shift Calculator

Working with old media and obsolete playback equipment can often require changing the pitch of the audio for things to sound correct. The Pitch Shift Calculator converts speed and tone changes (RPM, IPS, Hz) to semitones and cents so that accurate pitch correction can be performed.

 

	Current	Goal	Cents	Semitones
Speed (RPM):
Speed (IPS):
Hum (Hz):
Calibration Tone (Hz):
A440 (Hz):

 

Pitch Shift Calculator Inputs

Various audio editing tools may specify pitch shift values in either semitones or cents (or both). Depending upon your playback hardware, you may be working in RPM (Rotations Per Minute), IPS (Inches Per Second) or Hz (Hertz).

Enter the speed or frequency value that was obtained when you digitized the audio in the "Current" column.

Enter the speed or frequency that you desire in the "Goal" column.

Then hit either the "Tab" key or the "Calculate" button to view the results in the next two columns.

Pitch Shift Calculator Outputs

The output is given in two equivalent values: semitones and cents.

Some DAWs and audio editors will allow you to specify a single fractional value in semitones (for example, 14.89 semitones). Other DAWs and editors will require you to specify these separately (for example, 14 semitones and 89 cents). Yet others may accept a single value in cents (for example, 1489 cents).

About Equalization

When changing pitch, you must also change equalization. For example, when working with grooved disc media (aka records, 78s, LPs, 45s, dictation discs, transcription discs) you will need to make a FLAT (no equalization, or "EQ") transfer to a digital format, shift the pitch if necessary, then apply the appropriate EQ.

Perhaps you have a damaged 78 RPM record that needs to be played at a slow speed to prevent the stylus from skipping or repeating grooves. You may want to play that 78 shellac at 45 or 33.33 RPM instead. Naturally, the audio will not sound correct at these slow speeds, so you will need to shift the pitch (using the values in the Pitch Shift Calculator). In this example:

1. Obtain a phono preamp which offers FLAT EQ as an option (no equalization)
2. Playback the 78 RPM disc at 33.33 RPM and digitize the audio (for simplicity, we are leaving out many steps, like selecting the correct stylus, and setting the correct VTF, etc.)
3. Shift the pitch using your audio editor or DAW, using the values computed in the Pitch Shift Calculator
4. Apply the appropriate equalization using your audio editor

The last step of applying appropriate equalization is discussed elsewhere on this website in more detail. The above steps are considered best practice for archival work. There are variations to the above steps, but these mostly apply to audio reissue and remastering work where there are also aesthetic judgments made.