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Rion NA-27 Instruction Manual

Precision integrating sound level meter with 1/3 octave band real-time analyzer
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INSTRUCTION MANUAL
Precision Integrating Sound Level Meter
with 1/3 octave band real-time analyzer
NA-27
3-20-41 Higashimotomachi, Kokubunji, Tokyo 185-8533, Japan
http://www.rion.co.jp/english/

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  • Page 1 INSTRUCTION MANUAL Precision Integrating Sound Level Meter with 1/3 octave band real-time analyzer NA-27 3-20-41 Higashimotomachi, Kokubunji, Tokyo 185-8533, Japan http://www.rion.co.jp/english/...
  • Page 3 This manual describes the features, operation and other aspects of the Precision Integrating Sound Level Meter with 1/3 octave band real-time analyzer NA-27. If the unit is used together with other equipment to configure a measurement system, consult the documentation of all other components as well.
  • Page 4 Specifications Lists the technical specifications of the unit. EMC DIRECTIVE The NA-27 described in this manual is in conformity with the following International Standard; IEC 61672 - 1:2002 Class1 (Sound level meter) To conform to the EU requirement of the Directive...
  • Page 5 FOR SAFETY In this manual, important safety instructions are specially marked as shown below. To prevent the risk of death or injury to persons and severe damage to the unit or peripheral equipment, make sure that all instructions are fully understood and observed. Disregarding instructions Caution printed here incurs the risk of...
  • Page 7 Precautions Operate the unit only as described in this manual. The NA-27 is a precision instrument. Protect it from shocks and vibrations. Take spe- cial care not to touch the microphone diaphragm. The diaphragm is a very thin metal film which can easily be damaged.

  • Page 8: Table Of Contents

    Contents FOR SAFETY ....................iii Outline ........................ 1 Controls and Functions .................. 4 Carrying Case and Accessories ..............4 Top View ...................... 6 Side View....................10 Rear View ....................12 Bottom View ....................13 Measurement Screen ................... 14 Preparations ....................16 Backup Battery....................
  • Page 9 Takt-Max Sound Pressure Level Measurement (L ) ....... 54 Percentile Sound Pressure Level Measurement (L )........57 1/1-Octave and 1/3-Octave Analysis ............59 1/1-Octave and 1/3-Octave Analysis for Instantaneous Value ) .................... 59 1/1-Octave and 1/3-Octave Analysis for Maximum and Minimum Level ) ...................
  • Page 10 Microphone Extension Cable (EC-04 series) ........... 109 Amplifier Circuit Configuration ............... 112 Frequency Weighting Network ..............113 RMS Detection Circuit ................114 Measurement Functions ................117 Noise Floor ....................120 Background Noise..................121 Windscreen (WS-02) ................122 I/O Connector ................... 125 1/1-Octave Filter Characteristics ..............

  • Page 11: Outline

    JIS and IEC standards. Using the output signal from a single microphone, the NA-27 can determine values for different time constants and frequency weighting settings simultaneously. In addition to conventional noise level and sound pressure level measurements, the NA-27 can also determine the following quantities: Equivalent continuous sound pressure level L...
  • Page 12 Outline Processing functions in main channel and sub channel *1 L are calculated simultaneously from L sampled at 10 ms intervals. *2 L values are calculated simultaneously from L sampled at 100 ms intervals for measurement times up to 1 h. For measurement times over 1 h, the sampling inter- val increases by 100 ms for every hour.
  • Page 13 Outline Block diagram of NA-27...

  • Page 14: Controls And Functions

    Controls and Functions Carrying Case and Accessories The unit is supplied with the parts listed below. Verify that all parts are complete and that there is no damage. If any parts are missing or damaged, please contact the supplier.
  • Page 15 Controls and Functions...

  • Page 16: Top View

    Controls and Functions Top View Microphone/preamplifier The microphone and preamplifier are configured as an integrated assembly. The micro- phone and preamplifier are labeled with a serial number which must match the number shown on the rear of the main unit. The microphone/preamplifier assembly can be removed from the sound level meter and connected via an optional extension cable, for measurements a distance.
  • Page 17 Controls and Functions Operation keys START/STOP key Press to start and to terminate the sound pressure level measurement (including the various processing functions). The key is also used to store data in memory. PAUSE/CONT key Serves to temporarily pause and resume the measurement. When the data exclusion (back-erasing) function is used, data for a certain number of seconds before the key was pressed can be excluded from processing.
  • Page 18 Controls and Functions CAL key Pressing this key activates the built-in oscillator for electrical calibration of the NA-27 or for level matching of the NA-27 and connected equipment. FREQ WEIGHT key Selects the frequency weighting characteristic for the main channel. Available settings are "A"...
  • Page 19 Controls and Functions keys Serve to move the marker during frequency analysis. When a menu is displayed, the keys serve to select parameters. ENTER key When a menu is displayed, the key serves to accept a setting. PRINT key Serves to start and stop printout of the current measurement screen or of data stored in memory on a connected printer (DPU-414, CP-10, CP-11;...

  • Page 20: Side View

    Controls and Functions Hand strap The strap should be used to safely carry the unit during field work. Side View...
  • Page 21 Controls and Functions Power switch This sliding switch serves to turn the unit on and off. Contrast control Serves to adjust the display contrast. Use the supplied miniature screwdriver for the adjustment. Backlight key Pressing this key activates the display backlight. After about one minute, the backlight turns itself off automatically.

  • Page 22: Rear View

    The unit uses four main batteries (IEC R14P) and one lithium battery (CR-1/3N) for memory backup. Guide hole This hole serves to fasten the supplied tripod adapter NA-27-S05. Name plate The model name and type, certification number, microphone number, preamplifier...

  • Page 23: Bottom View

    Controls and Functions Bottom View Strap fastening screw The hand strap is to be fastened here. Using the supplied tripod adapter, the unit can also be mounted on a camera tripod. I/O connector Serves for input and output of control signals and measurement data. A printer or com- puter can be connected here.

  • Page 24: Measurement Screen

    Controls and Functions Measurement Screen The actual appearance of the measurement screen depends on the selected measurement parameters. A representative example is shown below. The illustration shown above may differ slightly from the actual screen display of the unit, regarding fonts, character size etc.
  • Page 25 Controls and Functions...

  • Page 26: Preparations

    Preparations This section describes the steps which are necessary before starting a measurement. Be sure to set the power switch to OFF before inserting or removing batteries and connecting or disconnecting any cables. Backup Battery The backup battery (CR-1/3N, lithium) serves to maintain settings and data stored in memory also while the unit is turned off.
  • Page 27 Preparations Important The life of the backup battery is about two years. To be on the safe side, you should replace the battery every 1 to 1-1/2 years. When the battery is removed, all stored data as well as the time and date settings are lost.

  • Page 28: Power Supply

    Preparations Power Supply The unit can be powered by four IEC R14P (size C) batteries (alkaline or manganese) or the optional AC adapter. The life of the batteries depends on various usage factors. Representative figures are shown below. Battery life (at room temperature, 1/3-octave analysis, continuous operation) Alkaline batteries: approx.
  • Page 29 Preparations Important Take care not to reverse the (+) and (-) polarity when insert- ing a battery. Always use four identical batteries, and replace batteries only as a set. Mixing battery types or old and new batteries can lead to damage. Remove the batteries from the unit if it is not to be used for a week or longer.
  • Page 30 Preparations For long continuous measurements, it is preferable to power the unit from the AC adapter. AC adapter connection To power the unit from the optional AC adapter (NC-94A), connect it as shown below. Important Do not use any other AC adapter except the optional NC-94A to prevent the possibility of overheating and damage.

  • Page 31: Tripod (Option) Mounting

    Preparations Tripod (option) Mounting For long-term measurements, the unit can be mounted on the sound level meter tripod ST-80 (option). In this case, the supplied tripod adapter is required. Proceed carefully, to avoid dropping the unit or tipping over the tripod. Wind noise at the microphone can cause measurement errors.
  • Page 32 Preparations Insert the stud of the tripod adapter into the guide hole on the rear of the unit, and fasten the adapter securely with the fastening screw. Microphone grid Important Never remove the microphone grid, because this can lead to damage.

  • Page 33: Trigger Input

    Preparations Trigger Input An external trigger signal can be used to initiate the measurement (see page 68). Use a logic-level signal or shorten the trigger connector. Using the Backlight Pressing the LIGHT key on the side of the unit turns the display backlight on, making it easier to read in dark locations.

  • Page 34: Setting The Date And Time

    Preparations Setting the Date and Time The NA-27 incorporates a clock which allows recording the date and time along with measurement data. Note The clock will stop running if power is turned off and no backup battery is inserted. Set the date and time as described below.
  • Page 35 Preparations 3. Use the keys to move the flashing cursor to the "DATE" item. The cur- rently set date (such as 96/04/08) is shown in the bottom left corner of the screen. 4. Use the keys to move the cursor to the year, month, and day field. Use the INC and DEC keys to set the numbers.

  • Page 36: Calibration

    Preparations Calibration Before starting a measurement, the NA-27 must be calibrated. There are two types of calibration, namely electrical calibration and acoustic calibration using a pistonphone. When compensation for atmospheric pressure is not required, it suffices to perform elec- trical calibration only.
  • Page 37 Preparations 5. Use the supplied miniature screwdriver to adjust the calibration control on the side of the unit so that the level reading is 94.0 dB. 6. Press the CAL key once more to return to the measurement screen. Note The calibration control is a multi-turn type.
  • Page 38 Preparations Acoustic calibration with pistonphone For acoustic calibration, the Rion pistonphone NC-72 (option) is mounted to the micro- phone of the sound level meter, and adjustment is performed so that the reading of the meter is equal to the sound pressure level inside the coupler.
  • Page 39 8. Insert the microphone very carefully and slowly all the way into the coupler. 9. Set the power switch of the pistonphone to ON. 10. Adjust the calibration control on the side of the NA-27 with the supplied miniature screwdriver so that the level reading matches the calibration value indicated on the pistonphone.

  • Page 40: Using The Menu Screens

    Preparations Using the Menu Screens The NA-27 has four types of menu screens, namely SETUP, MEMORY, DISPLAY, and I/O. Basic operation principles are the same for all four screens. The following example explains how to use the SETUP menu screen to set the L mea- surement time to 10 minutes and the time constant for the sub channel to "SLOW".
  • Page 41 Preparations 11. Press the ENTER key. The indication changes to "SLOW" and the cursor moves to the "Operation" item. The time constant of the sub channel is now set to "SLOW". 12. Press the SETUP key to return to the original screen. Menu screen conventions Pressing the same menu screen key again returns to the measurement screen.

  • Page 42: Menu Screens

    Preparations Menu Screens The contents of all menu screens are reproduced below. The left side always shows the setting item and the right side the parameter that can be changed. For more information on changing settings, please refer to the section about setting measurement parameters on page 36.
  • Page 43 Preparations DISPLAY menu screen MAIN ADD DISP : OFF Lmax / Lmin SUB DISP : OFF ADD DISP : OFF Lmax / Lmin Ltm3 / Ltm5 PEAK DISP : OFF Lx SELECT : OFF : OFF : OFF : OFF : OFF : OFF : OFF...

  • Page 44: Factory Default Settings

    Preparations Factory Default Settings The factory default settings for all menu screens are reproduced below. The left side shows the setting item and the right side the default parameter setting. SETUP menu screen MEASURE MODE : LEQ Leq Time : 1 S Lx Time : 10 S BACK ERASE TIME...
  • Page 45 Preparations DISPLAY menu screen MAIN ADD DISP : OFF SUB DISP : OFF ADD DISP : OFF PEAK DISP : OFF Lx SELECT : OFF : ON : ON : ON : ON : ON : OFF Lmax : OFF Lmin : OFF : OFF...

  • Page 46: Setting Measurement Parameters

    Setting Measurement Parameters Before carrying out a measurement or frequency analysis with this unit, the measurement parameters must be set up as described below. Menu screen settings SETUP menu screen MEASURE MODE: Selects whether to measure power (L ) or percentile values Leq Time: 1 to 99 S 1 to 99 M 1 to 99 H...
  • Page 47 Setting Measurement Parameters Explanation This example uses 10 frequency analysis results for instantaneous levels. Table 1 shows the values. The shaded data are the maximum levels for each frequency band. The framed column shows the frequency band data at the point when the all-pass level was maximum.
  • Page 48 Setting Measurement Parameters TRIGGER MODE: LEVEL EXTRN TIME Sets the trigger mode for starting the measurement. (See pages 68 to 73.) OFF: Trigger mode is disabled. LEVEL: Trigger level can be set from 10 to 140 dB in 1 dB steps. SLOPE: - or + are used to set the slope for level triggering.
  • Page 49 Setting Measurement Parameters MEMORY menu screen MEMORY BLOCK: AUTO1 AUTO2 MANU Selects the memory block for storing or recalling data. BLOCK CLEAR: EXEC Serves to erase stored data. AUTO STORE TYPE: SINGLE GROUP Determines whether auto store data are composed of a single processing function or of all processing functions.
  • Page 50 Setting Measurement Parameters Directory DOWN [ AU 1: 1 / 1 96 / 05 / 02 12:34:56 [ AU 2: 1 / 3 96 / 05 / 04 11:22:33 [ 001: 1 / 3 96 / 05 / 10 10:10:10 [ 002: 96 / 05 / 10 15:15:15...
  • Page 51 Setting Measurement Parameters I/O menu screen PRINT MODE: SINGLE SUCCESSIVE Determines whether the printer (DPU-414, CP-10, CP-11) prints only one sheet or operates continuously. The "SUCCES- SIVE" setting is valid only in recall mode. SUC. PRINT BLK: AUTO1 AUTO2 MANU Specifies the memory block for successive printing.

  • Page 52: Sound Pressure Level Measurement

    Sound Pressure Level Measurement The NA-27 offers various kinds of measurements: instantaneous value (L ), power (L ), and percentile value (L ). The maximum sound pressure peak level (L ), minimum sound pressure level (L ), and waveform peak hold (L...

  • Page 53: Instantaneous Sound Pressure Level Measurement (L )

    Sound Pressure Level Measurement If the date and time are not set, the indication "RTC Read Error!!" appears after turning on the power. In this case, use the I/O menu screen to set the date and time, as described on page 24.
  • Page 54 Sound Pressure Level Measurement 4. Use the TIME CONST key to select the desired time constant setting. Normally, the "FAST" setting should be used. 5. Use the LEVEL UP/DOWN keys to select the level range. Choose a setting in which the "OVER"...
  • Page 55 Sound Pressure Level Measurement 3. Use the keys to set the parameter to ON. 4. Press the ENTER key. The "SUB DISP" item is now set to ON. The cursor moves to the "ADD DISP" item. 5. Press the DISPLAY key to return to the measurement screen. The display appearance changes as shown below.

  • Page 56: Maximum And Minimum Sound Pressure Level Measurement

    Sound Pressure Level Measurement Maximum and Minimum Sound Pressure Level Measurement The maximum and minimum sound pressure level for a given measurement interval can be measured. To make the measurement, carry out the following steps. 1. Set the power switch on the side of the unit to ON and wait until the measurement screen appears.
  • Page 57 Sound Pressure Level Measurement 9. Use the TIME CONST key to select the desired time constant setting. Normally, the "FAST" setting should be used. 10. Use the LEVEL UP/DOWN keys to select the level range. Choose a setting in which the "OVER"...

  • Page 58: Waveform Peak Hold Measurement (L Peak )

    Sound Pressure Level Measurement Waveform Peak Hold Measurement (L peak The waveform peak sound pressure level for a given measurement interval can be mea- sured. This measurement is carried out in the sub channel. To make the measurement, carry out the following steps. 1.
  • Page 59 Sound Pressure Level Measurement 8. Press the DISPLAY key to bring up the DISPLAY menu screen. 9. Set "SUB DISP" to ON. 10. Set "PEAK DISP" to ON. 11. Press the DISPLAY key to return to the measurement screen. 12. Use the SLM / 1/1 / 1/3 key to activate the sound pressure level measurement screen. 13.
  • Page 60 Sound Pressure Level Measurement 14. Press the START/STOP key. The LED indicator and the mark on the display start to flash, and the waveform peak hold measurement begins. When the measurement time set in step 4 has elapsed, the measurement stops auto- matically.

  • Page 61: Equivalent Continuous Sound Pressure Level Measurement (L Eq )

    Sound Pressure Level Measurement Equivalent Continuous Sound Pressure Level Measurement To make the equivalent continuous sound pressure level measurement, carry out the fol- lowing steps. 1. Set the power switch on the side of the unit to ON and wait until the measurement screen appears.
  • Page 62 Sound Pressure Level Measurement 10. Use the LEVEL UP/DOWN keys to select the level range. Choose a setting in which the "OVER" and "UNDER" indications do not appear (the bar graph should register to about the middle of the range). 11.

  • Page 63: Sound Exposure Level Measurement (Lae )

    Sound Pressure Level Measurement Sound Exposure Level Measurement (L To make the sound exposure level measurement, carry out the following steps. The proce- dure is almost identical to the equivalent continuous sound pressure level measurement. 1. Set the power switch on the side of the unit to ON and wait until the measurement screen appears.

  • Page 64: Takt-Max Sound Pressure Level Measurement (L Tm3 , L Tm5 )

    Sound Pressure Level Measurement When the measurement time set in step 4 has elapsed, the measurement stops auto- matically. When wishing to terminate the measurement earlier, press the START/ STOP key. If an overload condition has occurred at least once during the measurement, the "OVER"...
  • Page 65 Sound Pressure Level Measurement 6. Press the DISPLAY key to bring up the DISPLAY menu screen. 7. Set "SUB DISP" to ON and set "ADD DISP" to "Ltm3/Ltm5". 8. Press the SETUP key to call up the SETUP menu screen. 9.
  • Page 66 Sound Pressure Level Measurement 11. Use the SLM / 1/1 / 1/3 key to activate the sound pressure level measurement screen. 12. Use the LEVEL UP/DOWN keys to select the level range. Choose a setting in which the "OVER" and "UNDER" indications do not appear (the bar graph should register to about the middle of the range).

  • Page 67: Percentile Sound Pressure Level Measurement (L X )

    Sound Pressure Level Measurement Percentile Sound Pressure Level Measurement (L To make the percentile sound pressure level measurement, carry out the following steps. The procedure is almost identical to the equivalent continuous sound pressure level mea- surement. 1. Set the power switch on the side of the unit to ON and wait until the measurement screen appears.
  • Page 68 Sound Pressure Level Measurement 7. Select up to five Lx settings out of L1 to Leq. If five settings are already selected and you wish to use other settings, turn unused settings OFF first. 8. Press the DISPLAY key to return to the original screen. 9.

  • Page 69: 1/1-Octave And 1/3-Octave Analysis

    1/1-Octave and 1/3-Octave Analysis Note If measurement settings such as level range or frequency weighting were changed during pause in instantaneous value mode, the new settings will apply immediately when pause is released. If measurement settings such as level range or frequency weighting were changed after processing, the new settings will be effective only when processing the next measure- ment.

  • Page 70: 1/1-Octave And 1/3-Octave Analysis For Maximum And Minimum Level

    1/1-Octave and 1/3-Octave Analysis 1/1-Octave and 1/3-Octave Analysis for Maximum and Minimum Level (L To make the measurement, carry out the following steps. The procedure is almost identi- cal to the instantaneous value measurement. 1. Set the power switch on the side of the unit to ON. Call up the DISPLAY menu screen by pressing the DISPLAY key, make the neces- sary settings, and press the DISPLAY key again to close the menu.

  • Page 71: 1/1-Octave And 1/3-Octave Analysis For Equivalent Continuous

    1/1-Octave and 1/3-Octave Analysis 1/1-Octave and 1/3-Octave Analysis for Equivalent Continuous Sound Pressure Level (L To make the measurement, carry out the following steps. The procedure is almost identi- cal to the instantaneous value measurement. 1. Set the power switch on the side of the unit to ON. Call up the DISPLAY menu screen by pressing the DISPLAY key and make the necessary settings.

  • Page 72: 1/1-Octave And 1/3-Octave Analysis For Percentile Sound Pressure Level

    1/1-Octave and 1/3-Octave Analysis 1/1-Octave and 1/3-Octave Analysis for Percentile Sound Pres- sure Level (L To make the measurement, carry out the following steps. The procedure is almost identi- cal to the instantaneous value measurement. 1. Set the power switch on the side of the unit to ON. Call up the DISPLAY menu screen by pressing the DISPLAY key and make the necessary settings.

  • Page 73: Explanation Of Analysis Screens

    1/1-Octave and 1/3-Octave Analysis Explanation of Analysis Screens 1/1-octave analysis The staircase shape on the display represents the 1/1-octave analysis result. From left, the bars correspond to 16, 31.5, 63, 125, 250, 500, 1 k, 2 k, 4 k, 8 kHz. To read the levels at these frequencies, use the keys to move the marker to the desired point.
  • Page 74 1/1-Octave and 1/3-Octave Analysis 1/3-octave analysis The staircase shape on the display represents the 1/3-octave analysis result. From left, the bars correspond to 12.5, 16, 20, 25, 31.5, 40, 50, 63, 80, 100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1 k, 1.25 k, 1.6 k, 2 k, 2.5 k, 3.15 k, 4 k, 5 k, 6.3 k, 8 k, 10 k, 12.5 kHz. To read the levels at these frequencies, use the and keys to move the marker to the desired point.

  • Page 75: 1/1-Octave And 1/3-Octave Analysis Precaution

    1/1-Octave and 1/3-Octave Analysis Numeric display Because it will be difficult to read all numeric values from the 1/1-octave and 1/3-octave screen, the numeric display function should be used for this purpose. Use the GRP/NUM/ L-T key to toggle between the graphical and numeric display. The numeric readings are shown in list format with the frequency on the left and the level on the right.

  • Page 76: Data Exclusion (Back-Erase) Function

    Data Exclusion (Back-Erase) Function When a measurement is being carried out and data are being processed, the PAUSE/ CONT key can be used to suspend the measurement. Normally, data up to the point at which the PAUSE/CONT key was pressed will be included in processing, but the data exclusion function makes it possible to exclude (back erase) data from an interval of 1 to 5 seconds before the key was pressed.
  • Page 77 Data Exclusion (Back-Erase) Function When the PAUSE/CONT key is pressed during measurement, the pause mark appears, the indication "BE" is shown on the top right of the display for about a second, and the data are back-erased. The measurement time is also reduced by the number of seconds set for the back-erase function.

  • Page 78: Trigger Function

    Trigger Function The NA-27 incorporates three kinds of trigger functions: level trigger, external trigger, and time trigger. The trigger can also be disabled completely. Trigger mode selection 1. Press the SETUP key to call up the SETUP menu screen. (For an explanation of how to use the SETUP menu screen, refer to page 30.) 2.
  • Page 79 Trigger Function When the trigger function is enabled, the indication "TRG" appears in the top left of the display. When the START/STOP key or the STORE key is pressed, the indication "TRG" is shown in reverse, and the unit goes into standby mode until the trigger condition is fulfilled. When the trigger condition is fulfilled, the "TRG"...
  • Page 80 Trigger Function Level trigger Level setting range: 10 to 140 dB in 1 dB steps Slope: + / - 1. Set the trigger level. 2. Set the slope. When set to (+), the measurement starts when the input signal exceeds the trigger level.
  • Page 81 Trigger Function External trigger The external trigger can either be a CMOS logic-level signal supplied to the trigger input or it can be activated by shortening the trigger input terminals. A. Using a CMOS logic-level signal 1. Set the power switch on the side of the unit to OFF and connect the trigger cable. 2.
  • Page 82 Trigger Function B. Shorting the trigger input 1. Set the power switch on the side of the unit to OFF and connect the trigger cable. 2. When the connection has been established, set the power switch to ON and use the SETUP menu screen to select the setting "EXTRN"...
  • Page 83 Trigger Function Time trigger TIME TRG (Measurement start time): 00 h 00 m to 23 h 59 m in 1 minute steps PERIOD (Measurement repeat interval): 0 h to 24 h in 1 hour steps 1. Set the measurement start time with the "TIME TRG" item. 2.

  • Page 84: Delayed Measurement

    Delayed Measurement The delayed measurement function allows the user to complete all preparations and per- form the steps for measurement start, while having the actual measurement start only after a preset delay time. 1. Press the SETUP key to call up the SETUP menu screen. (For an explanation of how to use the SETUP menu screen, refer to page 30.) 2.
  • Page 85 Delayed Measurement If the trigger function is used concurrently, the delay time starts at the trigger point.

  • Page 86: Memory Functions

    Memory Functions The NA-27 incorporates a memory that allows manual and automatic storing of measure- ment data ("mass memory") and a separate memory for measurement parameter settings ("condition memory"). Stored measurement results can be displayed by pressing the RE- CALL key. To protect stored data, the mass memory can be set to read-only.
  • Page 87 Memory Functions Group store 200 data Store interval: measurement time interval The memory upper limit can be set with the "NUM" item on the MEMORY menu screen, as described on page 39.

  • Page 88: Manual (Sound Pressure Level Mode)

    Memory Functions Manual (Sound Pressure Level Mode) Storing data in memory At the point where the STORE key is pressed, the current instantaneous value and the various processing results are stored in memory. The procedure is as described below. 1. Set the power switch on the side of the unit to ON and wait until the measurement screen appears.
  • Page 89 Memory Functions 6. Press the DISPLAY key to call up the DISPLAY menu screen. 7. Set "MAIN ADD DISP" and other items to the desired settings. 8. Press the DISPLAY key to return to the original measurement screen. 9. Use the SLM / 1/1 / 1/3 key to activate the sound pressure level measurement screen.
  • Page 90 Memory Functions Reading from memory The procedure for reading data from memory is described below. 1. Press the RECALL key. 2. Use the INC and DEC keys to select the memory address from which you want to display data. 3. Use the OPE MODE key to select the processing type for display (L etc.) The date/time shown on the display is the processing start date/time.

  • Page 91: Auto (Sound Pressure Level Mode) Single Store

    Memory Functions Auto (Sound Pressure Level Mode) Single Store Storing data in memory 1. Set the power switch on the side of the unit to ON and wait until the measurement screen appears. 2. Press the MEMORY key to call up the MEMORY menu screen. (For an explanation of how to use the MEMORY menu screen, refer to page 32.) 3.
  • Page 92 Memory Functions 7. Press the DISPLAY key to call up the DISPLAY menu screen. 8. Set "MAIN ADD DISP" and other items to the desired settings. 9. Press the DISPLAY key to return to the original measurement screen. 10. Use the SLM / 1/1 / 1/3 key to activate the sound pressure level measurement screen.
  • Page 93 Memory Functions Reading from memory The procedure for reading data from memory is described below. 1. Press the RECALL key. 2. Use the INC and DEC keys to select the memory address from which you want to display data. The date/time is indicated as follows. Instantaneous values: Date/time when instantaneous value was stored.

  • Page 94: Auto (Sound Pressure Level Mode) Group Store

    Memory Functions Auto (Sound Pressure Level Mode) Group Store Storing data in memory The procedure for storing data in memory is described below. 1. Set the power switch on the side of the unit to ON and wait until the measurement screen appears.
  • Page 95 Memory Functions 7. Press the DISPLAY key to call up the DISPLAY menu screen. 8. Set "MAIN ADD DISP" and other items to the desired settings. 9. Press the DISPLAY key to return to the original measurement screen. 10. Use the SLM / 1/1 / 1/3 key to activate the sound pressure level measurement screen.
  • Page 96 Memory Functions Reading from memory The procedure for reading data from memory is described below. 1. Press the RECALL key. 2. Use the INC and DEC keys to select the memory address from which you want to display data. 3. Use the OPE MODE key to select the processing type for display (L etc.) The date/time shown on the display is the processing start date/time.

  • Page 97: Manual (Frequency Analysis Mode)

    Memory Functions Manual (Frequency Analysis Mode) Storing data in memory At the point where the STORE key is pressed, the current instantaneous value and the various processing results are stored in memory. The procedure is as described below. 1. Set the power switch on the side of the unit to ON and wait until the measurement screen appears.
  • Page 98 Memory Functions Reading from memory The procedure for reading data from memory is described below. 1. Press the RECALL key. 2. Use the INC and DEC keys to select the memory address from which you want to display data. 3. Use the OPE MODE key to select the processing type for display (L etc.).

  • Page 99: Auto (Frequency Analysis Mode) Single Store

    Memory Functions Auto (Frequency Analysis Mode) Single Store Storing data in memory The procedure for storing data in memory is described below. 1. Set the power switch on the side of the unit to ON and wait until the measurement screen appears.
  • Page 100 Memory Functions 7. Press the DISPLAY key to call up the DISPLAY menu screen. 8. Set "MAIN ADD DISP" and other items to the desired settings. 9. Press the DISPLAY key to return to the original measurement screen. 10. Use the SLM / 1/1 / 1/3 key to activate the sound pressure level measurement screen.
  • Page 101 Memory Functions Pressing the STORE key again causes the process to be repeated from step 12. Upper limit can be set with MEMORY menu screen. Reading from memory The procedure for reading data from memory is described below. 1. Press the RECALL key. 2.
  • Page 102 Memory Functions 2. When moving the cursor with the keys, the frequency and level displayed at the right of the screen changes. The level-time display contains the following information. 1. Use the INC and DEC keys to select the memory address from which you want to display data.

  • Page 103: Auto (Frequency Analysis Mode) Group Store

    Memory Functions Auto (Frequency Analysis Mode) Group Store Storing data in memory The procedure for storing data in memory is described below. 1. Set the power switch on the side of the unit to ON and wait until the measurement screen appears.
  • Page 104 Memory Functions 7. Press the DISPLAY key to call up the DISPLAY menu screen. 8. Set "MAIN ADD DISP" and other items to the desired settings. 9. Press the DISPLAY key to return to the original measurement screen. 10. Use the SLM / 1/1 / 1/3 key to activate the sound pressure level measurement screen.
  • Page 105 Memory Functions Pressing the STORE key again causes the process to be repeated from step 12. * Upper limit can be set with MEMORY menu screen. Reading from memory The procedure for reading data from memory is described below. 1. Press the RECALL key. 2.
  • Page 106 Memory Functions 1. Use the INC and DEC keys to select the memory address from which you want to display data. 2. Use the OPE MODE key to select the processing type for display (L etc.). 3. When moving the cursor with the keys, the frequency and level displayed at the right of the screen changes.
  • Page 107 Memory Functions An example for 1/1 and 1/5 compression is shown below. 3. Use the keys to select the frequency band. 4. Use the OPE MODE key to select the type of processing.

  • Page 108: Erasing Data

    Memory Functions Erasing Data All data stored in an address block can be erased as follows. Take care not to accidentally erase data that you want to keep. 1. Press the MEMORY key to call up the MEMORY menu screen. 2.

  • Page 109: Recall Processing

    Memory Functions Recall Processing Using the recall processing function, power average (P_AVE), power sum (P_SUM), and reverb time (REVERB) can be calculated. The following explanation is for power average (P_AVE), but the procedure for other functions is identical. 1. Store data using the auto store function for frequency analysis in single (p. 89) or group (p.
  • Page 110 Memory Functions 6. Use the INC and DEC keys to select the processing start address. (The left border of the screen corresponds to the processing start address.) 7. Use the keys to select the processing end address. 8. The bottom of the screen shows "P_AVE .

  • Page 111: Remote Control (Na-27Rc1)

    The key also serves to terminate the store process. A, C keys Serve to select frequency weighting for the main channel. A: "A" characteristics C: "C" characteristics PRINT key Serves to print out the display contents of the NA-27 on a connecting printer (DPU-414, CP-10, CP-11).
  • Page 112 Remote Control To use the remote control, insert two IEC R03 (size AAA) batteries in the battery compart- ment on the rear. 1. Push the cover of the battery compartment down in direction of the arrow mark and slide it off. 2.

  • Page 113: Technical Notes

    Microphone Measurements of sound pressure level can be carried out with a variety of microphone types. The precision integral sound pressure level meter NA-27 employs the prepolarized condenser microphone UC-53A that is compact and delivers stable and reliable response. Construction and Operation Principle As shown in the drawing below, a prepolarized condenser microphone consists of four main parts: diaphragm, backplate, insulator, and housing.
  • Page 114 Technical Notes Frequency Response The frequency response of a sound field microphone is expressed as the frequency re- sponse in the reference direction of incidence (0º). The diagram below shows an example for the frequency response of the microphone UC-53A.
  • Page 115 The directional characteristics of a microphone is a measure of its differing sensitivity for sound waves arriving from various angles. Since the prepolarized condenser microphone used in the NA-27 is a pressure-sensitive type, it should be equally sensitive in all direc- tions. However, refraction and cavity effects cause a certain microphone directional char- acteristics at high frequencies.
  • Page 116 Technical Notes Thermal Characteristics The thermal characteristics of a microphone indicate how sensitivity changes at various temperatures. This is influenced by the choice of materials and the design of the micro- phone. Normally, materials with a linear expansion coefficient are used. The diagrams below show the thermal characteristics of the microphone UC-53A.
  • Page 117 Technical Notes Microphone (UC-53A) Specifications Nominal diameter: 1/2 inch Sensitivity: -28 dB (0 dB = 1 V/Pa at 1000 Hz) Frequency response: 10 to 20000 Hz Capacitance: 12 pF Diaphragm type: Titan alloy film Temperature coefficient: +0.005 dB/ºC (at 250 Hz) Humidity-dependent sensitivity change: 0.1 dB or less (at 250 Hz, RH below 95%, no condensation) Dimensions:...

  • Page 118: Preamplifier

    Technical Notes Preamplifier Preamplifier Requirement Since the condenser microphone is a small-capacity transducer, it has high impedance, especially at low frequencies. Therefore a very high load resistance is required to ensure uniform response extending to the low frequency range. The relationship between the microphone capacitance and the low-range cutoff frequency can be expressed as follows.

  • Page 119: Microphone Extension Cable (Ec-04 Series)

    Technical Notes Microphone Extension Cable (EC-04 series) To reduce measurement deviations due to refraction effects and the acoustic influence of the operator, the microphone/preamplifier assembly can be detached from the main unit and connected via an extension cable. Optional cables are listed in the table below. 1.
  • Page 120 Technical Notes 4. When mounting the microphone/preamplifier on a tripod, first fasten the micro- phone holder (supplied with the extension cable) to the tripod. Then insert the ex- tension cable connector into the microphone holder.
  • Page 121 Technical Notes When the output of the microphone/preamplifier is routed through an extension cable, certain limitations regarding measurable sound pressure level and frequency range will apply. This is due to the influence of the cable capacitance. The longer the cable, the lower the measurable sound pressure level and the lower the frequency limit.

  • Page 122: Amplifier Circuit Configuration

    Technical Notes Amplifier Circuit Configuration The amplifier circuit configuration and level diagram of the NA-27 are shown below. The degree of attenuation and degree of amplification depends on the level range setting.

  • Page 123: Frequency Weighting Network

    Technical Notes Frequency Weighting Network The NA-27 provides a choice between "A", "C" and "Flat" frequency weighting. The elec- trical characteristics of the weighting circuitry are as shown below. The volume impression (loudness) of a sound depends not only on the sound pressure level, but also on the frequency.

  • Page 124: Rms Detection Circuit

    The crest factor is defined as crest value divided by effective value. If the signal type is known, the crest factor can be calculated precisely. The rms detection error of the NA-27 is about ± 0.2 dB for an input signal with a crest factor of 3.
  • Page 125 "Slow" setting is used to determine the maximum level for each noise event. The "10 ms" setting of the NA-27 results in a very short time weighting, enabling the meter to closely follow noise fluctuations.
  • Page 126 Technical Notes Time weightings and time constant The time weighting circuit of the sound pressure level meter performs index averaging on the square of the sound pressure signal. The equivalent circuit is shown at right. τ is the time weighting, which equals CR. The response of the index averaging circuit to a single burst signal is shown below.

  • Page 127: Measurement Functions

    Expressing the above equation for sound pressure level yields the following equation. : Instantaneous sound pressure level A(t) In the sound pressure level meter NA-27, this statement is used as reference, and digital processing to determine L is carried out according to the following equation.
  • Page 128 (percentile sound pressure level) is the sound pressure level which was exceeded for x percent of the measurement time. The NA-27 allows the user to select five values for x (from 1 to 99, in 1-percent steps), and calculates the time percentile level for these five values simultaneously.
  • Page 129 (maximum and minimum sound pressure level) is the maximum sound pressure level and L the minimum sound pressure level encountered during a measurement. In the NA-27, the sampling interval for A/D conver- sion is 10 ms (100 samples per second), and the L and L values since the start of the measurement are stored.

  • Page 130: Noise Floor

    Technical Notes Noise Floor The diagrams below show the residual noise of the NA-27, in the frequency weighting "A", "C" and "Flat" positions. The measurement was made with a 1/3 octave filter and a frequency analyzer.

  • Page 131: Background Noise

    Technical Notes Background Noise When measuring a certain sound in a certain location, all other sounds present at that location except the measurement target sound are background noise (also called ambient noise or dark noise). Since the sound pressure level meter will display the combination of target sound and background noise, the amount of background noise must be taken into consideration when determining the level of the target sound.

  • Page 132: Windscreen (Ws-02)

    Technical Notes Windscreen (WS-02) During outdoor measurements or measurement of ventilation devices, wind noise can fal- sify measurement results. To counter such problems, the supplied windscreen WS-02 should be mounted on the microphone. The characteristics of the WS-02 are shown be- low.
  • Page 133 Technical Notes...
  • Page 134 Technical Notes...

  • Page 135: I/O Connector

    Technical Notes I/O Connector The I/O connector on the NA-27 serves for input of control signals and input/output of data. It has the following functions. Measurement data output to printer DPU-414, CP-10, CP-11 (with printer cable of 25 pins, male, straight type and communication cable for...

  • Page 136: 1/1-Octave Filter Characteristics

    Technical Notes 1/1-Octave Filter Characteristics The characteristics of the 1/1-octave filter in the NA-27 correspond to the JIS C 1513- 1983 Type II, ANSI S1.11 Type 1D, and IEC 1260 1995 Class 1 specifications. The graph below shows the allowable attenuation tolerance according to JIS and the actual...

  • Page 137: 1/3-Octave Filter Characteristics

    Technical Notes 1/3-Octave Filter Characteristics The characteristics of the 1/3-octave filter in the NA-27 correspond to the JIS C 1513- 1983 Type III, ANSI S1.11 Type 1D, and IEC 1260 1995 Class 1 specifications. The graph below shows the allowable attenuation tolerance according to JIS and the actual characteristics of the 1/3-octave filter in the NA-27.

  • Page 138: Error Messages

    Error Messages Error messages are shown when the unit is turned on. Messages 1 through 6 disappear after 3 seconds or when any key is pressed.
  • Page 139 Error Messages...

  • Page 140: Optional Accessories

    Optional Accessories Microphone Extension Cables (EC-04 series) To reduce measurement deviations due to refraction effects and the acoustic influence of the operator, the microphone can be detached from the unit and connected via an exten- sion cable. Optional cables are listed in the table below. View of EC-04C, EC-04D, EC-04E with drum...

  • Page 141: Level Recorder (Lr-04, Lr-06)

    By connecting a level recorder to the NA-27, the sound pressure level changes over time can be recorded. Connect the AC output on the side of the NA-27 to the level recorder, as shown above. Recording procedure The steps for recording the sound pressure level on a level recorder are shown below.
  • Page 142 Optional Accessories 4. Press the CAL key once more to return the NA-27 to the measurement mode. 5. Use the FREQ WEIGHT key of the NA-27 to set the frequency weighting charac- teristics. The time constant should be set at the level recorder.
  • Page 143 Optional Accessories To record measurement results from the sub channel also, the optional splitter adapter CC-59 is required. Use to two level recorders and connect them as shown below.

  • Page 144: Using A Printer (Dpu-414, Cp-10, Cp-11)

    Optional Accessories Using a Printer (DPU-414, CP-10, CP-11) Data gained during measurement and data stored in the memory of the NA-27 can be printed out on a printer. You can also produce hard copy of the menu screens. Connect the I/O interface on the bottom of the NA-27 to the printer (DPU-414, CP-10, CP-11), using a serial printer cable.
  • Page 145 2) serves for setting the data transfer speed. The ON position means 4800 bps and the OFF position 9600 bps. This setting must match the setting of the NA-27 (see de- scription of I/O menu screen on page 35).
  • Page 146 Optional Accessories Setting the software DIP switches of the DPU-414 Turn on the power while holding down the ON LINE key of the DPU-414. A printout showing the current status of the printer is produced. For details, please refer to the documentation of the DPU-414.
  • Page 147 Optional Accessories Printing measurement parameters 1. Press the key for the desired menu (SETUP, MEMORY, DISPLAY, I/O). 2. Press the PRINT key to print out the current screen. Printing the screen during measurement Pressing the PRINT key causes a hard copy of the current screen (measured level, fre- quency weighting, time constant, overload conditions etc.) to be printed out.
  • Page 148 Optional Accessories Printing when I/O menu is set to SINGLE When the PRINT key is pressed, the current display is printed. Printing when I/O menu is set to SUCCESSIVE A. In sound level meter mode When the PRINT key is pressed, stored numeric data and corresponding addresses are printed, as shown in the example on the right.
  • Page 149 Optional Accessories Printing in recall mode In normal operation (current) mode, printing is always carried out as in SINGLE mode. An example for successive printout of data gathered with group store in a Leq processing mode is shown below.

  • Page 150: Specifications

    Specifications Applicable standards General measurements, precision sound level meters IEC 61672-1:2002 Class 1, IEC 61260:1995 Class1 ANSI S1.11 Type1D, JIS C 1509-1:2005 Class1, JIS C 1514:2002 Class1, JIS C 1513:2002 Class1 IEC 60651 and IEC 60804 was withdrawn and replaced by IEC 61672-1. JIS C 1505 was withdrawn and replaced by JIS C 1509-1.
  • Page 151 Specifications Reference range 50 to 110 dB (Sound level meter mode), 40 to 110 dB (frequency analysis mode) Max. measurement level 140 dB rms, 133 dB at c.f. 3, 143 dB peak for peak hold Noise Floor Typical 17 dB (A) rms, max. 20 dB (A) rms A weighting: Less than 20 dB C weighting:...
  • Page 152 Specifications Frequency analysis mode (display range 70 dB) 70 to 140 dB 60 to 130 dB 50 to 120 dB 40 to 110 dB 30 to 100 dB 20 to 90 dB 10 to 80 dB Overload indication "Over" indication appears at +8 dB over display full-scale value Under range indication "Under"...
  • Page 153 Specifications Group store: Continuous simultaneous storing of all processing results Capacity: 200 data sets Store intervals: Equal to processing time Trigger Level trigger, external trigger, time trigger (processing start conditions) Level trigger: *** dB, + or - slope External trigger: Logic-level falling edge Time trigger: Start time and repeat interval settable...
  • Page 154 Specifications Microphone 1/2-inch prepolarized condenser type Model: UC-53A Sensitivity: -26.5 dB to -29.0 dB (0 dB = 1 V/Pa) Preamplifier NH-20 Inputs and outputs AC output (main channel and sub channel simultaneous output) Display full-scale point: 1 Vrms Output impedance (main): approx. 600 Ω approx.
  • Page 155 Specifications Power requirements Four IEC R14P (size "C") batteries Battery life (at 20ºC, 1/3-octave analysis, continuous operation) Alkaline batteries: approx. 8 hours Manganese batteries: approx. 4 hours External DC power supply 4 to 6 V (from AC adapter NC-94A) Current consumption (at room temperature, 1/3-octave analysis, 5 V): approx.
  • Page 156 Specifications Supplied accessories Carrying case NA-27-S04 Windscreen WS-02 Infrared remote controller NA-27RC1 Miniature screwdriver D-62 Tripod adapter NA-27-S05 Hand strap (attached) NA-09-058 Main batteries IEC R14P Remote controller batteries IEC R03 Backup lithium battery CR-1/3N Product name label NA-27-033 Instruction Manual...
  • Page 157 Specifications Unit: mm Dimensional Drawings...
  • Page 158 No. 41371 06-11 Printed in Japan...

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