Grason - Stadler GSI 17 Audiometer with Telephonics TDH 39 headphones. Tested with new genuine, metal, Telephonics TDH 39 headphones with new cord cables. Headphones from military stock - unused. Comes with a response switch and power supply.
This unit has been modified to use 10 Ohm headphones instead of 50 Ohm headphones by replacing R400 & R401 (130 Ohm) with 71.5 Ohm. With the new headphones, the GSI 17 should be calibrated with them. SN 20032589