G.R.A.S. 12HM 10-Channel Power Module for Lownoise Systems

Connection: Traditional 200 V
Channel(s): 10

The 12HM provides:

  • polarization voltage (200 V) for up to 10 condenser microphones
  • voltage supplies (±15 V) for powering up to 10 microphone preamplifiers
  • individual response setting, pressure or free field, for each channel
  • individual gain adjustement of ±3 dB for each channel

When connected to the 40HF/40HH/40HT Low-noise Microphone Systems, each channel of the Type 12HM supports the specifications of a G.R.A.S. low-noise measuring system, and can be used in sound-power measurements of low-noise products, such as disk drives, under anechoic or semi-anechoic conditions in accordance with IEC 745:1977.


All G.R.A.S. products are made of high-quality materials that will ensure life-long stability and robustness. The 12HM 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.

Output channel(s) 10
Output impedance Ω 30
Type Traditional power supply (LEMO)
Input channel(s), traditional power supply 10
Channel separation (20 Hz to 20 kHz) dB >90
Preamplifier supply V +-15
Polarization voltage V 200
Overload indication Yes
Power supply, external (±10 %) Vac 115 to 230
Power consumption W 35
Fuse 230 V / 115 V mA 160 / 315
Weight g / oz 5,500 / 194.01