BRUEL & KJAER 1625 User manual

InstructionManual
1 /3 - 1/1 Octave Filter Set Type 1625
Briiel a KJar
Type 1625
Fast~ Slow
Recording Sptled
Filter Step
~~·
·~
•
Step Size
1/ 3!1ji; / 1 Oct .
1/ 3 111 111 Oct.
Bandwidth
1/ 3 ..... 1/1 Octave Filter Set
A portable Band Pass Filter Set primarily in-
tended
for use with Sound Level Meter Type
2230,
2231 or 2233. Permits third-octave
frequency analysis, and octave frequency
analysis with a step of octave or third-oc-
tave. Fully automatic recording of the analy-
sis is possible with a Level Recorder Type
2317, 2306
or Type 2309. The scanning of
the filter and the Level Recorder are fully
controlled by the Filter Set
to obtain an op-
ti'Tlal recording. Two scanning speeds are
available for analysis of levels measured
with
"Slow" or "Fast" time weighting.
The selectable centre frequency range is
from
20Hz to 20kHz and a linear position
gives a frequency band from
3Hz to 75kHz.
The analysed signal may also be weighted
by selecting
"A" or "C" frequency weight-
ings on the Sound Level Meter.
+ BrUel &Kjrer

1Ja- 111 Octave Filter Set Type 1625
From serial no. 1032782
Revision
May 1985

CONTENTS
1. INTRODUCTION AND SPECIFICATIONS (PRODUCT DATA)............................................................................ 1
2. CONTROLS..................................................................................................................................................................5
3. OPERATION.................................................................................................................................................................9
3.1. PRELIMINARY ........................................................................................................................9
3.2. POWER SUPPLY..................................................................................................................10
Battery check........................................................................................................................10
Battery replacement ............................................................................................................10
Mains Power Supply and Charger ZG 0254..................................................................... 11
3.3. FREQUENCY ANALYSIS.....................................................................................................12
General Measurements .......................................................................................................12
Third-Octave Analysis Recording ......................................................................................12
Octave Analysis Recording ................................................................................................15
Frequency Analysis controlled by Level Recorder..........................................................17
4. APPENDIX ................................................................................................................................................................. 19
5. SERVICE AND REPAIR ........................................................................................................................................... 21

USES:
• Filter Sets
for Sound Level Meters
• Semi-automatic octave noise analysis (Type 1624)
• Automatic 113 octave and octave (with 111 or 113
oct. step) noise analysis (Type 1625)
• Attenuation of background noise
• Distortion measurements
FEATURES 1624:
• 10 octave filters in accordance with IEC
R 225-1966, DIN 45651 and ANSI S1.11-1966
Class II requirements; and unweighted linear
response
• Centre frequencies from 31 ,5Hz to 16kHz,
frequency range 22Hz to
22kHz (octave), 5Hz to
75kHz (Lin)
• 0dB nominal filter attenuation
Bruei&KJa
Type 1624
Ready for
neKtfilter
types 1624 and 1625
Octave Filter Set and
Third Octave/Octave Filter Set
• Loudness evaluation in accordance with ISO R
532 (Stevens and Zwicker)
• Noise checking to octave and third-octave limiting
curves
• Building acoustic measurements
• Sound power measurements on machines
FEATURES 1625:
• 31 third-octave and 31 overlapping octave filters
in accordance with IEC R 225-1966, DIN 45651,
DIN 45652, and ANSI S1.11-1966 Class II & Ill
requirements; and unweighted linear response
• Centre frequencies from 20Hz to 20kHz,
frequency range
18Hz to 22kHz (1/3 oct.)
and
14Hz to 28kHz (oct.), 3Hz to 75kHz (Lin)
• 0dB nominal filter attenuation
Centre Frequency
Hz
lin o
16 k.
8 k •
....
Recording
On
...
Reset
!l'r,;set Enable)
Centre Fr.,quency
Briiel& Kjaer
Type 1625
Hz
Filter Step
(Preset,
Octave Filter Set Type 1624 and
Third Octave/Octave Filter Set Type
1625 are primarily designed for use with
Sound Level Meters Types 2230, 2231
and 2233 for in situ octave and lja octave
acoustic analyses.
The Type 1624 en-
ables octave analysis
to be carried out,
while Type 1625 offers lja octave analy-
sis
and octave analysis in octave or lfa
octave steps. Both filters are compatible
with
either of the Sound Level Meters,
forming a complete, compact
and porta-
ble, lightweight unit. Semi or fully auto-
matic analysis recording is possible with
a portable Level Recorder
Type 2317 or
2309.
• 2 k •
+ ;;·
Start
•
Octave Filter Set
BP 0106-14
250.
U6o
63 •
31.6 .
Stop
Recording
Step Size
1 / 3 1/ 3 1/ 1 Oct .
Fast
Slow
1 / 3 1 / 1 1/ 1 Oct .
Bandwidth
Recording Speed
1/ 3 - 1/ 1 Octave Filter Set

Fig. 1. Sound Level Meter Type 2230 with
1/3- 1/1 Octave Filter Set Type 1625
The Octave Filter Set Type 1624
and the Third Octave/Octave Filter
Set Type 1625 are both active filters,
which are small
in size and light
weight. Both are easily fitted to the
bottom of the Sound Level Meter
Type 2230, 2231 or 2233, ensuring
both mechanical and electrical con-
nections
with proper matching of in-
put and output impedances.
Adding a Filter Set to a Sound Lev-
el
Meter greatly extends the uses of
the instrument, enabling detailed fre-
quency analysis
to be carried out.
The overall frequency range of both
filters sets covers the entire audio-fre-
quency range
with the centre frequen-
cies arranged according to the pre-
ferred frequencies
of ISO R 266, DIN
45401 and ANSI S 1.6-1960. The fil-
ters may be switched in successively
manually (Type 1624 or 1625), or
automatically (Type 1625). The level
in each frequency band is displayed on
the Sound Level Meter and may be
noted in a measurement report or
plotted on graph paper. For greater
convenience the analysis can be re-
corded
in situ, either semi-automati-
cally (Type 1624) or automatically
(Type 1625) using one of the portable
B &K Level Recorders Type 2317 (one
channel)
or Type 2309 (two channels).
The signal fed to the Filter Set is
also weighted as
selected on the Sound
Level Meter ("A", "C", "Lin. 20Hz to
20kHz" or "All Pass 10Hz to 50kHz").
Octave Filter Set Type 1624
The Type 1624 permits octave fre-
quency analysis
when used with a
2
DDDDOOODOOOOOOODOOOOOODOODODDDDOOOOOODDOOOOODOODOD
BrUel & Kj cer Potentiometer Range ~ _ _ d9 Rectifier: __ lower Lim. Freq .: __ Hz Wr . Speed: __ mm/sec Paper Speed :_ mm/sec.
52 ;1<>-75
Measuring Obj .:
---4020
---315
Rec. No .: _
Date: __
Sign .: __ 0 0
10 dB
10 20 Hz 50
OP 1124 Mulliply Frequency Seale by : 100 200 2
kHz 10 20
( 1612/2112)
8 60
6 5
4 po
2 5
0 0
40 0 A B C Lon .
A B C Lin .8J0067
Fig. 3. Frequency characteristics of the 10 octave filters in Type 1624
Sound Level Meter. The analysis can For semi-automatic recordings, the
be recorded semi-automatically with Filter Set is connected to the Level
the Level Recorder Type 2317 or 2309. Recorder by the control cable AQ
The Type 1624 contains 10 active
octave filters
with centre frequencies
from 31,5
Hz to 16kHz. Each octave
filter satisfies
the requirements of IEC
Recommendation R 225-1966, DIN
45 651 and ANSI Sl.ll-1966 ClassII,
see Fig.2.
The total frequency range is
from
22 Hz to 22 kHz as can be seen in
Fig.3. A linear position is also avail-
able covering
the frequency range
from
5Hz to 75kHz (-ldB).
m-2
"0 -1
5 0
·.p 1
~ 2
~ 3
~ 4
5
10
11
12
13
14
15
16
17
16
19
0034. The ground connection is en-
sured by cable AO 0173 used to con-
nect the Sound Level Meter to the
Level Recorder. See Fig.4. The SPL
for the selected frequency band is ob-
tained from the Sound Level Meter
Output, and the start/stop of paper
movement is controlled by the Filter
Set. The recording is made on gradu-
ated paper with a scale of 15 mm/oc-
tave, such as QP 0124 for Type 2317.
Level Recorder
2317
w ~
v •
n ~
0.5 0.6 0.7 0.6 0.9 1.0 1.2 u 1.6 1.6 2.0 2.5
Frequency relative to centre frequency f/fm
170125/2
Fig. 2. Top of an octave filter characteris-
tic from
the Filter Set Type 1624
Two Channel Level
Recorder 2309 850216
Fig. 4. Set-ups for semi-automatic octave
analysis
and recording with Type
2317 or 2309
oooooooooooooooooooooooooooooooooooooooooooooooooo
BrUel &Kiar Re co rding Mode·DC Lin Cl!l DC Log CJ ACLog 0 AC A..,-aint __ Aange: 2.Q__(d8• Paper ~peed : _ 3 _ mm/s Wr Speed· 250 mm /s
l
lllt~tlii!Jitl.l!lllliiiii!IIIJIII!tllrl1111"1lll~_l l_l_J
10
Aec. No .: __ dB B
Date! __
10
Tim• : __
Si gn .: __
Zero Levei,Jl.Q_ 0
M:~~~eob; . : _
1c
~
analysis 20
~
and
231
~~ ~ ~. Oct..--f-- 31 .5 Hz 63 125 250 500 1kHz 2 16 Lin .
QP 0151 St•rt Llf'e t/3 Octr~•- 20 25 40 so so 100 110 200 ~s 400 no 800 us t,& 2.s 3,ts 10 t2,5 20 !2s 3,
15
Fig. 5. Octave analysis of machine noise using the set-up in Fig.4
1613/161
83031912

When recording each octave, the fil-
ter output is disconnected from the
Sound Level Meter during the first
millimetre which corresponds
to the
settling time. Once the recording of
one octave is completed,
the paper
stops and the indicator READY FOR
NEXT FILTER lights up. At the end
of the analysis the SPL with the linear
weighting (or "A" or "C" if applied on
the SLM) is recorded.
1/3-lfl Oct. Filter Set Type 1625
The Type 1625 permits 1/ 3 octave
and octave frequency analysis. Octave
frequency analysis
can be made with
octave or 1/s octave step size. An un-
weighted frequency response (Lin)
from 3
Hz to 75 kHz is also available.
The Type 1625 contains 31 active 1/ 3
octave filters and 31 overlapping 1/1
octave filters at 1/ s octave intervals
covering 11 octaves. Centre frequen-
cies are from
20Hz to 20kHz. Each
filter fulfils the requirements of IEC
recommendation 225-1966, DIN 45652
and ANSI Sl.11-1966 Class III for 1/ s
octave filters; and DIN 45 651 and
ANSI Sl.11-1966 Class II for 1/1 octave
filters, see Fig.6.
The total frequency
range is from
18Hz to 22kHz (1/3 oct.)
and from 14Hz to 28kHz (1/1 oct.).
The level in each frequency band
can be read on the Sound Level Me-
ter's digital display, the centre fre-
quency of the filter being displayed on
the Filter Set. The filter centre fre-
quency being selected manually by
push button.
When the Filter is connected to a
Level
Recorder Type 2317 or 2309 the
recording of the analysis and the filter
stepping is carried out automatically.
The Level Recorder is connected to
the Sound Level Meter using cable AO
0173,
and to the Filter Set using con-
trol cable AQ 0034. See Fig.7.
The filter scanning is electronically
programmed and controlled to obtain
an RMS read out error less than 0,5
dB over the whole analysis range. The
settling time and the paper drive
speed are controlled by the Filter Set
to ensure a precise recording in a
minimum time.
The filter scanning is electronically
controlled
and programmed to opti-
mise
the recording. The Filter Set in-
creases
the Level Recorder paper
speed as the analysis band centre fre-
quency is increased. Thus, an accurate
recording is obtained in a minimum of
time.
co
-2
"0
Max. Ripple
c:
0
0 (peak-to-valley)
· ~
2 0,5
dB
:::1
c:
IEC
QJ
4
t:
<(
(DIN 45 652)
6
8
10
12
14
16
18
20
22
0.4 0,6 0,8 1 1,4 1,8 2,5
0,5 0,7 0,9 1,2 1,6 2,0
Frequency relative to centre frequency f/fm
170124/1
Fig. 6. Top of a 1 /3 octave filter characteris-
tic from
the Filter Set Type 1625
Two Channel Level
Recorder 2309 850217
Fig. 7. Automatic I/3 octave analysis and
recording with Type 2317 or 2309
oooaoooooooooooooooooooooooooooooooooooooooooo . oaoo
Bru.t&Kjar
20
Re<ordlngModo:OCL in. 1:81 DCLog .CJ ACLog .CJ ACAvor'\II .. __ Ronge :_ (dBI Pa .. r$pead , ~mm/o Wr . Spead : ~m~
Aee . No .: __ dE
Ooto: __
1c
Ti m• :-- ,
~~: ·' Lovo o, ..§Q. C
~~ct:~eObi- '- tC
113 octave
analysis
:ac
~
10 '
and 2317
15
QP o1s1 :~:: ~:: ,~:;:;;;: ~ 2s
31
'5: so
63
eo H)()
125
1eo 200
250
315 .oo
500
s)O eoo , k~2~ u 2 z.s 3, 15 , .,
8
10 12 .5
14
20 @1 ~:]
1
" · 3.~·· ~JE:~ti1~311!!Jtl
83032112
Fig. 8. Third-octave analysis of machine noise using the se t-up in Fig.7
oooaoooooooooooaooooooooooooooooooaooooooooooaoaoo
BrOot & Kjar Re<ordlng Modo:, OC Lin. R DC Log. CJ AC L og . CJ AC A-aolno -- Ronge, 2Q__(dBI Po .. r s .... ,~ mm /s Wr. Spead : ~m/o
w 10
R.e . No .: __ dB
O•te : __ ,O
Time : __ •
~~: : Level : 80 0
~~~h'l;;'e Obj .:_ 1ll
~
~oct. stef~
10
1l:2~i~:~;-
Start j'! Oc:taw___;~ 31 ,5 Hz 63 125 250 500 1kH z 2
QP 0151 St•rt L IM t/3 Oct.aw- 20 25 40 50 80 100 180 200 3t5 <400 630 1!100 1, 2$ U 2.5 3, 15
Fig. 9. Octave analysis with
1/3 oct.
step size of machine noise using the set-up in Fig.7
The starting frequency is selectable
to eliminate low frequency compo-
nents and the analysis can be inter -
rupted and restarted during recording
with the "Start/Stop" push button. An
analysis can also be stopped before
completion
and the paper automati-
cally moved to the next start position,
ready for a new run.
Recording of octave analysis with
1/ s
octave or 1/1 octave step size is also
automatic. For octave analysis with
octave step size, a choice between
three series of centre frequencies is
offered (lowest frequencies 20,
25 or
31,5 Hz).
Two analysis recording speeds
("Fast" or "Slow") are available to al-
low for stabilization
of the Sound Lev-
el
Meter detector depending on
whether a "Fast" or "Slow" time
weighting is selected on the Sound
Level Meter.
Power supply
The active filters contained in the
Filter Sets are powered from the
Sound Level Meter through the 15 pin
connector, provided the EXT. FIL-
TER switch on the Sound Level Meter
is set to "In". The battery pack in the
Filter Set contains 4 cells IEC LR 6
(B&K No. QB 0013) and is always
connected in parallel with the battery
pack in the Sound Level Meter. The
battery life (alkaline cells) of the
Sound Level Meter/Filter Set is ap-
proximately 12
hours with the Type
1624 and approximately 8 hours with
the Type 1625. The Mains Power Sup-
ply and Charger ZG 0254, including a
drawer
with rechargeable cells can be
used
to power the Filter Set.
3

Specifications 1624 and 1625
Filter Set Type 1624 Octave 1625 Third-Octave and Octave
·<·
Frequency Range
Selective
22Hz to 22kHz
18Hz to 22kHz (1 /3 oct) , 14Hz to 28kHz (1 11 oct.)
Linear Typical
5Hz to 75kHz (- 1 dB) Typical
3Hz to 75kHz (-1 dB)
''
Band-Pass Filters 10
active 6-pole Butterworth octave filters 31 active 6-pole Butterworth third-octave filters and
31 overlapping 111 oct. filters at 11 3 oct. intervals
covering 11 octaves
In accordance with standard IEC R 225-1966, DIN 45
651 and IEC R 225-1966, DIN 45 652, DIN 45
651 and
ANSI S 1,11-1966, Class II ANSI SU1-1966 , Class II & Ill
Centre Frequencies
31 ,5 Hz to 16kHz 20 Hz to 20 kHz
Attenuation at Centre Frequency 0 dB ± 0,5
dB 0 dB ± 0,5 dB
Peak-to-v.alley Ripple < 0,5 dB < 0,5
dB
Attenuation outside Pass Band See Fig.2 & 3, > 60 dB at 8 f0 and 1/s f0 See Fig.6, >
75 dB at 5 f0 and 1fs f0 (1/3 oct.)
> 60 dB at 8 f0 and 1fs f0 (1 11 oct.)
Filter Shift
Sl i der switch Manual or Automatic with Level Recorder . 11 3 oct. or
Green lamp indi cates time for filter switch i ng
111 Oct. steps for 111 oct. analysis
when used
with Level Recorder
Remote Control Semi
automatic of Level Recorders Types 2317 and Automatic to/from Level Recorders Types
2309 via cable AQ 0034 2317 and 2309
via cable AQ 0034
Input Impedance 10 kQ in series
with 5 JLF 10 kQ In series with 15 JLF
Input Tt~rminat i ng Impedance
.::;;; 100 n .::;;; 100 n
Input Voltage Max. 2 V sinus (2,8 V peak)
Max . 2 V sinus (2,8 V peak)
Output Impedance < 5 Q in series with 15 JLF
< 5 n·in series with 2,2 JLF
Output Terminating Impedance
;?::: 10k Q //1nF
;:::: 10kQ//1 nF
Inherent Noise f0 Hz max. JL V f0 Hz (oct.
or 1 f3 oct.)
max.JLV
31 ,5 Hz 200 (typ. 140)
20Hz-40kHz 250 (typ.170)
63Hz - 16kHz
150 (typ. 70) 50Hz-10kHz 150 (typ. 80)
Lin 250 (typ. 120) 12,5 kHz-20 kHz 200 (typ.11 0)
Lin 250
(typ .120)
Magnetic Sensitivity (50 Hz)
Approximately 1 mV output for 100 A/m field strength
Operating Temperature -10
to + so oc (+ 14 to +122° F)
Storage Temperature -20 to +50 °C (-4 to +122° F)
Batter ies Removed
Influence of Temperature on Attenuation < 0,5 dB (-10 to +50B°C)
Influence of Humidity on Attenuation ·< 0,5
dB for 0 to 90% relati ve humidity at .::;;; 40°C without condensation
Batteries 4 x 1,5 V IEC Type LR6 (QB 0013). Batteries used as extra supply for SLM
Dimensions
Length 105 mm (4,1 in) .::. Width 85 mm (3,3 in) -Height 47 mm (1 ,8 in)
Weight \ 450 g (1 lb) including batteries
Accessories Included 4 Alkaline
batteries
QB 0013
1 Plug JP 0802
Accessories Available 1,5m
control cable AQ 0034
1
,5m contro l cable
AQ 0182
Ma ins Power Supply and
Charger ZG 0254
T 005 17GB1

RESET (Preset Enable):
RECORDING
Start/Stop:
FILTER STEP (PRESET):
2. CONTROLS
Re<:mding
On ...
R eset
(P reMt Enable}
Recording
Bruel & Kjaer
Type 1625
Fast Slow
Recording Speed
Filter Ste p
(Preset}
, Step Si:re
1 / 3 113 1 / 1 Oct ,
1/ 3 1/ 1 1/ 1 OcL
Bandwidth
1/3 - 1/ 1 Octave filter Set
Fig. 2. 1. Front view of the Filter Set Type 1625
Resets the centre frequency of the filter to a preset centre frequency.
When
connected to a Level Recorder, it actuates the paper drive to
move the paper forward to the preset start frequency on the next
chart. It also allows setting of the preset centre frequency (see FILTER
STEP (preset)).
Start/stop push button for the automatic filter scanning and the paper
drive on the Level Recorder. The button is operative only if a Level
Recorder is connected and switched on. The filter dwell time at each
frequency band is programmed to allow optimal recording over the
complete frequency range of the analysis.
The analysis can be stopped at any time by momentarily pressing this
button, and
restarted by pressing it a second time. During this stop,
the
"Recording On" arrow (see below) stops flashing.
Two push buttons for manually stepping the centre frequency of the
111 octave or 113 octave filter.
"Up" Shifts the centre frequency one step higher when momentarily
pressed. When pressed and held in, the filter steps continuously after
a short delay.
"Down" Shifts the centre frequency one step lower when momentarily
pressed. When pressed and held in, the filter steps continuously after
a short delay.
5

RECORDING SPEED:
Fast
Slow
The centre frequencies are from 20 Hz to 20 kHz for both 1f3-octave
and
octave bands. See Table 3.1 for the 1f3 octave and preferred oc-
taves centre frequencies.
When RESET (PRESET ENABLE) is pressed, the
preset centre frequen-
cy of the Filter Set can be changed using the FILTER STEP (PRESET)
"Up" or "Down" push buttons.
Note:
-
Provided that the batteries produce sufficient voltage for stand-by,
both the
preset frequency and the centre frequency to which the Filter
was set are retained in the memory when the Filter Set is switched off
or detached from the Sound Level Meter. To be certain that these two
frequencies will be retained, it is recommended to switch EXT. FILTER
"Out" before the Sound Level Meter is switched off.
-When the Filter Set is
not powered (EXT. FILTER "Out" or Sound
Level Meter "Off") all its push buttons are inoperative.
-The Filter is
electrically disconnected from the Sound Level Meter
while the push buttons are depressed .
Two position slide switch for adapting the filter sweep speed to the
time weighting used on the Sound Level Meter. Set to "Fast" when
measuring with the
"Fast" time weighting on the Sound Level Meter;
and
to "Slow" when measuring with the "Slow" time weighting.
1fs Oct. - 1fs Oct.
(20 Hz -20 Hz)
3 min.
50s
7 min. 40 s
1fs Oct. - 1f1 Oct.
(20 Hz -20 Hz)
2 min. 15 s
6 min. 10 s
1f1 Oct. - 1f1 Oct.
(31 ,5 Hz - 31 ,5 Hz)
1 min. 20 s
2 min.
50s
T00504GBO
Table 2.1. Typical time from the beginning of one analysis to the beginning of the next one
STEP SIZE -BANDWIDTH:
LIQUID CRYSTAL DISPLAY:
6
Three position slide switch for selecting 1 /3 octave bandwidth (1/3 oc-
tave step), 111 octave bandwidth (1/3 octave step) or 1f1 octave band-
width (111 octave step) frequency analysis.
"Centre Frequency Hz" Digital display indicating the centre fr~quency
of the applied filter .
Fig. 2.2. Centre Frequency display

CONNECTOR:
"Recording On" For use when connected to a Level Recorder. An ar-
row on the display flashes quickly when recording a frequency band
(recording paper moving) and when the Filter Set controls the Record-
er. During the filter settling time (paper not moving) the arrow flashes
quickly when RECORDING SPEED is set to "Fast", and slowly when set
to "Slow" to indicate the longer settling time in the "Slow" position.
Note:
To avoid shortening the battery life, it is recommended not to switch
EXT. FILTER
"Off" on the Sourrct ~ t::e · 'iTel Meter while the "Recording On"
arrow is displayed.
It is
possible to externally step the filter to a higher centre frequency
at a maximum frequency of 15 Hz, by applying a square wave on pin 3
(alternating open circuit and ground connection) of the RECORDER
CONTROL socket (see Fig.2.4). When the "Lin." setting is reached pin
5 is set
to 0 V.
Filter Not Not Signal Filter
Output - 11 V OV used + 11 V used ground Input
80088088
8080080
Not
used
ov +5V
+Batt . -Batt . Power - 5V
On/Off
830457
Fig. 2.3. 15 pin connector for Sound Level Meter Type 2230 or 2233
RECORDER CONTROL:
8-pin DIN socket for synchronization of the Filter Set with the Level
Recorder Type 2317, 2306 or 2309.
It is
possible to externally step the filter to a higher centre frequency
at a maximum frequency of 15 Hz, by applying a square wave on pin 3
(alternating open circuit and ground connection) of the RECORDER
CONTROL socket (see Fig.2.4). When the "Lin." setting is reached pin
5 is set
to 0 V.
L:J Filter shift pulses
from Level Recorder
0 V to stop Level Recorder
immediately
Not used Pulses
output to
drive Recorder paper
Level Recorder
Ground
Fig. 2.4. Recorder Control socket
830075
7

BATTERY DRAWER:
8
Fig. 2.5. Side view of the Filter Set
Battery drawer which accepts four 1 ,5 V alkaline cells (IEC type LR6,
AA size). These are connected in parallel with the batteries in the
Sound Level Meter (see section 3.2). This drawer can be replaced by
the drawer fitted with rechargeable cells supplied with the Mains Pow-
er Supply and Charger ZG 0254 (optional extra).

3. OPERATION
3.1. PRELIMINARY
The Type 1625 and the Sound Level Meters Type 2230 or 2233 have matching 15-pin
push-fit connectors which facilitate direct coupling of the instruments to form one com-
pact unit. (See Fig.3.1 ). To attach the Filter Set to the Sound Level Meter, press the two
side-locks and engage the connectors. Push the Filter and the Sound Level Meter to-
gether gently until the two side locks return to their outer position. (See fig. 3.2.)
Fig. 3. 1. Filter Set with the Sound Level Meter Type 2230
To include the Filter Set in the measurement chain set the EXT. FILTER switch on the
Sound Level
Meter to "In". The signal measured with the Sound Level Meter is then
filtered in an 113 octave or octave band of centre frequency indicated on the Filter Set
digital display. The signal is also frequency weighted as selected on the Sound Level
Meter, i.e. "A", "C", "Lin.n" or "Lin." (10Hz to 50kHz). When no frequency weighting is
required,
it is recommended that the "Lin." rather than the "Lin. n" mode be employed.
The SPL for the selected 1;3 octave or octave band is displayed on the Sound Level
Meter's display.
9

Fig. 3.2. Mounting the Filter Set on the Sound Level Meter Type 2230 or 2233
3.2. POWER SUPPLY
3.2.1. Battery Check
The Filter
Set is powered via the particular Sound Level Meter connected. The batteries
contained in the Filter Set are not used to power the Filter Set directly, but to increase
the capacity of the Sound Level Meter's power supply and to retain the preset start
frequency and the current centre frequency of the Filter Set when it is switched off or
unplugged from the Sound Level Meter. When using with Sound Level Meter Type 2230
or 2233 and alkaline batteries are fitted, the battery life is approximately 10 hours .
To check the battery level of the Filter Set, connect the Filter Set to the Sound Level
Meter and remove the battery drawer from the Sound Level Meter. Switch on the Sound
Level
Meter and note whether a "BAT" sign is indicated on its display. If the "BAT" sign
is
present approximately half an hour operation time is left (assuming no batteries in the
Sound Level Meter). If the "BAT" sign plus a non-resettable "t" appear, the batteries in
the Filter Set
must be replaced, or recharged if Ni-Cd cells are fitted.
Note: One set
of batteries, either in the Sound Level Meter or in the Filter Set, is
sufficient for powering both instruments. However, the battery life is of course reduced.
For long term storage, it is recommended that the batteries are removed to conserve
their life time and as a general safety precaution.
3.2.2. Battery Replacement
10
Unlock the battery drawer and pull it out. Remove the deplenished batteries and place
four new ones with polarities as shown in the battery drawer. Push the drawer back into
place until the lock is secured . If the "Recording On" arrow flashes when EXT. FILTER
switch is set to "In", press RESET on the Filter Set and wait until the arrow stops
flashing. The Filter Set can then be preset to the desired centre frequency.

Fig. 3.3. Battery replacement
3.2.3. Mains Power Supply and Charger ZG0254 (option)
The
battery drawer of the ZG 0254, containing 4 rechargeable cells, fits into the Filter
Set
Type 1624 and can be recharged either in or outside the instrument via the socket
on the side. The Charger delivers enough current for simultaneously powering the Filter
Set and Sound Level
Meter and recharging the cells to which the charger is attached.
When only
recharging the cells (drawer pulled out or instrument switched off), a recharg-
ing cycle takes approximately 5 hours. When recharging cells while powering the instru-
ment, the recharging time is of course longer.
Note: It is not necessary for both battery sets, in the Sound Level Meter and in the Filter
Set,
to be rechargeable. To avoid confusion, however, only those with rechargeable cells
have the socket receiving the charger mounted on the side. If both instruments have
rechargeable battery sets, it is necessary to use a separate power supply for each set.
Fig. 3.4. Mains Supply and Charger
11

3.3. FREQUENCY ANALYSIS
In the following sections emphasis is placed on the practical aspects of performing 113
octave and octave analysis with the 1625. For a comprehensive theoretical understand-
ing of frequency analysis, the book "Application of B& K Equipment to Frequency Analy-
sis" by R. B. Randall should be consulted.
For recordings in AC mode, reference should be made to the Level Recorder Instruction
Manual and to the book mentioned above for a proper choice of Recorder Paper Speed
and Writing Speed settings.
3.3.1.
General measurements
For spot measurements, the SPL in the various frequency bands can simply be read on
the Sound Level
Meter display. To shift the frequency band manually proceed as follows:
1. Calibrate Sound Level Meter (see Instruction Manual)
2. On the Sound Level Meter set:
POWER:
REF.-OPERATE:
FSD:
RESET:
FREQ. WEIGHTING:
EXT. FILTER:
SOUND INCIDENCE:
DISPLAY:
TIME WEIGHTING:
DETECTOR:
3. On the Filter Set:
STEP SIZE -BANDWIDTH:
RECORDING SPEED:
"On"
"Operate"
As required
"All" or "Max./Min."
"Lin.", except if a frequency weighting is to be ap-
plied
"In"
As appropriate
"SPL" (LT for Type 2233)
"Fast" or "Slow"
"RMS"
As required
Irrelevant
4. Set the centre frequency required by pressing RESET or FILTER "Up/Down". If FIL-
TER "Up/Down" is kept depressed, the centre frequency starts stepping continuous-
ly after a few seconds. The SPL, corresponding to the selected frequency band is
displayed on the Sound Level Meter.
Note: It is recommended to set EXT. FILTER
to "Off" before the Sound Level Meter is
switched "Off" to avoid possible erasure of the "Preset Frequency".
3.3.2.
Third-Octave Analysis Recording
12
Fully automatic recording of octave- or 1f3-octave frequency analysis can be obtained
using Portable Level Recorders Types 2317, 2306 or 2309 (see Fig.3.5).
Since the Filter Set cannot change the averaging time of the Sound Level Meter, the
recording speed is controlled by the Filter Set to obtain an accurate recording in the
minimum time. To reduce the fluctuations in the low frequency bands and make interpre-
tation of the recorded signal level easier, the TIME WEIGHTING on the Sound Level

Fig. 3.5. Level Recorder Type 2317
Meter and the RECORDING SPEED on the Filter Set should be set to "Slow". When
frequency bands higher than 500 Hz are the main interest, it is recommended to set the
Sound Level Meter and the Filter Set to "Fast".
Recording with Type 2317
1. Carry out preliminary checks on all 3 instruments (battery level, etc.) and calibrate
the Sound Level Meter.
2. Load the Level Recorder with recording paper QP 0124. Connect the Sound Level
Meter to Level Recorder using cable AO 0173, and calibrate the Level Recorder for
AC Log or DC Lin (see Instruction Manual for Type 2230 and 2317).
3. Fasten the Filter Set to the Sound Level Meter and interconnect the REMOTE CON-
TROL sockets of the Filter and Level Recorder as shown in Fig.3.5. With earlier
Type 2306 Level Recorders use cable AQ 0182 (see section 3.3.4.).
Octave
Filter Set
1625
Two Channel Level
Recorder 2309
'\
I
I
I
I
I
-. -
•-
j
83004911
Fig. 3.6. Set-ups for automatic 1ft and 113 octave analysis and record-
ing with Type 2317 or 2309
13

14
4. Set the Sound Level Meter as described in section 3.3.1.
5.
Set the controls on the Filter Set as follows:
STEP SIZE-BANDWIDTH:
RECORDING SPEED:
"1/3- 1f3"
"Slow" or "Fast"; corresponding to the selected
TIME WEIGHTING on the Sound Level Meter (DC
Lin
recordings) or on the Level Recorder (AC Log
recordings)
6. Press RESET to display the preset frequency which is always the starting frequency.
To change the preset frequency press RESET (Preset Enable), and while keeping it
pressed, use the "Up" or "Down" push buttons to step the filter until the desired
starting frequency is indicated. When the desired starting frequency is displayed
release RESET (Preset Enable).
7. Set the Level Recorder as follows
WRITING SPEED:
PAPER SPEED:
POWER:
PAPER DRIVE:
PEN LIFT:
"Normal"
"Ext."
On
Off
Off
Proceed with recording of the frequency analysis, as outlined at the end of this section.
Recording with Type 2306 (or 2309):
1. Carry out preliminary checks on all 3 instruments (battery level, etc.) and calibrate
the Sound Level Meter.
2. Load the Level Recorder with recording paper QP 0124 (QP 2100 for Type 2309). If
the Sound Level Meter is equipped with a DC output, connect this output to the
Level Recorder using cable AO 0173 and calibrate the Level Recorder for DC Lin
recording (see 2230 and 2306 Instruction Manuals).
If
the Sound Level Meter used is the Type 2231, then its AC Output must be used.
The Level Recorder must then be calibrated for AC Log recordings, and its WRIT-
lNG SPEED set to "1 00 mm/s" (see point 7).
3. Fasten the Filter Set to the Sound Level Meter and interconnect the REMOTE CON-
TROL sockets of the Filter and Level Recorder as shown in Fig.3.5. With earlier
Type 2306 Level Recorders use cable AQ 0182 (see section 3.3.4.).
4. Set the Sound Level Meter as described in section 3.3.1.
5. Set the controls on the Filter Set as follows:
STEP SIZE-BANDWIDTH:
RECORDING SPEED:
"1/3- 1f3"
"Slow" or "Fast" corresponding to the selected
TIME WEIGHTING on the Sound Level Meter.
("Fast" when using Type 2231 ).
6. Press RESET to display the preset frequency which is always the starting frequency.
To change the preset frequency press RESET (Preset Enable), and while keeping it
pressed, use the "Up" or "Down" push buttons to step the filter until the desired
starting frequency is indicated. When the desired starting frequency is displayed
release RESET (Preset Enable).

7. Set the Level Recorder as follows
RECORDING MODE:
WRITING SPEED:
PAPER SPEED:
POWER:
PAPER DRIVE:
PEN DRIVE:
"DC Lin"
"250
mm/s" ("1 00 mm/s" when using Type 2231)
"Ext."
On
Off
On
Recordings with the Level Recorder Type 2309 are similar to those with the Type 2306.
Proceed with recording of the frequency analysis, as outlined below.
Recording the frequency analysis:
Place the recording
paper 2,5 mm before the corresponding centre frequency printed on
the
recording paper, and set PAPER DRIVE on.
Press RECORDING START/STOP to
start the automatic recording. The center frequency
of the applied 111 octave or 113 octave filter is displayed on the Filter Set. When record-
ing is in progress (recording paper moving) the "Recording On" arrow on the display
flashes quickly. During the filter settling time (paper not moving) the arrow flashes quick-
ly when RECORDING SPEED is set to "Fast", and slowly when set to "Slow" to indicate
the longer settling time.
Each 113
octave is recorded over 5 mm. At the start of each 113 octave band recording
the Sound Level Meter is disconnected from the filter and the pen moves downwards.
This allows time for correct averaging to take place and permits the pen to settle to the
correct level after switching from the previous filter. When the "Slow" time weighting is
applied to the Sound Level Meter's detector, the RECORDING SPEED on the Filter Set
should be set
to "Slow" to increase the time allowed for settling.
After the last 113 octave filter, a Lin (All-pass) filter is recorded. There after the paper
moves to the start position on the next chart, ready for a new analysis to be recorded.
To repeat a frequency analysis press RECORDING "Start".
To immediately interrupt a frequency recording momentarily press RECORDING "Start/
Stop". To resume recording, press the same button a second time. After a delay, the
recording is resumed and the last part of the current filter recording is correct.
To stop the recording before completion of the frequency analysis press RECORDING
"Stop" and keep it pressed until the pen reaches the bottom line on the paper, and then
press RESET
before releasing the RECORDING button. However, the time saved is mini-
mal since the analysis time for the high frequency bands is short.
3.3.3. Octave Analysis Recording
Automatic Recording of Octave analyses is similar to that used for third octave analysis
except for the choice of step size and positioning of the paper. For octave analysis with
111 oct. or 113 oct. step size, the STEP SIZE-BANDWIDTH must be set accordingly. The
pen
must be positioned 2,5 mm before the starting centre frequency on the paper for
octave frequency analysis with 113 oct. step, and 7,5 mm before for octave analysis with
111 oct. step size.
15

Centre
1f3 Oct.
Centre
1f3 Oct.
Centre
1f3 Oct.
Centre
1f3 Oct.
Frequency
B.W. at
Frequency
B.W. at
Frequency
B.W. at
Frequency
B.W. at
3,7 dB
3,7 dB
3,7 dB
3,7 dB
Hz Hz
approx.
Hz Hz
approx.
Hz Hz
approx.
Hz
Hz approx.
20 4,6 160 37 1,25 k 290 10 k 2300
25 5,8 200 46 1,6 k 370 12,5 k 2900
31,5 7,3 250 58 2k 460 16 k 3700
40 9,2 315 73 2,5 k 580 20 k 4600
50 11,6 400 92 3,15 k 730 Lin. -
63 14,5 500 116
4k 920
80 18,3 630 145
5k 1160
100 23
BOO
183 6,3 k 1450
125 29 1 k 230 Sk 1830
T00751GBO
Table 3. 1. Third octave centre frequencies. Bold characters denote preferred series for full octave centre
frequencies
16
To select the series of centre frequencies for octave analysis with octave step size, first
switch STEP SIZE to "1/3 Oct." and preset the starting frequency. Then select again a
"111 oct." STEP SIZE. See Table 3.1.
Note: When recording a frequency analysis with the Level Recorder Type 2317, the "Fil-
ter Shift" LED will light each 5 mm interval of paper movement.
Remark:
The band-edge lines of the recorded analysis may be used, to determine the BAND-
WIDTH and the STEP SIZE of the recorded analysis as well as the RECORDING SPEED
and TIME WEIGHTING used.
1.
With a 50 dB range on the Level Recorder, the "Fast" time weighting gives band-
edge lines between the bands approximately 32 dB long (See Fig.3.7 or 3.8), while
the "Slow" time weighting gives lines 16 dB long (See Fig.3.9).
oooooooooooooooooooooooooooooooooooooooooooooooooo
Sr Uel & Kja r RecOJd l ng Mode :DC Li n. 181 DC Lo g. 0 AC Log . 0 AC Avet"eg i nt __ Range : _ ( dB ) Paper Spe e d : ~ mm / s Wr . Speed : ~mm ll
Rec . No .:_ dB
Date : __
10
Ti me :_ _
Si gn .: _ _
Zero level : ~ C
Fig. 3. 7. Third Octave analysis on Type 2317
d8
oooooooooooooooooooooooooooooooooooooooooooooooooo
BrUel & Kj ar Re c ord i ng Mod e: DC Lin R DC l og D AC Log CJ AC Av..-egi ng __ Ran ge : __§Q____ (dB) Paper Speed : ~ mm /s Wr Speed · ~mmts
Rec. No .:_ dB
oate : __
10
Ti me : __
~ ~
9
,: ·= L ev el : 80 :
~~~h ~ ~~ Ob j .: _ 10
~
~.;:J~ - ~~1:)>
[1 625/ 23m- 30
Qp 0151 ~:: : : ~ : : ,<:;'~ ;:- ~ '25 ll , S~ ~ 50
63
80 1 00
125
11 50 200
2 50
JtS <100
50 0
&30 800
1
k1 ~ 2~ 1,6 2 2.5 3, 15
4 s 6.3 8 10
12 .5
16
20 lriiz~ i.:.::,- n · J . t;<s -;n..,-;Lc;;;-ln -----;"i;16W13/W1~]
Fig. 3.8. Octave analysis with third octave step size
/2