BRUEL & KJAER 2209 User guide

+ · Typ•2209
Impulse Precision Sound
Level Meter Type 2209
A compact and portable instrument
for precision sound and vibration
measurements. It conforms to IEC 179
for Precision Sound Level Meters,
the proposed IEC Recommendation
for Impulse Precision Sound Level
Meters and to DIN 45 633 parts 1
and
2.

IMPULSE PRECISION
SOUND LEVEL METER
TYPE
2209
December 1 973

CONTENTS
1. INTRODUCTION
7
1.1. Description of 2209 ... .............. ... .... ..... ....... .. ......... 7
1.2. Precision
Sound Level Meter Standards ...... ........... .. . 7
1.3. Impulse Sound Level Meter Standards ...................... 8
2. CONTROLS ........................................................................ 10
Meter Scale ........... ................................................ 10
Meter Switch ......................................................... 11
Weighting Network Switch .. .... .. ...... .. ........... ...... .. ... 11
Input Socket Switch .................. .. ...... .. ................... 12
Input Attenuator (black) .... .. ..... .. .. .. ................ .. .. .. .. .. 12
Output Attenuator (transparent) ............................... 12
Attenuator Scale ...... .. .. .. ........................................ 12
Gain Adjustment .................................................... 13
Overload Indicators .... .. .. .... .. .... ...... .. .. ......... ...... ..... 13
Meter Reset Button .. .. .. .. .. .... .. .. .... .. .. .. .. .... .... .. .. .. .. .. 13
External Filter Input and Output Sockets ...... ...... .. .. .. . 14
DC Output ........ .............................. .. ....... .... ....... ... 14
AC
Output .... ........... ........ ... ........ . .......................... 14
Pilot Light (Power) .................................................. 14
3. OPERATION ....................................................................... 15
3.1. Battery Replacement and
General Considerations .. .... .. .... ....... .. .. .. .... .. ....... ..... 15
Battery Replacement .... .. ..... .. .. .... ..... .. .. .... .. ........ .. .. 15
General Considerations .. .... .. .... .. .. .... .. ...... .... ......... .. 15
3.2 . Calibration for Sound Measurements ........................ 15
Using the Sound Level Calibrator or Pistonphone ....... 15
Using
the built-in Reference Voltage ........................ 17

3.3. Sound Measurements ............................................. 18
General Considerations .. .. .. .. .. .. .. .. .. .. .. .... .. .. .. ........ .. . 18
Specific Sound
Measurement Procedure ................... 19
3.4. Calibration for Vibration Measurements .................... 20
Using Accelerometer Calibrator 4291
Using the built-in Reference Voltage ........................ 22
3.5. Vibration Measurements ......................................... 23
General Considerations ........................................... 23
Specific Vibration Measurement Procedure .. ...... .. .. ... 24
3.6. Voltage Calibration and Measurement ...................... 25
4. DESCRIPTION ................................................................... 26
4.1.
4.2.
4.3.
4.4.
4.5.
4.6.
4.7.
4. 8.
4.9.
4.10.
4.11.
4.12.
Condenser Microphone ........................................... 26
Input Stage ........................................................... 28
Attenuator I and Input Amplifier ............................... 30
Reference Oscillator ............................................... 30
Overload Indicators ................................................ 30
Weighting Networks ............................................... 31
Attenuator II and Output Amplifier ........................... 31
RMS Detector ........................................................ 31
Impulse Detector .................................................... 33
Peak Detector ........................................................ 34
Hold Circuit ........................................................... 35
Power Supply ........................................................ 36
5. OPERATIONAL CHARACTERISTICS
AND ACCURACY ............................................................... 37
5.1.
5.2.
5.3.
5.4.
5.5.
5.6.
5.7.
5.8.
5.9.
5.1 0.
5.11.
5.12.
Directional Characteristics ....................................... 37
Random Incidence Response ................................... 43
Reflection . .. .... .. .. .. .... .. ........ .. .......... .. ..................... 43
Effect of Background Noise ...................................... 44
Input Capacitance .................................................. 45
Distortion ..... .. .. .... .. .... .. .... .. ............. .. .. .. .. .............. 46
Crest Factor Capabilities ......................................... 46
Temperature .......................................................... 49
Humidity ............................................................... 50
Inherent Noise Levels .. .. .. .. .. .. .. .. .. .. .. ........ .. .. .. .. .. .. .. . 51
Sound • .................................................................. 52
Vibration ............................................................... 53

50130 Pressure Oo 00 00 00 00 00 00 00 00 00 0000 00000000 000 00 00 00000 00000000 0000 0000000 59
50140 Wind 000 00 00 00 00 00 00 00 0000 00 00 0000 000000 0 00 00 0000 00 000000 0000000000000000 59
50 1 50 Electrostatic Fields 0000000000000000000000000000000000000 0. 0. 00000000 60
50 160 Magnetic Fields 000000000000000 0. 0. 00 0. 0. 0. 000000 0. 0. 000000 0. 00000000 60
50 17 0 Weighting Networks 0.0 0. 00000.. 000 0. 000.. 00..00000000000000000 0. 00 61
50180 Attenuator Frequency Characteristics 000 ooooooooo 00 00000 000 0 62
6. ACCESSORIES AND MEASURING SETS ............................ 63
601 0 Accessories Included with 2209 00000000000000000 00 000 0. 0... 0. 65
Adaptor JJ 2614 ........................... o ....................... 65
Half-inch to one-inoch Adaptor DB 0962 ···· '- ·············· 65
Flexible Extension Rod UA 0196 ..... ....... 0.. 0.....o ........ 65
Half-inch to one-inch Adaptor DB 0375 ................... 65
Random Incidence Corrector UA 0055 ····o····oo•·o···o··· 66
Windscreen UA 0207 ........... .. ........................ 0 ....... 66
Plugs JP 0006 .. 0. 0 ..... 0.......0 ........ 0 .......... 0 ....... 0 ....... 67
Attenuator Scales .................................. .......0 ••••••• 67
6020 Optional Accessories ..o.. o ....... o.. o·············o·····o·o······· 67
Octave Filter Set 161 3 .....0.....0 ...... 0.. . ..................... 67
Third Octave Filter Set 1 616 ........ .. ......... .... ........... 0 68
Adaptor JJ 261 5 Oo .o. 000 o•·o·· 000 Oo ...0o ........................... 69
Integrator ZR 0020 .. 0.. 00 ......... . ..... ... ........... 0....0 ...... 69
Accelerometers 0 ...................... 0 ............................. 0 70
Microphones .. . .... 0... ....... 0.......0 ........... 0.. 0.....0 ...... 0.. 70
Microphone Adaptors ..... .. o•· 0 •••••••••••••••• o ............. . o.o 71
Accelerometer Calibrator 4291 o·· ·· ··········· ·······o········ 72
Artificial Ears 41 52/53 ......................... 0......... ..... 0. 72
Artificial Mastoid 4930 0 ......................... 00......0 ........ 72
Connection Cable AO 0007 ....... .. ...... . ........ 0 ........ 0.. 72
Carrying Case KE 0055 .. ............ ........... .. ....... ........ 72
6030 Complete Measuring Sets ··0····0······························· 73
Sound and Vibration Sets Types 3507 and 3511 ...... 73
Audiometer Calibration Sets Types 3508 and 3512 .. o 74
7. USE WITH OTHER INSTRUMENTS ..................................... 75
7.1 0 Systems Considerations .......................................... 75
7 0 20 Level Recorders oo···ooo····o·······oo······o····o··················· 76
AC Recording ·····o········o······o·································· 76
DC Recording 00....0...0 0. 00..0 ......... 0 ............................ 76

7.3. Noise Nose Meter ........ .. .... .. .. .. .. .. .. .. .. .. .. .. .. .. .... .. .. .. 77
7.4. Tape and Digital Recording
...................................... 78
7.5. Analysis ................................................................ 78
7.6. Loudness Evaluation ............................................... 78
7.7. Maximum Acceleration ........................................... 78
8. SPECIFICATIONS ............................................................... 79
8.1.
8.2.
8.3.
8.4.
8.5.
8.6.
8.7.
8.8.
8.9.
8.1 0.
8.11.
8.12.
8.13.
8.14.
8.15.
8.16.
8.17.
8.18.
8.19.
8.20.
8.21.
8.22.
Frequency Response .............................................. .
Dynamic Range
..................................................... .
Input Stage .......................................................... .
Weighting Networks .............................................. .
External Filter Sockets
.......................................... ..
Output ................................................................. .
AC
Output ............................................................ .
DC Output ............................................................ .
Meter Damping ..................................................... .
Meter Indication .......... . ......................................... .
Inherent Noise ...................................................... .
Polarization Voltage
............................................... .
Overload Indicators ............................................... .
Calibration
........................................................... .
Sound
Measurements ............................................ .
Vibration
Measurements ....................................... ..
Sound,
Vibration and Voltage Measurements ........... .
Directional Characteristics
................................... ....
Effect
of Sound Field on Amplifiers ......................... .
Effect
of Static Pressure ........................................ ..
Effect
of Magnetic Field ........... . ............................ ..
Effect of Humidity .....· ........................................... ..
Operating
Temperature .......................................... .
Batteries
............ . ................................................. .
Dimensions .......................................................... .
Weight ...... ............ . .............................................. .
Accessories
.......................................................... .
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86

1. INTRODUCTION
1.1. DESCRIPTION OF 2209
The Bruel and Kjrer Impulse Precision Sound Level Meter Type 2209
is a compact, portable instrument for precision sound and vibration
measurement . It is designed to meet all current standards set by the IEC
for both Precision Sound Level Meters and Impulse Sound Level Meters.
The 2209 is designed so that in the impulse mode, its response char-
acteristics to short duration sounds (1 to 1 000 milliseconds) approximate
the response of the human ear . Thus it effectively measures the subjec-
tive loudness of short duration sound as heard by the human ear. The
impulse response characteristics meet all applicable IEC and DIN stand-
ards.
The 2209 is capable of measurements over a wide frequency and dy-
namic range. In addition, it can accurately measure the RMS values of
signals with crest factors up to 40 and also the peak values of signals
with duration greater than 20JJS. Built into the instrument are the A, B,
and C frequency weighting networks plus the D weighting network for
aircraft noise measurement.
With a wide range of accessories the 2209 is a versatile portable in-
strument. With the addition of the Third Octave Filter Set 1616 it be-
comes a portable, self-contained third octave measuring system.
1.2. PRECISION SOUND LEVEL METER STANDARDS
The IEC (International Electrotechnical Commission) has set various
standards for sound level meters. IEC Publication 1 23 gives the require-
ments for general purpose Sound Level Meters which are made more
stringent in Publication 1 79 for Precision Sound Level Meters. The
B & K
2209 meets or exceeds all requirements of IEC 179, the main
points of which are given below :
Free-field sound pressure level measurement accuracy of± 1 dB.
7

Essentially omnidirectional microphone characteristics (see sec-
tion 5.1). Square law type measurement indication.
Tolerances on meter scale calibration and range shift error are
specified.
- A "Fast" meter dynamic characteristic: R-esponse to ~ a 200 millisec-
ond pulse within -2 and 0 dB of the indication for a continuous sig-
nal of same frequency and amplitude. Damping such that overswing
on a suddenly applied steady signal is between + 0,1 and + 1,1 dB
An alternative "Slow" meter characteristic (optional): Response to a
500 millisecond pulse within -5 and -3 dB of the indication for a
continuous signal of same frequency and amplitude. Damping such
that overswing on a suddenly applied steady signal is between + 0,1
and + 1,6 dB compared to final steady indication (which must be
within 0,1 dB of level indicated with "Fast" characteristic).
Specifications are also given for frequency range capabilities, and
maximum permissible sensitivity to external and environmental in-
fluences.
The IEC publication specifical!y states that the Precision Sound Level
Meter is designed to give objective measurements which under certain
conditions approximate the subjective impression of sound. The 2209
meets all applicable IEC criteria and can be used for the measurement
of rnost continuous sounds.
1.3. I MPULSE SOUND LEVEL METER STANDARDS
Th e purpose of the impulse response circuit is to approximate the rise,
averaging, and storage time characteristics of the human ear for short
duratio n sounds. Both the German Standard DIN 45 633 part 2 and the
IEC draft for the extension of Publication 179 make similar specifica-
tions for Impulse Sound Level Meters. The 2209 conforms to all of
these and the main points of the IEC draft are given below:
8
Impulse Sound Level Meters must have same response characteris-
tics to steady sinusoidal signals as specified for Precision Sound
Level Meters.
Overload indicators at input to filters and at input to meter rectifi-
ers.

Minimum crest factor capability of 5.
Rectifier response time of 35 ms ± 0,5 ms. Storage circuit with rise
time less than rectifier and decay time constant of 3 s ± 0,5 s.
The IEC also specifies testing procedures to assure compliance to
standards . It should be noted that the 2209 is designed to approximate
the subjective impression of short duration sound, and not for objective
analysis of shock or other pulses .
9

2. CONTROLS
The external features and controls of the Impulse Precision Sound
Level Meter 2209 are shown in Figs. 2.1 and 2.2.
Random Incidence Correc. t. o .. r. ii4? .· .. . . ··
I! . 7'" !ill I ·I . ... ... .
Fig.2.1. Front view of 2209
METER SCALE
Removable by sliding out. The scale is reversible with one side cali-
brated for precision sound level measurements and the other for vibra-
tion measurements.
10

METER SWITCH
This is both the main power switch and meter function selector. It has
seven
positions:
"Off'
"Batt. (Rec.)"
"Slow"
"Fast"
"Imp.,
"Imp. Hold"
"Peak Hold"
Power off position. In all other pos1t1ons
power is on and POWER light flashes.
Battery check position. Meter deflection be-
low red area indicates batteries must be re-
placed. (See Sec. 3.1 ).
Provides the Slow RMS meter characteristic
specified in IEC Publication 179. See Intro-
duction for details.
Provides the Fast RMS meter characteristic
specified in IEC Publication 179. See Intro-
duction for details.
Provides the Impulse meter characteristic
for measurement of subjective level of short
duration sounds as specified in the pro-
posed
extension to IEC Publication 179 and
DIN 45 633 Part 2. See Introduction for de-
tails.
Holds the maximum RMS value of the ap-
plied signal until METER RESET is de-
pressed. Rise time is the same as the Im-
pulse characteristics . Decay time is
<
0,05 dB/s.
Holds the maximum peak value of the ap-
plied signal until METER RESET is de-
pressed. Rise time is< 20JJS.
WEIGHTING NETWORK SWITCH
This six position switch determines frequency response characteristics
of the instrument electronics:
11

"Lin."
"A", "B", "C", and "D"
"Ext. Filter"
INPUT SOCKET SWITCH
Gives linear response from 2Hz (or 10Hz
see section 4 .2) to 70kHz.
Selects appropriate frequency weighting
network for subjective indication of loud-
ness (see Fig.5.22).
Permits external filter connection across
EXT. FILTER sockets.
In this switch position
meter deflection is obtained only if external
filter is connected.
This screw operated switch is located in the center of the input stage
socket
(Fig.4.4). The lower frequency limit of the instrument is 2Hz
with this switch fully clockwise and 10Hz when fully anti-clockwise.
INPUT ATIENUATOH (Black)
Controls the gain of the input amplifier in 10 dB steps. Is used to-
gether with the OUTPUT ATIENUATOH to select the measuring range of
the instrument.
OUTPUT A TIENUATOH (transparent)
Controls the gain of output amplifier in 10 dB steps. For optimum sig-
nal to noise ratio and protection from overload, this control should be
kept
fully clockwise (red lines opposite black dot) whenever possible. The
measuring range of the 2209 is read between the red lines on this
knob.
ATIENUATOR SCALE
Ten reversible attenuator scales-are provided with the 2209 to permit
direct reading of virtually any sound or vibration unit. The scales are in-
terchanged by unscrewing the coin slotted screw in the center of the at-
tenuator knobs. With a properly calibrated meter, for sound level meas-
urement the sum of the number between the red lines on the attenuator
knob and the meter scale reading gives the correct result. For vibration
12

and voltage measurements, the number between the red lines gives the
full scale deflection of the meter .
GAIN ADJUSTMENT
This screwdriver operated potentiometer adjusts the gain of the input
amplifier over a 13 dB range permitt =ng calibration with various transdu-
cer sensitivities.
Fig. 2. 2. Rear view of 2 209
OVERLOAD INDICATORS
Separate flashing lights indicate overload on input and output amplifi-
ers . Adjust attenuators to remove overloads which will give erroneous
readings. If overload cannot be removed, note this together with meas-
urements.
METER RESET BUTION
Resets the meter in the "Peak Hold" or "Imp. Hold" positions.
13

EXTERNAL FILTER INPUT and OUTPUT SOCKETS
Socket IN:
Socket OUT:
DC OUTPUT
Connect to filter input. Minimum output
load of socket is 500 0.
Connect to filter output . Input impedance of
- sec~et i-s --1 46 kfl. Maximum iflJ)ut - vo~tage is
0,2 V RMS, 2 V peak.
Feeds DC voltage from meter rectifier. Output impedance is 25 kO
with 0,8 volts (open circuit) for full scale deflection. Meter reading is not
affected by load. Matches JP 0006 plug or AO 0007 cable.
AC OUTPUT
Feeds AC voltage from output amplifier. With METER SWITCH in
"Batt. (Rec.)" output is 5 V RMS (fsd) with > 10 kO load required. In
"Peak Hold", "Imp.", "Imp. Hold", "Fast", or "Slow" output is 0,5 V
RMS (fsd) with an output impedance of 600 0, but any load may be ap-
plied without affecting meter reading. Matches JP 0006 plug or
AO 0007 cable. Output voltages are open circuit values and may be
used
for tape recording purposes with any METER SWITCH position.
PILOT LIGHT (POWER)
Flashes
when the power is on .
14

3. OPERATION
3.1. BATTERY REPLACEMENT AND GENERAL CONSIDERATIONS
3.1.1. Battery Replacement
The three 1 ,5 volt standard flashlight cells (Type R 20 in IEC Publica-
tion 86-2) are replaced by sliding the cover off the rear of the instru-
ment. Observe polarity as marked in the battery compartment. See
Fig. 2.2.
Rechargeable nickel cadmium batteries may also be used giving the
advantages of longer operating time without battery change and reduced
long-term battery costs. They may be recharged using the 2808 Power
Supply with Battery Box ZG 0073 and Charging Adaptor AQ 0043. See
2808 Instruction Manual for details.
3.1.2. General Considerations
• Store the instrument in a dry, preferably warm place.
•
Remove batteries if instrument is not used for a long time.
• Connect and disconnect microphones and adaptors with the power
off .
• Assemble microphones and adaptors at the same temperature.
• Use only light finger torque to tighten microphone and adaptors.
• In dry weather, discharge static electricity from your body before fit-
ting microphones.
• Keep dust and foreign objects from the microphone diaphragm .
Never touch the diaphragm with any object.
3.2. CALIBRATION FOR SOUND MEASUREMENTS
3.2.1. Using the Sound Level Calibrator or Pistonphone
A source of known sound level and stability is placed over the meas-
uring microphone. The gain of the input amplifier is then adjusted to
15

calibrate the Meter to this reference level. For the Sound Level Calibra-
tor (4230) this is 94dB and for the Pistonphone (4220) 124dB. Individ-
ual calibration charts giving exact sound level outputs are provided with
the calibrators.
The procedure for calibration of the 2209 is as follows:
1. Turn the Meter Scale to "Precision Sound Level Meter".
2. Choose the appropriate attenuator scale depending on Microphone
sensitivity from Table 3. 1.
3. Attach the input stage and Microphone with desired accessories.
4. Check battery condition by turning METER SWITCH to "Batt. (Rec.)".
5. Set METER SWITCH to "Fast".
6. Set WEIGHTING NETWORK to "C".
7. Set attenuators to 90 for Sound Level Calibrator, 120 for Piston-
phone.
8. Place Pistonphone or Sound Level Calibrator over Microphone with
its normal protection grid and switch on the calibrator.
Microphone open 8 & K Microphone
Scale No
Red Sensitivity
circuit sensitivity Type Scale
40 -160 mV per
Pa * 4145 4144
1A
Upper
4161
4133 4134
11 -50 mV per Pa
4149
18 Lower
4163
4133 4134
4- 16 mV per Pa 4149
2A Upper
4163
1,1 -SmVperPa
4135 4136 28
Lower
0,4-1,6 mV per Pa 4138
3A Upper
* 1 Pa = 1 N/m
2 = 10
tLbar
073011
Table 3. 1. Attenuator Scales for sound measurements
16

9. Using a small screwdriver adjust the gain of the 2209 (GAIN ADJ)
to correspond to the calibration value of the calibrator as given on
its calibration chart. Correct as necessary for barometric pressure in
the case of the Pistonphone .
3.2.2. Using the built-in Reference Voltage
A stable internal voltage (± 0,2 dB at 2kHz) is fed to the input ampli-
fier whose gain is adjusted to make the 2209 correspond to the open
circuit sensitivity of the Microphone used. However, when possible, cali-
bration is preferable using the Pistonphone or Sound Level Calibrator
since this will take into account all possible Microphone and instrument
changes in sensitivity due to environmental factors.
The calibration procedure using the built-in reference voltage is as fol-
lows:
1. Turn the meter scale to "Precision Sound Level Meter".
2. Choose the appropriate attenuator scale depending on Microphone
sensitivity from Table 3.1.
3. Attach the input stage, desired Microphone and accessories.
4 . Check battery condition by turning METER SWITCH to "Batt . (Rec.)".
5. Set METER SWITCH to "Fast" .
6. Set WEIGHTING NETWORK to "Lin".
7. Set ATIENUATOR switches to "Ref." (between red lines).
8. Determine Microphone open circuit sensitivity in mV per Pa from
Microphone calibration chart. (1 Pa = 1 N/m
2 = 10 J.lbar)
9. Using a small screwdriver adjust the GAIN ADJ potentiometer until
the open circuit sensitivity of the Microphone in use is indicated on
the red MICR. SENS. scale. Use either the upper or lower MICR.
SENS. scale
depending on Microphone used. See Table 3.1. Note
that scaling differences by factors of 10 are accounted for by use of
appr . opriate attenuator scales.
17

3.3. SOUND MEASUREMENTS
3.3.1. General Considerations
1. Select a Microphone with appropriate dynamic range, frequency
r- ange -and dir-ectional-chaF-aeteristies. Cheese pFeper- attenuater
scales for the given Microphone sensitivity to permit direct reading
of levels. Also select appropriate accessories (see Chapter 6) for
various environmental and measurement conditions.
2. Whenever possible mount the 2209 on a tripod and use the flexible
extension rod to minimize interference from reflections from the
meter itself and the body of the observer. Stand at least one meter
from the instrument to reduce interference when making readings.
Position the Microphone so it faces the sound source.
3. When measuring sound fields other than normal incidence, use the
Random Incidence Corrector on the one-inch free field Microphone,
or use the half-inch Microphone for better omni-directivity.
4. Calibrate the 2209 before use to ensure correct, reproducible re-
sults.
5. Keep notes on measurement conditions, equipment and accessories
used,
background noise levels, cases of amplifier overload, weight-
ing networks and meter functions used.
6.
Before fitting the input stage, select the appropriate low frequency
cut-off: 10Hz with the input socket screw fully anti-clockwise, 2Hz
w hen fully clockwise. See Fig.4.4 . The 10Hz cut-off will help re-
d·Jce inaudible low frequency disturbances.
7. To ;naintain a high signal to noise ratio the gain should be kept as
low possible (OUTPUT ATTENUATOR as far clockwise as possible).
Instrument gain should be increased first using the INPUT ATTENU-
ATOR, then the OUTPUT.ATTENUATOR.
8. To make high accuracy measurements in accordance with the
standards of IEC 179 or DIN 45 633 parts 1 and 2, the 2209 must
be used with the following accessories:
18
Extension Rod
One-inch Microphone
Random Incidence Corrector
UA 0196
4145
UA 0055