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G.R.A.S. Sound & Vibration >
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Preamplifiers
- These G.R.A.S. microphone preamplifiers are small robust units optimised for acoustical measurements with condenser microphones.
- Connections to preamplifiers are most often made via a 7-pin LEMO series 1B connector; unless its a CCP* Preamplifier. These connectors are widely used, ensuring compatibility with a wide range of power supplies, analysers etc.
- All these preamplifiers are compatible with measurement microphones as defined in the international standard IEC 1094 “Measurement Microphones, Part 4: Specifications for working standard micro-phones”.
- All G.R.A.S. preamplifiers are based on a small ceramic substrate thick-film precision amplifier with very high input impedance. The casings are made of stainless steel for maximum strength and durability with minimum sensitivity to vibration and microphonics.
- G.R.A.S. microphone preamplifiers will work within their specifications up to a temperature of 70°C. They can, however, be used safely at temperatures up to 120°C without damage. The only effect of elevated temperatures is a slight increase in the self-noise of the preamplifier. This will affect the lower limit of the dynamic range of the microphone/preamplifier combination and limit it's ability to measure very low sound pressure levels.
- However, for a high-temperature application, such as measuring sound close to a diesel engine, this would normally not be a problem because of sufficiently high sound pressure levels.
- * Constant Current Power.
Click on images for details:
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| ¼" Pre-amplifiers : : G.R.A.S. Sound & Vibration |
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Type 26AA
Comment:
Intensity Measurements
preamplifier
With 30 cm lightweight cable
terminating in a 4-pin
LEMO 0B connector
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Type 26AC
Comment:
Built-in SysCheck
General-purpose preamplifier
With an integrated 3 metre
lightweight cable terminating
in a 7-pin LEMO connector
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Type 26AL
Comment:
General-purpose preamplifier
With integrated 7-pin LEMO
connector
Adapter, AF0008, included
for use with G.R.AS. ½"
microphones
No Cable
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Type 26HG
Comment:
Infra-sound use
Similar to Type 26AC but
with 40 GOhm input
impedance for low-level
noise measurements at
very low frequencies
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Type 26AB
Comment:
General-purpose preamplifier
With integrated 7-pin LEMO
connector
Adapter, AF0008, included
for use with G.R.AS.
½" microphones
No Cable
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Type 26AN
Comment:
For using insert-voltage
technique to determine the
open-circuit sensitivity of
microphones
With integrated 7-pin
LEMO connector
No Cable
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Type 26TC
Comment:
Built-in TEDS* preamplifier
With an integrated 3 metre
lightweight cable terminating
in a 7-pin LEMO connector
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- Features/Specifications
Frequency Range: 2 Hz - 200 kHZ (±0.2 Hz) Except Type 26HG: 1 Hz - 200 kHZ (±0.2 Hz)
Input Impedance: 0.4 pF, 20 GOhm Except Type 26HG: 0.4 pF, 40GOhm
Output Impedance: 55 Ohm
Output connector: 7-pin LEMO male Except Type 26AA: 4-pin LEMO male
Power Supply: Single: 28V, 0.7mA to 120V,2.5 mA, Dual: ±14V, 0.7 mA to ±60 V, 2.5 mA
Noise, A-weighted: <2.5 µV (typically 1.8 µV) Except Type 26HG: <2.3 µV (typically <1.5 µV)
Linear (20Hz - 20 kHz): <6 µV (typically 3.5 µV) rms Except Type 26HG: <5.7 µV (typically 3.2 µV) rms
Gain: -0.25 dB
*TEDS - Transducer Electronic Data Sheet as proposed by IEEE-P1451.4
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| ½" CCP* Pre-amplifier : : G.R.A.S. Sound & Vibration |
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Type 26CA
Comment:
General purpose preamplifier
Built-in TEDS**
For use with prepolarised
microphones
With integrated BNC
connector
No cable
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- Features/Specifications
Frequency Range: 2 Hz - 200 kHZ (±0.2 Hz)
Input Impedance: 0.4 pF, 20 GOhm
Output Impedance: <50 Ohm
Output connector: Coaxial BNC
Power Supply: 4mA to 20 mA (typically 4 mA) Requires constant current power* supply for proper operation
Noise, A-weighted: <2.5 µV (typically 2 µV)
Linear (20Hz - 20 kHz): <6 µV (typically 3.5 µV) rms
Gain: -0.25 dB
*CCP - Constant Current Power is the same as IEPE and CCLD and is compatible with ICP™, DeltaTron®, ISOTRON® etc.
(ICP™ is a registered trademark of PCB Group, Inc., DeltaTron® is a registered trademark of Brüel & Kjaer SVM A/S, ISOTRON® is a registered trademark of Endevco Corporation.)
**TEDS - Transducer Electronic Data Sheet as proposed by IEEE-P1451.4
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Want to learn more? Contact us or visit G.R.A.S. Sound and Vibration web site.
Other G.R.A.S. Sound and Vibration products
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ETMC Technologies Pty Ltd Macarthur House, 8 Melville Street, Parramatta NSW 2150, AUSTRALIA
p: 02 9555 1225 (+61 2 9555 1225) f: 02 8014 5198 (+61 2 8014 5198) e: contact@etmc.com.au
© 2009-2011, ETMC Technologies Pty Ltd All rights reserved
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