G.R.A.S. 12AB 2-Channel Power Module for G.R.A.S. Intensity Probes

Connection: Traditional 200 V
Channel(s): 2
  • 12AB Intensity Power Module
  • 12AB Intensity Power Module
  • 12AB Intensity Power Module
  • 12AB Intensity Power Module

Typical applications and use

  • Sound-intensity measurements
  • G.R.A.S. Sound Intensity Probe Type 50AI versions B, C, and D


The 12AB is built into a sturdy anodized aluminium cabinet and can be powered either by internal standard batteries or an external DC supply (12 V-18 V), e.g. a mains/line adapter.

The polarization voltage for the probe’s microphonescan be set to 200 V * — for use with Type 50AI, or 0 V — for prepolarized microphones. The voltage supply for the probe’s preamplifers can be set to 120 V * — for use with 50AI, or 28 V — for minimum power consumption.

The 12AB will run for up to 10 hours on fresh standard alkaline batteries. A Battery meter indicates the condition of the batteries.

The 12AB has a 9-pin D-sub socket wired up for connecting directly to the RS232 port of a computer; thus enabling software to make use of the remote control facilities of the G.R.A.S. 50AI Sound Intensity Probe. The input is a 12-pin LEMO socket on the front panel which is wired up for the G.R.A.S. 50AI Sound Intensity Probe versions B, C and D. This input is also connected to the 9 pin D-subconnector in order to:

a) Transmit the state (pressed/not pressed) of the two push buttons on the handle of the 50AI
When pressed: the blue button transmits DSR, the grey button transmits CTS

b) Signal the responses via the two LEDs also on the handle of the 50AI
When lit: the red LED is signalling RTS, the white LED is signalling DTR

By suitably programming the computer’s software, measurements and data acquisition can be controlled interactively via these push buttons and LEDs.

The two output signals of the probe are directly available via two standard BNC connectors (A andB) on the front panel.

The cabinet of the 12AB is 1/12 of a standard 19-inch rack; meaning that up to 12 of these Power Modules can be mounted in a standard 19-inch rack using the AK0040 Rack-mounting System.


All G.R.A.S. products are made of high-quality materials that will ensure life-long stability and robustness. The 12AB 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 (±0.2 dB) Hz 0.05 to 200 k
Output channel(s) 2
Output impedance Ω 30
Phase matching, equal gain, no filters IEC 61043
Linear mode Yes
Type Traditional power supply (LEMO)
Input channel(s), traditional power supply 2
Preamplifier supply V 28 / 120
Polarization voltage V 0 / 200
Power supply, battery 10 x LR6 (AA)
Power supply, external Vdc 12 to 18
Power consumption mA 180 to 210
Battery life, 28 V preamp. supply h 11
Battery life, 120 V preamp. supply h 9
Battery low indication Yes
Fuse mA 315 (slow)
Weight g / oz 770 / 27.161
G.R.A.S. Sound & Vibration reserves the right to change specifications and accessories without notice.


G.R.A.S. EL0001 10 x LR6 (AA) alkaline cells
G.R.A.S. AB0002 DC mains/line adapter, Europe
G.R.A.S. AB0003 DC mains/line adapter, USA


G.R.A.S. AK0040 19-inch Rack-mounting System

G.R.A.S. Sound & Vibration reserves the right to change specifications and accessories without notice.