How to Adjust the Pitch of Old Records

When playing back old records on modern turntables, it's common to encounter issues with pitch and speed. One such issue is when you want to play a 78 RPM record at a slower speed, such as 33.3 RPM or 45 RPM. This can result in a noticeable difference in pitch, making the music sound out of tune.

To correct this, you'll need to adjust the pitch of the record to match the new playing speed. But how many semitones is it necessary to shift the pitch up or down? The answer lies in the ratio between the old and new speeds.

For example, if you're trying to play a 78 RPM record at 45 RPM, you'll need to shift the pitch up by approximately 12 semitones. This is because the speed ratio of 78/45 is equivalent to a transposition ratio of 1.733, which means that for every one semitone, the pitch needs to be shifted up by approximately 0.533 semitones.

Using software such as Sound Forge's pitch shift effect can make this process simpler. You can enter any semitone-cent combination and the software will automatically calculate the corresponding transposition ratio. In the case of a 78 RPM record played at 33.3 RPM, you would need to shift the pitch up by approximately 14.72 semitones to achieve a speed ratio of 78/33.3.

However, things get more complicated when dealing with real players and turntables. For instance, if you're playing an old 78 RPM record on a modern player set to half-speed (45 RPM), you'll need to shift the pitch up by exactly 12 semitones to compensate for the speed difference.

In conclusion, adjusting the pitch of old records requires careful calculation of the speed ratio and transposition ratio. By understanding these ratios and using software or manual calculations, you can ensure that your old records sound as good as new.

33 1 3 45 and 78 rpm records