Sound Delivery Tubes for ER3C Tubal Inserts (2 pairs/pack)

Sound Delivery Tubes (ER3-21) including coupler for ER3C tubal insert earphones. The sound delivery tube is 26.5cm in length and have a constant diameter of 1.35 mm ID × 2.16 mm OD. Two ER3C Sound Delivery Tubes Pairs per pack (one red and one blue). The color-coded tubes are for easy binaural identification between the left (blue) and right (red) ear.

Sound Delivery Tubes are used to connect foam tips to the ER3C tubal insert earphone. The smooth frequency response of ER-3C earphones depends on maintaining a total of 292 mm (11.5 inches) of the sound channel between the case wall and the eartip outlet. Of this 292 mm total, 22 mm is provided in the eartip, 5.5 mm is provided by the small metal tip, and 264.5 mm is provided by the sound-delivery tubes.

Technical Specifications

• Compatibility: ER3C tubal insert earphones
• Tube length (without coupler): 26.5mm
• Inner diameter: 1.35mm
• Outer diameter: 2.16mm
• Material: Polyurethane
• Binaural identification: tubes are color-coded blue (left ear) and red (right ear)
• Packaging: 2 coupler tubes pairs (red and blue) including coupler for ER3C

Application Note

Caution: Do not cut the sound tube. A change of 10 mm in the length of the sound tube will change the frequency response by 0.5 dB at some frequencies.