What is recorded on the TTR-103? When was it discontinued?
The TTR-103 was discontinued circa 1975. It was a 45 rpm recording on a 12" LP disc.
The TTR-103 contained three trackability and distortion tests:
1) High frequency test - 10.8 kHz pulsed with a 270 Hz repetition rate
2) Mid-frequency test - 1000 Hz plus 1500 Hz
3) Low frequency test - 400 Hz plus 4000 Hz