Ampex Plug In Mic Preamp
User Manual: Ampex plug-in mic preamp
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Ampex plug-in Microphone Preamp 4010066
The preamplifier is wired so that a variable gain control may be inserted between the two stages. When used
with Ampex recorders (AG-440, AG-500, AG-600), the record level control on the equipment is so connected,
making the preamplifier a variable-gain device that accommodates a wide variety of professional-quality
microphones.
The unit can be used to drive any amplifier with a 100K ohm input impedance, at a 0.1 VRMS level. When so
used, the signal input is connected across pins 4 and 8, the unbalanced output is taken across pins 7 and 2
(ground). Power (+24VDC) is connected to pin 5, with pin 2 again as ground. The previously mentioned
variable-gain control (100K ohms) is connected across pins 3 and 6. Pin 1 should be connected to the case of
the unit, and should also be grounded.
(from the Ampex AG-600B user manual)
