G.R.A.S. 45CA User manual

Instruction Manual
Hearing-Protector Test Fixture Type 45CA
Skovlytoften 33, 2840 Holte, Denmark
www.gras.dk [email protected]
SOUND & VIBRATION
G R A S
...
.

Revision 28 November 2013
LI0024

G.R.A.S. SOUND & VIBRATION
CONTENTS
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Main Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 WhichCongurationtoUse ..........................................5
2 Delivered Components............................................6
3 IMPORTANT! Basic Assembly - Safety instructions ....................7
4 CongurationwithPressureMicrophone,
1"Type 40EN or ½"Type 40AP/40AD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.1 AssemblingMicrophoneandPreamplier ...............................8
4.2 Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.3 Mounting the Assembly into the Test Fixture ............................10
4.4 Acoustic Isolation Testing ...........................................14
4.5 Typical Application Setup ...........................................15
5 CongurationwithIEC60318EarSimulatorRA0039. . . . . . . . . . . . . . . . . . 16
5.1 EarSimulator/PreamplierAssembly .................................16
5.2 Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.3 Completing the Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.4 Mounting Assembly into Test Fixture ..................................19
5.5 Typical Application Setup ...........................................22
6 CongurationwithIEC60711EarSimulatorRA0045orRA0045-S1 . . . . . . 23
6.1 AssemblingEarSimulatorandPreamplier .............................23
6.2 Mounting the Assembly into the Test Fixture ............................24
6.3 Calibrating IEC 60711 Ear Simulator Coupler RA0045.....................27
6.4 Mounting the KEMAR Pinna .........................................28
6.5 Typical Application Setup ...........................................29
7 TechnicalSpecications .........................................30
8 WhattoOrder ..................................................31

G.R.A.S. SOUND & VIBRATION Page 4
Hearing-Protector Test Fixture Type 45CA
Blind Plug
GR1079
Resilient base
Neck
Fig. 1.1 Assembled test xture Type 45CA including Acoustic Plug and Acoustic Cup.
1 Introduction
The G.R.A.S. Hearing-Protector Test Fixture Type 45CA (Fig. 1.1) is for testing
• Hearing protection devices such as ear muffs and earplugs
• Sound sources such as headphones (supra-aural, circum-aural) and earphones.
Thetestxturecanbeusedwithoneofthefollowingmicrophonesorearsimulators:
• 1"or ½"pressure microphones. If used with 1"microphones,thetestcongurationconforms
with ISO 4869-3.
• IEC 60711 (IEC 60318-4) Ear Simulator RA0045.
• IEC 60318 (IEC 60318-1) Ear Simulator RA0039.
1.1 Main Features
The Test Fixture Type 45CA provides for reliable and exact measurements and was designed
withthefollowingfeatures:
• Thetestxture,mountedonaresilientbase(Fig.1.1)thatreducesthenoiseoortoamini-
mum in a typical test situation. Foam plugs and grease (Fig. 1.1) are supplied to avoid sound
leakage along the cable.
• Thetestxturehead,madeforoptimizingtheacousticisolation.
• An acoustic cup and plug for testing the acoustic isolation (Fig. 1.1).
• Arangeofmoulded-rubberKEMARpinnae,e.g.fortestingearplugs,canbetted.
Head
Pedestal (neck + resilient base)
Two 1.5 mm Allen grub screws - must
ALWAYS be tightened when pedestal
and head are assembled
Cup
GR0974
Tube of
Sealing Grease
MI0016
2 x Foam Plug
GR1281

G.R.A.S. SOUND & VIBRATION Page 5
Hearing-Protector Test Fixture Type 45CA
1.2 WhichCongurationtoUse
Table1showswhateachofthethreecongurationscanbeusedfor:
ISO4869-3Congurationwith1"(or½"*)Microphone*
Pressuremicrophones,bothexternallyandpolarizedtypesavailable.
Thecongurationisapplicablefortestingoutside-the-eardevices;i.e.
• For measuring the insertion loss of ear muffs
• For testing the sound quality of earphones
IEC60318CongurationwithEarSimulatorRA0039
RA0039 simulates an ear and is used for measuring the sound pressure at the ear entrance
point (EEP).
RA0039mustbeconguredwitha½"microphone,externallypolarizedorprepolarized.
IEC60711CongurationwithEarSimulatorRA0045
Theseearsimulatorsareforusewithapinnasimulator(articalear)formeasuringthesound
pressure at the eardrum (DRP), thus also applicable for ear inserts. RA0045 available both in
externallypolarizedorprepolarizedversions.
Standard ISO 4869-3 * IEC 60318 IEC 60711
Test Setup
(G.R.A.S.equip-
menttouse)
Pressure Microphone
– 1"40EN or
– ½"40AP/40AD
Ear Simulator RA0039
with ½"microphone:
– 40AG (ext. pol.) or
– 40AO (pre-pol.)
Ear Simulator
– RA0045 (ext. pol.) or
– RA0045-S1 (pre-pol.)
Device to test
Ear muffs
+ + +
Earplugs
- - +
Headphones
+ + +
Earphones
- - +
Hearing-aids
- - +
080016
*ThecongurationwillbeinconformitywithISO4869-3onlyif1"Microphone Type 40EN is used.
Table 1 Providing an overview: Which conguration to use

G.R.A.S. SOUND & VIBRATION Page 6
Hearing-Protector Test Fixture Type 45CA
1 x Acoustic plug
GR1079
1 x Acoustic cup
GR0974
1 x Resilient base
GR0986
1 x Test
xtureneck
Allenkeys:
1 x 6.0 mm YY0019
1 x 2.5 mm YY0016
1 x 2.0 mm YY0018
1 x 1.5 mm YY0012
2 Delivered Components
2 x Cover plate
GR1085
1xTestxturehead
1 x Allen
screw 6 mm
SK1544
Fig. 2.1 Parts delivered in the Type 45CA box.
2 x Insert
GR0970
Tube of
Sealing Grease
MI0016
2 x Foam Plug
GR1281

G.R.A.S. SOUND & VIBRATION Page 7
Hearing-Protector Test Fixture Type 45CA
3 IMPORTANT! Basic Assembly - Safety instructions
Beforeproceedingtooneofthethreecongurationoptionsinsections4,5,or6,dothebasic
assemblyofthetestxtureaccordingtostep1-4:
1. Placethetestxtureneckontoasolidtable,andndthesuppliedscrewand6mmAllenkey
(Fig. 3.1).
2. Place the screw into the bottom of the resilient base, and screw the base onto the neck with
the Allen key (Fig. 3.2).
Fig. 3.1 Fig. 3.2
Testxture
neck
Resilient base
3. After making sure both of the 1.5 mm Allen grub screws in the head’s steel tube are
loosened to their extreme positions, place the head onto the pedestal and carefully slide the
steel tube onto the top of the pedestal’s neck (Fig. 3.3).
4. Tighten both of the 1.5 mm Allen grub screws on the steel tube (Fig. 3.4).
IMPORTANT!
Tighten both of
these 1.5-mm
Allen grub screws
Fig. 3.3 Fig. 3.4
Testxture
head
Pedestal
Steel tube
1.5 mm Allen grub
screws loosened to their
extreme positions
Testxtureneck
Screw
6 mm
SK1544 Allen key
6 mm
YY0019
Allen key
1.5 mm
YY0012
ATTENTION!
When assembling head and pedestal, always make sure to tighten both of the 1.5 mm Allen
grub screws in the steel tube as indicated in Fig. 1.1.
Screw
6 mm
SK1544

1"Pressure
Microphone
Type 40EN
1"to ½"Adapter
RA0017
½"to ¼"
Adapter
RA0003,
NOT Included
with the
¼"Preamplier
Type 26AS
¼"Preamplier,Short
Type 26AS *
1"to ½"
Microphone
Adapter
RA0058
1"Microphone
Protection
Grid
RA0177
½"to ¼"Adapter
GR0010
(included with the
¼"Preamplier)
½"Pressure
Microphone
Type 40AP,
protection
grid removed
½"Pressure
Microphone
Type 40AD,
protection
grid removed
¼"Preamplier,Short
Type 26CS *
Cable AA0018
G.R.A.S. SOUND & VIBRATION Page 8
Hearing-Protector Test Fixture Type 45CA
Fig. 4.1 Assembly options (exploded view)
4 CongurationwithPressureMicrophone,
1"Type 40EN or ½"Type 40AP/40AD
Applications
Insertion Loss of Ear Muffs. If Microphone 1"Type40ENisused,thecongurationisinconform-
ity with ISO 4869-3.
RequiredAccessories
• The parts shown in Fig. 4.1 (choose one of the three assembly options)
• Pistonphone Type 42AP (recommended) or Type 42AA
• Test instruments such as those shown in Fig. 4.14
4.1 AssemblingMicrophoneandPreamplier
Fig.4.1displaysthreeoptionsforthemicrophone/preamplierassemblyrequiredforthemeas-
urements.
1"Type 40EN OR ½"Type 40AP OR ½"Type 40AD
_____________
* For space limitations, the super-short ¼"PreamplierType26AS/Type26CS(shown)isrequiredforbinauralmeasure-
ments. For monaural measurements, replaceType 26AS with Type 26AC and Type 26CS with Type 26CB.

4.2 Calibration
Beforemountingthemicrophone/preamplierassemblyintothetestxture,youmustcalibrate
the assembly using Pistonphone Type 42AP or Type 42AA (with optional 1"coupler adapter)
• Forinstructionsoncalibratingthemicrophone-preamplierassembly,refertothepiston-
phone’s instruction manual.
• The Pistonphone Type 42AP is delivered with an adapter for calibrating 1"microphones.
Fig. 4.2 Assembly of 1"microphone and ¼" preamplier to be calibrated
G.R.A.S. SOUND & VIBRATION Page 9
Hearing-Protector Test Fixture Type 45CA

4.3 MountingtheAssemblyintotheTestFixture
1. SeeFig.4.3:
– Mount the Cover Plate GR1085.
– Mount the Insert GR0970.
(Both items are already mounted at delivery).
G.R.A.S. SOUND & VIBRATION Page 10
Hearing-Protector Test Fixture Type 45CA
Fig. 4.3 Cover plate and insert to be mounted
2.UsingAllenkey1.5mm,loosenthetwo1.5mmgrubscrews(Fig.4.3),andseparate  
the head from the pedestal.
Up
Insert
GR0970
Allen grub screws,
1.5 mm
Right
Cover plate
GR1085
Screws,
2.0 mm
Hole for
screw,
1.5 mm