ID: 1745 / ver. 201
Adjustment
Read the tone’s sound level. Select noise with the channel 2 input selector. Adjust, with the channel 1
attenuator, so that the average level is 3 dB higher than the tone’s. Repeat the adjustment of tone and
masking with the right telephone. Use the channel 2 output selector to choose right channel.
Adjustment of the stereo insert phones
A set of stereo insert phones may be connected to the same outputs as the normal phones. To calibrate
them, press the TALK THROUGH button. This toggles between the phones and the inserts. A breef
text (PHON or INST) is showed in the frequency display, to indicate which are selected. In addition,
when the TALK THROUGH lamp is on, the inserts are selected. The calibration procedure is the
same as described in “Adjustment of the telephones”.
The hearing level offsets for inserts are different from those used with the phones. The table below
shows the hearing levels for Eartone 3A or 5A insert phones when using the DB-138 2cc coupler,
given in the ISO 389 standard. These levels are stored in mode 4, as default. They are used for both the
stereo insert set and for calibration of the mono insert output. If another coupler is used for calibration,
the values should be corrected to fit the table provided with the insert phones.
Hearing level table for Eartone insert phones
125
250
500
750
1000
1500
2000
3000
4000
6000
8000
26.0
14.0
5.5
2.0
0.0
2.0
3.0
3.5
5.5
2.0
0.0
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