Quest Engineering 215 User manual

15Sol
Octave
PH.35Pe
electronics

TABLE OF CONTENTS
[
MODEL 215SOUND LEVEL METER ..................... I ,_
General Description.................................. 1 :'
Specifications ...................................... 3.
Accessories ........................................ 3
Controls.......................................... 3
Principles ofOperation............................... ,t i
InternalElectricalNoise.............................. 6
}
Operating Procedure ................................. 6 -t
Example of OSHA Noise Exposure Meastlremel_t ........... 10
BatteryReplacement.................................11 q i
Calibration ........................................ 12 ._
MODEL OB.,15 OCTAVE BAND FILTER SET . ............. 1,1
i
General Description .................................. 1,11
Specifications ...................................... 1,1 .|
Controls.......................................... 15
t
Principles o f Operation ............................... I5
MODEL 215-,i5 OCTAVE BANI)ANALYZEB,.............. 17
General ........................................... 17
Operating Procedure ................................. I7
Operational Check ................................... 18
MODEL P11-35PEAK.I1OLO MODULE AND
fj_r i
,15 35 lEAK HOLDMEIER .......................... 19
General Description .................................. 19
Specifications ...................................... I9
Controls .......................................... 20
Principles of Operation ............................... 20
Operating Procedure ................................. 21
Calibration ........................................ 22
ACCESSORIES ....................................... 23
Model CA-12Sound Level Calibrator .................... 23
Model RA-100MV I_,ecorder #_.dnptor .................... 26
Model WS-3 Windscreen.............................. 28
ModelTp.1.Tripod .................................. 29
Model EC-9A I_arphorm Coupler ........................ 29
Model AS-15d5 AudiometricCalibration Stand ............ 29
nevi_ed January, 19/0

MODEL 215
!
SOUND LEVELMETER
,b
G P_NI_I{AL I)ESCRIPTION
! The Quest Model 235 is a get_eral pur_
i
I pose soulld level meter that conveniently Elnd
_,i ncettrately nleastlrcs sound il_ virttl_llly [lily en-
• virotlrnent: industry, transportation,construc-
,j
tion,mining, nirport -- anywhere there is
noise. Calil)ratiol_ or"audionleters is also _l
primaryuse, The 215 is designed to r4_0et or
excec'd ANSI Stlmd_trd $1.,I-lt,)71 for type 2
:r_instrunlelltatiola and IEC-R123. The unit has
i a dyllamic range from 30to 1,10dB (re
20pN/M2). It cnn he ltsed with the Mndel
:t
! OH-,15 Octave BaladFilter to form the Octavo
Hand Analyzer. hlodel 215-,15 and with the
,i P11-35 Peak Ilold Module to form the I)enk
Hold Meter. Model 215-35. ,\ linear (flat)re-Fi!tur01.
': si)onse selection is providedas well as A, B, nnd
i C weighted scab,s.
The 215 meter has a fixed microphone configttratiotl mottnted
' _ directly totiletop of the unit. The 215 is alsoawdhd)le with remote
• microphot_e capal)ility which is denoted by the letter "1]." at tile t_nd
'i of tile metermodel number, ie., 2151_., ltemotc microl)hono capa-
'_ bility must I)e built intothe meter during n_anufacture. ,\mating
: cotlnector is incorporated il'_ tile r(!movahle part which also includes
i tile nlicrophoneand pr(-,-aml)lifier. Because tile pro-anap is effectively
_! al_ iml)edtlllce reducer, all:,,length of microohol_e ettble up to 100
i feet can I)c used without affecting the overall aceur_lcy or perfor,
,nllttlee of the 111oi,o1'.
SI_I,,'CII,'ICATIONS
Sound Level l(ange: 30 to 1,10 dli (re 20,uN/M2). Sound Level
.'. Meter is accurate to within 1,0 dB up to 1,16 dl_ SPL without nota-
ble distortion. Maximum readal)le dh_ as a function of weighting
_letwork vs. frequency is reduced I)y the decihel difference between
Flat (Linear) respotlse and tile dl] level o£ tile wei_htil_g curve vs,
freqtleney,
1

Standards: Meets ANSI $1.d-1971, type 2 and iEC-I{123
Frequency Response: A, B, and Cweighted scales; linear (flat)
scale
Meter Response: Taut-bandtype meter wiUi FAST m' SLOW
selecllable respot_se_-"
"Slow" Response: With a pulseof 1000llz simlsoidal signal
appliedfor 0.5 seconds, tile maximum residing is between 2 and 0
(typical 3.5) decibels less than steady state level. Maximum over-
shoot for all frequencies betweel',03 llz and 8 Kilz is 1.6 dlt (typical
0.5) measured at,l dI3 below full scale.
Frequency Ilangc: 20 to 10,000Hz
Electrical Output: Approximately1.2 volts at full scale behind
1000 ohms. For connection use a Switchcraft type 780Tini-plug or
equivalent, F.lectrieal output jack (AC OUT) can he shorted without
causing a meter reading error greater than 0.1 dB, Output ilnl_edanee
from the jack is 1000 ohms.
Crest Factor: 13 dB ollallrIiilge positions except for the 1;10
dB range where crest factor is 0 dB (ld0 dB limit),
Detector: Sqaare Law.type, Quasi-RMS,
Calibration: At1000 llz using the Quest CA-10, CA-11, or
CA-12 Calibrator.orally other high quality acoustical calibrator that
can accept the microphonesize.
Micl_aphon__._e:lligh quality PZT ceramic,omnidirectional, 1.1'9--5
in, din,
Temperature llange: Operation: -10°C to +50°C
Storage (less batteries}: -.10°Cto ÷05°(;
Coefficient of Sensitivity: 0 to0.03 dB/
°Cat fi dB below ftdI scale meter reading.
Operating llumidity: 0% to95% relative hualidity produces less
than 0.5dE variation in SLM reading.
Effect of MagneticField: At field strength 1 oerstod (80
AT/I_I), 50.00 Hz produces less than ,t0 di:_indication measured with
Cscale weighting tit maxinlum sensitivity meter orientation. The
eqttivalent A-weighted response to a 1 oersted, 60Ilz magnetic fiald
is negligible. The equivalent A-weighted response toa 1 oersted, ,100
llz magnetic field is approximately 50 dE with the meter oriented
for maximum indication.
2

!
Effect of Vibration; When the sound level meter with attached
mieropbone is placed on a surhlce having anacceleration of 0.1g, the
:_ highest meter indications not influenced by background noise are ,19
dBAat 63 Hz. 72dl:IA at 250 Ilz, mid 83 cll:IAat I000 IIz.A similar
+;
test withthemicrophone replaced with an equivalent impedance
I
:.,iolds]1ometer indication,
'Batteries: TwoNEDA 16{),t standardtype 9V transistorradio
[ battery, Burgess 2U6,Eveready 216, or equivalent. Olmrating life is
approxin_ately 70 hours, (Battery life is affected by temperature --
! '*vhic]l depellds oil bilLterytlsed. Collsultnmrmfacturer's data for
specific battery at,Inlil]iaiilpdrain level.Cold temperatures at freez-
ing or below greatly reduce effective battery life.)
Tripod Mount:1/,1.20threaded insert inrearcoveraccepts
standar_d t-l_il)O_lmortaring screws.
Dimensions:Case:6 x 2-1/2 x 1-5/8 inches
Overall:7 x 3 x 2-1/8inches
Weight:19 ouilces including batteries.
Construv!,iol__!:Solidstate integratedcircuitry iri rugged alumin-
um housillg.
ACCF,SSOI_.|ES
Aeeessm'ies awfilahle for use with the 215 meterinclude the
OB-,15 Octave Braid FilLer Set, CA-12 Calibrator, EC.9A Earphone
Coupler, Pli-35 Peak Ilohl Module,ItA-10OMV RecorderAdaptor,
WS-3 Windscreen, andTP-1 Tripod.
CONTIIOLS
ON-OFF-BAT Switch -- A 3-position rocker switch to turl'L ill-
strumenton and off andto check battery condition.
FAST-SLOW Switch -- A2-position rocker switch toselect fast
orSlOW illeter resi)onse,
dB RANGE Switch --A 10*position rotm'y switch, graduated in
10 dB increments from,10to130, to select sotlnd level range.
WEIGIITING Switch - A 5-position rotary switch toselect A,
BorCscale weighted response,ortIN (linear-- noweighting)
response. In tile EXT {external) position tile switch provides for
tislng tileO1]-,t5 Octave Band FilLer and the PII,35 Peak field Meal-
tilewith thesound level meter,
3

A.C. OUTJack -- All output jack that furnishes nn AC voltage
of tile noise wave that has heen conditioned IWthe weighting or
filterposition selected and is proportional to the meter reading. The
jack acuepts a S,,vitehcraft, type 7S0-Thll-phlg or Oqtlivllle_It,This
Otl_J_tlt callbe usedfor Illaglletic tapt_ or chartrecorclJtlg j_tlrposes.
When recording',vitila DC chart recorder, the Quest Model
RA-100MV recorder adaptor is necess_lry toconw_rt tile ACsi$1al to :
DO.
External Connector -- A standard fi-pin Cinch-Jones type con-
nector provkles for _onnecting tile hinter to tile Quest OB-_I5 Octave
Band Filter and tile Pli-35 Peak Hold Module. Thupinsozlthis eoll-
nector are idenUfied in Pigure 2,
Facoof 215 Meter
gigna* Input _ _ Silltl;tl Outp,t
ooo.... i illiI
NOIItllUt j,qCk)
_(Ovolt ) V-
Figure 2, Ex[ernat ColmectorPins
CalibrationAdjustment -- A screwdriver adjustment located
*lear _he external connector on tile bottom of tht_ unit thatwu'ies the
amplifier gaintocalibrate tim instrument.
PRINCIPLES OFOPERATION
General
The 215 Sound LevelMeter uses _lll omnidirectional ceramic
microphone buffered byahigh impedance FET inputstage.The
electl'onics utilize solid state integrated circuitry for maximunl stabil-
ity, reliability and low noise opcr;ition. A block diahmtm of tile 215 is
shown in Figure 3,
,t

, ¸¸ 'fi/./_ _,_: ._: ..... ,
Figure 3, 215 Sound Level Meter Block Diagram
Selection ofWeighthlg Clmr_leLeristies
Tht_ Model 215 offers/% B,and Cweighting scalesas ,,veil as
linear (non.weighted) response.In most eases the scale selected will
bespecified by the test being n'mdc or the reguhg_ion being followed,
Forexample, most industrialnoise regulationsrequire "A" scale
measuren'_enL_. The linear scale can be used wheJ1 the Model 215is
beingused witha tape recorder or a real time analyzer. The standard
wcighth_g characteristics for the Mode]215 arc shown in Figure,l,
0 Li ...... I_--
--10
mi20 i
I
-00l-t=
-50
20 50 100 200 5001000 2000 5000 10,000
Figure 4,FreqLmncy RespmlseWeighting Characteristic
5

I
I
MicrophoneCharacteristics
The microphone usedinthe 21.5 Sound i.eveJ M_teris aShtlro
type d01 ceramic omnidirectionalunit Overalldiameter is 1.126
inches(2.8Gcn'0.Typicalsensitivityis59 dBbelow I veilper micro-
bar measuredatdO0Hz. l;'igurc5 isadiagnml of typicalnlierophoms
responsetarhath pc,rpendicalaralldrandom ineidcliee,
+I0
•"o
+'5 Porpond+c,_lar_ e+++
! '°°'"°a+°"i"' _._._j..-
° \
'.: ,qandam
-5 (and70o[nc[dal_co}
_,o I I ]
20 50 lOP_OO'_1I 2K 5K 7KIOK
Frequency- Hz
Figure5.Type401 MicrophoneResponse- PerpendicularandRandomIncidence
INTERNALELECTRICAL NOISE
Table1 ontile next pageshows tileinternalnoiseleveloftile
215 materwith the meterset at"C" scale weighting,Thenoise h+vals
are typicaland are determined bysubtracting the readingsshown
fromthereading orthemeter _ttfun scal_ d(_necLion,The figtlres m'e
shown for each Josition of the dB RANGE selector switch =it each
octavo landandat broad l)aild {allpassb Noiselevelson "A"weight-
ing arefurther r_duc:orl becauseof its attenuationcharacteristic,The
internal noiseis alway_.tleast 27dB below the full scale reading and
all reading_ .an thus be madewithoutexcessive noise prol_loms.
OPERATINGPROCEDUff.E
GOIIORI|
']'0 el)LainrelldillgSof nlaxJlllllmaccuracy,]lo[dthr, illstrumellt
awayfrom you Ilt an mlgle of zq)proxinlately 70° from thellorizon.
tal, Under cartain conditions slightly lass ace[l]I[|tl + readings mayre-
suit from pointing themierol_honedirectly at tha noise+source,.This
callbenoted frmntileMicrophoneItosponse elmrI.
6

Table 1.hlter_lM Eleetlqcal Noise Levels o[ t/le
Mode/215 Sotmd Level_lle ter(illdB below/'till setth!defleclioll).
RANGE SELECTOR SWITCH POSITION
405060 705090100 110120 130
BROADBAND
(ALL PASS) 27 37 ,16 54 53 54 55 55 55 55
31.5 48 57 67 75 78S0 E0S0 EO S0
¢¢
__ 63 44 54 647276 77 77 7777 77
I 125 41 51 617073 75 75 76 76 76
__25039 49 59 69 71 73 73 73 7373
=c__ = 500 38 48 5B 68 59 70707070 70
mm_1K 374757 5766 6768 6B6868
_: 2K 36 46 56 64 6565 65 65 65 65
P,u.
I _ _4K34 44 546362 6364 64 6d 64
BK 34 44 54 636162 63 636363
The 215 is designed to he hand-held,If tile unit is placed onany
Imrd surface suchasaI_d:le.top, cheek toseethat no sihqlificant
mechanical vibration exists which might yield false meter readings.
Tile microphonewillpick tip vihraHon as if it, were souncl.
Before each use of any battery-poweredinstrmnent,tile condi-
tion of the batt_ryshould he checked to =t_sure proper operation. On
the Model 215tile hatterit_s are tested by moving tile ON-OFF-BAT
switchI,o tile BAT position, mid clmcking tlutt the meter pointer
deflects to tile heavywcen Iim_ nlarked B/¢I'TI'_B,YCHECK. If tile
meter deflection is belowthis area, Lhe batteries must be replaced
before [LIly nleastlronlenLs are taken,
Basic Ol)eratioll
Before turning tile meteron,set tile dB I{ANGI'_ selector at or
above the expected sound pressure level. Choose tiledesiredweigllting
characteristic and select rest or s[ow meter response.Tlmn move tile
ON-OFF-BAT switch to the ON position.'l'l_e instrument is now
readytomakesotmd level measurements.
Maximum readability andaccuracy are obtainecl withtile meter
pohRer deflected to tile higher part of tile meter scale. When pos-
sible,therefore, select tlu_ raFige to prodttce a rt_aditlg})etweetl 0 alld
+10 on the met=zr,
7

Tilescale readings are added to or snbtmeted from the dB range
level selected. Forexample, if the range selector is set at80 dB, and a
meterreading of +8 is indicated, then the sound level measured is 88
dB, Similarly, if the meter needle is at -5 dB for the same range
selector setting, a noise levelof 75 dB is indicated. In the latter case,
better readability will result if tile 70 dB range is selected, In this
case the I'teedle will point to +5 dB. again yielding Lhe nleasuren'tent
of 75 dB.
Most meter readings can and should Im taken with the slow
meter response because the nleter needle is more stable and easier to
read. The fast response is intended for measurement of short dura-
tion noises, such as moving vehicles or impulsive sound, where tile
noise is not present sufficiently long to obtainthe maximun'_ reading
in theslow response mode. Keep in mind that for very short duration
impulse no[se even the fast i_sponse nlode lllay not be fast etlOtlgh to
indicate the truc peak noiselevel.
Effectof Operator'sPresence
Any objector surface can act _n a reflectorfor sound. An
operator close toasound level rglierol)hont_ ¢2allalso Dea reflector,
causing areadirtgerror. When the souz'td to be rneasLired is directional,
thesmmd level reading can be affected by the relative position of
meter and observer. The meter shouldnot be held hetweell the noise
source and the observer because ofsound reflections frolll tile body.
The meter should he held away from tim body or mounted on a tri-
pod with microphone pointedupwardalmost perpmldicuhr to noise
o
source (70 from path), keepingtile body out of the noise path
Effect of Backgromld Noise
If thesonnd level frorn a imrticular source is to be determined,
all surrounding sources of hoist! should,its nearly as possib/e, he
reduced or eliminated,When it is notpossible to eliminate snrrmmd.
ingnoise, tile curve shown in Figure 6 may be used to correctfor the
presence of this noise.
Use With Windscreen
Toprevent wind blowingacross the microphone mid causing the
erroneous measuren_ent ofsotlnd level,tlSe theModel WS-3micro-
phone Windscreen with the sound level meter. The windscreenis
made of reticulated polyurethane foam for the reduction of ambient
wind effects, and can also protect tile microphone underdusty, oily
or humid conditions,Tile screen is simply pushed onto tile micro-
phone when needed. Acoustic attenuation effect of tile windscreen
ontile meter reading is small and is shown ill Figure 7,
8

-n Errorin 6B |Subtler from TozalNoi_'l
FREQUENCY RE_ONSE ERROR
_=7,.4: ,_ _== _ ,!,
I0 _o.
- _
u-I

l
I
I EXAMPLE OFOSIIA NOISE EXPOSURE MEASUREMENT
(Based on Proposed Standard 1975)
Usingtile 215 Sound LevelMeter to determine OSHA compli.
antein a constant noise environment is a simple task, Merely read
tile sound level with A scale weightingat each wm'ker's station,
Recordthe date, reading and worker-station. From Tahle 2 determine
tile pernlissiblo length expostu'e for the nleasttred noise level.
[;'or a varying noiseenvironnlel31,_'ontintlous meastlremenl_s
must be taken over the work day. and the following formula must, be
solvedtodetermine worker exposure:
Co Cn=
1C+ _ + ,_ < I for total perraissible exposure1'1 12 ' '
Whore C is the length of time at a particular measured noise level, nnd
T istile time per (lay permitted at that noise level (from Tahle 2).
Table 2,OSHA [crmissiblcNoise Exposure
Length of Exposure- IT) Equivalent Maximum
(Hrs/Day) Noise Level(dBA)
(16) (85)
890
6 92
4 85
3 97
2IO0
1_ 102
1 105
110
¼ or less115
In order to use the Quest 215 or any other sound level inef.er in
avarying noiseenvironment,Illluly noisenleasuremelll,s shotdd _}e
made at tile workers station --enough so that the readiags are repre-
sentative of tile workers exposure.All noise levels must be read, and
the duration at each level noted, As many as 30 or more readings
may be necessary to account for all tile noisevm.iations, floweret, in
this example we assume that only four basic noise levels are present
and that tile duration of eachis shown onnext page. The nlaxinltinl
exposure time (T) for each reading is also shown.
10

....... • ,t _-_: : :_- ,i ¸ • :
Measurement AveragedBA Maximum
Duration {C) Measured ExposureTime(T}
1Hr. 92 6
1 Hr, 100 2
4 Hrs.908
2 Hrs, 83
It is a._samed that tbe aoise levelsremain relativelyconstant
duringtbe intervals betweenmcasurenwnL_. Some jud_nont Inuy be
requiredin makingsuch an assumptiom
Substittlting those values intile fornluhl gives tile following
result:
1 Hr@ 92 dBA = 1/6; 1 lh. @ 100dBA = 1/2;
,t llrs @ 90 dBA =d/8; 2 Hrs @ 83 dBA =0.
Summing the exposure fractions yields
1/6+ 1/2 +,I/8 + 0 =1.17
Since 1,0 is the maximum allowablevalue,the conll)tt[iltioll
indicates tbat workersill this area were ovm'-exposed by 17%.
It is obvious that in a changing noise environment the above
procedure call be very coml)lex, tiMe.consualhlg, costly, In suchon.
vironments itis suggested that tile Quest M.7 Noise Dosimeterbe
used rather titan a sound level meter, TheM-7automatically accuam.
lutes all variations in noise and produces a continuous readout of tile
percentage of permissibleexposure, No operator or calculations are
required.
BA'I'rERY REPLACEMENT
Batteries should be replaced whenever a battery test gives a low
indication on tim meter, To replacebatteries, remove tile rear cover
plate bytalscmwingtbe retaining screws. The batteriesare located in
the upper section of theunit. Carefully remove the used batteries
and replace them with two itew 9-volt batteries,Bttrgess 2U6 or
equivalent.
CAUTION
Tile batteries must be replaced with tile ON-OFF-flAT switch
in tbe OFF position to avoid possible damage to tile unit.
11

CALIBI_.ATIONOFMODELS 215#m':_
AND21,_RSOUNOLi_V_L,_iE'rl_l_s ._,.!m;
The 21,5meterisfactorycalibrated,and _ ;_:_J
with proper care should retain its accuracy. It _r_ _
is recommended, however, that the nmter be /_Ld
checked periodicallywith tile CA.12 or CA-/}_._ r
15 Calibrator preferably ill the same environ- /_mt_-
meet in which sound level measurements are l_ _t'
to be taken (OSIIA specifies daily calibration / /1ti_
ifyouo,o re,,It,rooord,,roeed
fo,io,w
I.,_irstfur.o.theZl_or.Oa_I__ound$t_p/
L0velI_,eter id c 10e{t_ebutteryevelndi-_A_]_'
eater. Replace batteries ,findicator is belo'.v[_¢_ ._m
green "good battery" level. _,_
po bthemotor,vitebtoand
leet the 100 dB rangeposition.
3.(CA-12): Switch on tileCA-12 Call-Pi0ure8.
brator and check b,attery level indicator. Re-
place batteries if indicator is below green "good battery" level.
(CA-15): Set tile Model CA-15 Calibrator OFI"-FR.EQUENCY
switch to 1000 IIz. If a tone is beard, the Calibrator otttput is accu-
rate and proper.
4. Carefully insert tile meter microplmne into the calibrator
coupler,If the Model 215RSound Level Meter is used with a micro-
phone extension cable, then calibration is performed with tile micro-
phone mounted on the extensioncable. Be sure microphone is inside
coupler resting flush on the inner rim. Turn on tile calibrator. The
110 decibel output of thecalibrator should produce a full scale +10
reading oil tile meter for whichever weighting scale is used. All
weighting readings are the same at 1000 llz. Note the correction in
calibrator output due to altitude effects explained in tileNOTI_ on
page 13 for the CA-12; or see "Altitude Effects" on ptlge S of the CA-
15 Instructions.
5, If reading is off slightly, insert a small screwdriver in tile
small hole on the bottom ofthe meter and slowly adjust the CAL ad.
just until the meter reads correctly.
6, Change the selector switch to tile 110 dB position on the
meter and note tile needle shoukl drop to tile zero position on tile
meter dial.
7. Meter isnow calibrated and ready for use,
12

NOTE
Effects of atmospheric pressure on the 215 meter are n0gligi-
hie. However, calibrator sound levels are affected by eleva-
tion above sea level. The actual sound output of theCA-12
calibrator is 0,1 dB less than the 110 dB rating for each 2000
feet of elevation above sea level. For example, at 0000 feet el-
evation the calibrator produces only 109.7 dB. Tim amter
should then beset at 109.7 dB.
The small adaptor ring ftlrnished with the CA-12 Calibrator
or215.12 Meter-Calibrator Kit is used only for chocking
other sound level meters with 1" micmphm_es. This adaptor
_'is net used with the 211A or 211FS or215 meters,
if another calibrator with a frequency other than 1000 Hz is
used, the equivalent "A" scale sound level must be known to
set tbe 215 meter properly, If the "A" scale level is uot
known, calibrate the 215 meter with the WEIGIITING switch
in tile LIN (linear) positiom
la

MODEL 0B-45
OCTAVE BANDFILTER SET
GENERAL DESCRIPTION
The Quest h'|odel OB.,15 Oct_ive Band
Filter ix a plug-in n'*odtlle cent;lining a selecta-
ble set of filters.It ix used primarily with tile
Quest l_lodel 215 Sound Level hleter forming
the Model 215-d5 Octave Band Analyzer. The
OB-,I5 meets the most stringent requirements
_)f ANSI $1,11-1971 for OctaveBand l,'ilters.
'Pileunit coat, ins nineselect_|l)le filter ranges
from 31.5 I1_. to 8 l(llz center frequencies
with full octaveband width. Primary uses ill-
elude frequency analysis for audiometric
rooms and audiometercalibrt_tion, Coulmuai-
ty noise,product noise emissiotl, and sLructur*_:i0ur09.
al and material acoustics. Active filters are om])loy¢_d throughout
permitting tile high accuracy and small size configunltion.
SPECIFICATIONS
FreqtlencyRange: Nine rallges, 31.5 I-lz to 8 l{Ilz center fre.
quencies, f_l]-dctave I)and ',vidth,
Filter Transmission Effectiveness: z_.ppro.ximlLtely 20 ell] down
per octave from centerfroqttency.
Standard: hleets ANSI $1.11-1971 for tYl)_ E, Class IIFilter
Sets,
I/ll)UL: (From 215 Soulld Level hleter) 0 to'Ivolts rms, 20 I-Iz
to 10-J_f"_.
O_:(To215 Sound Level_leter)0 to ,Ivoltsrms,output
impedance lessthan 1 ohm,
Power Source: No internalpower soul'co.Batteryvoltageisoil-
l_line¢lfrom the215 SoulldLevel51eterthrough the connector.
Ol)eratiIlgTempemture:-I0 °to +50°C
Op.__e.ratitlgllu_ulidity:0.95%relativehumidity.
Cotlnuctor: Six.pillCinch.Jones type.
1,t

_,_ _:,_ _,_.-r,,:'_¢ •,.. _ _ _ • _ _ ._,
Size: 3 x 3-1/2 9 2ol/8 inches with hack coverextcndhtg to
8-inch length.
Weight: 9 ounces.
Construction: Solid state integrated circuitry inrugged alumin-
um housing,
CONTROLS
FP_EQUENCY Band Selector -- A nine-position rotaryswitdl to
select the octave band filterdesired from 31.5 Ilz to S Kllz.(31.5,
fi3, 125, 250, 500, 1K, 2K. ,IK. 8K Hertz).
External Connector -- A six-pin Cinch-Jones type connector for
electrical connection to the 215 Sound Level Meter. The pins on this
connector are identified in Figure 10.
(O volt input) V+ --1"--_! ! I V-(9 volt input)
Commoll I_NC
Output Signal-- Input Signal
_-.- Face of OB.45 Filter
Figut010.ExternalConnectorPins
PDdNC[PLES OFOPEItATION
The OB-d5 isaClass 11 Octave Band Filterset conforming to
ANSI $1.11-1971 specifications, The normalized passband character.
istics of the filters are depicted inFigure11.
The filters are flat within 1 dBill the Imndpass, with tile 3dB
downpointslit ,707 Folind 1,dl,IFo where Fo is centerfreqtlency
of the band chosen. '1'11oFo/2 and the 2F o magnitudes are downby
npproximately 18.5 dB with the decade points down by greater than
60 dB.
The block diagram of the OB-,15 showing the signal input from
the 215 Sound Level Meter through tile filters andback to the Sound
Level Meter is illustrated inFigure 12,
15

Minimum
'+0+
20, ',
¢
I- _ +v°io+,II-
P 50 SI/Qi"45 FiIFr_.Maximun
go "_Limit
TL_'6Q dlt TL _'60dB
,°r , I,I,i,il,, i, idol
0,t 0,15 0,2 0,4 0,6 0,g 13 6 8 tO
Frequency RAtio -- f/fm
Figure 11, NormaJlzod Amplitude Rosporlso - OctaveBand Filter Class II
From215
I o°_,a_:,o,iI
,,,°o, II_l o+, ,
+
:
1 _'+'°°°'t J
...... SwitelI....
e posiliOrt
Figure12. 0B,45 OctavoBand FilterSetBlock Diagram
16

MODEL 215-45
OCTAVE BAND ANALYZER
GENERAL
The Model 215-15 Octave Blind Analyzer is made tq) of the 215
SottndI.ovel Meter and tim OB-,I5 Octave BandFilter Set.Thepre-
ceeding instructionsforthese twounits shouldbe read beforethe
following instructions ill that all tile proceduralinfornlation for the
meter and filter set is apl)licableto tile Analyzer. The two units arc
connected together throtlgh thesix pin connector, and arc locked
togetherwith tile separate thumb screwprovided.The rules of hold-
ing tile unit awayfrom tile body.oron atripod, are tile same as for
tile215 Soul'=d Level Meter.
OPERATINGPROCEDURE
1. Switch the 215 Sound LevelMeter to the BArr positionand
check tosee tiler the motor needle deflects intothe I.q'eenarea. If the
llet_d]o does notreit[!]l the green llroa, replace batteries,
2. Check the operation of tile amdyzer as outlined on Page 18.
3. Setthe dB ICANGE selector lmd FAST-SLOW switch on the
215 as appropriate for the noise beingine_tsured,
,I. Set the WEIGHTING switch on the 215 to EXT (external}.
This switch position, and only this position, electrically engages tile
OB-d5 Filter.
5. If youwish todetermine all fl'eCltlellcybands of noise pres.
eat, start with tile OB-:t5 FREQUENCY selector at 31 Hz.
6.Turn tile215 toON and you will be leading Iloise in the 31
Ilz bandonly. Adjust dB RANGE selectoroil tile 215 toobtain the
best sca[_! rcadirJg on the reeler and thenrecord the rending.
7.Repeat step 6 for eachof the frequency bands Lo8 Kllz.
Those reildings call be plotted ona chartof dB vs. eenterband fre-
quency.
8. ]f you wish to know overall noise unweightod, set the
weighting switchto LIN(linear). You will then be readi¢lg albpass
fiat rosllonse which IS tilenoiseSHillor ldl tile blinds nl(!llsuri!d,
17

9. Turn the216 switchto OPF whenyou hllve finished.
NoTE
Under celff,ldll (dretllllStIlllceS iti_ possilfle tooveHoad the
ill[0rllal _lnllllirit!r add eiltlSO;isJil_ht error illsomeroadillgs. A
snudl alter (in most eases IleglJgihle) can I)e developed olIly
when the overall linear rospOllSe noise level exceeds 126 dB
RMS, alldyou are tryklg toread octavell;tll/I levels onthe 70
dB range position or lower. Noise above 12(] dB will I)e
clipppd at that level when youusetile 70 dB range position
or lower. This clipping action causes sgltaring of the wave
i)ell]_.';and introduces small amollnts of]lllFtllonit: freqLleDck*s
which aetllally illily Dot beprose/it. The ltnlOtlllt Of error lit
worstc_,seis less than 1% oftheoverall noise, and tllllS for
IllO._t applications isnot it CO/learn. 111it similar milliner over
all noise almve 136dB will be clipped when reading octave
bands ontile 80 dBr_mgoor lower.
OPERATIONAL CHECK
'rile215meter should be calibrated alone using theQuest
CA-12Calibrator at outlhledon Page 10,With the 215 calibrated,
eOnlleCt it totileO11-,15, and lock them together with the thunlb
screw provided, The 216 meter w_ designed so that tilecalihration
screw is not accessiblewhen tile meter is attached to the OB-d5; the
motor therefore can notbeadjusted when it it attached to theOB-,t5.
The OB-,15 has a fixed input tooutput voltage ratioo1'one and there-
fore lea no external adjustments. Cheek the operation of the 215-,15
Analyzer as follows:
1. Set the 215 meter tothe 100 dli range position, and the
OB-d5 frequency band to 1000llz (1K).
2, Using tile CA-12 Calibrator (110 dB at 1000 IIz) insert the
microphone into tile Calibrator and turll both unitsON. With tim
meter set aL A, B,Cor LIN position,Itfilll scale deflection (+10)
should be obtained.
3. Move the WEIGHTING selector to EXT to engtlge tile
OB-d5*The metPr reading shotdd still he almost +10butrally beits
nltl_h llSD,5 all lower t]lilll full sellle I)eelltlse or tilecontour of the
filter in the bandpass zone (see Figure 11).
d. Next mow, the FgEQUENCY selector to2Kllz and then to
500 llz.Inboth positions filt_ meter reading should drop 18 to 19
dB (see Figure ill
5, Renlove tile calibrator,lllld the mlalyzer is ready tolisa.
18