The DT109 headphones have 400 ohm capsules and a 200 ohm dynamic microphone, units are available in the black shell version, with distinctive marking to distinguish them from standard non-protected versions. Limiting level is fixed at 93dB (note 1). As with in-line limiters, each headphone is individually calibrated. Standard connector options are available, and because the limiter is within the earshell, it is possible to use spare or replacement leads, as for standard versions. Due to the method of construction, it is not possible for replacement ear loudspeakers to be user-fitted in these types, units requiring repair must be returned to Canford. For the same reason, replacement limited ear loudspeaker units are not available as spare parts.

The DT109 level-limited headsets are available in four versions - two terminated, one unterminated and one without cable (XLR wiring is compatible with Tecpro and RTS intercom systems, see “Wiring Conventions” in the Tecpro section of this catalogue for details):

Notes
1) The quoted limit level of 93dB is for measurement using dummy head (or mannequin) systems. For measurements using flat plate calibrators the level will be 96dB. Health and Safety authorities are more inclined to use the dummy head type measurement.