Svantek SV 36 User manual

USER MANUAL
SV 36
ACOUSTIC CALIBRATOR
Warsaw, 2018-09-04
Rev. 02 Copyright © 2018 SVANTEK. All rights reserved.

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Contents
1. Introduction ........................................................................................................... 3
2. Acoustic calibrator SV 36 ..................................................................................... 5
2.1. General description ....................................................................................... 5
2.2. Using the calibrator........................................................................................ 6
2.2.1. Automatic calibration ............................................................................... 6
2.2.2. Button functions ...................................................................................... 7
2.2.3. Range diodes .......................................................................................... 7
2.3. Replacing the battery ..................................................................................... 8
3. SV 36 Technical specifications ........................................................................... 11

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1. INTRODUCTION
1.1. Calibration
Calibration determines the ratio between the input signal value and the indication on the
display of the measuring device (or measured result).
In principle, there are more or less large systematic deviations between the displayed
measured value and the true value of the measured signal for every measuring device. The
task of calibration is to determine these systematic deviations.
The simplest way to consider such systematic deviations is a correction of measurements by
calibration factor obtained with the use of an acoustic calibrator.
However, in many cases it is sufficient to determine that the systematic deviations are within
certain limits.
"Correct" value of the measured signal is set before calibration, and this value is compared
with a value measured by the measuring device.
Thus, calibration means establishing a relationship between the reference and measured
value of the variable for the corresponding standard to be able to take this ratio into account
in subsequent measurements as a correction factor (calibration factor).
1.2. Accuracy of calibration
Measuring equipment and measurement methods have deviations. The measured variable is
affected by environmental conditions (temperature and humidity), as well as the operator's
actions. The displayed value of the measured variable will therefore usually deviate from the
true value of the measured variable.
It is recommended to check the SV 36 every 2 years with periodic testing of the test
equipment to ensure that the level values do not change, and the test results are reliable.
It is important to carefully check who should perform such monitoring:
- internally by the monitoring body,
- SVANTEK's own calibration laboratory according to ILAC
- externally from PTB = Physikalisch-Technische Bundesanstalt
- another local accredited laboratory
Accuracy
There is a deviation between the true value and the average value of the series of
measurements under repetitive conditions, which is the result of repeated measurement of
the reference level.
Overview of the classification of sound level meters and calibrators
Classification of sound level meters and acoustic calibrators
The acoustic calibrators (see IEC 60942. 2003) and the sound level meters (see IEC 61672:
2002) are classified into their respective classes and types for accuracy.

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Type LS is subject to the strictest requirements of the device. Devices of this class are
classified as the most precise.
Each of the following types (LS, 1 and 2) allow a wider tolerance range (see Table 1).
Table 1. Tolerances for these types of acoustic devices, except for the maximum extended
measurement uncertainty (f = 1kHz)
Class / Type
LS
1
2
Sound level meters (dB) - 0.7 1.0
Acoustic calibrators (dB) 0.10 0.25 0.40
As shown in Table 1, the acoustic calibrator has unambiguously lower tolerances than the
sound level meter of the same class. Thus, the calibrator, as a reference of acoustic
pressure, should be more precise than a sound level meter.
With respect to acoustic measurements conducted in accordance with the standard, the
requirements for calibrating the measuring channel before each measurement and very often
also after measurement are mandatory.

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2. ACOUSTIC CALIBRATOR SV 36
2.1. General description
The SV 36 acoustic calibrator is a small, portable dual-range (94dB and 114dB) Class 1
device (sound source), see Picture 1. Powered by two LR03/AAA batteries, it contains a
loudspeaker producing acoustic pressure, reference piezoresistive sensor for monitoring
generated level, pressure and temperature sensors for measurements of atmospheric
conditions and a microprocessor system controlling the operation of the calibrator. Sinusoidal
waveform of 1 kHz frequency is digitally generated and feeds the loudspeaker. Sampled
signal from the reference piezoresistive sensor indicates the level of currently generated
signal in a feedback loop. On the basis of information about the level of the signal, actual
values of pressure and temperature, microprocessor adjusts amplification of the loudspeaker
signal in order to produce appropriate sound pressure level in the calibrator’s chamber.
Note: Due to the feedback regulation loop the SV 36 calibrator does not require
adjusting and operates in a wide range of temperatures and humidity (see SV 36
Datasheet).
The SV 36 is designed for calibration of sound level meters with ½” and ¼” microphones.
Picture 2 shows the calibration of Class 1 sound level meter SVAN 971 with a ½”
microphone.
Picture 1. Acoustic calibrator SV 36

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Picture 2. Calibration of the SVAN 971 sound level meter with a ½” measurement microphone
Note: For calibration of a meter with a ¼” microphone the SA 30 reduction
adapter must be applied.
2.2. Using the calibrator
2.2.1. Automatic calibration
The SV 36 calibrator is equipped with an optical system which detects the presence of a
microphone in the calibrator’s chamber. That allows the calibrator to be switched on
automatically, when it is placed on the microphone and to be switched off when it is
dismounted. For this reason, usage of the SV 36 calibrator is as simple as putting it on the
microphone, performing the calibration and taking it off the microphone.
Note: The SV 36 calibrator will always switch on in the range set at the moment
of switching it off.
Note: The automatic switching on will not work when the SA30 calibration
adapter is inserted into the calibrators chamber.
Note: Default range after replacing the battery is 114 dB.

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2.2.2. Button functions
The SV 36 calibrator is equipped with a multifunctional button for controlling operation of the
device. The functions of the button depend on the state of the calibrator (ON/OFF) and on
the time of its pressing (see Table 2).
When the calibrator is OFF, pressing the button turns it on immediately. Range
is automatically set to that one in which the calibrator was switched off. If the calibrator is not
put on the microphone within 3-5 seconds from turning on, it will switch off automatically.
When the calibrator is ON, short pressing of the button (less than 3-5 sec.) will cause
switching the range from 94 dB to 114 dB or the other way round.
Either when the SV 36 is ON or OFF pressing the button over 10 seconds and releasing it
will cause full reset of the system. Normally this function is not necessary. It has been
implemented in the case of inappropriate operation of the calibrator caused by external (EM
radiation, subnormal atmospheric conditions, etc.) or internal (inappropriate system reset as
a result of battery replacement) factors.
The operation time of the calibrator with a microphone put inside its chamber
is limited to 3 minutes. This functionality was added in order to save the battery, e.g. when
the calibrator is accidentally left with the microphone inside.
Note: Leaving the SA 30 reduction adapter in the chamber of the calibrator is
equivalent with the state of the microphone being left inside. Hence, the
calibrator will switch off automatically after 3 minutes from the moment the
adapter is put inside the calibrator.
Table 2. Functional description of the calibrator’s button.
Calibrator turned OFF
Button press Function description
Short, less than 3 sec. Turn on the device
Over 10 sec. Full reset of the system
Calibrator turned ON
Button press Function description
Short, less than 3 sec. Change the range of the device
Over 10 sec. Full reset of the system
2.2.3. Range diodes
In normal mode of operation, the calibrator’s diodes act as range indicators. In this mode
diode of the chosen range is lighting with continuous light, indicating that the device is ready
for to start the calibration procedure (see Picture 4).
After the calibrator is put on the microphone, switched on or the range is changed, acoustic
pressure inside the calibrator’s chamber is adjusted to the desired level. During that process,
appropriate range diode blinks with a frequency of 2 Hz.

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Note: Calibration should not be performed until the range diode is lighting with
continuous light.
Picture 4. The top view of the SV 36 calibrator with one diode on
The diodes blinking alternately indicate the low voltage of the battery. It is recommended to
not use the SV 36 calibrator in this state as the generated level may differ from the declared
values.
Note: Replace the batteries, when diodes blink alternately.
2.3. Replacing the battery
The battery should be replaced as follows:
a) remove the rubber cover on the button and diodes’ side

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b) holding the cover unscrew four fixing screws with your
fingers
c) take off the cover and remove discharged batteries
d) put new batteries in place of the discharged ones with
polarization as indicated on the printed board and
calibrator’s case
e) put on the cover so that the diodes fit the corresponding
holes in it
f) holding the cover with one hand fasten the fixing screws

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g) put on the rubber cover