Sennheiser IE 900 Audiophile in-Ear Monitors TrueResponse Transducers with X3R

What refines the X3R technology is its three Helmholtz resonator chambers and acoustic vortex which smoothens masking resonance. The three resonator chambers are precision-drilled into the elegant aluminum chassis of the IE 900 and placed between the diaphragm and the nozzle.

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