G.R.A.S. 26AK 1/2'' Standard Preamplifier with Integrated Connector

Freq range: 2.5 Hz to 200 kHz
Noise: 1.8 µV
Gain: -0.25 dB
Special feature: General purpose


G.R.A.S. 26AK is a preamplifier designed for general purpose in the laboratory and field and accommodates directly all IEC 61094 standardized ½” externally polarized measurement microphones.

It is rugged and reliable and can handle microphone signals up to 50 Vpeak within 2 Hz to 200 kHz. The printed circuit board is made by use of thick-film substrate technology and optimized with respect to maximum suppression of microphonics and moisture rejection.

The high-quality, standard 7-pin LEMO male connector is integrated into the preamplifier and ensures that only one type of connector and cable is required for both connection and extension.

26AK is factory calibrated individually and delivered with a calibration chart stating its A-weighted and linear self-noise.


26AK is compatible with ½-inch microphones as defined in international standard IEC1094 Measurement Microphones, Part 4: Specifications for working standard microphones. The mounting thread (11.7 mm - 60 UNS-2) is compatible with other available makes of similar microphone preamplifiers.

G.R.A.S. 26AK is integrated with a 7-pin LEMO series 1B plug.

Frequency range (±0.2 dB) with 18 pF microphone dummy Hz 2.5 to 200 k
Slew rate V/µs 20
Input impedance GΩ // pF 20 // 0.4
Output impedance Ω 75
Output Voltage Swing, max. @ ±14V/+28V power supply Vp 12
Output Voltage Swing, max. @ ±60V/+120V power supply Vp 50
Noise (A-Weighted) max. µV 2.5
Noise (A-Weighted) typ. µV 1.8
Noise (Linear 20 Hz – 20 kHz) max. µV 6
Noise (Linear 20 Hz – 20 kHz) typ. µV 3.5
Gain dB -0.25
Power supply, single V 28 to 120
Power supply, balanced V ±14 to ±60
DC-offset, min., single suppy V 0.5 x Vs - 1
DC-offset, max., single suppy V 0.5 x Vs + 4
DC-offset, balanced supply V -1 to 4
Temperature range, operation °C / °F -30 to 70 / -22 to 158
Temperature range, storage °C / °F -40 to 85 / -40 to 185
Humidity range non condensing % RH 0 to 95
Connector type 7-pin LEMO (FGG.1B.307)
CE/RoHS compliant/WEEE registered Yes / Yes, Yes
Weight g / oz 35.0 / 1.24
Conditions: 23 °C Ambient temperature, ±60V/+120V power supply, 18 pF dummy microphone, 3 m output cable.
G.R.A.S. AA0008 3 m extension cable (7-pin1B LEMO)
G.R.A.S. AA0009 10 m extension cable (7-pin1B LEMO)
G.R.A.S. AA0012 30 m extension cable (7-pin1B LEMO)
G.R.A.S. AA0014 100 m extension cable (7-pin1B LEMO)
G.R.A.S. RA0017 1-inch to ½-inch adaptor for use with G.R.A.S. 1-inch microphones
G.R.A.S. RA0019 ¼-inch to ½-inch adaptor for use withG.R.A.S. ¼-inch microphones