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RION Measuring Amplifier NA-42

For a wide range of high-precision acoustic measurements.

The NA-42 is a sound level measuring amplifi er covering a wide frequency range and level range.
For general acoustic measurements and for environmental measurements, selectable frequency weightings (A, C, and FLAT) and time weightings (FAST, SLOW, IMPULSE) are provided. Other measurement modes allow determining maximum values for sound level, as well as peak sound level.
Measurement result readout resolution can be switched to one or two decimal points, and the large LCD panel shows setting information as well.
The choice of outputs includes AC, DC, serial interface, as well as a comparator output, making the unit suitable for use in a wide range of measurement and monitoring applications.

Measuring Amplifier






  • Supports connection of several microphones useable: UC-53A, UC-52, UC-34P, UC-29, UC-27, UC-31 with suitable preamplifiers and cables.
  • Frequency weighting: A, C, FLAT
  • Time weighting: F (Fast), S (Slow), I (Impulse)
  • Frequency range: 1 Hz to 100 kHz (main unit characteristics)



Standard The electrical characteristics correspond to JIS C 1509-1 class 1 and IEC 61672-1 class 1 regarding “frequency weightings (A, C)” and “time weightings (Fast : F, Slow : S)”.
Measurement functions Sound pressure level, sound level maximum, peak sound pressure level
Input section Preamplifier input connector
Preamplifier power supply: ±12 V or ±45 V (switchable)
Microphone bias voltage: 30/60/200 V
Frequency range 1 Hz to 100 kHz (NA-42 only)
Frequency weighting characteristics A, C, FLAT
Measurement level range Dependent on microphone combination
Residual noise level
Residual noise level
(NA-42 only, without microphone and preamplifier)
A weighting: 1.5 μVrms or less
C weighting: 1.5 μVrms or less
Flat characteristics: 7 μVrms or less
Flat (HPF 20 Hz, LPF 20 kHz): 2.5 μVrms or less
Time weighting characteristics F (Fast), S (Slow), I (Impulse)
RMS detection By digital processing
Built-in filters High-pass filter (HPF): 3rd-order Butterworth filter, 20 Hz
Low-pass filter (LPF): 3rd-order Butterworth filter, 20 kHz
Calibration Electrical calibration using 1 kHz sine wave signal produced by internal oscillator
Microphone sensitivity setting range -69.99 dB to -10.00 dB (0.01 dB steps)
Outputs AC output
(BNC connector)
1 Vrms full-scale
Output impedance 600 Ω, load impedance 10 kΩ or more
DC output
(BNC connector)
6 V (1 V/10 dB) full-scale
Output impedance 50 Ω load impedance 10 kΩ or more
External filter input/output BNC connector
Output impedance 600 Ω, input impedance 100 kΩ
Interface Serial communication (for setting control from computer and data output)
D-sub 9-pin male connector
Comparator function Sound pressure level evaluating comparator (M3 screw terminal block)
Display LCD Numeric readout to 2 decimal points or 1 decimal point (switchable)
Bar graph Scale range 50 dB or 20 dB (switchable)
Other features Various setting indicators, backlight
Power requirements IEC R14 (size “C”) batteries x 4, or AC adapter (NC-98C, supplied)
Battery life Alkaline batteries (LR14) approx. 14 hours
Manganese batteries (R14P) approx. 6 hours
Ambient conditions for use -10 ℃ to +50 ℃ (10 % to 90 % relative humidity)
Dimensions and weight 171 (H) x 120 (W) x 236 (D) mm, 1.8 kg (without batteries)
Supplied accessories AC adapter (NC-98C) x 1, storage case x 1, IEC R14 (size “C”) batteries x 4

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