G.R.A.S. 26CF 1/2'' CCP Preamplifier with BNC Connector, Gain and Filters

Freq range: 2.5 Hz - 200 kHz
Noise: 1.8 µV
Gain: -0.25 / +20 dB
Special feature: 0/20 dB gain, A-weighting and HP filters

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 G.R.A.S. 26CF can be used with all G.R.A.S. prepolarized microphones, namely:

  • 1/2-inch microphones: G.R.A.S. 40AE, 40AD and 40AQ
  • 1/4-inch microphones: G.R.A.S. 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 describesG.R.A.S. 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 G.R.A.S. 40AD, 40AE, 40AO and 40AQ.

Frequency range (±0.2 dB) with 18 pF microphone dummy Hz 2.5 to 200 k
Slew rate V/µs TBD
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
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 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
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.

Frequency response of A-weighting filter (compliant with IEC 61672-1 Class 1)

G.R.A.S. Sound & Vibration reserves the right to change specifications and accessories without notice.

Optional items

G.R.A.S. AA0035

3 m BNC - BNC Cable

G.R.A.S. AA0039-CL

Customized Length BNC - BNC Cable

G.R.A.S. AL0008

1/2" Microphone Holder, POM

G.R.A.S. AL0012

1/2" Microphone Holder, Stainless Steel

G.R.A.S. AL0005

Swivel head

G.R.A.S. AL0006


G.R.A.S. RA0019

Adapter for 1/4" microphone and 1/2" preamplifier

G.R.A.S. RA0073

Adapter for 1" microphone and 1/2" preamplifier

G.R.A.S. RA0190

Right-angled (90º) Adapter for 1/2" Microphone and 1/2" Preamplifier

G.R.A.S. RA0018

20 dB Attenuator for prepolarized 1/2" microphones

G.R.A.S. RA0062

20 pF Preamplifier-input Adapter for 1/2" preamplifiers

G.R.A.S. 12AL

1-Channel CCP Power Module with A-weighting filter

G.R.A.S. 12AQ

2-Channel Universal Power Module with signal conditioning and PC interface


G.R.A.S. Sound & Vibration reserves the right to change specifications and accessories without notice.