G.R.A.S. 67AX Instruction Manual

Instruction Manual 67AX ½” CCP Ground Array Microphone System

Revision History Any feedback or questions about this document are welcome at [email protected]. Revision Date Description 1 27 May 2011 First publication 2 25 June 2012 Added calibration and verification information. Copyright Notice © 2011-2012 G.R.A.S. Sound & Vibration A/S http://www.gras.dk Any technical documentation that is made available by G.R.A.S. is the copyrighted work of G.R.A.S. and is owned by G.R.A.S. The content in this document is subject to change without notice. G.R.A.S. Sound & Vibration A/S is not liable or responsible for any errors or inaccuracies that may appear in this document. Trademarks KEMAR is the trademark of G.R.A.S. Sound & Vibration A/S. Any other product names mentioned in this document may be trademarks or registered trade- marks of their respective companies and are hereby acknowledged.

Contents Introduction .................................................................................. 4 The Package.............................................................................................. 4 Assembling the 67AX System ..................................................................... 4 Calibration and Verification ............................................................. 6 Calibrating the microphone .......................................................................... 6 Verifying the microphone ............................................................................ 6 Technical Specifications .................................................................. 7 Dimensions and Data for 67AX ................................................................... 7 Ordering Information ...................................................................... 8 Accessories ............................................................................................... 8 Calibration ................................................................................................. 8 Warranty ................................................................................................... 8 Service and Repairs .................................................................................... 9

Introduction This manual describes how to assemble, calibrate, and verify the 67AX ground array sets. The Package The parts for your 67AX are delivered unassembled. The following table lists the items included with the 67AX package. Item Part Number ½” CCP flush-mounted microphone, with 4 cm cable and Microdot-to- Microdot adapter AE1038 47AX-S1 O-ring, Ø13.5 mm OR0137 O-ring, Ø55 mm OR1512 Cover plate, with 8 screws (SK2015 M2.00 × 4.00) GR1426 Cable safety clip, with 2 screws (SK2008 M3.00 × 8.00) GR1427 Mounting plate GR1425 Windscreen for 67AX AM0375 3 m Angled Microdot-to-BNC cable AA0069 Manual LI0055 Assembling the 67AX System The first step to assembling the 67AX system is connecting the microphone to the cable as shown in Fig. 1. To assemble the 67AX system: 1. Place the small O-ring in the ridge in the center hole. 2. Place the assembled microphone, grid-side down, in the center hole on top of the small O-ring. Arrange the cable attached to the microphone in the cavity Fig. 1. An illustration of how to connect the Microdot-to-Microdot adapter on the microphone to the angled Microdot adapter on the 3 m cable.

surrounding the mounted microphone and fit the cable in the ridge that leads to the outer edge of the plate. 3. Place the large O-ring in the ridge near the edge of the cavity. The large O-ring must lie on top of the cable. 4. Fit the cover plate on top of the microphone and O-ring assembly and fasten in place with 8 screws. 5. Fasten the safety clip over the cable with 2 screws. These steps are shown in Fig. 2. 1 2 3 4 5 (× 8) Fig. 2. A view of the order for assembling the parts of the 67AX.

Calibration and Verification Note: For complete calibration information, see the pistonphone instruction manual. The instructions here explain the specific details related to the 67AX. G.R.A.S. recommends calibration prior to each use to ensure the accuracy of your measurements. Verification is performed in situations where you need to check that the microphone is functioning in its setup and cannot check it properly in the laboratory. Important: The pistonphone calibration adapter and the pistonphone field-verification adapter are designed for use with a 250 Hz pistonphone, such as the G.R.A.S. 42AP Pistonphone. Do not use them with any other calibrator or verification device. The 250 Hz pistonphone can be used for both calibration and daily verifications. Calibrating the microphone To calibrate the microphone in the 67AX, remove it from the mounting plate. 1. Set the pistonphone in an upright position, preferably using a calibration stand for stability. 2. Mount the pistonphone calibration adapter (RA0221) on the pistonphone. 3. Insert the microphone into the adapter on the pistonphone. Press gently to ensure that the microphone is inserted as far as it can go. 4. Turn on the pistonphone and calibrate as described in the instruction manual for the pistonphone. Verifying the microphone 1. Mount the field-verification adapter (RA0216) onto the pistonphone. 2. Hold the pistonphone steady while centering the opening in the adapter over the microphone. 3. Gently press the pistonphone with adapter over the microphone, ensuring that the microphone is as far in the pistonphone as it will go. Note: Due to the setup conditions for the microphone, you may not be able to hold the pistonphone steady. As a result, measurements may not be ideal and cannot be used for calibration purposes. These measurements can only be used for verifying that the measurement chain and the microphone especially is functioning as expected. Important: When performing verification in the field on a microphone with the grid removed, be extremely cautious during measurements. The membrane is vulnerable without the grid and can be easily damaged.

Technical Specifications Dimensions and Data for 67AX Dimensions Microphone Ø13.2 mm Housing Ø18.0 mm Microphone set height Without grid 8 mm With 9.20 mm Weight 15 g Mounting Plate Ø400 mm Data was collected in a temperature of 23 °C (±3 °C) and in a relative humidity of 60 % ±20 %. Frequency response for the set ±2.0 dB 3.15 Hz – 20 kHz ±1.0 dB 5 Hz – 12.5 kHz Nominal sensitivity for the set at 250 Hz 12.5 mV/Pa Polarization voltage 0 V Dynamic range for the set Upper limit (3 % distortion) 146 dB re. 20 μPa Thermal noise 22 dB(A) re. 20 μPa Temperature Operation –30 °C to +70 °C Storage –40 °C to +85 °C Static-pressure coefficient 250 Hz/25 °C -0.008 dB / kPa Humidity (non-condensing) Range 0 – 100 % RH Influence (250 Hz) <0.1 dB (0 – 100 % RH) Influence of axial vibration equivalent to 1 m/s² 66 dB re. 20μPa Venting Rear-vented

Ordering Information Included Items Part Number ½" Ground array microphone kit (includes 47AX-S1 ½” Flush-mounted microphone set, Ø400 mm mounting plate with assembly parts and cable, and windscreen) 67AX Manual LI0055 Accessories The following accessories are needed for the 67AX, but they are not included in the basic package. They must be ordered separately. Accessory Part Number Pistonphone field-verification adapter RA0216 Pistonphone calibration adapter RA0221 Important: The pistonphone calibration adapter and the pistonphone field-verification adapter are designed for use with a 250 Hz pistonphone, such as the G.R.A.S. 42AP Pistonphone. Do not use them with any other calibrator or verification device. The 250 Hz pistonphone can be used for both calibration and daily verifications. Calibration Before leaving the factory, all G.R.A.S. products are calibrated in a controlled laboratory environment using traceable calibration equipment. An individual test certificate is included with each product. The calibration information is also stored in the built-in TEDS. We recommend a yearly recalibration at minimum, depending on the use, measurement environment, and internal quality control programs. We recommend calibration prior to each use to ensure the accuracy of your measurements. Warranty All G.R.A.S. products are made of high-quality materials that will ensure life-long stabil- ity and robustness. The 67AX is delivered with a 5-year warranty.

Damaged diaphragms in microphones can be replaced. The warranty does not cover products that are damaged due to negligent use, an incor- rect power supply, or an incorrect connection to the equipment. Service and Repairs All repairs are made at G.R.A.S. International Support Center located in Denmark. Our Support Center is equipped with the newest test equipment and staffed with dedicated and highly skilled engineers. Upon request, we make cost estimates based on fixed repair categories. If a product covered by warranty is sent for service, it is repaired free of charge, unless the damage is the result of negligent use or other violations of the warranty. All repairs are delivered with a service report, as well as an updated calibration chart. G.R.A.S. Sound & Vibration continually strives to improve the quality of our products for our customers; therefore, the specifications and accessories are subject to change.