The GRAS 26AM ½-inch Preamplifier is a small robust unit optimised for acoustic measurements using condenser microphones. It hase a very low inherent noise level, a wide dynamic range and a frequency response from below 2 Hz to above 200 kHz.
Technology
Typical application & use
Precision measurements
Low-pressure measurements
General-purpose preamplifiers
Design
All GRAS microphone preamplifiers are based on a small ceramic thick-film substrate with a very high input impedance. The ceramic substrate is shielded by a guard ring to minimise the influence of stray capacitance and microphonic interference. The casing is made of stainless steel for maximum strength and durability. The small dimensions of the 26AM preamplifier ensures reliable operation under humid conditions owing to the heat generated by internal power dissipation.
Compatibility
The 26AM preamplifier 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 compatiblewith other available makes of similar microphone preamplifiers.
26AM is provided with a 3 m high-quality cable terminating with a 7-pinLEMO series 1B plug.
Connector
.jpg)
7-pin LEMO 1B male (ext. view)
Specifications
| Parameter |
Unit |
Value |
| 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 |
10 |
| 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 |
| High-pass filter @3dB cut-off |
Hz |
TBD |
| 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 |
| Humidity coefficient @250 Hz |
dB/% RH |
TBD |
| Connector type |
– |
7-pin LEMO (FGG.1B.307) |
| CE/RoHS compliant/WEEE registered |
– |
Yes/Yes, Yes |
| Weight |
g / oz |
32.0 / 1.13 |
Conditions: 23 °C Ambient temperature, ±60V/+120V power supply, 18 pF dummy microphone, 3 m output cable.
.jpg)
Low frequency response for various microphone capacities
.jpg)
Max. RMS output signal for various cable loads with 120 V supply
GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.
Dimensions
.jpg)
