G.R.A.S. SOUND & VIBRATION
Power Module Type 12AQ
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1
General Description
1 .1 Introduction
The G.R.A.S. Power Module Type 12AQ (Fig. 1.1) is a dual-channel power supply for preampli-
fiers (CCP as well as traditional) used with measurement, condenser microphones.
It has facilities for both manual control and remote control. Manual control is via its front-panel
switches and push buttons. Remote control is via its RS232 interface.
The Type 12AQ is for general use in acoustic measurements as well as for intensity measure-
ments; both in the laboratory and in the field.
Fig. 1.1 The Power Module Type 12AQ
1 .2 Salient Features
1.2.1 Traditional preamplifiers
For traditional preamplifiers such as Type 26AL (¼″) or Types 26AJ and 26AH (½″), the Type
12AQ provides:
• a voltage supply (± 15 V or ± 60 V) for powering up to two microphone preamplifiers.
• a polarization voltage (200 V or 0 V) for two condenser microphones.
• a SysCheck signal (1000 Hz) for calibration checks.
1.2.2 CCP preamplifiers
For CCP (constant-current power) preamplifiers such as Types 26CB and 26CC (¼″
) or Types
26CA and 26CF (½″), the Type 12AQ provides:
• a constant current supply (4 mA) sourced at 28 V DC for two CCP microphone preamplifiers.
