BRUEL & KJAER 2225 - Technical Specifications of 2225 and 2226; Performance and Environmental Specifications

The DC amplifier drives the dis-
play and the DC output, which is in-
tended for use with level recorders,
providing a DC voltage proportional
to the dB value of the measured sig-
nal with the same dynamic range
as the instrument.
2226 only
An overload detector monitors
both the input to the attenuator and
the output from the A-weighting ne-
twork, and the display flashes at
full scale if an overload is detected.
In addition, on this instrument, the
maximum sound pressure level is
held on the display until reset, con-
tinous operation of the display be-
ing obtained when the "DC Output"
plug is inserted, or when the "DC
Output" push-button supplied is de-
pressed.
Specifications 2225 and 2226
Measuring Range:
25 dB(A) to 140 dB(A) peak in 4 ranges
20- 60dB(A)
50- 90dB(A)
80 - 1 20 dB(A)
100- 140dB(A)
Frequency Response:
See curves Figs.3 and 4
Frequency Weighting :
A-weighting
Detector:
Characteristics :
RMS and Peak (2225) or Impulse (2226)
in accordance with IEC 651 * Type 2,
DIN
45634 and ANSI S.1 . 4-1971 Type
S2A
Dynamic Range:
60 dB(A) (40 dB(A) on scale + 20 over)
Limited by measuring range
Crest Factor:
20 dB at upper limit of measuring range,
rising linearly with decreasing signal le-
vel to a maximum of 40 dB for Sound Le-
vel and 50 dB for leq
Time Constants:
"Slow" and "Fast" to IEC 651
2225 only:
"Peak hold" better than ±0, 1 dB/ s with
30 IJS rise time
2226 only:
"Impulse " to DIN, IEC
"Max. hold" on " Fast ", " Slow", and "Im-
pulse" better than ±0 , 1 dB/ s
Display:
"Thermometer" type display with 41
LEOs giving a 40 dB range with 0,5 dB
display resolution. Overrange and under-
range warning
Linearity:
Better than± 0,25dB
• except for "Max . hold " on 2225
Read out interval:
Read-out updated 1000 times per sec-
ond
Brightness:
Automatically controlled with respect to
external light level. Visible even in direct
sunlight
DC Output:
Output impedance : 1 0 kO, short circuit
proof
Nominal output voltage: 50 mV / dB
Offset : bottom of scale = 0 V
Reset Function:
Operation of "Reset (Batt.)" or any func-
tion resets all time constants and re-
starts measurement 200 msecs after re-
lease
Automatic Switch-off:
Instrument turns off automatically 2 min-
utes after the last switch is operated, ex-
cept
when the "DC output" plug is being
used.
Microphone:
Type: 1 / 2-inch B & K Prepolarized Con-
denser Microphone Type 4175
Sensitivity: 50 mV / Pa
Capacitance: 1 2 pF
Calibration:
Screwdriver operated potentiometer ad-
justment using Sound Level Calibrator
Type 4230
Reference Conditions for Calibration Valid-
ity:
Type of Sound Field: Free
Reference Incidence direction: Per-
pendicular to microphone diaphragm
Reference SPL: 94 dB (re 20 11Pa)
Reference Frequency: 1 kHz
Reference Temperature: 20°C
Reference Measuring Range: 80 -
120dB(A)
Effect of Magnetic Field: (at 50 Hz, 80 Ai m
( 1 0rsted)) < 20 dB(A)
Effect of Humidity: (at 40°C ( 1 04°F),
1000Hz)
< 0,5 dB change in sensitivity in the
range of relative humidities from 65% to
90%
Effect of Temparature: (at 1000Hz)
Temperature range -1 0 to ± 50°C (re
20°C)
Temperature coefficient of · microphone-
/ preamplifier -0,025 d8 / °C
Temperature coefficient of complete in-
strument -0,025 (± 0,016) d8 / °C
Warm-up time:
< 1 s
Batteries:
Type:
Three 1, 5 V Alkaline cells IEC type LR 6
(B & K order No. QB 001 3)
Life:
Approx . 30 hours continuous normal use
Approx . 1 0 hours in maximum sunlight
Overall Dimensions:
201 X 72 X 22 mm (7 ,9 X 2,8 X 0 ,9 in)
Weight:
370 g (0 ,81b) with batteries
Accessories included:
1 half-inch Prepolarized Condenser Mic -
rophone Type 4175
1 Leather carrying case KE 0177
1 2,5 mm mini - jack plug JP 0213
1 Windscreen UA 0459
3 cells QB 0013
Accessories Available:
Sound Level Calibrator Type 4230
Level recorder cable AO 0173
3 m microphone extension cable AO
0185 with threaded attachment (UNC
1 / 4" x 20) for direct connection to
tripod
10m cable as above AO 0186