G.R.A.S. 43BA Series, 43BA-1, 43BA-2, 43BA-3 Instruction Manual

www.gras.dk

LI0105 – 11 December 2013

Instruction Manual

43BA ¼” 0.4cc High-frequency Coupler Kit

43BA-1 ¼” 0.4cc High-frequency Coupler Kit

43BA-2 ¼” 0.4cc CCP High-frequency Coupler Kit

43BA-3 ¼” 0.4cc CCP High-frequency Coupler Kit, High Sensitivity

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Revision History

Any feedback or questions about this document are welcome at [e-mail].

Revision Date Description

1 11 December 2013 First publication

Copyright Notice

© 2013 G.R.A.S. Sound & Vibration A/S

www.gras.dk

Trademarks

Product names mentioned in this document may be trademarks or registered trademarks of their
respective companies and are hereby acknowledged.

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Contents

Introduction and Description ............................................................ 4

Design ...................................................................................................... 4

Performance .............................................................................................. 5

Delivered Items ............................................................................. 7

Assembling the Coupler .................................................................. 9

Mounting and Dismounting the Microphone ...................................... 10

Calibration ................................................................................. 10

Ordering Information .................................................................... 11

Specifications and Warranty .......................................................... 13

Specifications .......................................................................................... 13

Calibration ............................................................................................... 14

Service and Repairs .................................................................................. 14

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Introduction and Description

The G.R.A.S. 43BA is a ¼” 0.4cc High-Frequency coupler made for and with the hearing aid
industry. Compared to the reference 2cc coupler it has a smaller volume and a ¼” microphone.
It retains the advantages of the 2cc coupler, but adds the capability of delivering differentiated
and precise data up to 16 kHz because of the combination of the smaller volume and the ¼”
microphone.

The 0.4cc coupler body fits all G.R.A.S. ½” 2cc standard ear mould and tube adapters.
Therefore, the 0.4cc coupler can be used for the same type of tests as the traditional 2cc coupler,
but with the added benefit of a wider frequency range. It is designed for repetitive use and is
equally suited for research, quality assurance and production test applications.

Design

The coupler housing is dimensioned to accomodate the ear mould and tube adapters normally
used with the 2cc coupler, but the inner volume is only 0.4cc.

Its 0.4cc volume is a well defined cylinder where the diaphragm of the microphone is flush with
the bottom of the cylinder. The cylinder is machined to within ±2% of the nominal 0.4cc volume.
The exact volume of each individual coupler is stated in the accompanying calibration chart. The
performance of the 0.4cc coupler can therefore be accurately simulated, and it can easily be a
part of a complete simulation model.

The microphone-preamplifier set is kept firmly in position by a very precise locking mechanism,
which automatically centers and locks the microphone at the same time, eliminating the risk
of measurement errors caused by incorrect positioning of the microphone. An O-ring ensures a
tight sealing of the microphone. The microphone can easily be removed for sensitivity calibration
without the use of tools.

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Performance

An important benefit of the small volume and the ¼” microphone is the fact that the resonance
frequency at 30 kHz is so high that it does not interfere with measurements in the audible
frequency range. Therefore it can be used for measurements up to 16 kHz, one octave higher
than achievable with the reference 2cc coupler.

Because of the small volume, the measured sound level from the coupler is about 13.5 dB higher
than with the 2cc coupler. This effect raises the measured signal with respect to the noise floor
and thus improves the signal-to-noise ratio. This difference of signal levels is shown in Fig. 1.

Therefore, the signal-to-noise ratio obtainable with the 0.4cc coupler and a ¼” microphone with a
sensitivity of about 1.5mV/Pa is almost as good as that of a 2cc coupler using a ½” microphone
with a sensitivity of 12.5mV/Pa. The 43BA-1 has a sensitivity of 1.5 mV/Pa and the noise floor
is 39dB(A), the 43BA-2 has a sensitivity of 1.45 mV and the noise floor 44dB(A).

When used with a high-sensitivity microphone (18 mV/Pa), the 0.4cc is very close to the 2cc
coupler in this respect. With the 43BA-3 high sensitivity version, the noise floor is 25dB(A).

Refer to page 13 for more information about the 43BA’s specifications.

0,0

10,0

20,0

30,0

40,0

50,0

60,0

70,0

80,0

90,0

100 1000 10000

Magnitude [dB re 20 uPa]

Frequency [Hz]

Typical Frequency Response

With G.R.A.S. 1/4" pressure microphone as receiver @ 1Vrms input signal

0.4cc coupler response

2cc coupler response

Fig. 1. 0.4cc coupler compared to the reference 2cc coupler, with a ¼” microphone used as receiver.

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As can be seen in Fig. 1, the 0.4cc coupler does not produce the very sharp resonance at about
12 kHz typical of the 2cc coupler (dotted line). The 0.4cc coupler’s high frequency behavior
is much more linear and does therefore not degrade the reproducibility of high frequency
measurements.

A typical receiver response is shown in Fig. 2.

60

70

80

90

100

110

120

130

140

150

100 1000 10000

Magnitude [dB re 20uPa]

Frequency [Hz]

Typical receiver response, with 9mm Ø1,4 tubing

1/12 oktave frequency response 04CC

Typical Receiver Response with 9mm Standard Tubing

Fig. 2. Typical receiver response with 9 mm standard tubing.

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Delivered Items

Delivered Items

G.R.A.S. 43BA-1 ¼” LEMO 0.4cc High-frequency Coupler Kit

¼” Ext. Polarized

Pressure Microphone

40BP

¼” LEMO Preamplifier
with Integrated Cable,
Very Short

26AS

0.4cc Coupler

RA0252

Tube Adapter, Large

RA0271

Ear-mould Adapter

RA0270

In-ear Adapter

RA0272

G.R.A.S. 43BA-2 ¼” CCP 0.4cc High-frequency Coupler Kit

¼” Prepolarized

Pressure Microphone

40BD

¼” CCP Preamplifier
with Microdot
Connector, Very Short

26CS

0.4cc Coupler

RA0252

Tube Adapter, Large

RA0271

Ear-mould Adapter

RA0270

In-ear Adapter

RA0272

3 m Cable Microdot-BNC

AA0070

GR0917

GR0924

GR1440B

RA0045

26AS

45EA

46BP

GR1153

40AG

GS0158

GR0010

46BD

1

2

4

3

5

L

B-2 B-1

0

2010

01020

J

26AS

45EA

26AS

45EA

45EA

GS0158

GR0010

1

2

4

3

5

L

B-2 B-1

0

2010

01020

J

GR0917

GR0924

GR1440B

RA0045

26AS

45EA

46BP

GR1153

40AG

GS0158

GR0010

46BD

1

2

4

3

5

L

B-2 B-1

0

2010

01020

J

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Delivered Items

G.R.A.S. 43BA-3 ¼” CCP 0.4cc High-frequency Coupler Kit, High Sensitivity

¼” Ext. Polarized

Pressure Microphone,

High Sensitivity

40BL

¼” CCP Preamplifier
with Microdot
Connector, Very Short

26CS

0.4cc Coupler

RA0252

Tube Adapter, Large

RA0271

Ear-mould Adapter

RA0270

In-ear Adapter

RA0272

3 m Cable Microdot-BNC

AA0070

G.R.A.S. ¼” 0.4cc Coupler - Non configured

0.4cc Coupler

RA0252

26AS

45EA

45EA

GS0158

GR0010

1

2

4

3

5

L

B-2 B-1

0

2010

01020

J

GR0917

GR0924

GR1440B

RA0045

26AS

45EA

46BP

GR1153

40AG

GS0158

GR0010

46BD

1

2

4

3

5

L

B-2 B-1

0

2010

01020

J

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Assembling the Coupler

You can assemble the coupler to suit the type of hearing aids you want to test.

Locking mechanism
and lever

O-ring

End stop

Venting canal

Coupler Housing

Union Nut

Fig. 3. Cross section of the RA0252 coupler without adapter.

B-B ( 5 : 1 )

B

B

In-ear Adapter
RA0272

¼” Microphone

40BP/40BD/40BL

Fig. 4. 43BA mounted with microphone and RA0272 In-ear Adapter.

B-B ( 5 : 1 )

B

B

Union Nut

RA0271
Tube Adapter, large

¼” microphone

40BP/40BD/40BL

Fig. 5. 43BA mounted with microphone and RA0271 Tube Adapter.

B-B ( 5 : 1 )

B

B

Union Nut

¼” Microphone

40BP/40BD/40BL

Tube Adapter, small

RA0270
Ear-mould Adapter

Union Nut

Fig. 6. 43BA mounted with microphone and the RA0270 Ear-mould Adapter (which includes Union Nut and Tube
Adapter).

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Mounting and Dismounting the Microphone

The microphone can easily be inserted and removed using the locking mechanism lever on the
side of the coupler body.

1. Ensure that the locking mechanism is unlocked.

2. Gently push in the microphone assembly until it touches the end stop and will go no further.

3. Push the locking mechanism lever to its forward position (See Fig. 7).

Push to unlock

Engraving
indicating the
locked position

Push to lock

Fig. 7. Locking and unlocking the microphone.

Calibration

You must remove the microphone/preamplifier when you need to calibrate it. Proceed as follows:

1. Unlock the locking mechanism by pushing it, as shown in Fig. 7.

2. Gently pull out the microphone set.

For proper sensitivity calibration (114 dB at 250 Hz), we recommend the 42AP Intelligent
Pistonphone, but the 42AA Pistonphone can also be used. Refer to the respective manuals for
instructions.

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Ordering Information

G.R.A.S ¼” 0.4cc High-Frequency Coupler

Included Items Part Number

0.4cc Coupler including Union Nut

RA0252

G.R.A.S. 43BA-1 ¼” LEMO 0.4cc High-frequency Coupler Kit

Included Items Part Number

0.4cc Coupler including Union Nut

RA0252

¼” Ext. Polarized Pressure Microphone

40BP

¼” Standard Preamplifier with 3 m Integrated Cable, Very Short

26AS

Ear-mould Adapter Kit for RA0038 / RA0252 Couplers

RA0270

In-ear Adapter for RA0038 / RA0252 Couplers

RA0272

Tube Adapter for RA0038 / RA0252 Couplers

RA0271

G.R.A.S. 43BA-2 ¼” CCP 0.4cc High-frequency Coupler Kit

Included Items Part Number

0.4cc Coupler including Union Nut

RA0252

¼” Prepolarized Pressure Microphone

40BD

¼” CCP Preamplifier, Very Short

26CS

Ear-mould Adapter Kit for RA0038 / RA0252 Couplers

RA0270

In-ear Adapter for RA0038 / RA0252 Couplers

RA0272

Tube Adapter for RA0038 / RA0252 Couplers

RA0271

3 m Cable Microdot - BNC AA0070

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G.R.A.S. 43BA-3 ¼” CCP 0.4cc High-frequency Coupler Kit, High Sensitivity

Included Items Part Number

0.4cc Coupler Housing, including Union Nut RA0252

¼” Prepolarized Pressure Microphone, High Sensitivity 40BL

¼” CCP Preamplifier, Very Short 26CS

Ear-mould Adapter Kit for RA0038 / RA0252 Couplers

RA0270

In-ear Adapter for RA0038 / RA0252 Couplers

RA0272

Tube Adapter for RA0038 / RA0252 Couplers

RA0271

3 m Cable Microdot - BNC AA0070

Optional Accessories Part Number

7-pin LEMO-LEMO, 3 m AA0008
BNC-BNC, 3 m AA0035

For calibration

Pistonphone with built-in barometer and thermometer (114 dB at 250 Hz) 42AP
Pistonphone (114 dB at 250 Hz) 42AA

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Specifications and Warranty

Specifications

RA0252 Coupler

Volume 400 mm3±2%

Resonance Frequency 30 kHz
Weight, g 42

43BA-1

Microphone Set 40BP + 26AS

Set sensitivity mv/Pa 1.5

dB re 1 V/Pa -56.5
Resonance frequency 30 kHz
Theoretical dynamic range with 40BP + 26AS 39 dB(A) to 172 dB
Temperature range, °C -30 to 60
Temperature coefficient (@250Hz, °C/dB) -0.01
Humidity range (% RH) , non condensing 0 to 95
Connector LEMO

43BA-2

Microphone Set 40BD + 26CS

Set sensitivity mv/Pa 1.45

dB re 1 V/Pa -57
Resonance frequency 30 kHz
Theoretical dynamic range with 40BD + 26CS 44 dB(A) to 168 dB
Temperature range, °C -30 to 60
Temperature coefficient (@250Hz, °C/dB) -0.01
Humidity range (% RH) , non condensing 0 to 95
Connector Microdot 10/32-BNC

43BA-3

Microphone Set 40BL + 26CS

Set sensitivity mv/Pa 18

dB re 1 V/Pa -35
Resonance frequency 30 kHz
Theoretical dynamic range with 40BL + 26CS 25 dB(A) to 147 dB
Temperature range, °C -30 to 60
Temperature coefficient (@250Hz, °C/dB) -0.01
Humidity range (% RH) , non condensing 0 to 95
Connector Microdot 10/32-BNC

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WEEE directive:
2002/96/EC

CE marking directive:
93/68/EEC

Manufactured to conform with:

RoHS directive:
2002/95/EC

Calibration

The 43BA is delivered with

• a calibration chart specifying its exact volume.

• a calibration chart for the microphone/preamplifier combination.

We recommend a yearly recalibration at minimum, depending on the use, measurement environ­ment, and internal quality control programs.

Warranty

All G.R.A.S. products are made of high-quality materials that will ensure life-long stability and
robustness. 43BA is delivered with a 5-year warranty. Damaged diaphragms in microphones can
be replaced.

The warranty does not cover products that are damaged due to negligent use, an incorrect power
supply, or an incorrect connection to the equipment.

The warranty for cables is 6 months.

Service and Repairs

All repairs are made at G.R.A.S. International Support Center located in Denmark. Our Support
Center is equipped with the newest test equipment and staffed with dedicated and highly skilled
engineers.Contact your local G.R.A.S partner for further information. If a product covered by war­ranty is sent for service, it is repaired free of charge, unless the damage is the result of negligent
use or other violations of the warranty. All repairs are delivered with a service report, as well as an
updated calibration chart.