GRAS 40SC CCP Probe Microphone
Freq range: 2 Hz to 8 kHz
Dyn range: 40 dB to 160 dB
Sensitivity: 3 mV/Pa
The CCP Probe Microphone 40SC is a small, constant-current powered, compact unit for sound-pressure measurements in small enclosures, in harsh environments and in very close proximity to sound sources. The high acoustic input impedance at the tip of the probe minimizes its influence on the acoustic field, while the stainless-steel tube of the probe can withstand temperatures of up to 800 ºC.
Technology
Typical applications and use
- Acoustic-impedance measurements
- Exhaust-system measurements
- Near-field measurements
- Measurements at high temperatures
- Pressure-distribution measurements in small enclosures
Design
The GRAS 40SC is constructed with detachable stainless-steel probes tubes which guide the acoustic signal to a prepolarised microphone inside the housing of the 40SC. After being sensed by the microphone, the acoustic signal is passed on to an impedance-matching wave guide which eliminates unwanted internal reflections. The result is a smooth frequency-response ranging from 2 Hz up to 20 kHz. The internal microphone is connectedto an CCP preamplifier with a high dynamic range; ensuring a measurement range from approximately 40 dB to 160 dB re. 20 μ Pa.
The integrated BNC socket is for drawing power from, and delivering the signal to, a constant-current power supply, e.g. the GRAS 12AL CCP Supply, or any other compatible constant-current power supply.
The CCP Probe Microphone 40SC is internally compensated to equalize the internal pressure of the microphone with the static pressure at the probe’s tip . The static pressure within the 40SC will therefore adjust itself to the static pressure existing at the probe’s tip; which it does with a time constant of approximately 0.1 s.
The 40SC can be used with various probe lengths and is delivered with four standard probe lengths, i.e.: 20 mm, 40 mm, 80 mm and 160 mm. Intermediate lengths can be made by cutting these standard lengths. Also, the stainless steel tubes can be bent to a radius as low as 5 mm without downgrading the system’s acoustics. A flexible probe tube is also provided for use in measurements where stiff stainless-steel tubes are not practical. This does, however, slightly downgrade the system’s acoustic performance.
The right angled design of the 40SC makes it particularly well suited for measurements on exhaust-gas systems and other machinery in general as well as for scanning vibrating surfaces such as loudspeaker diaphragms and cabinets.
The compact size, low weight and all-stainless-steel construction of the 40SC make it robust, easy to handle and easy to mount.
Specifications
Pressure-equalization time constant: Internal to tip static pressure: typically 0.1 s
Typical frequency response
GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.
Dimensions
Where not specified, measures are in mm.
Length (housing) | 83.80 |
Diameter | 12.7 |
Probe tube outside diameter | 1.25 |
Probe tube inside diameter | 1 |
Cable diameter | 2.5 |
Cable length | 3 metres |
Ordering info
Included items
GRAS GR0265 | Pistonphone adapter for stainless steel probe |
GRAS GR0266 | Pistonphone adapter for flexible probe |
GRAS GR0267 | Heat sink and tool |
GRAS RA0326 | Calibration coupler |
GRAS GR0263 | 1.3 mm insert pin for calibration coupler |
GRAS GR0266 | 1.6 mm insert pin for calibration coupler |
GRAS YY0004 | Pair of pliers |
GRAS YY0005 | File |
GRAS MI0016 | Silicon grease |
GRAS EK0018 | Teflon tubing (L=0.5 m, Dia.: 1.6 mm) |
GRAS GR0258 | 20 mm probe tube |
GRAS GR0259 | 40 mm probe tube |
GRAS GR0260 | 80 mm probe tube |
GRAS GR0261 | 160 mm probe tube |
GRAS GR0401 | Flexible probe tube |
GRAS SK5546 | Needle (for cleaning the probe) |
Optional items
3 m BNC - BNC Cable | |
| 2-Channel Power Module with gain, filters and SysCheck generator | |
2-Channel Universal Power Module with signal conditioning and PC interface | |
Pistonphone, Class 1 | |
Intelligent Pistonphone, Class 0 |
GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.
