3 Electronic Description
Access to the majority of the electronics of. the recorder can be obtained by removing
the base of the recorder. The REVOX G-36 has two identical record- and replay-
channels. The common bias and erase Oscillator can be switched onto either one or
both channels, thus allowing stereophonic recordings, two-track sound with sound and
monophonic recordings. Each channel is equipped with pre-amplifier stages to accept
low-level signals from linear high-impedance sources. (Step-up transformers are
required where low-impedance dynamic microphones are being used.) For
monitoring the signal level, the recorder is equipped with two VU-meters and
associated matching amplifiers. The built in power amplifier drives a 21 cm Ø
loudspeaker and an appropriate switching arrangement permits listening to either one
- or both channels, before and after tape.
3.1 Circuit checks and adjustments
3.1.1 Measuring instruments
The following items are essential:
a) 10 000 Ω/V DC Multi range meter
b) VTVM with min. sensitivity of 3 mV full scale
c) Low distortion audio generator
d) Appropriate calibration tape (use “REVOX Bezugsband” or “Bezugsband” 19 DIN
45513" both of which have a frequency response corresponding to the G-36
equalization characteristic)
Where a test tape with response characteristics of the recorder under examination is
not available, other test tapes may be used and a set of correction figures for the
individual frequencies can be obtained from the following equation:
Ґ
1
and Ґ
2
designate the time constants of the equalization characteristics.
Other desirable but not essential instruments include a Distortion Factor Meter and an
Oscilloscope.
Direct record and replay figures can only be taken when a suitable bias filter is
connected between the output of the recorder and the measuring instrument.
An external filter will not be necessary for those REVOX G-36 Recorders which are
already equipped with the bias-suppression circuit (printed circuit with L3, L4, C 48,
C76, C77, C78, R112 and R113 on amplifier chassis to the left of P1, see fig. 14 and
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