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Sound and Vibration Instrument Hire and Calibration

B&K 2250 BZ 7228 Sound Insulation Specifications


To see the specifications for the various options available, click a link

Bruel & Kjaer Sound Level Meter
 
BZ 7222 : Sound Analysis Software
BZ 7223 : Frequency Analysis Software
BZ 7224 : Logging Software
BZ 7225 : Enhanced Logging Option
BZ 7226 : Sound Recording Software
BZ 7227 : Reverberation Time Option
BZ 7228 : Sound Insulation Option
BZ 7230 : FFT Analysis Option
BZ 7231 : Tone Assessment Option
 
B&K 2250 : Home Page
B&K 2250 : Specifications
B&K 2250 : Detailed Image
 
Bruel & Kjaer 2250 + Sound Insulation Software - BZ 7228 £ 41 a day *
 

Correction Filters


For Microphone Types 4189, 4191, 4193, 4950 and 4952, BZ-7228 is able to correct the frequency response to compensate for sound field and accessories
 

Broadband Analysis


Detectors
A and C-weighted broadband detectors with F exponential time weighting
Overload Detector: Monitors the overload outputs of all the frequency weighted channels
Under Range Detector: Monitors the under range of all the frequency weighted detectors when set to High Range. Under range is set if level is below lower limit of Linear Operating Range
 

Measurements


LAF and LCF for Display as Numbers or Quasi-analogue Bars
 

Measuring Ranges


When using Microphone Type 4189:
Dynamic Range: From typical noise floor to max. level for a 1 kHz pure tone signal, A-weighted:
Single Range: 16.6 to 140 dB
High Range: 28.5 to 140 dB
Low Range: 16.6 to 110 dB
Primary Indicator Range: In accordance with IEC60651, A-weighted:
Single Range: 23.5 to 123 dB
High Range: 41.7 to 123 dB
Low Range: 23.5 to 93 dB
Linear Operating Range: In accordance with IEC61672, A-weighted: 1 kHz:
Single Range: 24.8 to 140 dB
High Range: 43.0 to 140 dB
Low Range: 24.8 to 110 dB
 

Frequency Analysis

- Centre Frequencies
1/1-octave Band Centre Frequencies: 63 Hz to 8 kHz
1/3-octave Band Centre Frequencies: 50 Hz to 10 kHz
 

Measuring Ranges


When using Microphone Type 4189:
Dynamic Range: From typical noise floor to max. level for a pure tone signal at 1 kHz 1/3-octave:
Single Range: 1.1 to 140 dB
High Range: 11.3 to 140 dB
Low Range: 1.1 to 110 dB
Linear Operating Range: In accordance with IEC 61260:
Single Range: < 20.5 to 140 dB
High Range: < 39.1 to 140 dB
Low Range: < 20.5 to 110 dB
 

Internal Generator


Built-in pseudo-random noise generator
Spectrum: Selectable Pink or White
Crest Factor:
Pink noise: 4.4 (13 dB)
White noise: 3.6 (11 dB)
Bandwidth: Follows measurement frequency range
Lower Limit: 50 Hz (1/3-oct.) or 63 Hz (oct.)
Upper Limit: 10 kHz (1/3-oct.) or 8 kHz (oct.)
Output Level: Independent of bandwidth
Max.: 1 Vrms (0 dB)
Gain Adjustment: -80 to 0 dB
When bandwidth is changed, the level for all bands is automatically adjusted to comply with the set output level
Turn-on time and Turn-off Time: Equivalent to RT = 70 ms
Repetition Period: 175 s
Output Connector: Output Socket
Control: See Measurement Control
 

External Generator


Selectable as alternative to Internal Generator
For controlling external noise generator
Levels: 0 V (Generator off), 3.3V (Generator on)
Rise-time and Fall-time: 10 µs
Control: See Measurement Control
 

Measurements


Measurements are done at a number of positions and categorised in functions (L1 for Source Room levels, L2 for Receiving Room levels, B2 for Receiving Room Background noise levels and T2 for Receiving Room Reverberation Time measurements)
 

Levels L1, L2 and B2


LZF spectrum for display only
LZeq in 1/1-octave or 1/3-octave bands
L1 and L2 simultaneously or as single channels
Averaging time: 1 s to 1 hour
Range (L1 and L2 simultaneously only): Auto-range or manually set to High Range or Low Range
Averaging: Up to 10 source positions each with up to 10
measurement positions or up to 100 measurements may be averaged
Status Indications: Overload, under range, etc.
Crosstalk:
5Hz - 10 kHz < -110dB
10 kHz - 20 kHz < -100 dB
 

Reverberation Time T2


T20 and T30 in 1/1-octave or 1/3-octave bands
Decays: LZeq spectra sampled at 5 ms intervals
Evaluation Range: -5 to -25 dB for T20 and -5 to -35 dB for T30
Measurement Time: Automatic selection of measurement time for the decays based on the actual reverberation time of the room
Maximum Measurement Time: From 2 to 20 s Averaging: T20 and T30 measurements can be averaged (arithmetic averaging or ensemble averaging)
T20 and T30 Calculation: From slope in evaluation range
Slope Estimation: Least squares approximation
Quality Indicators: Quality indicators with status information like
Overload, Curvature in %, etc.; extensive list of Status information
Quality Indicators are available on reverberation time spectra for each frequency band, and as overall quality indicators for each measurement position and for the averaged result
Reverberation Time Range: Max. 20 s, min. 0.1 - 0.7 s, depending on bandwidth and centre frequency
Manual Data Entry: A T2 value may be entered in any frequency band of a measured spectrum
 

Overview


Table of measurement positions for each function (L1, L2, B2 or T2) with readout for selectable frequency band on each position together with quality indicator.
Positions can be included/excluded from average
 

Sound Level Spectrum


LZF spectrum plus A and C broadband bars
LZeq spectrum for L1@Pos, L2@Pos, B2@Pos, L1, L2, B2, L1-L2, L2-B2
Y-axis: Range: 5, 10, 20, 40, 60, 80, 100, 120, 140 or 160 dB. Auto-zoom or auto scale available
Cursor: Readout of selected band quality indicator for each frequency band
 

Reverberation Time Spectrum


One or two spectra can be displayed
Y-axis: Range: 0.5, 1, 2, 5, 10 or 20 s. Auto zoom available
Cursor: Readout of selected band quality indicator for each frequency band
 

Spectrum Table


One or two spectra can be displayed in tabular form
 

Decay


Decay curve for a position or the room average available for each frequency band (if Ensemble Average selected)
Display of evaluation range and regression line
Readout of Curvature in %
Y-axis: Range: 5, 10, 20, 40, 60, 80, 100, 120, 140 or 160 dB. Auto zoom or auto scale available
 

Result Displays

- Overview
Table of measurement positions for all functions (L1, L2, B2 or T2) with readout of quality indicators.
Positions can be included/excluded from result
 

Calculations


Shows the sound reduction index (spectrum and weighted) according to the selected standard, along with the reference curve (if any), or deviations (from the reference curve).
 

Measurement Control


Measurement Sequence: Supports measuring:
at all microphone positions before using another source
at a microphone position for all sources before measuring at a new position
at subsequent microphone positions without source information
at manually selected source and microphone positions
Measurements are started manually and can be automatically stored on completion of measurement
Generator (L1, L2 and T2): The noise generator is turned on and off automatically
Escape Time: 0 to 60 s
Build-up Time: 1 to 10 s
The generator can be turned on and off manually for checking equipment and sound levels
 

Excitation T2:


Interrupted Noise: Measurements are started manually and can be automatically stored on completion of measurement
Number of Decays per Measurement: 1 to 100, ensemble averaged into one decay
Impulse: Manual start of first measurement. When level (say from starter pistol) exceeds the user-selected trigger level, the decay is recorded and backwards integration performed (Schroeder Method).
The trigger can then be armed automatically for measuring at the next position
Sound Recording: Recording of the Z-weighted measured signal can be done at each position
Sound Recording requires a CF or SD Card for data storage
Sound Recording requires license for Sound Recording Option BZ-7226
 

Measurement Status


On Screen: Information such as overload, awaiting trigger and running/paused are displayed on screen as icons or text
Traffic Light: Red, yellow and green LEDs show measurement status and instantaneous overload as follows:
Yellow LED flashing every 5 s = stopped, ready to measure
Green LED flashing slowly = awaiting trigger or calibration signal
Green LED on constantly = measuring
Yellow LED flashing slowly = paused, measurement not stored
Red LED flashing quickly = intermittent overload, calibration failed
 

Calibration


Initial calibration is stored for comparison with later calibrations
Acoustic: Using Sound Calibrator Type 4231 or custom calibrator.
The calibration process automatically detects the calibration level when Sound Calibrator Type 4231 is used
Electrical: Uses internally generated electrical signal combined with a typed-in value of microphone sensitivity
Calibration History: Up to 20 of the last calibrations made are listed and can be viewed on the instrument
 

Signal Monitoring


Input signal A-, C- or Z-weighted can be monitored using an earphone/headphones connected to the headphone socket
Headphone Signal: Input signal can be monitored using this socket with headphones/earphones
Gain Adjustment: -60 dB to 60 dB
 

Voice Annotations


Voice annotations can be attached to the building acoustics project and to measurements at each position
Playback: Playback of voice annotations or sound recordings can be listened to using earphone/headphones connected to the headphone socket
Gain Adjustment: -60 dB to 0dB
 

Data Management


Project Template: Defines the display and measurement setups
Project: Measurement data for all positions defined in source room (L1) and receiving room (L2, B2 and T2), stored with Project Template
Re-use of data: Data for L1, B2 or T2 in one project can be re-used in another project
Job: Projects are organised in Jobs
Explorer facilities for easy management of data (copy, cut, paste, delete, rename, view data, open project, create job, set project name)
 
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E&OE - specifications subject to change without notice.