The instrument
The D 1200 microphone certainly came onto the market after the D 1000 (1968), probably around 1970. According to a company brochure, it was still in production in 1988.
Details
Frequency: * Bass, 25-17'000 Hz: full unattended frequency range with emphasis on the bass sounds, strong proximity effect. * Medium, 50-17'000 Hz: partial pass-cut giving rise to clear reproduction of mid-frequency range. Particulary suitable for instrumental and orchestral. * Sharp, 100-17'000 Hz: Acute bass roll-off. Ideal for locations with high power amplifications where acoustic feed-back is like to occur.
Sensitivity: 0.23, 2.8, 0.12 mV/Pa
Impedance: 200 ohms
(source: AKG)