How do you tune an E.F. Durand Baritone Model BA 1420B?

To tune an E.F. Durand Baritone Model BA 1420B, first ensure the instrument is properly warmed up. Use a digital tuner or tuning app set to the baritone's concert pitch, which is typically in the key of B♭. Adjust the tuning slide to bring each note into harmony by matching the pitch produced to the reference pitch. Fine-tune individual valves as needed, listening for consistent intonation across different registers.