Bruel and Kjaer 4230 Sound Level Calibrator

Bruel and Kjaer 4230 Sound Level Calibrator
Manufacturer: Bruel & Kjaer
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Bruel and Kjaer 4230 Sound Level Calibrator  

Bruel and Kjaer 4230 Sound Level Calibrator

Rent me for $100 a month

   Designed for accurate everyday calibration of sound level meters using .5 in. and 1 inch microphones. Pocket sized sound source designed for for accurate, everyday field calibration of sound level meters using .5 in. and 1 inch microphones.

Features

  • Calibrator Output: Provides 94 dB re 20 uPs sound level at 1 kHz.
  • Calibration Accuracy: +/- 0.3 dB
  • Power Source: Internal. 9 Volt battery

   The 4230 is designed for the calibration of 1'' and 1/2'' diameter microphones. An adaptor is placed over the opening for use with 1/2'' microphones and is removed when 1'' microphones are to be calibrated. The calibrator should be stored and operated in its leather case. The sound pressure level produced by the 4230 is 94 dB re 20 µPa. However, when calibrating a microphone which is to be used for free field measurements, a small correction is necessary to compensate for the difference between free field response at 0° incidence and the pressure response. The correction is -0,4 dB for 1'' free field microphones and -0,2 dB for 1/2" free field microphones. This makes the effective calibration levels 93,6 dB and 93,8 dB respectively. No correction is required when calibrating pressure response microphones.
   Adaptors are available so that the B & K 1/4" and 1/8" microphones can be calibrated using the 4230. For 1/4" microphones, the adaptor DB 0310 is required. For 1/8" microphones both adaptors DB 0310 and DB 0352 are required. In each case the extra adaptors fit inside the 1/2" microphone adaptor supplied (DB 0311).

Calibration Procedure

  1. Select and fit the requisite adaptor to the 4230
  2. Place the 4230 snugly over the microphone
  3. Press the button on the 4230. A hold circuit maintains the signal for up to one minute (with a new battery) after the push button is released.
  4. Adjust the sensitivity of measuring equipment to read the appropriate value (see Table)

Table: Indication required from measuring equipment for various microphone types

Pressure Response
94 dB
Free Field Response
1 inch microphones: 93,6 dB
1/2 inch microphones: 93,8 dB

Replacement of Battery

   If the calibration signal lasts only a few seconds after the push-button on the 4230 has been released the the battery needs replacing. To do this, the 4230 is taken out of its leather case and the bottom part of the calibrator housing is unscrewed, exposing the battery. The battery is a 9 V type IEC 6F 22 or NEDA 1604 and has the B & K oder number QB 0010. The battery is replaced and the 4230 reassembled.

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