The GRAS 1/2-inch Preamplifier GRAS 26CF is a general purpose preamplifier optimized for use with prepolarized condenser microphones. It is a small, robust unit and uses a GRAS CCP power supply, e.g. GRAS 12AL. It has low inherent noise level, a large dynamic range and a frequency response from 2.5 Hz to 100 kHz.
Technology
Gain and filter switch settings
There are two flush-mounted switches for selecting various combinations of gain and filtering, i.e.:
Gain switch settings:
- 0 dB - for normal microphone signals.
- +20 dB - for boosting weak microphone signals.
Filter switch settings:
- A-Weighting - as required in standard measurements.Linear - to let the microphone signal passunfiltered.
- High-pass - to cut off unwanted low frequencies.
Its small ceramic thick-film substrate has a very high input impedance, and is shielded by a guard ring to minimise the influence of stray capacitance and microphonic interference.
The GRAS 26CF can be used with all GRAS prepolarized microphones, namely:
- 1/2-inch microphones: GRAS 40AE, 40AD and 40AQ
- 1/4-inch microphones: GRAS 40BE and 40BD, using the optional 1/2-inch to 1/4-inch adaptor RA0019
It has an integrated BNC output connector.
The casing is made of stainless steel for maximumstrength and durability.
CCP stands for “Constant Current Power” and describesGRAS power supplies that maintain a constant level ofcurrent for driving IEPE transducers like this preamplifier which can be used with prepolarized microphone cartridges such as GRAS 40AD, 40AE, 40AO and 40AQ.
Specifications
| Parameter |
Unit |
Value |
| Frequency range (±0.2 dB) with 18 pF microphone dummy |
Hz |
2.5 to 80 k (1 V input) |
| Slew rate |
V/µs |
1 |
| Input impedance |
GΩ // pF |
20 // 0.4 |
| Output impedance |
Ω |
< 50 |
| Output Voltage Swing, min. @ 24–28 V CCP voltage supply |
Vp |
3.5 (20–20 kHz) |
| Noise (A-Weighted) max. |
µV |
6 |
| Noise (A-Weighted) typ. |
µV |
5 |
| Noise (Linear 20 Hz – 20 kHz) max. |
µV |
8.5 |
| Noise (Linear 20 Hz – 20 kHz) typ. |
µV |
8 |
| High-pass filter @3dB cut-off |
Hz |
20 |
| Gain |
dB |
-0.35 |
| Power supply (Constant Current Power) |
mA |
4 to 20 (typ. 4) |
| DC bias voltage, typ. |
V |
15 |
| 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 – 95 |
| Connector type |
– |
BNC |
| CE / RoHS compliant / WEEE registered |
– |
Yes / Yes / Yes |
| Weight |
g / oz |
30.0 / 1.06 |
Conditions: 23 °C Ambient temperature, 4 mA / 24 V open loop CCP voltage, 18 pF dummy microphone & 3 m coax-cable.
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Frequency response of A-weighting filter (compliant with IEC 61672-1 Class 1)
GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.
Dimensions
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