NTi Audio NTI-XL2 Users Guide

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OPERATING MANUAL

HANDHELD AUDIO AND

XL2

ACOUSTIC ANALYZER

Contact NTi Audio at

Headquarter +423 239 6060 info@nti-audio.com Americas +1 503 684 7050 americas@nti-audio.com China +86 512 6802 0075 china@nti-audio.com Czech +420 2209 99992 czech@nti-audio.com Japan +81 3 3634 6110 japan@nti-audio.com South Korea +82 2 6404 4978 korea@nti-audio.com United Kingdom +44 1438 870632 uk@nti-audio.com

www.nti-audio.com

NTi Audio AG Im alten Riet 102, 9494 Schaan Liechtenstein, Europe is an ISO 9001:2008 certiﬁed company.

Firmware V3.10 Version 3.10.00 / January 2016

All information subject to change without notice. © All rights reserved. ® Minirator is a registered trademark of NTi Audio. ™ XL2, XL2-TA, EXEL, M2230, M2230-WP, M2211, M2215, M4260 and MA220 are trademarks of NTi Audio.

Ma d e i n

Switzerland

Table of Contents

1. Introduction .....................................................................5

2. Overview .......................................................................... 7

Operation The Screen Display

3. Getting Started

Power Supply Attaching the Hand Strap Unfolding the Stand Connecting the XL2 Switching the XL2 On and Off Select Measurement Function Calibration prior Measurement

4. Sound Level Meter ........................................................ 22

Overview Sound Level Meter - Getting Started RTA Measurement - Getting Started Reporting Logging Wav-File Recording Events (optional) Limits Correction Value KSET Locked Run Mode

....................................................................... 9

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........................................................ 63

5. Acoustic Analyzer ..........................................................64

FFT Analysis + Tolerance Reverberation Time RT60 Polarity

.........................................................................86

Delay Time 1/12 Octave + Tolerance (optional) Noise Curves (optional) Speech Intelligibility STIPA (optional)

6. Audio Analyzer ............................................................134

RMS / THD+N Oscilloscope

7. Calibration ...................................................................138

8. Proﬁles

9. Spectral Limits Option (Capture + Tolerances) .........149

10. System Settings

Settings Information Scheduler

...................................................................90

............................................................ 134

..............................................................137

......................................................................... 142

........................................................ 161

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................................................................164

................................................................... 165

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Table of Contents

11. Data Management ....................................................168

Record Voice Notes Recall Measurements Append Measurements

12. XL2 Data Explorer (optional)

13. XL2 Projector Software

14. NoiseScout

15. Remote Measurement

16. Microphones ............................................................192

17. Further Information .................................................. 196

My NTi Audio Tips and Troubleshooting Firmware Update Options and Accessories Warranty Conditions Service and Repairs Calibration Certiﬁcate Declaration of Conformity

18. Technical Data XL2 .................................................... 216

19. Technical Data Microphones ....................................224

................................................................ 190

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................................... 186

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............................................................. 196

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.......................................................199

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.................................. 215

Appendix

.........................................................................233

Appendix 1: Standard - Optional Features Appendix 2: Factory Default Proﬁles Appendix 3: Description Sound Levels Appendix 4: Common Sound Levels

.................233

.........................237

......................242

..........................247

20. Technical Data PreAmpliﬁer

......................................232

1. Introduction

Introduction

Thank you for purchasing the XL2 Audio and Acoustic Analyzer. The XL2 Analyzer forms the unique combination of a state-ofthe-art Sound Level Meter, a comprehensive Acoustic Analyzer as well as a powerful Audio Analyzer. The wide range of functionalities is tailored for:

Audio-Acoustic Installations •

Installed Sound

Life Safety Systems

AV Installations Cinemas

Noise Measurements•

Live Events

Environmental Noise

Occupational Health

Vehicle Noise

Live Sound•

Sound Level Monitoring

Front of House

PA Rental

Broadcast• Building Acoustics• Industrial Quality Control and Aerospace•

How to Read this Manual

The XL2 push buttons are displayed as icons

, , , , . A detailed description of the push buttons is

listed in the chapter Overview - Operation.

Menu items displayed on the XL2 page screens are shown in this user manual by a bold font, e.g., SLMeter, Parameter, ...

, , , ,

Introduction

Product Conﬁgurations

The following items are included with the respective model:

XL2 without Microphone:

XL2 + M2230:

XL2 Analyzer• Test Signal CD• USB cable• Li-Po battery• Hand strap• Operating manual•

XL2 Analyzer• M2230 Measurement Microphone• consisting of

MA220 Microphone PreAmpliﬁer

Microphone Capsule for M2230

50 mm Windscreen• Microphone-holder MH01 • with Adapter 5/8“ - 3/8“ Individual Frequency Response Chart• Test Signal CD• Li-Po battery• USB cable• Hand strap• Operating manual•

XL2 + M2211:

XL2 + M4260:

XL2 Analyzer• M2211 Measurement Microphone• consisting of

MA220 Microphone PreAmpliﬁer

Microphone Capsule for M2211

33 mm Windscreen• Microphone-holder • with Adapter 5/8“ - 3/8“ Test Signal CD• Li-Po battery• USB cable• Hand strap• Operating manual•

XL2 Analyzer• M4260 Measurement Microphone• 33 mm Windscreen• Microphone-holder • with Adapter 5/8“ - 3/8“ Test Signal CD• Li-Po battery• USB cable• Hand strap• Operating manual•

2. Overview

Overview

Tripod Mount

XL2 interfaces:

XLR Input

RCA Input

Voice Note Input

Speaker

Digital I/O

USB Connector

DC Power Socket

SD Card

TOSLink Output

Headphone Output

Overview

XLR Signal Input

Either a balanced audio signal, an NTi Audio measurement microphone or the microphone pre-ampliﬁer MA220 plug directly into the XLR input. The Automated Sensor Detection (ASD) technology reads the electronic data sheet of any connected NTi Audio device after the 48 V microphone phantom power is activated.

RCA Input

Unbalanced audio signal input.

Voice Note Input

Internal microphone for recording voice notes and measuring polarity and delay time. For polarity measurements, an external microphone may also be used.

DC Power Socket

Socket for mains power adapter. Further details in the chapter Power Supply in this manual.

USB Connector

Mini-B USB connection, for accessing the SD Card.

Digital I/O

Programmable digital inputs/outputs.

SD Card

For storing data, screenshots, voice notes, wav-ﬁles.

TOSLink Output

24 bit linear PCM audio signal output. For future use; not active at this time.

Headphone Output

The XLR/RCA input signals are routed to the headphone connector (3.5 mm Minijack; mono monitor wired to both channels of stereo jack). Connecting headphones mutes the internal speaker. To connect the headphone output directly to a line input, a load impedance < 8 kOhm is required for proper operation. This can be achieved by inserting a 1 kOhm resistance between tip and ground of the output jack.

Speaker

The XLR/RCA input signals are routed to the speaker. Press the speaker button

to toggle the speaker on/off. Press and hold the speaker button to access the volume control. Set the speaker level with the rotary wheel

Tripod Mount

Mechanical mount for attaching the XL2 to a tripod or microphone stand.

Overview

Operation

9 8 7

Page Control

Switches among various screens depending on the menu function selected.

Volume of Speaker and Headphone Output

Press the button• brieﬂy to enable or disable the speak- er.

 The speaker is activated and the speaker or headphone

icon shows up in the upper menu bar.

Press and hold the speaker button •

 A pop-up window for volume is displayed.

Overview

Hold the speaker button •

down and adjust the level

of the speaker and headphone outputs with the rotary wheel

. Digital gain control prevents gain increases beyond a level that will cause signal clipping. The maximum gain setting depends on the connected input signal. The headphone output provides a linear output signal • using the SLMeter function (for input levels of approx.

-30 dBu and higher, which equals at M2230: 85 dBA, M2211: 92 dBA utilizing a pink noise test signal).

Power & Backlight

The power button switches the instrument on. The XL2 is immediately ready for operation. Holding down the power button a brief press of the power button

for one second switches the XL2 off. Additionally,

toggles the backlight

during operation.

Limit

SLMeter: • The limit button lights up green, yellow or red

according to the settings in the Limit page. Press the limit button

to access the Limit page. For more details

visit the chapter Sound Level Meter: Limits. FFT + Tol: • The limit button lights up green for results within tolerance and red for out-of-tolerance results. Polarity: • The limit button lights up green at positive polar- ity and red at negative polarity.

1/12 Oct + Tol: • The limit button lights up green for results within tolerance and red for out of tolerance results.

Pause

Pauses the current measurement. Press the pause button

or the start/stop button to continue the measure-

ment. The data logging is continued in the function SLMeter/RTA during the pause period and listed in the log ﬁle.

Start/Stop

Starts and stops a measurement.

Enter

Conﬁrms a selection.

Rotary Wheel

Selects the required measurement function or the individual measurement parameter.

ESC

Terminates an entry, returns to the top menu level or closes an open window.

Overview

The Screen Display

The XL2 displays the actual sound levels also in case of no measurement has been started. Any displayed averaged level refers to the previous measurement period. The XL2 shows four lines in case of no previous measurement period is applicable.

Display Contrast Setting

Hold down escape • desired contrast is reached.

Updating of display

Numeric values• Updated every 500ms independent of the measurement function. The maximum time span between the end of the measurement period and the ﬁrst test result display is 500ms. Graphs and spectra• Updated every 50ms

and turn the rotary wheel until the

2 3 4 75 986

The display is updated continuously during measurement.

Overview

Measurement Results

Individual level measurement results.

Main Menu

SLMeter/RTA SPL & RTA Measurement

FFT + Tol FFT Analysis with optional Tolerance

Management

RT60 Reverberation Time RT60

Polarity Polarity

Delay Time Delay Time

RMS/THD+N RMS Level and Distortion

Oscilloscope Scope

1/12 Oct + Tol Spectral Analysis with Tolerance Man-

agement (optional)

Noise Curves Noise Curves

STIPA Speech Intelligibility (optional)

Cinema Meter Calibration and veriﬁcation of cinema

loudspeaker systems (optional)

Calibrate Calibration Menu for microphone

Proﬁle ... Store and load measurement proﬁles

System System Settings

Page Selector

Toggles between available measurement and result pages within the same function menu. Alternatively use the page button

Input Selector

Select XLR or RCA input connectors as the source.

Memory Menu

The memory menu is used for data storage management. One of the following symbols ﬂashes before or after starting the measurement:

9-8-7 Time

in seconds until instrument is settled and

measurement will start.

RUN Indicates the ongoing measurement.

LOG Indicates the ongoing measurement with data

logging.

AUD Indicates the ongoing measurement with data

logging and audio recording.

Evt Indicates an ongoing triggered-event recording.

Overview

After a completed measurement, the memory symbol indicates a non-saved measurement report. Your measurement needs to be stored manually. For more details visit the chapter Data Management.

Speaker/Headphone

Indication of enabled rear speaker or headphone output.

Phantom Power Supply

48V T

he XL2 provides 48 V phantom power supply

to the connection microphone or sensor.

ASD An NTi Audio measurement microphone with

automated sensor detection ASD is connected. The XL2 reads the electronic data sheet of the microphone and switches the 48V phantom power automatically on

48V Phantom power is switched off.

Real-Time Clock

The real-time clock is set in the System menu.

Battery Symbol

The battery symbol indicates the battery status as follows:

Using rechargeable Li-Po battery:

Level indication 100% (U > 4.0 Volt).

Level indication: 75%: U = 3.9 - 4.0 Volt 50%: U = 3.8 - 3.9 Volt 25%: U = 3.7 - 3.8 Volt

Level indication 0% (U < 3.7 Volt). The battery is almost empty and must be recharged.

The battery is being recharged by the mains power adapter or the USB connection to PC.

Using standard AA batteries:

No level indication as long as U > 4.5 Volt.

Level indication 0% (U < 4.5 Volt). The batteries are almost empty and should be replaced.

Using mains or supply:

No indication of battery status.

Getting Started

3. Getting Started

Power Supply

The XL2 offers ﬂexible power management options and can be operated either by

Replaceable, rechargeable lithium-polymer (Li-Po) battery • (included with the XL2 Analyzer) 4x AA-batteries• Mains Power Adapter•

The new battery is charged to approximately 50% and should be fully charged before use with:

Battery Charger (optional)

Mains Power Adapter (optional)

USB Power from PC

Charging Time: approx. 3 hours NTi Audio #: 600 000 332

Charging Time: approx. 6 hours Leave the battery inside and switch off the XL2 NTi Audio #: 600 000 333

Charging Time: approx. 6 hours Switch off the XL2 ing.

for charging.

for faster charg-

Operation using Mains Power Supply

You can also operate the XL2 with the optional NTi Audio Mains Power Adapter. During such operation it is recommended to leave the batteries inside the instrument.

Mains Power Adapter

Electrically-isolated, linear DC power supply• A decreased THD+N performance will oc-• cur with unbalanced input signals when using switching-type power supplies (approx. 3 dB). Non-NTi Audio power supplies may have fur-• ther negative effects on measurements. Damage caused by using an inappropriate ex-• ternal DC supply is not covered by warranty.

DC Power supply speciﬁcations

Voltage: 7.5 - 20.0 Volt• Power: minimum 6 Watt• Connector type: 2.1 x 5.5 x 9.5 mm• Polarity: •

Getting Started

Rechargeable Li-Po Battery

Open the battery cover at the rear of the instrument.• Insert the rechargeable Li-Po battery with the contacts edge • ﬁrst. Close the battery cover.•

Switch off the XL2 for faster recharging by mains power adapter or USB connection.

Caution

Switch the XL2 off prior opening the battery • cover in order to prevent any electronic discharges. Avoid short-circuits.• Operate and charge the battery between 0°C • and 45°C (32°F - 113°F). Do not heat the battery above 60°C.• Do not place the battery in or near ﬁre.• Do not solder directly on to the battery.• Do not disassemble the battery.• Do not insert the battery in reverse polarity.•

Getting Started

AA-Batteries

Alternatively, the XL2 can be powered by AA type batteries

Open the battery cover.• Insert 4 fully-charged AA batteries, observing correct polarity • of the +/- indications in the battery compartment.

 The polarity alternates with successive batteries.

Close the battery cover.•

Switch the XL2 off prior opening the battery • cover in order to prevent any electronic discharges. Use only similar batteries from the same • manufacturer. Replace discharged batteries with new ones.• Do not mix used and new batteries.• During operation, the battery temperature • may increase noticeably. This is not a defect. Remove all batteries if the XL2 is not to be • used over a long period of time.

Getting Started

Attaching the Hand Strap

To avoid accidentally dropping the XL2, a hand strap is supplied with the instrument.

Pull the loop of the hand strap through the opening.• Pull the other end of the hand strap through the loop.• Pull the hand strap tight.•

2.1. 3.

Getting Started

Unfolding the Stand

A convenient table stand is attached to the rear of the instrument.

Unfold the stand and rest the XL2 on a ﬂat surface.•

Connecting the XL2

Acoustic Measurements

Connect an NTi Audio measurement microphone to the XLR input connector of the XL2.

Getting Started

Audio Measurements: XLR Connection

Connect the source to the XL2 with an XLR cable.• Select the XLR input in the menu.•

Audio Measurements: RCA Connection

Connect the source to the XL2 with an RCA (cinch) cable.• Select the RCA input in the menu.•

Getting Started

Switching the XL2 On and Off

Switching On the XL2

Press power

 There is a brief sound of relays and the display illuminates.

Switching Off the XL2

Press power the XL2.

to switch on the XL2.

and hold it down for one second to switch off

Select Measurement Function

Navigate with the rotary wheel • to the main menu bar. Conﬁrm with enter •

 The main menu window opens

Scroll up/down with the rotary wheel • to select the re- quired function and conﬁrm with enter

to select the measurement function.

Main menu with enabled options

The measurement function is selected.

Getting Started

Setting the Parameters with the Rotary Wheel

Turn the rotary wheel • screen.

to navigate within the display

The selected parameter is highlighted with a black back-

ground.

Conﬁrm with enter • .

 The parameter display ﬂashes and/or available parameters

or settings are shown.

Turn the rotary wheel • enter Conﬁrm with enter • .

through the settings.

to set the parameter or toggle with

Now the parameter is set.

Calibration prior Measurement

We recommend the daily calibration of the XL2 Analyzer with the precision calibrator. This ensures accurate measurement results.

For more details see chapter Calibration.

Sound Level Meter

4. Sound Level Meter

The XL2 provides, together with the measurement microphone, a precise sound level meter for monitoring live sound events and/or environmental noise.

The Type Approval Option upgrades the instrument to the XL2-TA, the sound level meter dedicated to certiﬁed measurements. The XL2 with the M2230 microphone forms a type approved sound level meter offering class 1 performance according IEC61672 (see chapter Options and Accessories)

For example, Actual, Lmin, Lmax, Leq with frequency weighting A, C and Z and time weighting F and S can be measured at the same time. All measurement results are simultaneously available. You may log all acquired level information, including real-time information, onto the removable SD Card. To complete the documentation of the measured sound pressure levels, the XL2 offers wav-ﬁle recording, as well as the facility to add voice notes for each measurement. The XL2 measures correction values between the loudest point of the live event and the actual measurement positions in accordance with DIN 15905-5 and SLV. In parallel with the wide band parameters, the XL2 measures the real-time spectrum either in 1/1 or 1/3 octave-band resolution. The RTA perfectly suits tasks such as optimization of sound systems

Extended Acoustic Pack (optional)

The Extended Acoustic Pack offers the following additional features for sound-level and acoustic measurements:

SLMeter/RTA function•

Recording of linear wav-ﬁles (24 bit, 48 kHz)

Percentiles for wide band and spectrum with ﬂexible set-

ting from 0.1% to 99.9% Sound Exposure Level L

100ms logging

Event-triggered audio and data recording

Time weighting: Impulse (LxI, LxIeq with x= A, C, Z)

True peak level in 1/1 and 1/3 octave resolution

Clock-Impulse Maximum Level (TaktMax) and values as

speciﬁed in DIN 45645-1

FFT function•

High-resolution Zoom-FFT with selectable frequency

ranges and resolution up to 0.4 Hz in the range of 5 Hz to 20 kHz

RT60 function•

Reverberation time RT60 in 1/3 octave resolution

Sound Level Meter

The sound level meter offers different pages:

Page Selection using the Page Button

Press page • to toggle between the 123 SLMeter page and the RTA page.

Page Selection using the Rotary Wheel

Select the page • 123 SLMeter with the rotary wheel . Conﬁrm with enter •

Menu with enabled options

You have selected the individual sound level meter page.

123 SLMeter: Sound Level Meter

Displays the selected broadband sound level results. You can change the font size of the result. Depending on the font size chosen, the XL2 shows 3 or 5 results simultaneously. Individual frequency weighting, time weighting, actual, minimum, maximum and correction values can be chosen for each displayed result.

RTA: Real-Time Spectrum

Displays the 1/3 or 1/1 octave spectrum of the selected sound level within the audio band. Additionally the wide band result is shown graphically by a bar.

Reporting: Report Setting

Here you set which sound pressure levels shall be stored in a .txt ﬁle after the completed measurement. Choose between:

ALL Stores all sound pressure levels.

Selected Stores up to 10 different individually-deﬁned

sound pressure levels.

For details refer to the chapter Reporting.

Sound Level Meter

Logging: Setup of Data Logging

The XL2 features a powerful sound level meter data logger, which allows you to record all required sound level values during the measurement. In the logging page you set which sound pressure levels shall be logged over time. For details refer to the chapter Logging. Choose between:

ALL Logs all sound pressure levels.

Selected Logs up to 10 different individually-deﬁned sound

pressure levels.

Event Trigger: Event Setting (optional)

The event function is available with the optional Extended Acoustic Pack. The XL2 event feature offers the following functionalities:

Automated event triggered at noise levels above/below a • preset value including setting markers for speciﬁc noise categories. Application example: Recording the noise level for LAF > 80 dB. Event triggered by external key press of the XL2 Input Key-• pad. You can utilize four keys (1-4) to categorize any noise of interest or noise to be later excluded in the post-processing. A typical application is categorizing any annoying industrial noise by persons living in the neighborhood.

Limit LED: Limit Setting

ere you set the function

of the limit LED , thereby highlighting any sound level that exceeds the pre-set limits in orange or red color. Further, external peripherals are controlled by the optional Serial I/O Interface based on the sound level, such as displaying sound levels on a large external red-orange-green lamp. For details refer to the chapter Limits.

SET Correction: Setup of Correction Values

This page provides a wizard to measure correction values, which could be helpful for compliant sound level monitoring of live events. It measures the correction values between the actual measurement position and the loudest position accessible by the audience. The XL2 displays and logs the selected sound pressure levels including the correction values, allowing the sound engineer to monitor the sound level at the loudest position in the audience. The measurement meets the requirements of the standards DIN15905-5 and SLV. For details refer to chapter Correction Value K

SET.

Sound Level Meter

Set EQt, L%: Selection of measured levels

This page allows setting the following levels:

Moving Time-average Sound Level• Gliding Leq with selectable time window from ﬁve seconds to one hour. Four individual levels can be conﬁgured. Percentile Sound Level•

Allows the individual conﬁguration of seven statistic lev-

els from 0.1% to 99.9% (optional with Extended Acoustic Pack). The

- Broadband Source for the calculation of the level sta- tistics can be chosen from a set of different levels with either a frequency weighting A, C or Z. The time weightings F, S and the moving time-averaged sound level for one second are supported.

Sound Level Meter

Overview

Numeric Result Page

The numeric result page 123 SLMeter displays the selected broadband sound level results. You can change the font size of the result. Depending on the font size chosen, the XL2 shows three or ﬁve results simultaneously. Individual frequency weighting, time weighting, actual, minimum, maximum and correction values can be chosen for each displayed result.

4 5

Real-Time Analyzer Page

The real-time analyzer page RTA measures and displays the 1/3 or 1/1 octave spectrum from 6.3 Hz to 20 kHz including wideband results. The real-time spectrum RTA is measured in parallel with the A and Z-weighted wideband levels.

Sound Level Meter

Sound Level Result 1

All sound levels are measured and logged simultaneously. You select which sound levels should be displayed.

Change Parameter

Turn the rotary wheel • Press enter •

to open the selection menu and choose

to select the parameter Lxx.

the wideband sound pressure level to be displayed. Turn the rotary wheel • parameters and conﬁrm with enter

to select the required test result

Change Font Size

Turn the rotary wheel • Press enter •

1x, 2x or 3x to set the font size to small,

to select the actual test result.

medium or large.

The XL2 shows 3 sound levels on the display if a large font is chosen, otherwise it shows 5 sound levels.

Sound Level Result 2 & 3

Follow the setting instructions for sound level result 1.

Sound Level Result 4 & 5

To display sound level results 4 & 5, choose a smaller font for all results. Follow the setting instructions for sound level result 1.

Input Range

The XL2 Analyzer provides three input ranges to accommodate the wide range of input signals. The individual ranges are based on the microphone sensitivity setting in the calibration menu of the XL2. For example at a sensitivity S=20mV/Pa the input ranges are

Low: 10 - 110 dBSPL• Mid: 30 - 130 dBSPL• High: 50 - 150 dBSPL•

Select the lowest possible input range according to the maximum level expected during the measurement; e.g., if the sound pressure will always be below 110 dBSPL, then select the lowest input range 10 - 110 dBSPL.

Run Indication

Sound Level Meter

Actual Measurement Time

Counts actual measurement time in hrs:min:sec. Supports time modes: continuous, single and (synchronized) repeat.

Timer Mode Continuous

(applicable for standard measurements) All values are recorded and monitored continuously after starting a measurement with start The actual measurement time is shown.

Timer Mode Single

Automatically stops the measurement after the pre-set measurement time.

Set the required measurement time.• Start the measurement •

 The actual measurement time counts back to zero and

the measurement ends.

All measurement results may be recalled.•

Timer Mode Repeat

Provides automated repeated measurements with user-deﬁned, preset measurement time cycles.

Set the required measurement time.• Press start •

 The actual measurement time counts back to

zero. When the preset measurement time has elapsed, the measurement time and the measurement results are reset and a new measurement is started. All measurement results of the previous cycle are reset.

For consecutive storage of all measurement cycles, select the parameter Naming+Saving: auto in the memory menu. Each individual cycle result is then automatically stored to the SD Card.

Sound Level Meter

Timer Mode Repeat Synchronized

Provides automated repeated measurements synchronized to the XL2 real-time clock. Press start

to begin the measurement. In order to align the selected preset measurement time with the real-time clock, the XL2 shortens the ﬁrst cycle to match the real-time clock synchronization. All following measurement cycles are synchronized to the real-time clock.

Phantom Power Supply

48V T

ASD An NTi Audio measurement microphone with

he XL2 provides 48 V phantom power supply

to the connection microphone or sensor.

automated sensor detection ASD is connected. The XL2 reads the electronic data sheet of the microphone and switches the 48V phantom power automatically on

For example, the cycle time setting is 30 minutes and the measurement starts at 7.50 a.m. -> the ﬁrst test cycle measures from 7.50 - 8.00 a.m. Thereafter a new test cycle starts automatically for 30 minutes. The 30-minute cycles repeat until the measurement is stopped.

The measurements in the synchronized repeat timer mode start exactly on the half or full hour in accordance with DIN 15905.

Preset Measurement Time

Adjustment of preset measurement time for single and repeat timer setting.

48V Phantom power is switched off.

Result Symbols / Capture

This ﬁeld offers two functions:

Symbols for measurement results •

Upper RTA parameter displayed as line.

Lower RTA parameter displayed as bargraph.

Sound Level Meter

Capture• One of the displayed RTA readings may be captured. Any measurement data can then be compared with this captured reference live on the XL2 Analyzer. For example, compare the RTA spectrum of the left and right speakers.

Select the parameter to be captured• . Conﬁrm with enter • Select the upper RTA parameter • Capt. Conﬁrm with enter •

 The lower RTA reading can be compared with the previ-

ously-captured reference data.

Measurement Result

Actual level result of the indicated frequency band. The cursor readout displays the center frequency and the level of the band pointed to by the arrow.

, to capture the reading.

and choose

Y-Scale setting

Select the Y-Axis with the rotary wheel • with enter

and conﬁrm

Select the zoom factor between • 20, 10, 5, 2.5 dB/div and conﬁrm with enter

. Scroll up and down with the rotary wheel • to select the Y-axis range. Conﬁrm with enter •

RTA Measurement Result

Real-time analyzer results in 1/1 octave or 1/3 octave band resolution. Adjust the resolution at

X-Scale setting

Toggles X-scale range between

20 Hz - 20 kHz RTA levels including wide band results

6.3 Hz - 8 kHz RTA levels including wide band results

Upper parameter displayed as line.

Lower parameter displayed as bargraph.

6.3 Hz - 20 kHz RTA levels

Select the X-Axis with the rotary wheel • and conﬁrm with enter

. Toggle with the rotary wheel • between the ranges. Conﬁrm with enter •

Sound Level Meter

Broadband Results

Actual sound level. The broadband sound pressure level Leq, Lmin, Lmax and Live are displayed here. The Live level is displayed with time weighting Fast.

A A-w

Z Broadband sound pressure level without any fre-

Readout Frequency

You may select any frequency to read out individual levels. The selected frequency is indicated by the cursor arrow.

Choose between the following settings:

eighted broadband sound pressure level

quency weighting

The cursor follows automatically the highest level, e.g. tracing feedback frequencies at live sound.

Select the frequency with the rotary wheel • Press enter • You may readout any individual frequency.• Return to auto frequency with enter •

 The cursor returns to the frequency with high-

est level bar.

The cursor read out may be set manually to any frequency band or wide band level. The read out remains at the selected frequency.

Select the frequency with the rotary wheel • Press enter • Select the frequency of interest.• Conﬁrm with enter •

 The cursor readout

ment results of the selected frequency band.

Setting of Test Result Resolution

Set the RTA result display to 1/1 octave or 1/3 octave band resolution as follows:

Turn the rotary wheel • Press enter • to set this parameter.

displays the measure-

to select the parameter 17.

to toggle between 1/1 OCT and 1/3 OCT.

Sound Level Meter

Measurement Unit

Select the measurement unit as follows:

dB Sound level in dBSPL

This measurement unit is permanently selected upon connecting a NTi Audio measurement microphone with electronic data sheet.

dBu Input level in dBu

dBV Input level in dBV

V Input level in Volt

LOW - Indication

The low indicator for an individual level < is displayed when:

The measured sound pressure level is below the selected • linear measurement range. In this case the results shown are most likely higher than the actual sound pressure level -> choose the next lower measurement range.

The measured sound pressure level is just above the resid-• ual noise of the connected NTi Audio measurement microphone, which reduces the measurement accuracy -> choose another microphone dedicated for low level measurements.

The low condition is registered in the log and report ﬁle in the column “Low(eq/peak)“ individually for all frequency weightings, the RMS and the peak levels.

Sound Level Meter

Overload Indication

In case the measurement result exceeds the preset measurement range, then limit arrows tion. The arrows as long as the overload exists. Furthermore the once exceeded measurement range triggers the OVR indication in the bottom line, which remains displayed for the complete measurement period. These exceeded range indications are reset at starting a new measurement. Any overload condition is registered in the log and report ﬁle.

Possible causes for exceeding measurement ranges are

The measured sound pressure level exceeds the pre-set • measurement range during the measurement period. Once this happens, the OVR indication remains displayed for the complete measurement period -> select the next higher measurement range or reduce the input signal level as applicable. The input level is near the maximum level of the connected • NTi Audio measurement microphone.

are displayed for minimum 1 seconds and

indicate this overload condi-

Sound Level Meter

Sound Level Meter - Getting Started

Test Preparations

The XL2 reads the electronic data sheet of any connected ASD microphones provided by NTi Audio and switches the 48V phantom power automatically on as follows:

Connect the measurement microphone to the XL2.• Switch on the XL2 •

Position the XL2 at the measurement location using a micro-• phone stand or a tripod. Select the • SLMeter function in the measurement menu and toggle with page

All wideband and RTA levels are measured and logged simultaneously. You select which sound levels should be displayed.

to the numeric result page .

 The 48V phantom power indication in the upper menu bar

changes to ASD. The XL2 is ready for acoustic measurements.

Sound Level Meter

Select Displayed Test Result

This example describes the setting of the commonly-used actual sound pressure level L weighting F).

Select the ﬁrst parameter setting with the rotary wheel • Conﬁrm with enter •

Press start to measure and display the sound levels results indicated with ----.

(frequency weighting A, time

Select Frequency Weighting

The pop-up window FREQ WEIGHTING shows up.

Select the frequency weighting • A.

Pop-up windows shown at installed

Extended Acoustic Option

Conﬁrm with enter • .

Sound Level Meter

Select Time Weighting

The pop-up window extends with TIME WEIGHTING.

Select the required time weighting; e.g. •

Conﬁrm with enter • .

(=Fast).

Select Parameter

The pop-up window extends with PARAMETER settings.

Select the parameter • live.

Conﬁrm with enter • .

Sound Level Meter

Select Correction Value

The pop-up window extends with CORRECTION settings.

Select the parameter • off.

Conﬁrm with enter • .

The pop-up window closes and the measured sound pres-

sure level LAF is displayed.

Select further Sound Levels

Select further sound pressure levels as described above; • e.g., L

Aeq

and L

AFmax

Sound Level Meter

Select Input Range

Select the lowest possible input range according to the maxi-• mum level expected during the measurement. Wrong input ranges are indicated by a < in front of the measurement value or a ﬂashing OVR message in the lower menu bar. Select the input range • RNGE and press enter Turn the rotary wheel • to set the applicable input range and conﬁrm with enter

The numeric result page and the real-time analyzer page use the same input range.

Start Measurement

The XL2 is ready to measure the sound levels L• L

AFmax

Press start •

, L

Aeq

and

The run indication switches to running . The integrated

sound pressure level over time L el in the measurement period L parameter RUN, LOG (logging is enabled) or AUD (audio

recording is conﬁgured) ﬂashes in the memory menu.

and the maximum lev-

Aeq

are displayed. The

AFmax

Sound Level Meter

Stop Measurement and Data Saving

Press stop • .

The XL2 stores the broadband sound pressure levels and

the real-time analyzer results simultaneously.

Press enter • to conﬁrm. The measurement data are stored on the SD Card in ASCII format.

Data Post-Processing

The XL2 stores all data and audio onto the SD card for direct transfer to the computer. Audio data is stored as .wav ﬁles. Data reports and log ﬁles are stored in plain text format, which can be opened with any text editor (Notepad, Wordpad, etc.). The data is tab-delimited, so dropping the .txt ﬁle into a spreadsheet application will conveniently show the results in columns.

Furthermore a series of free MS Excel application templates provide a convenient way to view the measurement results of speciﬁc tasks and create simple reports. They are available as free download for all registered XL2 customers on the support website at http://my.nti-audio.com. (Enable all macros when opening the document.)

For the most comprehensive analysis of logged noise monitoring data, use the XL2 Data Explorer software. The data import into the software is enabled by the Data Explorer Option, which needs to be installed in the XL2 Sound Level Meter. More details in chapter XL2 Data Explorer.

 The sound pressure level measurement is completed.

Sound Level Meter

RTA Measurement - Getting Started

Test Preparations

The XL2 reads the electronic data sheet of any connected ASD microphones provided by NTi Audio and switches the 48V phantom power automatically on as follows:

Connect the measurement microphone to the XL2.• Switch on the XL2 •

 The 48V phantom power indication in the upper menu bar

changes to ASD. The XL2 is ready for acoustic measurements.

Position the XL2 at the measurement location using a micro-• phone stand or tripod. Select the • SLMeter function in the measurement menu and toggle with page

All wideband and RTA levels are measured and logged simultaneously. You select the sound levels to be displayed.

to the real-time analyzer (RTA) page

RTA Conﬁguration

The XL2 displays two different sound pressure levels at the same time. You conﬁgure which test results to display; e.g., L

and L

ZFmax

Ensure no other measurement is going on. The run indication • should display the stop symbol

Select the • LZF value with the rotary wheel .

live

Conﬁrm with enter • .

Sound Level Meter

Select RTA Frequency Weighting

The pop-up window FREQ WEIGHTING shows up.

Select the frequency weighting • Z.

Conﬁrm with enter • .

Press start to measure and display the sound levels results indicated with ----.

Select RTA Time Weighting

The pop-up window extends with TIME WEIGHTING.

Select the required time weighting; e.g., •

Conﬁrm with enter • .

(=Fast).

Sound Level Meter

Select Upper/Lower RTA Parameter

Select the parameter shown to the right of the upper • LZF value with the rotary wheel Press enter •

; e.g. max.

The pop-up window PARAMETER shows up.

Select the parameter • max.

Conﬁrm with enter • . Follow the same instruction and select the lower RTA pa-• rameter live.

Select Input Range

The numeric result page and the real-time analyzer page use the same input range.

Sound Level Meter

Start RTA Measurement

The XL2 is ready to display the measured sound pressure • levels L Press start •

ZFmax

and L

live

The run indication switches to running . The actual sound

level L The parameter RUN , LOG (logging is enabled) or AUD (au- dio recording is conﬁgured) ﬂashes in the memory menu.

and the maximum level L

ZFlive

AFmax

are displayed.

Stop the Measurement and Data Saving

Press stop • .

The XL2 stores the broadband sound pressure levels and

the real-time analyzer results simultaneously.

Press enter • to conﬁrm. The measurement data are stored on the SD Card in ASCII format.

 The RTA measurement is completed.

Sound Level Meter

Reporting

A report saves the conducted measurements onto the installed SD Card. The XL2 Supports setting the individual levels to be stored in the report after the measurement is completed.

Add Spectra

No No R

Leq The RTA Leq level is stored in the report.

TA measurement reporting.

Leq, Lmax, Lmin

he RTA Leq, Lmin, Lmax levels are stored

in the report.

All All RTA levels are stored in the report.

Report Values

Choose between the following result reporting:

ALL Records all available sound pressure levels

without correction values.

Selected Records a subset of up to 10 different levels,

including correction values if you require.

Select • Report Values with the rotary wheel . Press enter •

Selected Report Values

By setting • Selected at

to toggle between All or Selected.

up to 10 individual report val-

ues can be chosen. Select the ﬁrst value Lxx with the rotary wheel

and press enter .

The pop-up window for level selection shows up.

Select the reporting level with the rotary wheel • conﬁrm with enter

and

Sound Level Meter

Logging

The XL2 features a powerful sound level meter data logger, which allows you to record all required sound level values during the selected period of time. All results are logged onto the SD Card. The measurement results can be loaded to a PC for documentation and visualization. The LOG menu offers the detailed setup of the log report.

Logging

Select Logging with the rotary wheel

and press enter

to enable the automated logging of test results.

On The XL2 logs measurement data every

interval dt

Off No Logging

Interval Dt

Adjust the logging interval. The optional Extended Acoustic Pack offers the additional 100 ms logging.

Add Spectra

Select Ye s to log additionally the RTA spectrum at each logging interval.

Sound Level Meter

Log Audio

The XL2 logs audio data as a wav-ﬁle. Choose among the following settings:

Off A

udio logging is off

On Audio logging is activate from mea-

surement start to stop.

Events Only Audio logging of triggered events

only.

For more details read the chapters Wav-File Recording and Events.

Format

Choose among the following audio recording settings:

Compressed Compressed audio logging

Compressed+AGC Compressed audio logging with

automated gain control

24Bit_48kHz Linear audio logging in 24 bit,

48 kHz resolution (optional with Extended Acoustic Pack)

Log Value Setting

Choose between the following settings:

ALL Logs all available sound pressure levels with-

out correction values.

Selected Logs a subset of up to 10 different sound

pressure levels, including correction values if you require.

Select • Log Values with the rotary wheel Press enter •

Selected Log Values

By setting Selected at

to toggle between All and Selected.

up to 10 individual log values can

be chosen.

Select the ﬁrst value • Lxx with the rotary wheel press enter

The pop-up window for level selection shows up.

Select the logging level with the rotary wheel • ﬁrm with enter

At 100ms Logging is the log value selection limited to ﬁve different parameters.

and con-

and

Sound Level Meter

Wav-File Recording

The XL2 records a wav-ﬁle of the measured input signal and stores it on the SD Card. The available formats are:

Compressed• (default, using ADPCM compression). A new wav-ﬁle is started automatically after 12 hours of recording (typical maximum wav-ﬁle size = 512 MByte) Compressed+AGC• , compressed with automated gain con- trol. The gain control increases the level of low-level signals, so that the wav-ﬁle is well-leveled during playback on the PC. 24Bit_48kHz• , linear wav-ﬁle logging in 24 bit, 48kHz resolu- tion with the optional Extended Acoustic Pack. A new wavﬁle is started automatically after 1 hour of recording (typical maximum wav-ﬁle size = 512 MByte)

Broadcast Wave Format BWF

The XL2 stores date and time of the recording within the wav-ﬁle (according to EBU TECH

3285). This information is available through professional audio/video tools typically used in broadcast.

Sample name of wav-ﬁle:

MyTest_SLM_000_Audio_FS133.0dB(PK)_00.wav

MyTest

2 3 4

File name deﬁned by user.

SLM

Measurement function.

000

Automatically incrementing ﬁle number.

Audio_FS133.0dB(PK)

Audio ﬁle with full scale peak level. In case of a Compressed + AGC recording, the ﬁle name reads “AGC”; this

ﬁle contains corrected level information only.

For wav-ﬁle recording over longer periods, the XL2 splits the audio data into individual wav-ﬁles with about 500 MB (compressed audio: 12 hours; linear: 1 hour), keeping the ﬁle size small for easier handling on the PC. The number increments for each successive wav-ﬁle.

Sound Level Meter

The advantage of wav-ﬁle recordings is to identify and document sound sources after the measurement. For example, at a live event an excessive peak level may have been measured and logged. Actually, this peak level was caused by people shouting nearby the measurement microphone, and not by the audio system being monitored. The recorded wav-ﬁle assists in verifying this and the test results can then be post-processed.

Pausing Measurement

If any ongoing measurement is paused , the XL2 continues the recording of wav-ﬁles during the paused period. The logged data and audio data can be synchronized using the stored realtime information.

Events

The wav-ﬁles are stored in a folder, named, for example, 2011-11-30_SLM_000_AudioEvent_0001-0200. The actual wav-ﬁles are named for example, as xxxx_FS133.0dB(PK).wav (xxxx = incrementing number)

Another example is environmental noise monitoring: Listening to the recorded wav-ﬁle after the measurement may help to determine the predominant sound source. The XL2 Analyzer preserves the original absolute test signal level in the recorded wav-ﬁle. The XL2 Analyzer provides three input ranges to accommodate the wide range of input signals. The dynamic range of the recorded wav-ﬁle is set according to the selected input range. For example, at a microphone sensitivity of S= 20 mV/Pa, the full scale peak level is:

Range Name Range Level Full scale peak level

Low 10 - 110 dBSPL 117.8 dBSPL

Mid 30 - 130 dBSPL 135.9 dBSPL

High 50 - 150 dBSPL 159.9 dBSPL

Select the lowest possible input range according to the maximum level expected during the measurement; e.g., If the sound pressure will always be below 110 dBSPL, select the lowest input range 10 - 110 dBSPL.

Sound Level Meter

Events (optional)

The event function is available with the XL2 Extended Acoustic Pack Option. The XL2 Analyzer may be conﬁgured to record wav-ﬁles and additional noise levels only when triggered, instead of the complete measurement duration.

Advantages

Reduces the data volume acquired, thereby

Simplifying data post-processing of the complete measure-• ment period Saving data memory for long-term measurement applica-• tions.

Events

Events are triggered either automatically by sound levels above/ below a preset value or manually by external key press using the XL2 Input Keypad.

Event Functions

The XL2 event feature offers the following functionalities:

Automated event triggered at noise levels above/below a • preset value including setting markers for speciﬁc noise categories. Application example: Recording the noise level for LAF > 80 dB.

Event triggered by external key press of the XL2 Input Key-• pad. You can utilize four keys (1-4) to categorize any noise of interest or noise to be later excluded in the post-processing. A typical application is categorizing any annoying industrial noise by persons living in the neighborhood.

Data Logging

The XL2 Analyzer logs the data speciﬁed in the LOG setting for the complete measurement duration into a log ﬁle. The markers and triggered events results are added to the same log ﬁle.

The XL2 Input Keypad is available as an accessory. Please see chapter Options and Accessories for details.

Sound Level Meter

Trigger Events: on level above/below

100

Level [dB]

13 12

Event Duration

Time [seconds]

Features:

The levels L•

Aeq

, L

Zeq

and L

are recorded for the event

CPeak

duration. Audio data are recorded for the triggered event duration only, • thus simplifying data post-processing and saving memory space for long-term measurements. Setting markers by external key press of the XL2 Input Key-• pad.

Sound Level Meter

Trigger Events

Choose from the following settings:

Off No event triggering

on level above

on level below

on ext.

Events are triggered at noise levels above the preset value

for the start duration 13.

Events are triggered at noise levels below the preset value

for the start duration 13.

Events are triggered by external key press.

key press

Start [dB]

Set the level at which the triggered event is started.

Start Duration

The event start is triggered when the noise level is higher (or lower ) than the preset value and continues for the preset duration.

Stop [dB]

Set the level at which the triggered event is stopped.

on level

Stop level = Start level

- Hysteresis

above

on level

Stop level = Start level

+ Hysteresis

below

Stop Duration

The event stop is triggered when the noise level is lower (or higher) than the preset value and continues for the preset duration.

Hysteresis

Set the hysteresis to an appropriate value to prevent rapid switching on and off as the level drifts around the Start level.

Level Selection

Deﬁne the level type to be monitored.

Sound Level Meter

Log Audio

The XL2 logs audio data as a wav-ﬁle. Choose from the following settings:

Off A

udio logging is off

On Audio logging is activated from

measurement start to stop.

Events Only Audio logging of triggered events

only.

For more details read the chapter Wav-File Recording.

Format

Choose from the following audio recording formats:

Compressed Compressed audio logging

Compressed+AGC Compressed audio logging with

Automated Gain Control (AGC)

24Bit_48kHz Linear audio logging in 24 bit,

48 kHz resolution. (Required for post-processing on the PC with Extended Acoustic Pack)

Audio Logging Period

If Log Audio

is set to Events Only, then the duration

for the audio recording may be further speciﬁed:

Recording whole ev

ent

Stop recording after

Records a wav-ﬁle for the whole triggered event duration.

Records a wav-ﬁle for the speciﬁed period after the event start is triggered.

Status Information

Displays current trigger status:

Waiting for trigger• Armed • (during start duration

)

Audio + data recording• Completing log cycle•

Actual Level

Measurement result of the deﬁned level

Event Counter

Counts the number of triggered events that have occurred during the ongoing measurement.

Sound Level Meter

Trigger and Marker Monitor

Answers the question: What caused the triggered event?

Lvl Event automatically triggered by level.

1 Event triggered or marker added by pressing key 1

of the XL2 Input Keypad.

Trigger Events: on external key press

Event recording by pressing a button at the external input keypad with automated or manual stop of the event.

100

Event Duration

Level [dB]

Event Duration

2 Event triggered or marker added by pressing key 2

of the XL2 Input Keypad.

3 Event triggered or marker added by pressing key 3

of the XL2 Input Keypad.

4 Event triggered or marker added by pressing key 4

of the XL2 Input Keypad.

Stop Duration

See

Start Duration

See

Hysteresis

See

Features:

The levels L• duration. Audio data may be recorded for the user-deﬁned event dura-•

tion Retrigger with every repeated key press within the event • duration.

key press

Time [seconds]

, L

and L

Zeq

Aeq

after the key press.

key press

are recorded for the event

CPeak

Sound Level Meter

Event Stop Mode and Event Duration

on key release T

he event is recorded as long as the button of the input keypad is kept pressed; minimum the preset duration at Min. Event Duration.

on ext. keypress

The event is stoped by pressing a button on the external input keypad; latest after the preset duration at Max. Event Duration.

Button Functionality of Input Keypad

treat each key

ately

separ

All four buttons operate individually. For example pressing the button 2 will be recorded as button 2 in the measurement report. This allows characterizing different acoustic noise sources.

treat all keys as Key 1

All four buttons operate parallel and will be recorded as button 1 in the measurement report.

Sound Level Meter

How to Setup the XL2 for Triggered Event Measurements

Select the logging page, set• Logging On, Interval dt: 00:00:01 and choose the required log values.

Setup the event page. For example, the screenshot below • starts the event recording after LAF exceeds 80 dB for 2 seconds and stops after LAF is lower than 70 dB for 3 seconds.

Select the memory menu and create a new folder. This folder • will then be displayed in the memory menu. All log data and event wav-ﬁles are stored in this folder.

Logging Enabled

Triggered-event recording requires the activation of sound level logging. Using the default

Interval dt: 1 second is recommended.

Auto Save

If Log Audio the XL2 sets per default Naming+Saving: auto in the memory menu. This ensures that the recorded triggered event data is stored on the SD Card. For convenience, in case more than 20 triggered events have been recorded, the Au- tosave -> Delete function is disabled, as deleting such multiple wav-ﬁles on the XL2 takes a long time.

Wav-ﬁles

All triggered-event wav-ﬁles are stored in an individual folder. For details see chapter Logging.

is set to Events Only, then

 The XL2 is ready for the triggered event measurement.

Sound Level Meter

Limits

The limit page offers two functions:

Setup of limit LED • any sound levels that exceed the pre-set limit in orange or red color. The default color is green. Limit parameter setup for the external Digital I/O Adapter • which connects to the digital I/O interface of the XL2. Both, the Digital I/O Adapter PCB and Box are optional accessories for the XL2 Analyzer. They serve the control of any external peripherals, such as the NTi Audio Stack Light.

function; enabling the XL2 to highlight

Limit LED On/Off

Select Limit LED with the rotary wheel

and press enter

to enable/disable the limit function.

LED - Level 1

Select one sound level for the limit LED indication

Select the soun• Press enter •

d level ﬁeld with the rotary wheel . and select the sound level for the limit

LED indication.

Selected Level Values

To set the level values for the limit LED

Select the Red or Orange soun• wheel

and press enter .

d level with the rotary

Set the level value with the rotary wheel • and conﬁrm with enter

I/O Box On/Off

Select I/O Box with the rotary wheel

and press enter

to enable/disable the limit function.

Sound Level Meter

I/O - Level 1

Setup the level for the control of e.g. the external Digital I/O Adapter Box.

Select the • Press enter •

level ﬁeld with the rotary wheel .

and select the level for the control of the

external Digital I/O Adapter Box..

Selected Sound Level Values

To set the level values for the control of the external Digital I/O Box.

Select the Out 1, Out 2, Out 3 or Out 4 • tary wheel

and press enter .

level with the ro-

Set the level value with the rotary wheel • and conﬁrm with enter

I/O - Level 2

Follow the setting for I/O Sound Level 1. The I/O level 1 may be combined with I/O level 2 using and/or combinations, providing indications in level ranges. Alternatively, other levels can be selected for the control of the external Digital I/O Adapter Box.

LED - Level 2

Follow the setting for LED - Level 1.

I/O Box Limits with Triggered Events

If triggered-event recording is enabled, the digital output 4 (OUT4) is utilized as conﬁrmation feedback to the XL2 Input Keypad, thus the setting is disabled.

Sound Level Meter

Correction Value KSET

The correction value page offers a measurement wizard for live event monitoring, applicable in case the measurement location differs from the loudest position in the live event area.

Measurement Position

The goal at live event monitoring is to measure the sound level at the loudest position accessible by the audience. Setting up any sound level measurement at this loudest location is typically not practical, thus an alternative measurement position is chosen. The recommended measurement position in order to minimize the inﬂuence that audience noise has on the measurement:

Mount the measurement microphone in front of the main • speakers Position the XL2 Analyzer at front of house (FOH)• Connect the XL2 Analyzer and measurement microphone • using a professional audio cable

Positioning the measurement microphone at front of house (FOH) may result in audience noise interfering with the measurement results. The audience noise will be further ampliﬁed by the measured k-values.

Level Difference

Prior to the start of the live event, the level difference between the loudest and the measurement position is measured. The XL2 Analyzer calculates the level difference automatically based on the individual sound level measurements at both locations. This level difference is included in the sound level reading during the live event, and the XL2 thereby displays and records the sound pressure level of the loudest point.

Measurement

Position

(Microphone)

Level difference

audience area

XL2 positioned at FOH

Loudest

Audience

Position

Sound Level Meter

How to Measure the Correction Value

Play a pink noise signal at the typical sound pressure level of • the live event. (signal source Minirator, NTi Audio Test CD) Select the correction page • Search the audience area for the location with the highest • sound pressure level and position the XL2 Analyzer. Turn the rotary wheel • to Audience and press enter

to select the parameter RUN next

Wait until the measurement is completed.• Position the XL2 at the measurement position.• Turn the rotary wheel • to Measure and press enter

to select the parameter RUN next

The XL2 measures the sound level at the loudest position

for 5 seconds. The timer counts down to zero.

The XL2 measures the sound level at the measurement

position for 5 seconds. The timer counts down to zero.

Sound Level Meter

Wait until the measurement is completed.• The correction values k1 and k2 are calculated and displayed • including date and time (in accordance with DIN15905).

Manual Setting of Correction Values

You may ﬁne-tune the correction values k1 and k2 manually. Such ﬁne-tuning adds the remark “Manually Adjusted” in the log ﬁle.

Turn the rotary wheel • to select the correction value and press enter

The selected correction value starts ﬂashing.

Sound Level Meter

Set the correction value with the rotary wheel • .

The note “Manually Adjusted” is displayed at

Reset Correction Values

You may clear all correction values back to zero by pressing the Clear All

enter

and conﬁrm with

To undo the manual setting turn the rotary wheel • the parameter UNDO at Conﬁrm with enter •

to select

Display k1 and k2 during Measurement

The correction values k1 and k2 can be displayed in the numeric result page during the ongoing sound level measurement instead of any other sound levels.

Correction Values in Proﬁles

The correction values k1 and k2 can optionally be stored within proﬁles. This allows to use proﬁles with different correction values.

Wav-ﬁle Recording

A simultaneously-recorded wav-ﬁle supports post-event reviewing of the cause of excessive sound levels.

Sound Level Meter

Locked Run Mode

The Locked Run Mode simpliﬁes sound level monitoring. You just need to power up the XL2 and the measurement starts automatically. The measurement continues until you switch off the instrument using the power button data are stored by default.

Start Locked Run Mode

Set the required parameters in the sound level meter for • your noise monitoring application. Press and hold the start/stop button •

The Locked Run Mode is now activated. The Run Indicator

displays L. The Info window is displayed at the same

time.

Switch off the instrument.•

. The measurement

for 3 seconds.

The page button • el meter and real time analyzer window. All other buttons are deactivated during Locked Run Mode.

allows toggling between the sound lev-

The measurement is stopped and the data are saved.

Switch on the instrument.•

The sound level measurement starts automatically and

continues as long as the device is powered on.

End Locked Run Mode

Press and hold the start/stop button • for 3 seconds during the ongoing measurement.

The measurement is stopped and the Locked Run Mode

deactivated.

FFT Analysis + Tolerance

5. Acoustic Analyzer

Besides the comprehensive sound level meter function, the XL2 Audio and Acoustic Analyzer offers the following acoustic measurement functions:

FFT Analysis with optional tolerance function• Reverberation Time RT60• Polarity• Delay time• 1/12 Octave + Tolerance Analysis (optional)• Noise Curves (optional)• Speech intelligibility STIPA (optional) •

FFT Analysis + Tolerance

The FFT measurement is the ideal tool for visualization of comb ﬁlters and narrow band effects. It allows a detailed frequency response investigation of audio and acoustic systems. The XL2 includes an extremely fast, real-time FFT. Optional features are

High-resolution Zoom-FFT up to 0.4 Hz steps in the fre-• quency range 5 Hz - 20 kHz provided with optional Extended Acoustic Pack or the Spectral Limits Option Capture and tolerance function provided with Spectral Limits • Option; thus the main menu function reads FFT + Tol.

FFT Analysis + Tolerance

Result Symbols / Capture & Start Tolerance Mode

This ﬁeld offers two functions:

Symbols for measurement results •

1214

Upper result displayed as line.

Lower result displayed as bargraph.

Capture & Start Tolerance Mode• The displayed readings may be captured as reference

reading C1 to C8 for

Comparing measurement results against captured •

traces with relative or absolute curve display. Creating tolerance masks based on captured refer-• ence curves for passed / failed measurements.

Capture EQ Capt

ures the upper parameter

5 7

Capture Live Captures the lower parameter

FFT Analysis + Tolerance

Manage capt

ures

Allows to rename captures, clear recorded captures, save captures to SDCard for export from the XL2 or load captures from SD-Card for import to the XL2.

Start tolerance mode

Starts the tolerance mode for passed/ failed measurements comparing the actual measurement results against a tolerance band.

Measurement Result

Actual level result of the indicated frequency band. The cursor readout displays the center frequency and the level of the band indicated by the arrow.

Upper parameter displayed as line.

Lower parameter displayed as bargraph.

Y-Scale setting

Select the Y-Axis with the rotary wheel • with enter

and conﬁrm

Select the zoom factor between • 20, 10, 5, 2.5 dB/div and conﬁrm with enter

. Scroll up and down with the rotary wheel • to select the Y-axis range. Conﬁrm with enter •

Measurement Result

Displays the actual and averaged measurement results.

Input Range

Lower range: 10 - 110 dBSPL• Middle range: 30 - 130 dBSPL• Upper range: 50 - 150 dBSPL•

Select the lowest possible input range according to the maximum level expected during the measurement; e.g., if the sound pressure will be always below 110 dBSPL, then select the lowest input range 10 - 110 dBSPL.

FFT Analysis + Tolerance

Time Weighting

Offers selectable time weighting of 0.1, 0.2, 0.5, 1.0 second as well FAST (125 ms) and SLOW (1 second). Applications:

Short Time W

eighting

Long Time Weighting

Run Indication

High resolution in time with minimum averaging

Low resolution in time with longer averaging

The run indication shows the measurement status running, paused or stopped. Various measurement settings are locked during ongoing measurements, such as changing the input ranging or the preset measurement time. For passed/failed measurements with the Spectral Limits option the run indication may display A for a preset automated level trigger.

Actual Measurement Time

Counts actual measurement time in hrs:min:sec. Supports setting of time modes: continuous and single.

Timer Mode Continuous

(applicable for standard measurements) All values are recorded and monitored continuously after starting a measurement with start The actual measurement time is shown.

Timer Mode Single

Automatically stops the measurement after the pre-set measurement time.

Set the required measurement time.• Start the measurement •

Preset Measurement Time

Adjustment of preset measurement time for single timer setting.

FFT Analysis + Tolerance

Readout Frequency

You may select any frequency to read out individual levels. The selected frequency is indicated by the cursor arrow. Choose between the following settings:

The cursor follows automatically the highest level, e.g. tracing feedback frequencies at live sound.

Select the frequency with the rotary wheel • Press enter • You may readout any individual frequency.• Return to auto frequency with enter •

 The cursor returns to the frequency with high-

est level bar.

The cursor read out may be set manually to any frequency. The read out remains at the selected frequency.

Select the frequency with the rotary wheel • Press enter • Select the frequency of interest.• Conﬁrm with enter •

 The cursor readout

ment results of the selected frequency band.

displays the measure-

Zoom Mode

(optional, applicable with the Extended Acoustic Pack or the Spectral Limits Option)

Select the readout frequency • The zoom mode is displayed above the ﬂashing arrow.• Select the zoom-in frequency with the rotary wheel •

Press limit • out with the rotary wheel Release limit • or right with the rotary wheel

Phantom Power Supply

48V T

ASD An NTi Audio measurement microphone with

48V Phantom power is switched off.

and zoom the linear frequency scale in or

and scroll the linear frequency scale left

he XL2 provides 48 V phantom power supply

to the connection microphone or sensor.

automated sensor detection ASD is connected. The XL2 reads the electronic data sheet of the microphone and switches the 48V phantom power automatically on

and press enter

FFT Analysis + Tolerance

Measurement Unit

Select the measurement unit as follows:

dB Sound level in dBSPL

This measurement unit is permanently selected upon connecting a NTi Audio measurement microphone with electronic data sheet.

dBu Input level in dBu

dBV Input level in dBV

V Input level in Volt

Page Selector X-Scale and Parameter Setting

20k Sho

ws FFT result of the frequency band range.

484.38 Hz - 20.453 kHz in a resolution of

140.62 Hz with 143 bins shown on the display.

1k7 Shows FFT result of the frequency band range.

58 Hz - 1.722 kHz in a resolution of 11.72 Hz with 143 bins shown on the display.

200 Shows FFT result of the frequency band range.

7 Hz - 215.01 Hz in a resolution of 1.46 Hz with 143 bins shown on the display.

Usr User Range

(applicable with optional Extended Acoustic Pack or Spectral Limits Option) 5 Hz - 20 kHz in zoom mode with a minimum resolution of 0.366 Hz and 143 bins displayed.

Set Selection for FFT Windowing:

Hann• : Default for acoustic measurements Dolph-Chebyshev• : for analyzing small signals

(e.g. harmonics) close to a dominant signal.

The page button

switches these display modes.

FFT Analysis + Tolerance

FFT Analysis - Getting Started

Test Preparations

Connect the measurement microphone to the XL2.• Switch on the XL2 •

 The 48V phantom power indication in the upper menu bar

changes to ASD. The XL2 is ready for acoustic measurements.

Position the XL2 at the measurement location using a micro-• phone stand or tripod.

Conﬁguration

The XL2 displays two different sound pressure levels at the same time. You conﬁgure to display either the levels Live, Max, Min, EQ or captured results.

Select the upper result parameter with the rotary wheel •

Conﬁrm with enter • .

FFT Analysis + Tolerance

Select Upper/Lower Reading

The pop-up window Select reading shows up.

Select the integrated averaged reading • EQ. All available se- lections are Z-weighted (= no weighting).

Conﬁrm with enter • .

The pop-up window Select reading mode shows up.

Select • EQ for normal absolute display of measurements. Follow the same instruction and select the lower FFT read-• ing Live.

Press start to measure and display the sound levels results indicated with ----.

FFT Analysis + Tolerance

Select Input Range

Select the lowest possible input range according to the maxi-• mum level expected during the measurement. Select the input range • RNGE and press enter Turn the rotary wheel • to set the applicable input range and conﬁrm with enter

Start Measurement

The XL2 measures the selected sound pressure lev-• els Live and EQ. All available sound levels are Z-weighted (= no weighting). Press start •

The run indication switches to running . The actual sound

level Live and the averaged level EQ are displayed. The parameter RUN ﬂashes in the memory menu.

FFT Analysis + Tolerance

Stop Measurement and Data Saving

Press stop • .

The XL2 stores the measurement data automatically.

Press enter • to conﬁrm. The measurement data are stored on the SD Card in ASCII format.

 The measurement is completed.

Capture References and Create Tolerances

The Spectral Limits Option extends the function range of the XL2 with trace capturing, relative curve display and comprehensive tolerance handling for the FFT Analysis and the high resolution 1/12 Oct + Tol spectral analysis.

Features:

Captures multiple traces in the internal memory• Comparing measurement results against captured traces • with relative or absolute curve display Comprehensive tolerance handling• Creating tolerance masks based on captured reference • curves for passed / failed measurements Export and import of tolerance and capture ﬁles• True peak level in 1/1 and 1/3 octave resolution• High-resolution Zoom-FFT up to 0.4 Hz steps in the frequen-• cy range 5 Hz - 20 kHz

Read the detailed description in the separate chapter Capture + Tolerance.

Reverberation Time RT60

The XL2 measures the energy decay from 63 Hz to 8 kHz using the Schroeder method in 1/1 octave resolution. The optional Extended Acoustic Pack enables 1/3 octave band resolution from 50 Hz to 10 kHz. Use either an impulse source (e.g., a starter pistol) or an interrupted pink noise as the test signal.

What is Reverberation Time RT60?

Reverberation time RT60 is the time required for the sound pressure level to decrease by 60 dB after the sound stimulus signal is stopped. For simple practical measurements the applicable standard ISO 3382 speciﬁes the following two measurement methods:

T20•

The measurement requires just a small dynamic measure-

ment range of ~35 dB above the ambient noise level for each frequency band. RT60 (T20) = 3 x decay time of 20 dB

T30•

The measurement requires a dynamic measurement range of ~45 dB above the ambient noise level for each frequency band. RT60 (T30) = 2 x decay time of 30 dB

In detail the RT60 is based on a linear least-squares regression of the measured decay curve. If the overall RT60 is short (e.g. < 0.3 seconds) the room acoustic is referred to as being “dead”; for example, a heavily furnished room with thick carpets, curtains and upholstered furniture may have such an acoustic character. If the overall RT60 is long (say more than 2 seconds) the room acoustic is referred to as being “live” and echoic; for example, a large empty room with painted plaster walls and a tiled ﬂoor may have such an acoustic character.

Level [dB]

0 dB

-5 dB

20 dB level range to

distance to

noise ﬂoor

-35 dB

obtain the reverberation time

-25 dB

Time

RT60 Measurement with T20 method

Reverberation Time RT60

RT60 Run Test Page

RT60 Result Page

1112

9 8

Reverberation Time RT60

RT60 Cycle Result Page

Set Level Markers

Prior to conducting a reverberation time measurement, the environmental noise is measured, and the required energy level of the test signal is determined.

Select • SET and press enter

to measure the actual en-

vironmental noise.

 The required level markers appear in grey color.

Input Range

Select between the lower, mid and upper input range. The exact ranges depend on the microphone sensitivity setting in the calibration menu of the XL2.

Run Indication

This icon displays the running and stop status of the reverberation time measurement. It is controlled by start/stop

Reverberation Time RT60

Measurement Status STAT

Displays the actual measurement status. Start and stop the reverberation time measurement with start/stop following status information is displayed:

ARMED Measurement is waiting for the test signal

to exceed at least one measurement trigger marker, then the measurement is triggered automatically.

NOISE A sound stimulus signal above the trigger

marker is being received.

DECAY Decay is being measured.

PAUSE The measurement has been paused by press-

ing pause

STOP No RT60 measurement is presently being per-

formed.

Average AVRG

Counts the measurement cycles. When using an interrupted noise test signal, a minimum of 3 sequential cycles is recommended.

. The

Actual Real-Time Spectrum

The black bars indicate the actual signal, including background noise. While setting up the reverberation time measurement you should increase the test signal level until the black bars exceed the grey bars completely and the status

displays NOISE.

Level Marker

The grey bars indicate the signal level required for effective reverberation time measurements in each octave band. The marker has a length of 35 dB, and can be set by

Selecting • SET Press enter •

with the rotary wheel

to measure the environmental noise in

the silent room.

Band Status

Indicates a successful reverberation time measurement above each octave band with a tick

Measurement Method

Select between the measurement methods T20 and T30. T20 requires just a small dynamic measurement range of ~35 dB above the ambient noise level for each frequency band. T30 requires a dynamic measurement range of ~45 dB.

Reverberation Time RT60

Measurement Resolution

Reverberation time measurement selectable in 1/3 octave or 1/1 octave band resolution. The optional Extended Acoustic Pack enables 1/3 octave band resolution from 50 Hz to 10 kHz.

Phantom Power Supply

48V T

he XL2 provides 48 V phantom power supply

to the connection microphone or sensor.

ASD An NTi Audio measurement microphone with

automated sensor detection ASD is connected. The XL2 reads the electronic data sheet of the microphone and switches the 48V phantom power automatically on

48V Phantom power is switched off.

Page Selector RT60

Select between the RT60 run test page and the result page. The page button

toggles between these displays.

RT60 run test page

RT60 result page. Toggle with the measurement result selection

among

AVRG RT60 result page showing average

of all cycles and uncertainty factor

CYC xx RT60 result page for each cycle

Last RT60 result page for last cycle

Y-Axis Reverberation Time

Reverberation time in seconds. The scaling is automatically adjusted.

Reverberation Time RT60

Uncertainty Factor

The uncertainty factor is displayed in the RT60 average result page. It indicates the uncertainty of the averaged measurement results, reduces as more cycles are measured, and depends on the measured reverberation time and the bandwidth of the individual frequency band; lower bands show a higher uncertainty factor. The number of measurement cycles is displayed at

Overall Reverberation Time Test Result

Readout of reverberation time and uncertainty factor.

Uncertainty factor. For more details see

Reverberation time measurement results.

X-Axis

RT60 Octave Bands 63Hz - 8 kHz

Cursor Readout

Select the individual frequency band and read out the following numeric measurement results

Uncertainty factor in % or correlation in %.• Reverberation time RT60 (T20), of the selected frequen-• cy band, in seconds (s).

Measurement Result Selection

The RT60 measurement function allows consecutive measurements within one test sequence. An averaged test result of all measurements is automatically calculated.

Select CYC and scroll with the rotary wheel

through the

individual test result cycles showing

Last Last Test Result

Displays the result of last measurement cycle.

xx Single Test Cycle Results

The individual single test results are marked with CYC xx, where xx is an incriminating num- ber. You may delete individual test results. The averaged reverberation time result uses only the remaining valid measurements. To delete results in a cycle,

Select • DEL with the rotary wheel Conﬁrm with enter • .

AVRG Averaged Test Result

The averaged test results of all cycles are calculated and displayed.

Reverberation Time RT60

Correlation Factor in %

The correlation factor is 100% for perfectly linear sound pressure level decay after the sound source has ceased. The natural deviation from this linearity results in lower correlation values. The correlation factor is typically 80 100%.

Cycle Reverberation Time Test Result

Readout of cycle reverberation time and correlation factor

when selection 18 is CYC xx or Last.

Correlation Factor. Scale is on the right Y-axis. For more details see

Reverberation time measurement result of individual displayed cycle. Scale is on the left Y-axis.

Y-Axis Correlation Factor

The right Y-axis shows the correlation factor in %. The correlation factor Y-axis is displayed when test result selection

is CYC xx or Last.

Test Signals

Use either an interrupted pink noise or an impulse source as the test signal.

Interrupted pink noise • Precision measurements require an omnidirectional speaker with identical radiation characteristic in all directions. Various interrupted pink noise test signals with different on/off times are offered by the NTi Audio Test CD included with the XL2 or the Minirator signal generator. Minimum three measurement cycles shall be performed. The XL2 averages thee readings automatically.

Impulse • The trigger signal is an impulse source, such as a starter pistol, starter clap or bursting balloon. Individual measurements, or test sequences with repeated trigger signals, can be carried out.

Delete Cycle Results

Individual cycle results may be deleted, thereby excluding them from the calculation of the AVRG result.

Reverberation Time RT60

RT60 Measurement - Getting Started

Test Signal: Pink Noise

Play a pink noise signal through an omnidirectional speaker in the room under test. The sound source should be played for a long enough time period to ensure that a balance between injected and absorbed acoustic energy has been reached. For example the sound reﬂections should be given enough time to reach all reﬂective surfaces in the room. As a rule of thumb, ensure that the pink noise is played for at least the time period of the estimated RT60 test result. If in doubt, play the Minirator MR-PRO or the Test Signal CD as sound source for at least 5 seconds for each cycle. Each time the source signal stops, the XL2 recognizes this interruption, triggers, measures the decay time and calculates the reverberation time automatically. Minimum three measurement cycles shall be performed.

Test Signal: Impulse

Fire an impulse sound source in the room under test, e.g. use a starter pistol, starter clap or bursting balloon. The XL2 measures the decay time and calculates the reverberation time automatically.

Test Preparations

The XL2 reads the electronic data sheet of any connected ASD microphones provided by NTi Audio and switches the 48V phantom power automatically on as follows:

Connect the measurement microphone to the XL2.• Switch on the XL2 •

 The 48V phantom power indication in the upper menu bar

changes to ASD. The XL2 is ready for acoustic measurements.

Position the XL2 at the measurement location using a micro-• phone stand or tripod. Select the • RT60 function in the measurement menu and toggle with page Prepare the environment for the measurement. For example • mute all sound sources to establish silence.

to the run page RUN.

Reverberation Time RT60

Set Level Markers

Select the parameter • SET with the rotary wheel and press enter

 The environmental noise is measured and the grey level

markers are set.

Get Ready for the Reverberation Time Measurement

Protect the ears against high sound pressure levels, as the • test signals might be very loud.

Setting the pink noise level:

Start the pink noise test signal with the appropriate on/off • time according to the room. Use an initial low level. Increase the test signal level until all level markers for the • minimum test signal level are passed. Use an equalizer to push individual band levels. Switch off the interrupted pink noise signal after you have • ﬁnished setting the pink noise level.

Reverberation Time RT60

Start the Measurement

Press start • . The status indication switches to ARMED. Enable the test signal; e.g., switch on the interrupted pink • noise signal or ﬁre a starter pistol. The black bars have to exceed the grey bars completely.•

Continue the Measurement

Using pink noise: The interrupted pink noise test signal continues with the preset on/off time. The XL2 automatically triggers at each cycle. Complete a minimum of three test cycles to accurately calculate the uncertainty factor. Perform more cycles to increase the measurement accuracy (= smaller uncertainty factor).

Using an impulse source: A single measurement is sufﬁcient, thus press stop the measurement. No further measurements are required to increase the statistical measurement accuracy.

Conﬁrmation marks indicating successful measurements, are displayed above each band.

to end

Reverberation Time RT60

Stop the Measurement and Read Out the Result

Press stop • . If applicable, switch off the pink noise test signal.• Select the result page • RES with page

The average reverberation time for each frequency band is displayed in seconds and the measurement uncertainty in %.

•

Read Out the Individual Cycle Result

If multiple cycles have been recorded, then select • CYC with the rotary wheel cycle result with the rotary wheel .

Within each cycle, the reverberation time for each frequency band is displayed in seconds and the correlation factor in %.

, press enter and select the individual

•

 The RT60 reverberation time measurement is completed.

Reverberation Time RT60

Error Indications

Various error indications are displayed for unsuccessful RT60 measurements. Corrupt cycles can be deleted individually. These results are then excluded from the average calculations.

LOW LEVL•

This is the abbreviation of “low test signal level” during the measurement. Increase the test signal level until the black level markers exceed the grey level markers in every frequency band. Also, ensure that the level falls below the grey level markers, otherwise use a RT60 test signal with longer on/off times.

T>18S •

The measured reverberation time exceeds the time limit of 18 seconds. This is commonly caused by either an incorrect analyzer range setting or environmental noise. In the ﬁrst case, choose another range setting. In the second case, ensure that the environmental noise remains constant during the measurement, and/or SET the level markers again while the environmental noise is high.

Polarity

Polarity measurement is important in matching the left and right speakers for a good stereo sound image. The polarity function measures the polarity of cables, single speakers and speaker cabinets. For testing, use the polarity signal provided on the NTi Audio Test CD or the Minirator test signal generator.

The polarity of individual speakers or speaker cabinets might change with the frequency. For example, the mid-range speaker polarity may differ from the woofer polarity within the same speaker cabinet. Therefore the polarity detailed result page of the XL2 displays the measured polarity of the individual octave bands from 125 Hz to 8 kHz. This allows in-depth veriﬁcation of the polarity - frequency relationship.

Polarity is a simple test within the very com-• plex science of signal phasing. Drivers, speakers and crossovers all cause phase shifts of the audio signal. The polarity of various speakers within the • same cabinet may differ by design! Polarity testing is useful for checking the cor-• rect wiring of similar speaker systems.

Positive/Negative Result Page

Polarity

Detailed Result Page

connected directly to XL2 Analyzer

Polarity result for Minirator

Input Selection

Select the signal source as follows:

Select • Signal Source with the rotary wheel Press enter •

Voice Note Mic

XLR

Input

to select either

Use the internal voice note microphone of the XL2 for polarity measurements. This selection disables the rear speaker.

Measure the acoustic polarity with a measurement microphone. Alternatively, measure the

polarity of an electrical signal connected with

RCA Input

Polarity Test Result

an XLR audio cable.

Measure the polarity of an electrical signal connected with an RCA audio cable.

Displays either POSITIVE, NEGATIVE or ??? (=undeﬁned). For further visual indication, the limit button

illuminates

green for POSITIVE and red for NEGATIVE polarity.

Level RMS

Measures the absolute level of the input signal. The unit’s dBu, dBV and V are selectable.

Polarity

Balance Indicator

Indication of the audio signal balance between pin 2 and 3 on the XLR input for input signals > -34 dBu.

The input signal is balanced.

The signal is unbalanced. The level of pin 2 is higher than pin 3. The signal is unbalanced. The level of pin 3 is higher than pin 2.

Relative Level Indicator

The grey area shows the measured signal energy within the individual frequency bands. The bands with the biggest energy have the most effect on the actual displayed POSI- TIVE / NEGATIVE polarity result.

Polarity Indication

olarity of frequency band is positive. The polarity re-

+ P

sult is in the upper display area; the + area.

- Polarity of frequency band is negative. The polarity result is in the lower display area; the - area.

X-Axis

Seven octave bands with center frequencies from 125 Hz to 8 kHz. SUB displays the polarity of Sub-woofers; frequency range < 100 Hz.

Negative Polarity Area

Measurement results area with negative polarity (-). The black line in the middle of relative level indicator

displays the measured polarity of the individual frequency band. The dashed line indicates the lower limit of the measurement result area.

Uncertain Polarity Area ???

Polarity results for frequency bands in this area are uncertain. Therefore the polarity result ??? is displayed.

Positive Polarity Area

Measurement results area with positive polarity (+). The black line in the middle of relative level indicator

displays the measured polarity of the individual frequency band. The dashed line indicates the upper limit of the measurement result area.

Polarity

Polarity Measurement - Getting Started

For acoustic polarity measurement you can use the internal voice note microphone, or an external measurement microphone, plugged into the XLR input. The polarity result for left and right speaker cabinets should match for a good stereo sound image.

Feed the speaker cabinet with the polarity test signal of the • Minirator. Adjust the test level (at Minirator or ampliﬁer) until the test • signal is clearly heard. Enable the polarity test signal at the left speaker cabinet; • mute the right speaker cabinet. To activate the internal microphone, select • Signal Source with the rotary wheel enter Measure the polarity of the left speaker cabinet and save the • screenshot in the memory menu Enable the polarity test signal at the right speaker cabinet; • mute the left speaker cabinet. Measure the polarity of the right speaker cabinet.• Compare the polarity test result of both speaker cabinets. •

 The polarity measurement is completed.

and choose Voice Note Mic with

The sample result shows the polarity as:

Sub-woofer: Low energy, no sub installed• Woofer: Positive• Mid-range: Negative• Tweeter: Positive (with small levels) •

The major part of the signal energy is measured in the mid-range frequency bands. Therefore the overall displayed polarity is NEGATIVE.

Delay Time

The delay time measurement function is suitable for accurate conﬁguration of delay line setups, by optimizing the directionality of the signal source. The XL2 measures the delay time between the reference signal and the acoustic signal from the speaker. The acoustic delay settings are displayed, allowing you to easily set the measured delay time into the delay device in the rack. The NTi Audio delay time test signal is provided either by the Minirator MR-PRO, MR2 or the Test CD included with the XL2.

Delay Signal Source

Select the signal source for the delay measurement:

CD Player Using the supplied NTi Audio Test CD; this

setting implies the synchronization time bar is set to 100 seconds = 1 min. 40 sec.; after 100 seconds the XL2 has to be synchronized to the delay test signal again.

Minirator The Minirator MR-PRO and MR2 provides

a more reliable test signal source than a CD player. Therefore the XL2 offers an extended time range without synchronization. Only after 300 seconds (5 minutes) does the XL2 have to be synchronized to the delay test signal again.

Store Button

Press the store button to record the actual delay reference speaker.

Reference Delay Time

Individually-stored delay time of reference speaker.

of the

Delay Time

Calculated Distance

Distance from measurement position to speaker in meters or feet, based on the deﬁned temperature in °C or °F

Synchronization Time Bar

The automated synchronization allows delay time measurements without any connected electrical reference signal for 100 seconds using the NTi Audio Test CD or 300 seconds using the Minirator, MR2 or MR-PRO. It displays the time remaining until the next required synchronization.

Calculated Delay Time: Store - Actual

Calculated difference between delay time of speaker A and speaker B as shown on the next page. The automated difference calculation simpliﬁes the veriﬁcation of delay line arrangements, such as those used in larger halls or auditoriums.

Actual Delay

Actual measured delay time referring to the electrical reference signal.

Delay Test utilizes VoiceNote Microphone

The XL2 uses the internal VoiceNote microphone to measure the acoustic delay. Do not connect any measurement microphone to the XL2 for the delay time measurement.

Rear Speaker

The rear speaker on the XL2 is disabled during delay measurements, thereby avoiding measurement failures. The headphone output is active.

Delay Time

Delay Measurement - Getting Started

The delay time measurement is conducted between the synchronized electrical input signal and the acoustic signal measured by the built-in voice note microphone. In this example, the delay between speakers A and B in the illustrated auditorium is measured.

speaker A

front left

lecturer

speaker B

sub left

measurement

position

speaker

front right

speaker

sub right

Test Preparations

Prepare the delay test signal; use either the•

NTi Audio Test CD• NTi Audio Minirator for analog systems •

NTi Audio Digirator for digital or Dolby/DTS systems• Start the delay test signal.• Connect the generated delay test signal with an audio cable • to the RCA or XLR input of the XL2, e.g. take the reference signal from an auxiliary channel of a mixing console. Select XLR or RCA input in the upper XL2 menu• Set the actual environment temperature, to ensure that the • distance is displayed correctly later.

Delay Time

Wait until the XL2 synchronizes to the incoming delay test • signal, then the synchronization time bar ﬁlls up.

Disconnect the audio cable, with the synchronizing signal, • from the XL2, allowing you to move around freely for the delay measurement. When selecting Minirator as the delay signal source, the XL2 has to be synchronized to the signal source again after 5 minutes. When selecting CD Player as the delay signal source, the XL2 has to be synchronized to the signal source every 100 seconds.

Measure Reference Speaker A

Start the delay test signal at speaker A, mute speaker B.• Position yourself with the XL2 at the measurement position • next to speaker B sub left as indicated above. This is the worst-case position in the auditorium with regard to acoustic delay in the sound ﬁeld. The XL2 uses the VoiceNote microphone for the delay test; do not connect any measurement microphone.

 The XL2 measures the delay time of speaker A in reference

to the electrical input signal in milliseconds.

Delay Time

Store Reference

Select the displayed • 0.0 ms below Act. Delay with the rotary wheel

and press enter .

 The reference result of speaker A is stored for the differ-

ence calculation of delay A - B.

Stop the delay test signal at speaker A.•

Measure Sub Speaker B

Start the delay test signal at speaker B. Mute speaker A.• Position yourself with the XL2 at the shown measurement • position. The XL2 uses the VoiceNote microphone for the delay test; do not connect any measurement microphone.

 The XL2 measures the delay time of speaker B in reference

to the electrical input signal in milliseconds.

Delay Time

Automated Difference Calculation

The delay time difference between speaker A and B is • automatically calculated and shown below the Act. Delay result.

 The delay time is measured.

Delay Test utilizes VoiceNote Microphone

The XL2 uses the internal VoiceNote microphone to measure the acoustic delay. Do not connect any measurement microphone to the XL2 for the delay time measurement.

Measurement Position

Do not position the XL2 too close to reﬂecting surfaces, such as walls or ﬂoors. The reﬂections are likely to prevent accurate measurements.

Result Interpretation

The resulting time in milliseconds shows • the time difference of the sound signal from speaker A and B arriving at the measurement position. Speaker B has to be delayed by the displayed difference result. To optimize directionality, add a further 5 ms • to the calculated difference. The main signal from speaker A then arrives at the measurement position ﬁrst. The acoustic signal from sub speaker B arrives 5 ms later. This improves the subjective directionality perception of the listeners.

Distance in meter/feet

The distance results in meter/feet are displayed below for easy veriﬁcation of the test results accuracy. The readings are based on 330 m/s sound speed at 0°C / 32°F.

1/12 Octave + Tolerance

1/12 Octave + Tolerance (optional)

The Spectral Limits Option extends the XL2 function range with an RTA analyzer with spectral resolutions from 1/1 octave down to 1/12th octave. Trace capturing, relative curve display and comprehensive tolerance handling are supported in the FFT Analysis and the high resolution 1/12 Oct + Tol spectral analysis.

Features

High resolution RTA function “1/12 Oct + Tol” with select-• able 1/1, 1/3, 1/6 and 1/12 octave spectral resolution Capturing of multiple readings into the internal memory • Comparing measurement results against captures with rela-• tive or absolute curve display Comprehensive tolerance handling with tolerance masks • based on captures for passed/failed measurements Export and import of tolerance and capture ﬁles• Frequency band listening at rear speaker•

Applications

PA-rental: Verifying the frequency response of returned • speakers and microphones against reference records ensuring they are back in stock in good working condition. Industrial quality testing: Passed/Failed test in the production • line or during service of any audible quality criteria, such as with motors, machines, vacuum cleaners, ... Cinema: Comparing frequency responses against an ideal • response curve according the X-Curve requirements.

Tolerance Handling

The XL2 Analyzer compares spectral measurements against a tolerance band and visualizes exceptions in every frequency band. The passed/failed condition is further visualized by the limit button ment in order to drive an external alarm device such the accessory SPL Stack Light.

Tolerance curves can either be imported from txt-ﬁles or directly derived from captured measurements. The XL2 calculates tolerance bands based on

Single captured results• Manually generated txt-ﬁles on the PC• Mean average of multiple captures• Min/Max curves of multiple captures•

and forwarded to the I/O interface of the instru-

1/12 Octave + Tolerance

Result Symbols / Capture & Start Tolerance Mode

This ﬁeld offers two functions:

Upper parameter displayed as line.

Symbols for measurement results •

Lower parameter displayed as bargraph.

Capture & Start Tolerance Mode•

The displayed spectral readings may be captured in C1

- C8 for Comparing measurement results against captures • with relative or absolute curve display. Creating tolerance masks based on captures for • passed / failed measurements.

Capture EQ Capt

ures the upper parameter

5 7

Capture Live Captures the lower parameter

1/12 Octave + Tolerance

Manage captures

Allows to rename captures, clear recorded captures, save captures to SDCard for export from the XL2 or load captures from SD-Card for import to the XL2.

Start tolerance mode

Starts the tolerance mode for passed/ failed measurements comparing the actual measurement results against a tolerance band.

Measurement Result

Actual level result of the indicated frequency band. The cursor readout displays the center frequency and the level of the band indicated by the arrow.

Upper parameter displayed as line.

Lower parameter displayed as bargraph.

Y-Scale setting

Select the Y-Axis with the rotary wheel • with enter

and conﬁrm

Select the zoom factor between • 20, 10, 5, 2.5 dB/div and conﬁrm with enter

. Scroll up and down with the rotary wheel • to select the Y-axis range. Conﬁrm with enter •

Spectral Measurement Result

Spectral results in 1/1, 1/3, 1/6 or 1/12 octave band resolution. Adjust the resolution at

1/12 Octave + Tolerance

Input Range

Lower range: 10 - 110 dBSPL• Middle range: 30 - 130 dBSPL• Upper range: 50 - 150 dBSPL•

Time Weighting

Offers selectable time weighting of 0.1, 0.2, 0.5, 1.0 second as well FAST (125 ms) and SLOW (1 second). Applications:

Short Time W

eighting

Long Time Weighting

High resolution in time with minimum averaging

Low resolution in time with longer averaging

Run Indication

Actual Measurement Time

Counts actual measurement time in hrs:min:sec. Supports setting of time modes: continuous and single.

Timer Mode Continuous

(applicable for standard measurements) All values are recorded and monitored continuously after starting a measurement with start The actual measurement time is shown.

Timer Mode Single

Automatically stops the measurement after the pre-set measurement time.

Set the required measurement time.• Start the measurement •

100

1/12 Octave + Tolerance

Preset Measurement Time

Adjustment of preset measurement time for single timer setting.

Broadband Results

User-selectable display of broadband results:

Broadband A A-weighted level

Broadband C C-weighted level

Broadband Z without any frequency weighting

- none

Sum of bands

Sum of displayed frequency bands (only available when #HideUnusedBands is set to True within the tolerance ﬁle)

Readout Frequency

You may select any frequency to read out individual levels. The selected frequency is indicated by the cursor arrow.

Choose between the following settings:

The cursor follows automatically the highest level, e.g. tracing feedback frequencies at live sound.

Select the frequency with the rotary wheel • Press enter • You may readout any individual frequency.• Return to auto frequency with enter •

 The cursor returns to the frequency with high-

est level bar.

The cursor read out may be set manually to any frequency band or wideband level. The read out remains at the selected frequency.

Select the frequency with the rotary wheel • Press enter • Select the frequency of interest.• Conﬁrm with enter •

 The cursor readout

ment results of the selected frequency band.

displays the measure-

NTi Audio NTI-XL2 Users Guide

Specifications and Main Features

Frequently Asked Questions

User Manual