Echo Series Simple models (can be played on one side) that have a tremolo sound particularly sought after for traditional folk music. Blades: 32 Music game: Copper: 0.3mm Body: wood (maple). Length (cm): approx. 13.7 Traditional and popular designs. Tremolo harmonicas are mainly used in folk music. They can be easily recognised by the division of their mouthpiece. Each channel has 2 blades for a note, a pair for blown notes, a pair for sucked notes. These blades are very slightly separated from each other. When played together, they produce that characteristic vibration of Tremolo sound.