G.R.A.S. 12AQ 2-Channel Universal Power Module with signal conditioning and PC interface

Connection: Traditional 200 V / CCP
Channel(s): 2

Typical applications and use

  • General-purpose dual-channel precision measurements
  • Intensity measurements
  • Standard and custom signal conditioning
  • Manual and digital control
  • CCP and traditional power supplies
  • 0 V or 200 V polarization


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 12AQ is for general use in acoustic measurements as well as for intensity measurements; both in the laboratory and in the field.

Traditional Preamplifiers

For traditional preamplifiers such as 26AL (1/4") or 26AJ and 26AH (1/2"), the 12AQ provides:

  • Voltage supply (± 15 V or ± 60 V) for powering up to two microphone preamplifiers
  • Polarization voltage (200 V or 0 V) for two condenser microphones
  • SysCheck * signal (1000 Hz) for calibration checks

CCP Preamplifiers

For CCP (constant-current power) preamplifiers such as 26CB and 26CC (1/4") or 26CA and 26CF (1/2"), the 12AQ provides a constant current supply (4 mA) sourced at 28 V DC for two CCP microphone preamplifiers.

Signal Conditioning

Each channel can be set-up independently in terms of gain, filter, input, output and polarization voltage.


The gain can be set from – 20 dB to 70 dB in discrete steps of 10 dB.

A series of front-panel LEDs follows and indicates the current gain setting.


The filter characteristics can be selected from one of the following:

  • Lin for linear response with a high-pass filter of 0.2 Hz
  • HP for linear response with a high-pass filter of 20 Hz
  • AW for an A-weghted response
  • Ext for an optional, customized signal-response network (contact G.R.A.S. for further details)


The microphone signal can enter the 12AQ via either of the following input sockets on the rear panel.

  • BNC sockets for microphones used with CCP preamplifiers
  • 7-LEMO sockets for microphones used with traditional preamplifiers


The conditioned output signals, via the BNC output sockets on the rear panel, can be made available as either floating or non-floating.

Polarization voltage

Applicable to 7-pin LEMO preamplifier inputs on the rear panel. Can be set to either 0 V or 200 V.

Preamplifier supply voltage

This can be set to either ± 15 V or ± 60 V. The chosen value will apply to both 7-pin LEMO preamplifier inputs.


This can be set to either SysCheck signal (1000 Hz) on or off. The chosen condition will apply to both7-pin LEMO preamplifier inputs.

Power Supply

The 12AQ can be powered either by internal standard alkaline cells (6 x LR14 {C}) or from the included mains/line Adapter for either 115 V AC or 230 V AC.


All G.R.A.S. products are made of high-quality materials that will ensure life-long stability and robustness. The 12AQ is delivered with a 2-year warranty. The warranty does not cover products that are damaged due to negligent use.

Service and Repairs

All repairs are made at G.R.A.S. International Support Center located in Denmark. Our Support Center is equipped with the newest test equipment and staffed with dedicated and highly skilled engineers. Upon request, we make cost estimates based on fixed repair categories. If a product covered by warranty is sent for service, it is repaired free of charge, unless the damage is the result of negligent use or other violations of the warranty.

Frequency response (±0.1 dB) @ Gain ≤50 dB Hz 10 to 100 k
Frequency response (±0.2 dB) @ Gain ≤50 dB Hz 2 to 200 k
Frequency response (±0.1 dB) @ Gain ˃50 dB Hz 10 to 20 k
Output channel(s) 2
Output impedance Ω 100
Inherent noise, LIN (20 Hz to 20 kHz) re input, when not dominated by output µVrms <2
Inherent noise, LIN (20 Hz to 200 kHz) re input, when not dominated by output µVrms <5
Inherent noise, (20 Hz to 20 kHz) re input, when dominated by output µVrms <10
Inherent noise, (20 Hz to 200 kHz) re input, when dominated by output µVrms <25
Gain settings, 10 dB steps dB -20 to +70
Gain error dB ± 0.1
Phase matching, equal gain, no filters IEC 61043
A-weighting filter according to IEC 61672 Class 1
High-pass filter 3-pole Butterworth, -1 dB @ 20 Hz
Linear mode Yes
SysCheck level @ 1 kHz Vrms 1
Type Constant Current Power (CCP) and Traditional power supply (LEMO)
Input channel, CCP 2
Input channel(s), traditional power supply 2
Preamplifier supply V ±15 / ±60
CCP preamplifier supply @ +28 V mA 4
Polarization voltage V 0 / 200
Overload indication Yes
Overload level Vp 9
PC controlable Yes
External filter option Yes
Power supply, battery 6 x LR14 (C)
Power supply, external Vdc 8 to 18
Battery low indication Yes
Weight g / oz 1,350 / 47.62
Weight with batteries g / oz 1,750 / 61.7

Included Items

G.R.A.S. EL0002

Battery LR14 (6pcs incl.) 

G.R.A.S. AA2005

RS-232 cable, 1,8 m

One of these Power Supplies:

(Depending on country)

G.R.A.S. AB0002

Power supply 230 VAC to 15 VDC. EU-connector

G.R.A.S. AB0006

Power supply 230 VAC to 15 VDC. UK-connector

G.R.A.S. AB0003

Power supply 120 VAC to 15 VDC. USA-connector

Optional Items

G.R.A.S. RP0001-XX

Customised Signal-response Network for switch pos.
Ext. To be factory mounted.
Contact your G.R.A.S. representative if needed