User manual SENNHEISER HDI 302

[. . . ] VARIANTS HDI 302 Infra-red stereo stethoset receiver which can be switched between "channel I", "channel II" and stereo transmission. It is especially suitable for applications which require two-channel transmission, e. RI 250 Infra-red mono stethoset receiver, designed for use as a personal sound amplifier for people with impaired hearing. [. . . ] The BA 151 can be recharged in the Set 250 and Set 500 transmitters, in the L 151 charger (suitable for charging two individual accupacks) or in the L 151-10 charging unit. For commercial use, Sennheiser offers charging and transport/storage units for recharging a larger number of stethoset receivers at a time. FREE LINE OF SIGHT Infra-red light is transmitted in the same way as the light from a light bulb. Do not obstruct the path of the light between the transmitter and the receiver, and stay in the room where the transmission is taking place!Make sure that you wear the stethoset receiver the right way round, with the "Sennheiser" logo at the front. There is a simple rule: If you can see the transmitter or the infra-red radiator from where you are, transmission can take place without any interference. When people use headphones, they tend to choose a higher volume than with loudspeakers. Listening at high volume levels for long periods can lead to permanent hearing defects. Please protect your hearing, Sennheiser headphones have an excellent sound quality even at low volumes. SPECIAL ADJUSTMENT POSSIBILITIES ON THE RI 250, RI 250-J AND RI 500 STETHOSET RECEIVERS: ADJUSTING THE BASS ATTENUATION You can use the two supplied sealing tapes to seal the small holes in the headphone systems. The more holes you seal with the sealing tapes, the greater the bass attenuation. This increases the intelligibility without increasing the volume - which is an advantage for persons with a slight hearing impairment. ADJUSTMENT FOR HEARING IMPAIRMENT Is your hearing capacity different for each ear?You can use the balance control to adjust your RI 250 (all variants) or RI 500 stethoset receiver to your individual needs. [. . . ] TECHNICAL DATA Modulation Carrier frequencies AF frequency response THD Signal-to-noise ratio Operating time with one accupack Weight with / without accupack Max. Sound pressure level SENNHEISER TECHNOLOGY AND SENNHEISER SERVICE ARE FUTURE-ORIENTED Even after many years, you will still have unlimited pleasure from your infrared sound transmission system. You can buy replacements for wearing parts such as ear-cushions and accupacks for many years to come. [. . . ]