Radio Shack 33-2055 User manual

33 -205 5
OWNER'S MANUAL
Pleaseread before using this equipment.

FEATURES
Your new Radio Shack Digital Sound Level
Meter precisely measures area noise and other
sound level. The meter's digital design and
special measuring features, such as the
bargraph and data hold, ensure pinpoint
accuracyfor checking any acoustic environment.
The meter is lightweight and easy to operate.
1
Your meter also hasthesefeatures:
)
&Digit Liquid Crystal Display - makes it easy
to readsound measurements.
21-Dot Analog Bargraph
- gives you a visual
representationof the measuredsound.
Modelcondition lndicators - show you the cur-
rent mode and status of the meter.
Wide Sound-Measuring Abilities
- measures
from 50 dB to 126dB
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
secondswiththe bargraph.
Integrated Averaging - measures the inte-
grated average, and holds the maximum sound
levelsfor a preset period.
Under range and Over range lndicators
-
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 measure-
ment.
Selectable Bargraph Response
- lets you
1 select a slow (0.5 second) or fast (0.2 second)
bargraph response.
Peak Level Indication
- shows you when the
meter registers the maximum level measurement
on the bargraph.
Reset Button
- lets you clear the current mea-
surements from the meter's memory and begin a
new measurement.
9-Volt Battery Operation
- lets you power the
meter with a 9-volt battery.
Tripod Ready - letsyou attach the meter to atri- Phono Output Jack
- lets you connect the
pod 6.35 mm (114-inch) for more accurate sound
, meterto your stereo system or test equipment.
measurements. Low-Battery Indicator
- shows you when the
Data HOI~ - lets you freeze a measurement on ' batteryneeds to be replaced.
the display.
0 1996 InterTANInc.
All RightsResewed.
RadioShack is
a registeredtrademark
used byTandy Corporation.

CONTENTS INSTALLING
THE BATTERY
Installingthe Battery ........................................ 5
MakingMeasurements ..................................... 7
..............................
Settingthe Sound Range 7
....................................
Settingthe Weighting 8
Settingthe Response
.................................. 9
...................
Making NormalMeasurements 10
................
Making MaximumMeasurements 11
.........................................
Level Indications 12
...........................
U nderrange Indication 13
Overrange Indication
............................. 13
..........................................
Using Data Hold 14
Making an Integrated
..........................
Average Measurement 15
Making Maximumand Minimum
MeasurementDuringan
UndeterminedTime Period
................... 17
............
Checking Stereo System Acoustics 18
...................................
Calibratingthe Meter 19
Care and Maintenance
............................. 20
Specifications ................................................. 21
The meter requires one 9-volt battery for opera-
tion. Followthese steps to installthe battery.
1. Set RANGE to OFF.
n
2. Remove the battery compartment cover bv
pressing inboth sides and liftingoff the cover.
-
\
,
Press
3. Install the battery as indiczed by the diagram
marked in the compartment. Place the battery
over the red ribbonto make it easy to remove
the battery later.

r
MAKING MEASUREMENTS
4. Replacethe battery compartment cover.
Notes:
When you are not usingthe meter, set RANGE
to OFF.
If you will not use the meter for a week or
more, removethe battery.
When the battery becomes low, BATT
appears on the display. Replace the battery
with a fresh one of the same type.
SETTING THE SOUND RANGE
The meter can measuresound levels withinseven
different ranges. Each range covers
20 dB. The
number of eachrangerepresentsthe center of the
range. For example, if you set
RANGE to 70, the
meter measuressound levelsfrom 60 to
80 dB.
RANGED
Set RANGE 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 mea-
sured value is lower or higher than the set range,
an under range or over range indicator appears.
See "Level Indications."
Notes:
If you set RANGE to 120, the meter measures
soundlevelsfrom 11
0 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.

SETTINGTHE WEIGHTING
The WEIGHTING button lets you set the meter's
weighting characteristics, which determine the
meter's frequency responsecurve. You can select
A-weightingor C-weighting.
A-weighting has A-curve frequency characteris-
tics. This setting causes the meter to respond
mainly to frequencies in the 500-to-10,000
Hz
range, which is the human ear's most sensitive
range. Select A-weighting to determine an area's
noise-level. Take measurements at several diffe-
rent points inthe area.
C-weightinghas C-curve (flat) frequency charac-
teristics. This setting causes the meter to respond
mainly to frequencies in the 32-to-10,000
Hz
range. Select C-weighting to measure sound le-
vels of musicalmaterial.
I
1
When you set RANGE to OFF, the meter automati-
cally selects C-weighting.
Press WEIGHTING to change the weighting
betweenA and C.
DH RESET MIN MAX
(o r r 01
WEIGHTING RESPONSE
( LJ 0 1
The display shows the current setting
(WEIGHTING
A or WEIGHTING C).
Note: You can change the weighting setting only
during a continuous average or maximum mea-
surement.
SETTINGTHE RESPONSE
The RESPONSE button lets you set the interval at
which the meter revises the bargraph sound level
reading. There are two settings
- fast and slow.
When you set RANGE to OFF, the meter automati-
'
cally sets the responsefor fast.
At the fast setting, the meter revises the bargraph
reading after about 0.2 second. At the slow set-
ting, the meter revises the reading after about
every 0.5 second.
Press RESPONSE to change the bargraph's
responsebetweenfast and slow.
The display shows the selected setting
(RESPONSE
SLOW Or RESPONSE PAST).
Note: You can change the response setting only
during a continuous average or maximum mea-
surement.

MAKING NORMAL
MEASUREMENTS
Followthese steps to measurethe averagesound
level.
1. Set
RANGE for the desired sound 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 sound ~an~e%nd"Level Indications.")
/ m
2. Set the weighting and response. (See "Setting
the Weighting" and "Settingthe Response.")
3. Face the sound source. Then hold the meter
to one side and point its microphone at the
sound source.
sound Source 0.
SW"0 LtVIL YITIR
Sound Level Meter
----
The meter begins to display the continuous
average sound level. This is the average
sound level during a 1-second sampling
period, which the meter updates once per se-
cond. The bargraph shows the continuous
average for either a 0.2-second or 0.5-second
period, dependingon the responsesetting.
4. When you complete a measurement, set
RANGE to OFF.
MAKING MAXIMUM
MEASUREMENTS
To measurethe continuousmaximumsound level,
follow the steps in "Making Normal Measure-
ments" and press
MAX so MAX appears on the
display.
7
I SOUND LEVEL METER
DH RESET MIN MAX -- - - - --
n n 7 '"
The meter displays only the loudest measured
sound level during the 1-secondsampling period.
The bargraph shows the maximum level of every
0.2 or 0.5 seconds. The bargraph segment that
correspondsto the peak readingstays on the dis-
play for 2 seconds or until the meter measures a
higher maximumlevel.

Press MAX again to cancel the continuous maxi-
mum measurement and resume a normal continu-
ous average measurement.
LEVEL INDICATIONS
The meter displays the sound level using num-
bers and a bargraph. The numbers show the
sound level in dB within *I0 dB of the selected
range and the meter updatesthe readingonce per
second.
The bargraph's center point representsthe center
level of the selected range (60 dB, 70 dB, 80 dB,
and so on).
The points to the left of the center indicate mea-
surements less than the center level (downto -10
dB below the selected range). The points to the
right of the center indicate measurementsgreater
than the center level (up to +10 dB above the
selected range).
The bargraph updates every 0.2 or
0.5 second,
depending on the responsesetting. (See "Setting
the Response.")
Underrange Indication
When the measuredsound level is lower than the
lowest level of the selected range,
LO appears
and the bargraph disappears. If this happens,
select a lower range.
,
llEmml
FAST
l WEIGHTING l
dB C
Overrange lndication
When the measured sound level is higher than the
highestsoundlevelof the selectedrange (except for
the 120 dB range),the bargraphand digits that re-
present the next higher rangeflash onthe display.
For example,
if the meter measures 91 dB in the
80 dB range,90 and the bargraphflash.
If the meter measures more than 126 dB in the
120dB range,
126 and the bargraphflash.
If you get an over range indication, change the
RANGE setting untilyou get a reading in the upper
half of the range (0to +10 dB).

Notes:
The under range or over range indication can
also appear when you recall a measurement
using data holdandthe measurement is under
or over the selected range. See "Using Data
Hold."
The meter cannot measure sound levels lower
than
50 dB or higherthan 126dB.
USING DATA HOLD
The data-hold function lets you store the current
measurementsin memory and
freeze a measure-
ment on the display.The meter storesthe continu-
ous average, the maximum, and the minimum
sound levelsfor the last 1second.
To store the current measurements, press
DH du-
ring a continuous average or maximum measure-
ment. The last average measurement or last
maximum measurement (with
MAX) appears on
the display.
DH RESET MIN MAX
(0 0
Press MIN to freeze the current minimum mea-
surement.
MIN also appears onthe display. Press
MIN again to return to the average measurement.
Press
RESET to return to a continuous average or
maximummeasurement.
Notes:
You cannot change the RESPONSE and
WEIGHTING settings during data hold.
When you set RANGE to a different range du-
ring data hold, you cancel the function and
return to a continuous measurement.
MAKINGAN INTEGRATED
AVERAGE MEASUREMENT
Followthese steps to monitor the sound leveland
average the measurement over a preset time
periodof 1 to 199seconds. The meter stores the
average, the maximum, and the minimum sound
levels during the set time period.
1. Press and hold down
DH for about 2 seconds
during a continuous average or maximum
measurement.
1 appears on the display.
Press
MAX to freeze the current maximum mea-
surement if the last average measurement (with-
out
MAX) is on the display. Press MAX again to
return to the average measurement.

2. Repeatedly press, or press and hold down,
MAX or MIN to set the desired measuring
periodfrom 1to 199seconds.
DH RESET MIN MAX
3. Positionthe meter for the measurement.
4. Press RESET 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 untilthe set time ends.
When the set time ends,
DH appears, and MIN
and MAX continueto flash. The meter displaysthe
total integratedaverage sound level.
Press
MAX to display the maximum sound level
for the set time. Press
MAX again to return to the
total integrated average sound level.
Press
MIN to display the minimum sound level for
the set time. Press
MIN again to return to the total
integratedaverage sound level.
Press
RESET after you check the integrated ave-
rage 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 measure-
ment resumes. You must repeat the procedurefor
making an integratedaverage measurement.
MAKING MAXIMUMAND MINIMUM
MEASUREMENTDURINGAN
UNDETERMINEDTIME PERIOD
You can check the maximumand minimumsound
level over any length of time. To do so, press
RESET during a continuous average or maximum
average measurement.
Dl4 RESET MI MAX
(El r a ill
WEIGHTING RESPONSE
/
1 r- r1 7
At the end of the desired time period, press DH.
DH appears.

TO display the maximum sound level during the
CALIBRATING THE METER
time period, press MAX if both MIN and MAX flash
on the display and the last average sound level
The recessedcalibration control (labelled CAL on
appears. press MAX to return to the ave-
the meter's leftside) is intended for service tech-
rage sound level.
nicians only.
Note: If only MIN flashes on the display, the
Attempting to calibrate the meter yourself might
.
meter is already showing the maximum sound
' result ininaccurate measurement.
level duringthe time period.
Press MIN to display the minimum sound level
.
during the time period. Press MIN again to return
to the last average sound level.
Press
RESET after you check the maximum or
minimum sound level. The meter resumes a nor-
mal continuous average or maximum measure-
ment.
CHECKING STEREO SYSTEM
ACOUSTICS
To check the sound of a stereo system, use a test
recordingthat producespure tones, one at a time,
at intervalsthat spanthe entire audio spectrum.
Use C-weightingwith 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 responseof the
total audiosystem -
including the room. To smooth out the response,
adjustthe tone control,vary the speaker placement,
and usea frequency equalizer.