Uses
- Field measurements of sound and vibration
- Field recording of data
- Measurements of sound insulation
- Traffic noise measurements
| Features
- Two identical channels
- Cross switching between inputs and outputs
- 200 V, 28 V or 0 V polarization voltage supply for condenser microphones
- Fits Brüel & Kjær modular cassette system for rack mounting
- Standard 1.5 V dry cells
- Meter indication of battery condition
- Two 28 V 10 – 32 UNF Microdot sockets for preamplifiers
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Two channels are provided. The inputs and outputs can be interchanged by a single switch to facilitate measurement at two positions without reconnecting the equipment.
Two additional power output Microdot sockets are available at the back, each supplying 28 V DC. Maximum current is 2 ° 2 mA or 1 ° 4 mA.
For use with the wide range of condenser microphones available from Brüel & Kjær, 0 V, 28 V or 200 V microphone polarization may be selected by a simple internal modification to the printed circuit board located under the bottom panel of the 2804. The polarization voltage setting can be checked from a socket on the rear panel of the instrument. Half-inch Condenser Microphone Type 4130 is designed for use with a nominal polarization voltage of 28 V, while 0 V is used for Prepolarized Condenser Microphone Types 4155, 4188 and 4189.
To prevent battery drain the heating elements in the Types 2639 and 2645 are not powered from Type 2804. However, provision is made on the rear of the 2804 for feeding the heating element from an external 6 V DC supply.
For a full Description and Specifications, see
Product Data
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