Radio Shack 33-2055A Owner's Manual

Digital Sound Level
Meter

Owner’s Manual

Please read before using this equipment.

ˆ

Contents

Features ............................................... 3

Installing the Battery ........................... 5

Making Measurements ........................ 7

Setting the Sound Range ............... 7

Setting the Weighting ..................... 8

Setting the Response ..................... 9

Making Normal Measurements .... 10

Making Maximum Measurements 12

Level Indications .......................... 12

Underrange Indication .......... 13

Overrange Indication ............ 14

Using Data Hold ........................... 15

Making an Integrated Average

Measurement ............................... 16

Making Maximum and Minimum
Measurements During an

Undetermined Time Period .......... 19

Checking Stereo System

Acoustics ...................................... 20

Calibrating the Meter .................... 20

Care .................................................... 21

Specifications ............. ... ... ................. 22

2000 RadioShack Corporation. All Rights Reserved.

©

RadioShack and RadioShack.com are trademarks used

2

by RadioShack Corporation.

ˆ

Features

Your new RadioShack Digital Sound Lev­el Meter precisely measures area noise
and other sound levels. The meter’s digital
design and special measuring features,
such as the bargraph and date hold, en­sure pinpoint accuracy for checking an
acoustic environment. The meter is light­weight and easy to operate.

Note:

This meter should be used for
home/hobbyist use only. This meter
does not meet the requirements set
forth by the American National Stan­dards Institute (ANSI), Standard S1.4.

Your meter also has these features:

3-Digit Liquid Crystal Display

it easy to read sound measurements.

21- Dot Analog Bargraph

visual representation of the measured
sound.

Mode/Condition Indicators

the current mode and status of the meter.

Features

— makes

— gives you a

— show you

3

Wide Sound-Measuring Abilities

—
measures from 50 dB to 126 dB SPL with
seven ranges.

Average or Maximum Sound Level Dis­play

— continuously shows the average
or maximum sound level: per second with
digits, per 0.2 or 0.5 seconds with the bar­graph.

Tripod Ready

meter to a tripod (

— lets you attach the

1

/4-inch) for more accu-

rate sound measurements.

Date Hold

— lets you

freeze

a measure-

ment on the display.

Integrated Averaging

— measures the
integrated average, and holds the maxi­mum and minimum sound levels for a pre­set period.

Underrange and Overrange Indicators

— show you when the sound level reading
is under or over the selected range.

A and C Weighting

— lets you select ei­ther type of weighting to suit the purpose
of the measurement.

Selectable Bargraph Response

— lets
you select a slow (0.5 second) or fast (0.2
second) bargraph response.

4

Features

Peak Level Indication

when the meter registers the maximum
level measurement on the bargraph.

— shows you

Reset Button

measurements from the meter’s memory
and begin a new measurement.

9-Volt Battery Operation

power the meter with a 9-volt battery.

Phono Output Jack

the meter to your stereo system or test
equipment.

Low-Battery Indicator

when the battery needs to be replaced.

ˆ

Installing the

— lets you clear the current

— lets you

— lets you connect

— shows you

Battery

The meter requires one 9-volt battery for
operation. For the best operation and
longest life, we recommend RadioShack
alkaline batteries. Follow these steps to
install the battery.

Installing the Battery

5

1. Set

RANGE

to

OFF

.

2. Remove the bat­tery compartment
cover by pressing
in both sides and lifting off the cover.

3. Install the battery as indicated by the
diagram marked in the compartment.
Place the battery over the red ribbon
to make it easy to remove the battery
later.

4. Replace the battery compartment
cover.

Notes:

• When you are not using the meter,
set

RANGE

to

OFF

.

• If you will not use the meter for a
week or more, remove the battery.

• When the battery becomes low,

BATT

appears on the display.

6

Installing the Battery

Replace the battery with a fresh one
of the same type.

ˆ

Making

Measurements

SETTING THE SOUND
RANGE

The meter can measure sound levels
within seven different ranges. Each range
covers 20 dB. The number of each range
represents the center of the range. For ex-

RANGE

ample, if you set
measures sound levels from 60 to 80 dB.

to 70, the meter

Making Measurements

7

RANGE

Set

for the approximate sound lev­el you want to measure. If you do not
know the sound level, start with the high­est range setting (120) and gradually re­duce the setting. When the measured
value is lower or higher than the set
range, an underrange or overrange indi­cator appears. See “Level Indications” on
Page 12.

Notes:

• If you set

RANGE

to

120

, the meter
measures sound levels from 110 dB
to 126 dB.

• If you change the range setting during
a measurement, you clear all the cur­rent data and a normal continuous
measurement resumes.

SETTING THE WEIGHTING

WEIGHTING

weighting characteristics, which deter­mine the meter’s frequency response
curve. You can select

weighting

A-weighting has A-curve frequency char­acteristics. This setting causes the meter
to respond mainly to frequencies in the

8

lets you set the meter’s

A-weighting

or

.

Making Measurements

C-

500-to-10,000 Hz range, which is the hu­man ear’s most sensitive range. Select A­weighting to determine an area’s noise­level. Take measurements at several dif­ferent points in the area.

C-weighting has C-curve (flat) frequency
characteristics. This setting causes the
meter to respond mainly to frequencies in
the 32 to 10,000 Hz range. Select C­weighting to measure sound levels of mu­sical material.

When you set

RANGE

to

OFF

, the meter

automatically selects C-weighting.

WEIGHTING

Press

to change the weight-

ing between A and C.
The display shows the current setting

WEIGHTING A

(

Note:

You can change the weighting set-

WEIGHTING C

or

).

ting only during a continuous average or
maximum measurement.

SETTING THE RESPONSE

RESPONSE

which the meter revises the bargraph
sound level reading. There are two set­tings –

lets you set the interval at

fast

Making Measurements

and

slow

. When you set

9

RANGE

sets the response for
At the fast setting, the meter revises the

bargraph reading after about every 0.2
seconds. At the slow setting, the meter re­vises the reading after about every 0.5
seconds.

to

OFF

, the meter automatically

fast

.

RESPONSE

Press
graph’s response between fast and slow.

The display shows the selected setting

RESPONSE SLOW

(

FAST

).

Note:

You can change the response set­ting only during a continuous average or
maximum measurement.

to change the bar-

RESPONSE

or

MAKING NORMAL
MEASUREMENTS

Follow these steps to measure the aver­age sound level.

RANGE

1. Set
range. If you do not know the sound
level, start at the highest range set­ting (120) and reduce the setting until
you get a reading. (See “Setting the

10

for the desired sound

Making Measurements

Sound Range” on Page 7 and “Level
Indications” on Page 12.)

2. Set the weighting and response. (See
“Setting the Weighting” on Page 8
and “Setting the Response” on
Page 9.)

3. Face the sound source. Then hold
the meter to one side and point its
microphone at the sound source.

The meter begins to display the

tinuous average

sound level. This is

con-

the average sound level during a 1­second sampling period, which the
meter updates once per second. The
bargraph shows the continuous aver­age for either a 0.2-second or 0.5­second period, depending on the
response setting.

When you complete a measurement, set

RANGE

OFF

to

.

Making Measurements

11

MAKING MAXIMUM
MEASUREMENTS

To measure the continuous maximum
sound level, follow the steps in “Making
Normal Measurements” on Page 10 and

MAX

press
play.

The meter displays only the loudest mea­sured sound level during the 1-second
sampling period. The bargraph shows the
maximum level of every 0.2 or 0.5 sec­onds. The bargraph segment that corre­sponds to the peak reading stays on the
display for 2 seconds or until the meter
measures a higher maximum level.

MAX

Press
ous maximum measurement and resume
a normal continuous average measure­ment.

MAX

so

again to cancel the continu-

appears on the dis-

LEVEL INDICATIONS

The meter displays the sound level using
numbers and a bar graph. The numbers
show the sound level in dB within ±10 dB
of the selected range and the meter up­dates the reading once per second.

12

Making Measurements

The bargraph’s center point represents
the center level of the selected range (60
dB, 70 dB, 80 dB, and so on).

The points to the left of the center indicate
measurements less than the center level
(down to –10 dB below the selected
range). The points to the right of the cen­ter indicate measurements greater than
the center level (up to +10 dB above the
selected range).

The bargraph updates every 0.2 or 0.5
seconds, depending on the response set­ting. (See “Setting the Response” on
Page 9.)

Underrange Indication

When the measured sound level is lower
than the lowest sound level of the select-

LO

ed range,

appears and the bargraph

Making Measurements

13

disappears. If this happens, select a lower
range.

Overrange Indication

When the measured sound level is higher
than the highest sound level of the select­ed range (except for the 120 dB range),
the bargraph and digits that represent the
next higher range flash on the display.

For example, if the meter measures 91 dB

90

in the 80 dB range,
flash.

and the bargraph

If the meter measures more than 126 dB
in the 120 dB range,
flash.

14

Making Measurements

126

and the bargaph

If you get an overrange indication, change
the range setting until you get a reading in
the upper half of the range (0 to + 10 dB).

Notes:

• The underrange or overrange indica­tion can also appear when you recall
a measurement using data hold and
the measurement is under or over the
selected range. See “Using Data
Hold.”

• The meter cannot measure sound
levels lower than 50 dB or higher than
126 dB.

USING DATA HOLD

The data-hold function lets you store the
current measurements in memory and

freeze

a measurements on the display.
The meter stores the continuous average,
the maximum, and the minimum sound
levels for the last 1 second.

To store the current measurements, press

DH

during a continuous average or maxi­mum measurement. The last average
measurement or last maximum measure-

MAX

ment (with

) appears on the display.

Making Measurements

15

MAX

Press

to freeze the current maximum

measurement if the last average mea-

MAX

surement (without

MAX

Press

again to return to the average

) is on the display.

measurement.

MIN

Press
measurement.
display. Press

to freeze the current minimum

MIN

also appears on the

MIN

again to return to the

average measurement.

RESET

Press

to return to a continuous av-

erage or maximum measurement.

Notes:

• You cannot change the response and

weighting settings during data hold.

RANGE

• When you set

to a different
range during data hold, you cancel
the function and return to a continu­ous measurement.

MAKING AN INTEGRATED
AVERAGE MEASUREMENT

Follow these steps to monitor the sound
level and average the measurement over
a preset time period of 1 to 199 seconds.
The meter stores the average, the maxi-

16

Making Measurements

mum, and the minimum sound levels dur­ing the set time period.

DH

1. Press

for about 2 seconds during
a continuous average or maximum
measurement. 1 appears on the dis­play.

2. Repeatedly press or hold down

MIN

or

to set the desired measuring

MAX

period from 1 to 199 seconds.

3. Position the meter for the measure­ment.

RESET

4. Press

to start the monitoring.

The meter measures the integrated aver­age, maximum, and minimum sound lev­els for the set time. The meter updates the
current integrated average display every
second and

MIN

and

MAX

flash until the

set time ends.

DH

When the set time ends,

MIN

MAX

and

continue to flash. The

Making Measurements

appears, and

17

meter displays the total integrated aver­age sound level.

MAX

Press
level for the set time. Press

to display the maximum sound

MAX

again to
return to the total integrated average
sound level.

MIN

Press
level for the set time. Press

to display the minimum sound

MIN

again to
return to the total integrated average
sound level.

RESET

Press

after you check the integrat­ed average sound level and the maximum
or minimum sound level. The meter re­sumes a continuous average measure­ment.

Note:

If you change the

RANGE

setting
during an integrated measurement, you
clear any stored data and a normal contin­uous average measurement resumes.

18

Making Measurements

You must repeat the procedure for making
an integrated average measurement.

MAKING MAXIMUM AND
MINIMUM MEASUREMENTS
DURING AN UNDETERMINED
TIME PERIOD

You can check the maximum and mini­mum sound level over any length of time.
To do so, press
ous average or maximum average mea­surement.

At the end of the desired time period,

DH

press
To display the maximum sound level dur-

ing the time period, press
and
average sound level appears. Press
again to return to the average sound level.

. DH appears.

MAX

flash on the display and the last

RESET

during a continu-

MAX

if both

MIN

MAX

Note:

If only
the meter is already showing the maxi­mum sound level during the time period.

Press
level during the time period. Press
again to return to the last average sound
level.

MIN

flashes on the display,

MIN

to display the minimum sound

Making Measurements

MIN

19

RESET

Press
mum or minimum sound level. The meter
resumes a normal continuous average or
maximum measurement.

after you check the maxi-

CHECKING STEREO
SYSTEM ACOUSTICS

To check the sound of a stereo system,
use a test recording that produces pure
tones, one at a time, at intervals that span
the entire audio spectrum.

Use C-weighting with either slow or fast
response.

Make a graph or table that shows the
sound level each tone generates. This
gives you a clear idea of the frequency re­sponse of the total audio system – includ­ing the room. To smooth out the
response, adjust the tone control, vary the
speaker placement, and use a frequency
equalizer.

CALIBRATING THE METER

The recessed calibration control (labeled

CAL

on the meter’s left side) is intended

for service technicians only.

20

Making Measurements

Attempting to calibrate the meter yourself
might result in inaccurate measurements.

ˆ

Care

Your RadioShack Digital Sound Level
Meter is an example of superior design
and craftsmanship. The following sugges­tions will help you care for the meter so
you can enjoy it for years.

• Keep the meter dry. If it gets wet,
wipe it dry immediately. Liquids might
contain minerals that can corrode
electronic circuits.

• Use and store the meter only in nor­mal temperature environments. Tem­perature extremes can shorten the
life of electronic devices and distort or
melt plastic parts.

• Handle the meter gently and care­fully. Dropping it can damage the cir­cuit boards and cause the meter to
work improperly.

• Keep the meter away from dust and
dirt, which can cause premature wear
of parts.

Care

21

• Wipe the meter with a damp cloth
occasionally to keep the meter look­ing new. Do not use harsh chemicals,
cleaning solvents, or strong deter­gents to clean the meter.

• Use a fresh battery of the recom­mended size and type. Always
remove an old or weak battery. It can
leak chemicals that destroy electronic
circuits.

ˆ

Specifications

Battery.........................................9-volt Alkaline

Microphone......................... Electret Condenser

Range......................................50 dB to 126 dB

Accuracy

Reference...................0 dB = 0.0002 Micro Bar

Weighting .............................................A and C

Display Response ......................Fast and Slow

Signal Output:

............................±

Voltage...................1 Volt Peak-Peak Min.

(Open Circuit, Full Scale at 1 kHz)

Impedance.............. 10 Kilohms Min. Load

Distortion..............Less than 2% at 1 kHz.

(Input: Mic Out, Output: 10 Kohm)

2 dB at 114 dB SPL

0.5 V p-p Output

22

Specifications

Operating Temperature..............32 °F to 122 °F

Storage Temperature............... -40 °F to 149 °F

Dimensions (HxWxD)..6 ¼ × 2 ½ × 1 ¾ Inches

(159 × 64 × 44 mm)

Weight..................................................... 5.8 oz

(165 g Approx.)

Specifications

23

Limited Ninety-Day Warranty

This product is warranted by RadioShack against manufacturing defects
in material and workmanship under normal use for ninety (90) days from
the date of purchase from RadioShack company-owned s tores and au­thorized RadioShack franchisees and dealer s. EXCEPT AS PROVIDED
HEREIN, RadioShack MAKES NO EXPRESS WARRANTIES AND ANY
IMPLIED WARRANTIES, INCLUDING THOSE OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE, ARE LIMITED IN DU­RATION TO THE DURATION OF THE WRITTEN LIMITED WARRAN­TIES CONTAINED HEREIN. EXCEPT AS PROVIDED HEREIN,
RadioShack SHALL HAVE NO LIABILITY OR RESPONSIBILITY TO
CUSTOMER OR ANY OTHER PERSON OR ENTITY WITH RESPECT
TO ANY LIABILITY, LOSS OR DAMAGE CAUSED DIRECTLY OR INDI­RECTLY BY USE OR PERFORMANCE OF THE PRODUCT OR ARIS­ING OUT OF ANY BREACH OF THIS WARRANTY, INCLUDING, BUT
NOT LIMITED TO, ANY DAMAGES RESULTING FROM INCONVE­NIENCE, LOSS OF TIME, DATA, PROPERTY, REVENUE, OR PROFIT
OR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, EVEN IF RadioShack HAS BEEN A DVISED OF TH E POS­SIBILITY OF SUCH DAMAGES.
Some states do not allow limitations on how long an impl ied warranty
lasts or the exclusion or limitation of inciden tal or consequential dam­ages, so the above limitations or exclusions may not apply to you.
In the event of a product defect during the warranty period, take the prod­uct and the RadioShack sales rec eipt as proof of purcha se date to any
RadioShack store. RadioShack will, at its option, unles s otherwise pro­vided by law: (a) correct the defect by pr oduct repair without charge for
parts and labor; (b) replace the product with one of the s ame or similar
design; or (c) refund the purchase price. All rep laced par ts and p ro duc ts,
and products on which a refund is made, become the property of Ra­dioShack. New or reconditioned parts and products may be used in the
performance of warranty service. Repaired or repla ced parts and prod­ucts are warranted for the remainder of the original warranty period. You
will be charged for repair or replacement of the product made after the
expiration of the warranty period.
This warranty does not cover: (a) damage or failure caused by or attribut­able to acts of God, abuse, accident, misuse, improper or abnormal us­age, failure to follow instructions, improper install ation or maintenance,
alteration, lightning or other incidence o f excess voltage or current; (b)
any repairs other than those provided by a RadioShack Au thorized Ser­vice Facility; (c) consumables such a s fuses or batteries; (d) cosmetic
damage; (e) transportation, shipping or insurance costs; or (f) costs of
product removal, installation, set-up service adjustment or reinstallation.
This warranty gives you specific legal rights, and you may also have
other rights which vary from state to state.

RadioShack Customer Relations, 200 Taylor Street, 6th Floor, Fort

Worth, TX 76102

We Service What We Sell

12/99

09A00 811023970E

A

33-2055

Printed in China