PCB Piezotronics 377 Series User manual

Model 377C20/426A14
377C20 microphone paired with a 426A14 preamplifier
Installation and Operating Manual
For assistance with the operation of this product,
contact the PCB Piezotronics, Inc.
Toll-free: 716-684-0001
24-hour SensorLine: 716-684-0001
Fax: [phone]
E-mail: [email protected]
Web: www.pcb.com

Manual 21354 Rev E
ECN 50523
Repair and Maintenance
PCB guarantees Total Customer Satisfaction through its
“Lifetime Warranty Plus” on all Platinum Stock Products
sold by PCB and through its limited warranties on all other
PCB Stock, Standard and Special products. Due to the
sophisticated nature of our sensors and associated
instrumentation, field servicing and repair is not
recommended and, if attempted, will void the factory
warranty.
Beyond routine calibration and battery replacements
where applicable, our products require no user
maintenance. Clean electrical connectors, housings, and
mounting surfaces with solutions and techniques that will
not harm the material of construction. Observe caution
when using liquids near devices that are not hermetically
sealed. Such devices should only be wiped with a
dampened cloth—never saturated or submerged.
In the event that equipment becomes damaged or ceases
to operate, our Application Engineers are here to support
your troubleshooting efforts 24 hours a day, 7 days a
week. Call or email with model and serial number as well
as a brief description of the problem.
Calibration
Routine calibration of sensors and associated
instrumentation is necessary to maintain measurement
accuracy. We recommend calibrating on an annual basis,
after exposure to any extreme environmental influence,
or prior to any critical test.
PCB Piezotronics is an ISO-9001 certified company whose
calibration services are accredited by A2LA to ISO/IEC
17025, with full traceability to SI through N.I.S.T. In
addition to our standard calibration services, we also offer
specialized tests, including: sensitivity at elevated or
cryogenic temperatures, phase response, extended high
or low frequency response, extended range, leak testing,
hydrostatic pressure testing, and others. For more
information, contact your local PCB Piezotronics
distributor, sales representative, or factory customer
service representative.
Returning Equipment
If factory repair is required, our representatives will
provide you with a Return Material Authorization (RMA)
number, which we use to reference any information you
have already provided and expedite the repair process.
This number should be clearly marked on the outside of
all returned package(s) and on any packing list(s)
accompanying the shipment.
Contact Information
PCB Piezotronics, Inc.
3425 Walden Ave.
Depew, NY14043 USA
Toll-free: [phone]
24-hour SensorLine: [phone]
General inquiries: in[email protected]
Repair inquiries: [e-mail]
For a complete list of distributors, global offices and sales
representatives, visit our website, www.pcb.com.
Safety Considerations
This product is intended for use by qualified personnel
who recognize shock hazards and are familiar with the
precautions required to avoid injury. While our equipment
is designed with user safety in mind, the protection
provided by the equipment may be impaired if equipment
is used in a manner not specified by this manual.
Discontinue use and contact our 24-Hour Sensorline if:
Assistance is needed to safely operate equipment
Damage is visible or suspected
Equipment fails or malfunctions
For complete equipment ratings, refer to the enclosed
specification sheet for your product.
Definition of Terms and Symbols
The following symbols may be used in this manual:
DANGER
Indicates an immediate hazardous
situation, which, if not avoided, may
result in death or serious injury.

Manual 21354 Rev E
ECN 50523
CAUTION
Refers to hazards that could damage
the instrument.
NOTE
Indicates tips, recommendations and
important information. The notes
simplify processes and contain
additional information on particular
operating steps.
The following symbols may be found on the equipment
described in this manual:
This symbol on the unit indicates that
high voltage may be present. Use
standard safety precautions to avoid
personal contact with this voltage.
This symbol on the unit indicates that
the user should refer to the operating
instructions located in the manual.
This symbol indicates safety, earth
ground.

Manual 21354 Rev E
ECN 50523
PCB工业监视和测量设备 - 中国RoHS2公布表
PCB Industrial Monitoring and Measuring Equipment - China RoHS 2 Disclosure Table
部件名称
有害物质
铅(Pb)
汞
(Hg)
镉
(Cd)
六价铬(Cr(VI))
多溴联苯 (PBB)
多溴二苯醚(PBDE)
住房
O
O
O
O
O
O
PCB板
X
O
O
O
O
O
电气连接器
O
O
O
O
O
O
压电晶体
X
O
O
O
O
O
环氧
O
O
O
O
O
O
铁氟龙
O
O
O
O
O
O
电子
O
O
O
O
O
O
厚膜基板
O
O
X
O
O
O
电线
O
O
O
O
O
O
电缆
X
O
O
O
O
O
塑料
O
O
O
O
O
O
焊接
X
O
O
O
O
O
铜合金/黄铜
X
O
O
O
O
O
本表格依据 SJ/T 11364 的规定编制。
O：表示该有害物质在该部件所有均质材料中的含量均在 GB/T 26572 规定的限量要求以下。
X：表示该有害物质至少在该部件的某一均质材料中的含量超出 GB/T 26572 规定的限量要求。
铅是欧洲RoHS指令2011/65/ EU附件三和附件四目前由于允许的豁免。
CHINA RoHS COMPLIANCE

Manual 21354 Rev E
ECN 50523
Component Name
Hazardous Substances
Lead (Pb)
Mercury (Hg)
Cadmium (Cd)
Chromium VI
Compounds
(Cr(VI))
Polybrominated
Biphenyls (PBB)
Polybrominated
Diphenyl Ethers
(PBDE)
Housing
O
O
O
O
O
O
PCB Board
X
O
O
O
O
O
Electrical Connectors
O
O
O
O
O
O
Piezoelectric Crystals
X
O
O
O
O
O
Epoxy
O
O
O
O
O
O
Teflon
O
O
O
O
O
O
Electronics
O
O
O
O
O
O
Thick Film Substrate
O
O
X
O
O
O
Wires
O
O
O
O
O
O
Cables
X
O
O
O
O
O
Plastic
O
O
O
O
O
O
Solder
X
O
O
O
O
O
Copper Alloy/Brass
X
O
O
O
O
O
This table is prepared in accordance with the provisions of SJ/T 11364.
O: Indicates that said hazardous substance contained in all of the homogeneous materials for this part is below the limit
requirement of GB/T 26572.
X: Indicates that said hazardous substance contained in at least one of the homogeneous materials for this part is above the limit
requirement of GB/T 26572.
Lead is present due to allowed exemption in Annex III or Annex IV of the European RoHS Directive 2011/65/EU.

1
PRODUCT GUIDE
377 SERIES MICROPHONES
426 SERIES PREAMPLIFIERS
Contents:
1.0 Introduction................................................................................ 1
2.0 Standards.................................................................................... 1
3.0 Setting up a Microphone Measurement System ........................ 1
4.0 Taking Measurements................................................................ 3
5.0 Accessories and Miscellaneous.................................................. 3
6.0 Maintenance............................................................................... 4
7.0 Calibration.................................................................................. 5
8.0 Warranty and Service................................................................. 5
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 develop-
ment 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 appro-
priate 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 Stand-
ards Institute (ANSI) and the International Electrotechnical Commission (IEC). IEC 1094-4 establishes
specifications for the mechanical dimensions and certain electroacoustic characteristics for standard indus-
trial 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 pre-
polarized 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.

2
Phantom powered microphone systems use a 3 pin XLR connector. A phantom powered microphone sys-
tem should use a 48V phantom power supply or signal conditioner for optimum performance; however
these microphone systems may be powered with a 24V or a 12V phantom power supply, but this will limit
the maximum output voltage.
Externally Polarized Microphone System
Prepolarized Microphone System
Phantom Powered Microphone System
The phantom powered preamp may be used with either a ¼’’ or a ½’’ microphone cartridge by using the
adapter provided. All IEC 61094-4 compliant microphones can be used with the phantom powered preamp.
Adapters for Phantom Powered Preamp

3
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:
dB
PS
V
SPL
ref
rms 















Log20
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
Pressure
Example
0
0.00002 Pa
Threshold of Hearing
60
0.02 Pa
Business Office
80
0.2 Pa
Shop Noise
94
1 Pa
Large Truck
100
2 Pa
Jackhammer
120
20 Pa
Airplane Take-Off
140
200 Pa
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.
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 & Miscellaneous
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.

4
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 exter-
nally 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. Should you need to remove the grid cap to replace it with PCB’s enhanced rugged
grid cap (shown below, and as an independent part of a rugged kit) to extend the lifespan of the precision
measuring device, caution should be taken to ensure the delicate diaphragm sensing element remains un-
touched and safe.
Use of accessories, like windscreens, and desiccants will help keep moisture off the microphone and main-
tain 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 dia-
phragm and cause a change in sensitivity. Store the microphones and preamplifiers in their protective cases
when not in use.
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 be-
comes 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.

5
If the microphone is ever dropped (the effects of this can be minimized by PCB’s rugged grid cap or utilizing
rugged microphone kits), or comes into contact with any contamination, or is exposed to extreme tempera-
tures, immediate recalibration of the microphone should be performed. When using a rugged grid cap, a
handheld calibrator with a 1” diameter (example CAL250, or pistonphone) is required for recalibration,
along with the larger (079A59) calibration adapter. 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. Changes in the environmental conditions: temperature, humidity or atmospheric
pressure, may cause a change in your microphones sensitivity and thus, changes in your output accuracy. It
is always recommended to calibrate both before and after your test, within the test environment. Performing
a single point handheld calibrator check, both before and after your test, ensures reliability of the test data.
With proper maintenance, the microphone and preamplifier should provide stable and accurate results for
years to come.
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 calibra-
tion against relevant specifications. We also carry a line of acoustic calibrators that can be used to calibrate
microphone sensitivity on site as needed.
Hand calibration of sensitivity for most prepolarized microphones may be performed with a Larson Davis
CAL250 or CAL200 (or equivalent). The CAL250 produces 114 dB SPL at 251.2 Hz. The CAL 200
produces either 94 dB or 114 dB (user selectable) at 1000 Hz. Note that both the CAL250 and CAL 200
are compliant with ANSI S1.40-2006, Specifications and Verification Procedures for Sound Calibrators,
Class1 and IEC 60942-2003, Class 1, Sound Calibrators.
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, con-
tained with this manual, for information on our service, repair and return policies, procedures and instruc-
tions. 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.
3425 Walden Avenue, Depew, NY 14043-2495 24-hour SensorLineSM: 716-684-0001
E-Mail: [email protected] U.S.A. Fax: [phone]
Website: www.pcb.com Toll-free (in the U.S.A.): 800-828-8840
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: F
ECO 51020
Printed in the U.S.A.

Model Number
377C20 PRECISION CONDENSER MICROPHONE Revision: B
ECN #: 47338
[4]
Performanc
e
ENGLISH S
I
Nominal Microphone Diameter 1/2" 1/2"
Frequency Response Characteristic Random Incidence Random Incidence
Open Circuit Sensitivity 50 mV/Pa 50 mV/Pa [3]
Open Circuit Sensitivity(± 1.5 dB) -26 dB re 1 V/Pa -26 dB re 1 V/Pa [3]
Frequency Range(± 2 dB) 3.15 to 16,000 Hz 3.15 to 16,000 Hz
Frequency Range(± 1 dB) 5 to 6300 Hz 5 to 6300 Hz
Lower Limiting Frequency(-3 dB) 1.0 to 2.4 Hz 1.0 to 2.4 Hz
Resonant Frequency(90° Phase Shift) 12 kHz 12 kHz [1]
Inherent Noise 14 dB(A) re 20
µPa 14 dB(A) re 20 µPa [1]
Dynamic Range(3% Distortion Limit) 146 dB re 20 µPa 146 dB re 20 µPa [1]
Standards Designation(IEC 61094-4) WS2D WS2D
Environmenta
l
Temperature Range(Operating) -40 to +248 °F -40 to +120 °C
Temperature Coefficient of Sensitivity(+14 to +122°F (-10 to +50°C)) 0.005 dB/°F 0.009 dB/°C [1][3]
Static Pressure Coefficient -0.01 dB/kPa -0.01 dB/kPa [1][3]
Humidity Coefficient of Sensitivity(0 to 100%, non-condensing) ± 0.001 dB/%RH ± 0.001 dB/%RH [3]
Influence of Axial Vibration(0.1g (1 m/s²)) 63 dB re 20 µPa 63 dB re 20 µPa [1]
Electrica
l
Capacitance(Polarized) 11 pF 11 pF [1]
Polarization Voltage 0 V 0 V [2]
Physical
Housing Material Stainless Alloy Stainless Alloy
Venting Rear Rear
Mounting Thread(Preamplifier) 0.4606 - 60 UNS 11.7 mm - 60 UNS
Mounting Thread(Grid) 0.5 - 60 UNS 12.7 mm - 60 UNS
Size (Diameter x Height)(with grid) 0.52 in x 0.64 in 13.2 mm x 16.2
mm
Size (Diameter x Height)(without grid) 0.5 in x 0.6 in 12.7 mm x 15.3
mm
Weight 0.28 oz 7.8 gm [1]
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.
OPTIONAL VERSIONS
Optional versions have identical specifications and accessories as listed for the standard model
except where noted below. More than one option may be used.
NOTES:
[
1
]
T
yp
ical
.
[2] Prepolarized
[3] re 250 Hz
[4] See PCB Declaration of Conformance PS167 for details
.
SUPPLIED ACCESSORIES:
Model ACS-20 Calibration of Precision Condensor Microphones (1)
Entered: LK Engineer: MT Sales: MV Approved: MT Spec Number:
Date: 10/19/2017 Date: 10/19/2017 Date: 10/19/2017 Date: 10/19/2017 58702
3425 Walden Avenue, Depew, NY 14043
Phone: [phone]
Fax: [phone]
E-Mail: [email protected]

CODE
IDENT. NO.
52681
DWG. NO.
SCALE: SHEET
DRAWN CHECKED ENGINEER
TITLE
UNLESS OTHERWISE SPECIFIED TOLERANCES ARE:
DIMENSIONS IN MILLIMETERS
[ IN BRACKETS ]
ANGLES 2 DEGREES
3425 WALDEN AVE. DEPEW, NY 14043
[phone] E-MAIL: [e-mail]
DIMENSIONS IN INCHES
ANGLES 2 DEGREES
FILLETS AND RADII
.003 - .005
FILLETS AND RADII
0.07 - 0.13
OUTLINE DRAWING
29288
1 OF1
4X
1/2" PRE-POLARIZED
MICROPHONES
DECIMALS XX ±.03
XXX ±.010
DECIMALS X ± 0.8
XX ± 0.25
JDM 9/14/05 ECB 9/14/05 CCL 9/14/05
1
1
2
2
A A
B B
.60 [15.3]
.64 [16.4]
.36 [9.2]
.50 [12.7] .4606-60 UNS
[11.7 mm-60 UNS]
THREADS
.52 [13.2]

.47 [12.0]
.48 [12.1]
.5000-60 UNS
[12.7mm-60 UNS]
THREADS
DIAPHRAGM
WITH GRID CAP WITHOUT GRID CAP
.04[1.0]
BLACK O-RING
REVISIONS
REV DESCRIPTION DIN
NR RELEASED TO DRAFTING
29288
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.