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 Type 26CF can be used with all G.R.A.S. prepolarized microphones, namely:
- ½-inch microphones:Types 40AE, 40AD and 40AQ
- ¼-inch microphones:Types 40BE and 40BD, using the optional½-inch to ¼-inch adaptor RA0019
It has an integrated BNC output connector.
The casing is made of stainless steel for maximumstrength and durability.
1 CCP stands for “Constant Current Power” and describesG.R.A.S. power supplies that maintain a constant level ofcurrent for driving IEPE transducers like this preamplifierwhich can be used with prepolarized microphones such asTypes 40AD, 40AE, 40AO and 40AQ.
|Frequency range (±0.2 dB) with 18 pF microphone dummy||Hz||2.5 to 200 k|
|Input impedance||GΩ // pF||20 // 0.4|
|Output impedance||Ω||< 50|
|Output Voltage Swing, min. @ 24-28 V CCP voltage supply||Vp||8|
|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|
|Noise (Linear 20 - 20 kHz, 20 dB gain)||µV||TBD|
|Noise (High-pass, 0 dB gain)||µV||TBD|
|Power supply (Constant Current Power)||mA||4 to 20 (typ. 4)|
|DC bias voltage, typ.||V||14|
|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|
|CE/RoHS compliant/WEEE registered||Yes / Yes, Yes|
|Weight||g / oz||30.0 / 1.06|