1
Introduction.
The mixer has been designed to meet the following requirements:
1.1
To be suitable for fixed or mobile use.
1.2
To be light, easily dismantled and transported.
1.3
To comprise cassettes, which can be assembled in different
combinations, to form mixers with up to 24 inputs for up to 8-track
recording.
1.4
When a multi-track recording is being made, to provide for
simultaneously feeding a 2-track stereo tape machine.
1.5
To be complete with all foreseeable facilities required for both
classical and pop recording.
1.6
To have a very high degree of reliability.
1.7
Any faults which may occur to be easily located.
1.8
Spare cassettes to be easily inserted to remove faults.
2.
General
2.1
Terminology
2.1.1 Drawing numbers
Throughout this handbook when a reference is made to a Drawing Number, it
assumed to be preceded by TG12345 unless otherwise stated.
2.1.2 Signal levels
Signal voltage levels are expressed in dBv, this being the voltage level in
decibels with respect to 0.447v (this being the r.m.s. voltage across a 200
Ω
resistor
when dissipating one milliwatt). The figures quoted are not all strictly accurate as
they do not, in general, take into account the loading effect of a high impedance
load across a 200
Ω
or lower impedance source.
In the manufacturing test specifications which require more precision,
sending levels are expressed in dBi, this being the indicated sending level of a
200
Ω
Gain Set. At an indicated level setting of 0dBi, the gain set would deliver a
zero level signal, 0dBm, i.e. 1 milliwatt, into a 200
Ω
load. Thus at the output of the
Gain Set when loaded with 200
Ω
, dBm, dBv and dBi are numerically equal. If the
output is completely unloaded then dBV=dBi + 6.02
2.2
General Drawings
The general scheme of the Mixer is shown on the block schematic, Drawing
number DE1.
The top panel layout of each of the six types of cassette is shown on Drawing
number D143.
