Model 426B03 Microphone Preamplifier

Model 426B03
Microphone Preamplifier
Installation and Operating Manual
For assistance with the operation of this product,
contact PCB Piezotronics, Inc.
Toll-free: 800-828-8840
24-hour SensorLine: 716-684-0001
Fax: 716-684-0987
E-mail: info@pcb.com
Web: www.pcb.com
Warranty, Service, Repair, and
Return Policies and Instructions
The information contained in this document supersedes all similar information that
may be found elsewhere in this manual.
Total Customer Satisfaction – PCB
Piezotronics guarantees Total Customer
Satisfaction. If, at any time, for any
reason, you are not completely satisfied
with any PCB product, PCB will repair,
replace, or exchange it at no charge. You
may also choose to have your purchase
price refunded in lieu of the repair,
replacement, or exchange of the product.
Service – Due to the sophisticated nature
of the sensors and associated
instrumentation provided by PCB
Piezotronics, user servicing or repair is
not recommended and, if attempted, may
void the factory warranty. Routine
maintenance, such as the cleaning of
electrical connectors, housings, and
mounting surfaces with solutions and
techniques that will not harm the
physical material of construction, is
acceptable. Caution should be observed
to insure that liquids are not permitted to
migrate into devices that are not
hermetically sealed. Such devices should
only be wiped with a dampened cloth
and never submerged or have liquids
poured upon them.
Repair – In the event that equipment
becomes damaged or ceases to operate,
arrangements should be made to return
the equipment to PCB Piezotronics for
repair. User servicing or repair is not
recommended and, if attempted, may
void the factory warranty.
Calibration – Routine calibration of
sensors and associated instrumentation is
recommended as this helps build
confidence in measurement accuracy and
acquired data. Equipment calibration
cycles are typically established by the
users own quality regimen. When in
doubt about a calibration cycle, a good
“rule of thumb” is to recalibrate on an
annual basis. It is also good practice to
recalibrate after exposure to any severe
temperature extreme, shock, load, or
other environmental influence, or prior
to any critical test.
PCB Piezotronics maintains an ISO9001 certified metrology laboratory and
offers calibration services, which are
accredited by A2LA to ISO/IEC 17025,
with full traceablility to N.I.S.T. In
addition to the normally supplied
calibration, special testing is also
available, such as: sensitivity at elevated
or cryogenic temperatures, phase
response, extended high or low
frequency response, extended range, leak
testing, hydrostatic pressure testing, and
others. For information on standard
recalibration services or special testing,
contact your local PCB Piezotronics
distributor, sales representative, or
factory customer service representative.
Returning Equipment – Following
these procedures will insure that your
returned materials are handled in the
most expedient manner. Before returning
any equipment to PCB Piezotronics,
contact your local distributor, sales
representative, or factory customer
service representative to obtain a Return
Materials
Authorization
(RMA)
Number. This RMA number should be
clearly marked on the outside of all
package(s) and on the packing list(s)
accompanying the shipment. A detailed
account of the nature of the problem(s)
being experienced with the equipment
should also be included inside the
package(s) containing any returned
materials.
PCB for a complete statement of our
warranty. Expendable items, such as
batteries and mounting hardware, are not
covered by warranty. Mechanical
damage to equipment due to improper
use is not covered by warranty.
Electronic circuitry failure caused by the
introduction of unregulated or improper
excitation power or electrostatic
discharge is not covered by warranty.
A Purchase Order, included with the
returned materials, will expedite the
turn-around of serviced equipment. It is
recommended to include authorization
on the Purchase Order for PCB to
proceed with any repairs, as long as they
do not exceed 50% of the replacement
cost of the returned item(s). PCB will
provide a price quotation or replacement
recommendation for any item whose
repair costs would exceed 50% of
replacement cost, or any item that is not
economically feasible to repair. For
routine calibration services, the Purchase
Order should include authorization to
proceed and return at current pricing,
which can be obtained from a factory
customer service representative.
Contact Information – International
customers should direct all inquiries to
their local distributor or sales office. A
complete list of distributors and offices
can be found at www.pcb.com.
Customers within the United States may
contact their local sales representative or
a
factory
customer
service
representative. A complete list of sales
representatives can be found at
www.pcb.com. Toll-free telephone
numbers for a factory customer service
representative,
in
the
division
responsible for this product, can be
found on the title page at the front of this
manual. Our ship to address and general
contact numbers are:
Warranty – All equipment and repair
services provided by PCB Piezotronics,
Inc. are covered by a limited warranty
against
defective
material
and
workmanship for a period of one year
from date of original purchase. Contact
DOCUMENT NUMBER: 21354
DOCUMENT REVISION: B
ECN: 17900
PCB Piezotronics, Inc.
3425 Walden Ave.
Depew, NY 14043 USA
Toll-free: (800) 828-8840
24-hour SensorLineSM: (716) 684-0001
Website: www.pcb.com
E-mail: info@pcb.com
PRODUCT GUIDE
377 SERIES MICROPHONES
426 SERIES PREAMPLIFIERS
Contents:
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
Introduction ................................................................................ 1
Standards .................................................................................... 1
Setting up a Microphone Measurement System ........................ 1
Taking Measurements ................................................................ 2
Accessories ................................................................................. 3
Maintenance ............................................................................... 3
Calibration .................................................................................. 4
Warranty and Service ................................................................. 4
1.0 Introduction
Thank you for your purchase of a PCB high quality microphone. These microphones offer highly accurate
and reliable acoustic measurements and are typically used in research and design applications. They are
accurate enough for laboratory usage, yet rugged enough for field-testing.
Sound within the typical 20 to 20,000 Hz audible range of a healthy human ear can either be pleasing to
the ear, as in music, or unpleasant (or harmful), as in noise. As a result, many applications, from the development of consumer products to research in acoustics, measure sound, even sound outside the range of
human hearing. The instrument typically used to measure sound is the microphone, which is designed,
like the human ear, to transform pressure oscillations into a corresponding voltage oscillation.
2.0 Standards
Before selecting an acoustical instrument, it is important to identify which acoustical standards are appropriate for the application in which the instrument will be used. Whether for legal purposes or for quality
assurance programs, these standards will help determine the required quality, accuracy and consistency of
the instrument. Standards that correspond to the performance requirements, dimensions and characteristics of acoustical components are established for microphones, sound level meters, calibrators, or other
related components. The most common organizations producing these standards are the American National Standards Institute (ANSI) and the International Electrotechnical Commission (IEC). IEC 1094-4
establishes specifications for the mechanical dimensions and certain electroacoustic characteristics for
standard industrial microphones. The performance specification sheet supplied with each PCB microphone identifies the standards to which the microphone is compliant.
3.0 Setting up a Microphone Measurement System
After the proper microphone has been selected, the corresponding preamplifier, cabling, power supplies,
signal conditioning and data acquisition selections are ready to be installed. Not all of these components
are required for all test set-ups. The figures below show typical set-ups for externally polarized and prepolarized microphone systems.
A prepolarized microphone can be used with a standard Microphone Power Supply designed for externally polarized microphones, and its preamplifier, provided the supply voltage is set to zero.
1
Externally Polarized Microphone System
Prepolarized Microphone System
4.0 Taking Measurements
The following formula is used to calculate the pressure measured by the microphone from the output voltage signal. The sensitivity of a microphone is typically measured at 250 Hz.
Pressure (Pa) = Voltage (mV) / Sensitivity (mV/Pa).
The lowest amplitude a healthy human ear can detect is 20 millionths of a Pascal (20Pa). Another scale
more commonly used to describe sound pressure level is the decibel (dB). To convert the output voltage
signal (measured in Vrms) to sound pressure level (measured in decibels), use the following formula:

 V
SPL   20 Log  rms
SP

ref



 dB


where S is the sensitivity of the microphone in mV/Pa, and Pref is the reference pressure in air, which is
20 x 10-6 Pa. The decibel scale is logarithmic and more closely matches the response reactions of the
human ear to the pressure fluctuations. Some examples of typical sound pressure levels are shown in the
table below.
dB
0
60
80
94
100
120
140
Pressure
0.00002 Pa
0.02 Pa
0.2 Pa
1 Pa
2 Pa
20 Pa
200 Pa
Example
Threshold of Hearing
Business Office
Shop Noise
Large Truck
Jackhammer
Airplane Take-Off
Threshold of Pain
At very high-pressure amplitudes, the microphone’s diaphragm will start to distort the measured sound
pressure. The maximum rated sound pressure level of a microphone is expressed as the amplitude at
which the Total Harmonic Distortion (THD) reaches a specified amount, typically 3% THD. It is important to note that the highest sound pressure level that can be measured with a microphone system may
be limited by other parts of the system, such as the preamplifier, signal conditioner, or instrumentation.
Conversely, the Cartridge Thermal Noise (CTN) specification provides the lowest measurable sound pressure level that can be detected above the electrical noise inherent within the microphone.
2
Temperature and pressure will affect the sensitivity of a microphone but these effects can be accounted
for by adjusting the recorded microphone values using the coefficients specified for each microphone
model. Simply calculate the difference in temperature and ambient pressure from those recorded during
calibration and multiply this value by the proper coefficient to determine the sensitivity offset. In most
cases, the offset will be very small and is therefore unnecessary.
5.0 Accessories
Transducer Electronics Data Sheet (TEDS)
Preamplifiers can incorporate TEDS devices, which have a built in read/write memory that contains relevant information about the sensor and its use. Information includes manufacturer name, model number,
serial number, sensitivity, etc. The operation of TEDS devices is defined by IEEE P1451.4. A TEDS microphone system includes a microphone mated with a preamplifier that contains the TEDS memory programmed with both the microphone and preamplifier information. This is particularly helpful when using
large channel count systems and array set-up.
A-Weight Inline Filter
The inline filter is used in conjunction with an ICP® preamplifier to provide A-weighting for acoustical
measurements. The filter’s frequency response is weighted according to the A-weighting filter portion of
both ANSI S1.4 and IEC 60651 Type 1 Sound Level Meter Standards. ICP® signal conditioners of 4 mA
or greater are recommended when using inline filters.
Windscreens and Nose cones
Wind induced noise can be reduced by using a windscreen. This can offer some protection against dust
particles and mechanical damage. In the presence of high-speed airflow from a well-defined direction,
such as wind tunnels, a nose cone is recommended. When using windscreens and noise cones, the frequency response of the microphone will be attenuated at higher frequencies.
Clamps and stands
When holding a microphone in place, it is important to minimize the influence of the stand on the sound
being measured. This can be accomplished by using low profile stands and clamps available from PCB.
Cables and Electronics
PCB carries LEMO cables as well as coaxial cables with BNC and 10-32 connectors. Traditional externally polarized microphone power supplies along with a variety of ICP® signal conditioners are available
that will fit almost any need.
6.0 Maintenance
Microphones are very stable over long periods of time, provided they are handled and stored properly.
The microphone contains fragile components that can be damaged by misuse, in particular the diaphragm,
which is made up of a very thin proprietary material and should be kept clean of dust, dirt, moisture and
free any type of imperfection (scratch, dent, etc.).
The microphone’s grid cap is designed to let the true sound pressure level through to the diaphragm while
preventing items from coming in contact with it. We do not recommend that you ever remove the grid cap
or clean the microphone. If you take the precautionary measures to keep the microphone clean and dry, it
should not be necessary. Use of accessories, like windscreens, and desiccants will help keep moisture off
the microphone and maintain the specified sensitivity level. Nose cones will help keep turbulence off the
microphone diaphragm and allow the sound pressure to be measured with greater accuracy.
Keep the microphone and preamplifier assembled while preparing for testing. Keep the rubber maintenance caps on the preamplifier’s electrical connector only. Do not place these rubber caps over the microphone. This will create a vacuum and undo pressure on the microphone diaphragm, which can stretch the
diaphragm and cause a change in sensitivity. Store the microphones and preamplifiers in their protective
3
cases when not in use. With proper maintenance, the microphone and preamplifier should provide stable
and accurate results for years to come.
Dust, rain, oil, moisture or exposure to extreme temperatures may adversely affect the microphone and
preamplifier’s performance. If the microphone or the inside of the connection area of the preamplifier becomes contaminated, use a light pressure rubber bulb to gently blow clean, dry air onto the unit in order to
remove the dust. In the event that you absolutely must take off the grid cap and clean the microphone diaphragm, we recommend using a blow bulb or a light pressure, clean and dry air hose to gently blow contamination off the diaphragm. The direction of the air should be parallel with the diaphragm, not directly
(0 degree incidence) pointed at the diaphragm. Do not touch the microphone’s diaphragm with your fingers or let it come in contact with any sharp or pointed object. Please note that any contact to the microphone’s diaphragm can negatively impact the sensitivity and long term stability of the microphone.
If the microphone is ever dropped or comes into contact with any contamination, or is exposed to extreme
temperatures, we recommend immediate recalibration of the microphone. Please note that heat from your
hands can affect the calibration results. It is always good practice to wait a minimum of 30 seconds after
placing the microphone on a test system before taking a calibration reading in order to minimize the effect
that heat from your hands has on the calibration.
7.0 Calibration
PCB offers recalibration services for our precision microphones, as well as units produced by other A2LA
manufacturers. Our internal metrology laboratory is certified to ISO 9001, accredited by A2LA to ANSI/IEC 17025 and ANSI/NCSL Z540-1, complies with ISO 10012-1 (and former MIL-STD-45662A), and
uses equipment directly traceable to one or more of the following National Labs (NIST, PTB or DFM).
Our investment in equipment, traceability and conformance to industry standards ensures accurate calibration against relevant specifications. We also carry a line of acoustic calibrators that can be used to calibrate microphone sensitivity on site as needed.
8.0 Warranty and Service
All equipment and repair services provided by PCB Piezotronics, Inc. are covered by a warranty against
defective material and workmanship under a Total Customer Satisfaction policy. If, at any time, for any
reason, you are not completely satisfied with any PCB product, PCB will repair, replace, or exchange it at
no charge. You may also choose to have your purchase price refunded. See the supplemental sheet, contained with this manual, for information on our service, repair and return policies, procedures and instructions. When unexpected problems arise, call our 24-Hour SensorLineSM (716-684-0001) to speak with an
Application Engineer. Visit www.pcb.com for a complete statement of our warranty.
24-hour SensorLineSM: 716-684-0001
U.S.A. Fax: 716-684-0987
Toll-free (in the U.S.A.): 800-828-8840
3425 Walden Avenue, Depew, NY 14043-2495
E-Mail: info@pcb.com
Website: www.pcb.com
A PCB GROUP COMPANY
ISO 9001 CERTIFIED
A2LA ACCREDITED to ISO 17025
 2014 PCB Group, Inc. In the interest of constant product improvement, specifications are subject to change without notice.
PCB and ICP are registered trademarks of PCB Group, Inc. Sensor Line is a service mark of PCB Group, Inc. All other trademarks are properties of the respective owners.
Manual Number: 27042
Manual Revision: C
ECO 42502
Printed in the U.S.A.
4
Model Number
426B03
Performance
Nominal Microphone Diameter
Gain
Frequency Response(± 0.1 dB)(re 1 kHz)
Frequency Response(± 0.2 dB)(re 1 kHz)
Frequency Response(-3 dB)(re 1 kHz)
Phase Linearity(<1 °)
Electrical Noise(A-weight)
Electrical Noise(A-weight)
Electrical Noise(Flat 20 Hz to 20 kHz)
Electrical Noise(Flat 20 Hz to 20 kHz)
Distortion(3 V rms input at 1 kHz)
Output Slew Rate
TEDS Compliant
ECN #: 42966
ENGLISH
SI
OPTIONAL VERSIONS
1/4"
-0.19 dB
5 to 126,000 Hz
3.2 to 126,000 Hz
<0.7 Hz
63 to 20,000 Hz
<3.2 µV
1.9 µV
<5.6 µV
3.4 µV
<-70 dB
2 V/µS
Yes
1/4"
-0.19 dB
5 to 126,000 Hz
3.2 to 126,000 Hz
<0.7 Hz
63 to 20,000 Hz
<3.2 µV
1.9 µV
<5.6 µV
3.4 µV
<-70 dB
2 V/µS
Yes
Optional versions have identical specifications and accessories as listed for the standard model
except where noted below. More than one option may be used.
-40 to 158 °F
-40 to 185 °F
<0.03 dB
0 to 95 %RH
<0.03 dB
-40 to 70 °C
-40 to 85 °C
<0.03 dB
0 to 95 %RH
<0.03 dB
20 to 32 VDC
2 to 20 mA
2x1010 Ohm
0.15 pF
10 to 14 VDC
<50 Ohm
±8V
20 to 32 VDC
2 to 20 mA
2x1010 Ohm
0.15 pF
10 to 14 VDC
<50 Ohm
±8V
Stainless Steel
0.25 in x 1.74 in
0.21 oz
10-32 Coaxial Jack
0.2244 - 60 UNS
Stainless Steel
6.4 mm x 44.2 mm
6 gm
10-32 Coaxial Jack
5.7 mm - 60 UNS
[1][2]
[2]
[1][2]
[2]
[1][2]
[1]
[3]
NOTES:
Environmental
Temperature Range(Operating)
Temperature Range(Storage)
Temperature Response
Humidity Range(Non-Condensing)
Humidity Sensitivity
Revision: D
MICROPHONE PREAMPLIFIER
[1]
[2]
[3]
[4]
Typical.
Measured with an 18 pF reference microphone.
TEDS Capable Digital Memory and Communication, compliant with IEEE P1451.4
See PCB Declaration of Conformance PS076 for details.
Electrical
Excitation Voltage
Constant Current Excitation
Impedance(Input)
Capacitance(Input)
Output Bias Voltage
Impedance(Output)
Output Voltage(Maximum)
[1]
[1]
[1]
Physical
Housing Material
Size (Diameter x Length)
Weight
Electrical Connector
Mounting Thread(Microphone to Preamplifier)
SUPPLIED ACCESSORIES:
Model ERC-16 Calibration of microphone preamplifier (1)
Entered: AP
Engineer: MT
Sales: MV
Approved: MT
Spec Number:
Date: 6/2/2014
Date: 6/2/2014
Date: 6/2/2014
Date: 6/2/2014
22760
[4]
All specifications are at room temperature unless otherwise specified.
In the interest of constant product improvement, we reserve the right to change specifications without notice.
ICP® is a registered trademark of PCB Group, Inc.
3425 Walden Avenue, Depew, NY 14043
Phone: 716-684-0001
Fax: 716-684-0987
E-Mail: info@pcb.com
4
3
2
1
REVISIONS
23553
PCB Piezotronics Inc. claims proprietary rights in
the information disclosed hereon. Neither it nor any
reproduction thereof will be disclosed to others
without the written consent of PCB Piezotronics Inc.
.25 [6.4]
REV
DESCRIPTION
DIN
B
ADDED ADDITIONAL VENT HOLE
43127
0.2244-60 UNS - 2A
[5.7mm-60 UNS]
CONNECTOR (INPUT)
.090 [2.29]
B
B
1.74 [44.2]
1.53 [38.8]
2X .032 [.81] 1
.11 [2.9]
10-32 COAXIAL
CONNECTOR (OUTPUT)
A
A
UNLESS OTHERWISE SPECIFIED TOLERANCES ARE:
DIMENSIONS IN INCHES
DECIMALS
1
VENT HOLES PRESENT ON MODEL 426B03 ONLY.
4
3
XX ±.03
XXX ±.010
DIMENSIONS IN MILLIMETERS
[ IN BRACKETS ]
DECIMALS
X ± 0.8
XX ± 0.25
ANGLES  2 DEGREES
ANGLES  2 DEGREES
FILLETS AND RADII
.003 - .005
FILLETS AND RADII
0.07 - 0.13
2
DRAWN
JDM
7/7/14
CHECKED
ECB
7/7/14
ENGINEER
NJL
7/7/14
TITLE
OUTLINE DRAWING
1/4" MICROPHONE PREAMPLIFIER
3425 WALDEN AVE. DEPEW, NY 14043
(716) 684-0001 E-MAIL: sales@pcb.com
DWG. NO.
CODE
IDENT. NO.
52681
SCALE:
4X
1
23553
SHEET
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