Realistic 31-1987 User manual

PLEASE READ BEFORE
USING THIS EQUIPMENA
CUSTOM MANUFACTURED FOR RADIO SHACK
A DIVISION OF TANDY CORPORATION

Speakers 
Components  P.A. Products Radios

Recorders 
Phonographs
REALISTIC AUDIO PRODUCTS are the proud result of Radio Shack engineer-
ing, research, development, and over 50 years of experience in electronics.
Laboratories are maintained in Boston, Ft. Worth, Los Angeles, and abroad.
In every sense a national brand, the Realistic label is worn with equal distinc-
tion by our highly original Communications and Citizens Band (two-way radio)
products, and numerous other items including: tape, headphones, antennas,
intercoms, and tubes.
SEA L/S17L
THE BRAND WITH OVER 1,000,000 CUSTOMERS
In choosing this fine Realistic product you have
demonstrated a rather acute awareness of the good
old American custom called "getting the most for
your money". With Realistic this is not an idle boast.
The "line" was born in Boston, long famous for
Yankee ingenuity -- and thrift. Its original intent was
to bridge a gap between $100 equipment and $25
equipment where, at the time, there was a real void
in hi-fi merchandise.
Early products were a $39.95 FM tuner, a $29.95
preamp/amplifier, a $19.95 speaker. Soon we found
ourselves a unique niche as manufacturing retailers.
Capacity and ability grew simultaneously. Our
Realistic Electrostat-3 ® electrostatic tweeter was
called a "best buy" by the country's leading product-
review magazine. Our 10TRF radio out-performed
practically anything then available. And dealers from
all over the world began requesting a Realistic fran-
chise.
Recent "firsts" include: the first medium cost DC/AC
communications receiver totally engineered in solid
state — the Realistic DX-150A; the first properly
designed low-cost police band radio — the Realistic
Patrolman; the Realistic Optimus-1 loudspeaker,
bringing "over $120 sound" down 33%; the first
lifetime-guaranteed vacuum tube; and the Realistic
STA-120B stereo receiver which combined massive
power, modern styling, and a veritable host of new
ideas at a cost fully $100-$200 below its value
under traditional marketing practices.
— 2 —

RADIO SHACK LIMITED WARRANTY
This equipment is warranteed against defects for 2 years from
date of purchase. Within this period, we will repair it without
charge for parts and labor. Simply
bring your sales slip
as proof of
purchase date to any Radio Shack store. Warranty does not cover
transportation costs. Nor does it cover equipment subjected to
misuse or accidental damage.
This Warranty gives you specific legal rights and you may also have other
rights which vary from state to state.
We Service What We Sell
SPECIFICATIONS
Two (Left & Right),
with separate controls for each
+0. 5
5 to 100,000 Hz

dB
—1.0
.± 12 dB @60,240,1000,3500 and
10,000 Hz
0.02% @0.775 volts output
0.02% @0.775 volts output
(20-20,000 Hz)
80 dB (2.45 volt input)
Up to 10 volts RMS
0 dB
: 75 K ohm
:  10 ohm
: 
MAIN IN, TAPE MON itor
: MAIN OUT, TAPE OUT
Power Switch (indicated with L.E.D.),
10 Linear Sliding Frequency Controls
(5 each channel), Tape Monitor Switch
120 volt AC, 60 Hz, 10 watts for UL
& C.S.A. models (220/240 volt AC,
50 Hz 10 watts for European and
240 volt AC, 50 Hz 10 watts for
Australian models)
Number of Channels
Frequency Response
(flat setting)
Tone Control Range
Intermodulation Distortion
Harmonic Distortion
Hum and Noise (shorted input):
Dynamic Range (flat setting) :
Total Gain (flat setting)
Input Impedance
Output Impedance
Inputs
Outputs
Controls
Power Requirements
The
REALISTIC Stereo Frequency Equalizer
is designed to tailor
the frequency response of your stereo system. Since it has separate
controls for each channel, it gives you an almost infinite combination
of control variations. The controls each have a range of approximately
24 dB (.± 12 dB) and are marked in 4 dB increments.
There are many reasons why you need such a specialized component.
The speakers, the room, your ears and your personal preferences vary
greatly. For example, if a speaker is simply moved 6 to 8" (15 to 20
cm) away from the wall, the bass response at 50 Hz could drop as
much as 8 to 10 dB.
The furnishings in the room, such as stuffed chairs, draperies and
floor covering can affect the high and middle frequency response
very dramatically.
It is a known fact that our hearing changes with age and varies
greatly from person to person or if the sound pressure or volume is
decreased. The ear's low frequency response at low volume can drop
as much as 15 dB at normal conversational levels.
Normal Tone Controls vary too much of the audio spectrum.
If
we
want to increase the low bass, we also increase the middle bass which
very often muddies up the whole bottom end. The same is true with
the treble control.
We cannot boost or cut the midrange without affecting the entire
high frequency response.
The Frequency Equalizer with its five frequency ranges can give
almost an infinite number of possible frequency response variations.
It will allow you to match your speakers to your room and the music
to your ears — without adding distortion, hum or hiss.
The Equalizer can also be used when making recordings of old LP's
or 78's without losing the main portion of the music. It can get rid of
the scratchy top, add a little needed bass • • • and really bring some of
those old 78's alive again.
The circuit of the Equalizer is a new type of tone control circuit
which yields extremely low distortion. The components used are of
the highest quality and we wish you many years of good sound.

0
MAIN MAIN TAPE TAPE
OUT IN OUT MON
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AMPLIFIER/RECEIVER
STEREO FREQUENCY EQUALIZER
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MAIN MAIN TAPE TAPE
OUT IN OUT MON
'TO AC
CONNECTIONS
With an Amplifier/Receiver Incorporating "PRE OUT" and
"MAIN IN" Jacks or with Separate Preamp and Basic
Amplifier
If your audio system has a Pre-amplifier separate from the
Power Amplifier, connect the Frequency Equalizer between
the two, observing the correct channel notations. The
Equalizer tape MONITOR
switch must be in the
- our
position (button extended). Make connections as shown in
Figure
1A.
With an Amplifier/Receiver Incorporating a Tape Monitor
Switch
With an integrated Amplifier/Receiver which has a Tape
Monitor Switch, make connections as shown in Figure
1B.
Set the Amplifier/Receiver's Tape Monitor switch to the IN
or MONITOR position. To disconnect the Equalizer, set the
Amplifier/Receiver's Monitor switch to the OUT position.
NOTE: With this connection, the Tape Monitor switch on
the Amplifier/Receiver will not be performing its original
function (to "monitor" tape recordings). Thus, we've added
a Monitor function to the Equalizer (with switch and jacks).
AMPLIFIER/RECEIVER

STEREO FREQUENCY EQUALIZER
Figure 1A
Figure 1B
4

STEREO FREQUENCY EQUALIZER
TAPE RECORDER
Figure 2A
To incorporate the Tape Monitor feature
with wiring as shown in Figure 1B, change
connections to be as shown in Figure 2A.
If your Tape Recorder has monitor func-
tion (a 3-head deck), press the Equalizer's
MONITOR
button to hear the recording
after it has been made (also, for normal
Playback of tape from your Recorder).
For Monitoring, both the Amplifier/Re-
ceiver's Monitor and the Equalizer's
MONITOR
switch must be "in". If you
don't need " - rnonitoring", the Equalizer's
MONITOR
switch can be set to either
position. If you want to process the
"source" signal through the Equalizer,
leave Amplifier/Receiver's Monitor switch
"in".
IMPORTAN — T NOTE:
When you are
using connections as illustrated in Figure
2A, when you "monitor" the recording, it
will have been processed by the Equalizer
— and thus will not be an accurate
"monitor" signal. For accurate monitor-
ing under these conditions, you must set
the Equalizer's sliding frequency controls
to the center "0" position.
AMPLIFIER/RECEIVER

MIRO flEIIIENCY EQUILIZEIl l  I  I
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AC 120V 60H,
101aV
STEREO FREQUENCY EQUALIZER
TAPE RECORDER
MAIN MAIN TAPE TAPE
OUT IN OUT MON
TO AC
Figure 2B
Recording Equalized Sound
AMPLIFIER/RECEIVER
When you make connections as shown in
Figure 2A, the signal
to the Recorder
does
not
go through the Equalizer. If you'd
like to control the recording through the
Equalizer, you can make connections as
shown in Figure 2B and leave the Equal-
izer's
MONITOR
switch in the "out
-
position. You should realize that this type
of connection will result in other than
ordinary recordings, but you may want to
experiment with this approach.
With connections made according
- to
Figure 2B, you can monitor the recording
(assuming your Tape Recorder has 3
heads) by using the Amplifier/Receiver's
Monitor switch. With these connections,
the "source" signal will not be processed
by the Equalizer.

1000 Hz
240 
1000  Hz  240
d1 5
10
5
0
-5
240 Hz: +12 dB Boost
1000 Hz . +12 dB Boost
(All other at 0 dBl
240 Hz . +12 dB Boost
1000 Hz Cut
—10
—15
100
Figure 3
1000
10000
Frequency — Hz
100
Figure 4
1000
10000
Frequency — Hz
dB
15
10
—10
-15
All Frequency
Controls at
+ 12dB Position
.
Single
Control at
+12dB. All
others at
. 0 dB.
Single
Control at
—12dB All
others at
0 dB
All Frequency
Controls at
—12dB Position.
100

1000

10000 20000

Frequency — Hz
Figure 5
NOTES:
1.
Set the Amplifier/Receiver's tone controls to their "flat"
position (or use "Tone Flat" switch if you have such a
switch).
2.
Depending on the location of the Equalizer, you may notice
some hum pickup (this would be from magnetic lines of flux
from nearby power transformers). If this happens, try
repositioning the Equalizer — as far away as possible from
such sources of magnetism.
OPERATING CONTROLS
Before applying power to the Receiver or Amplifier
o
Check Volume control — ,set it to Minimum.
o
Make connections as shown in Figure 1A, 1B, 2A or 2B.
When Connected Between PRE OUT and MAIN IN jacks:
1.
Press in
POWER
switch.
2.
Select the signal source you want to play through your
Amplifier/Receiver.
3.
Adjust sliding frequency controls for the desired sound tailoring.
TYPICAL FREQUENCY RESPONSE CURVES
de
15
10
5
—5
—10
—15
TYPICAL FREQUENCY RESPONSE PER CHANNEL
60 
240 
1000

3500  10000  Hz
When Connected To The Tape Monitor Jacks of an Amplifier/
Receiver:
1.
Set Amplifier/Receiver's Tape Monitor switch to the "in"
position.
2.
Press in Equalizer's POWER
switch.
3.
Select the signal source you want to play through your
Amplifier/Receiver.
4.
Adjust the sliding frequency controls for the desired sound
tailoring.
5.
If you are using a Tape Recorder —
A.
To playback tapes, connect as shown in Figure 2A and press
in the Equalizer's
MONITOR
switch.
B.
To monitor the recording, use the connection shown in
Figure 2A and turn "on" the Equalizer's MONITOR
switch.
C.
To record through the Equalizer, make connections as shown
in Figure 2B.
Frequency Slide Controls
Each control varies the level of a narrow band of frequencies
centered around the frequency noted above the control -- variation is
+
or —12 dB. In order to provide smooth frequency control, the
effect of these controls must overlap slightly; thus, the 1000 Hz
control has a slight effect on the range of frequencies covered by
both the 240 and 3500 Hz controls. The net effect of the controls is
all in the same direction — to emphasize (+) or cut (—) : refer to
Figure 3. Figure 4 illustrates a typical frequency response setting
and Figure 5 shows the overall effect of all the controls.

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THE MUSICAL SPECTRUM
This chart correlates familiar musical instruments with
the numerical frequencies that they produce. Given the
often talked about musical range of 20 to 20,000 Hz, it
is surprising to see how low musical fundamentals
actually are. (Almost all are under 3500 Hz.) It should
be understood however that if all instruments were
perceived only by their fundamental frequency output
(B)ack areas), they .
would all sound alike. It is the
harmonics or overtones (Shaded areas) that give each
individual instrument its character or timbre and set it
apart from the rest.
Interestingly enough, the human ear is more sensitive to
certain octaves in the musical spectrum than to others.
Whoever designed this engineering marvel deemed it
necessary to tune the ear more toward the midrange
frequencies where speech and voice communication
occur, than to the outer octaves of low bass and high
musical overtones. As a result, very small energy changes
here will cause a more drastic psychoacoustic effect
than larger changes would at the frequency extremes.
In order to discuss the qualitative effects of adjustment
in tonal balance, it is best to arbitrarily divide the
musical spectrum into five ranges:
The Bass (approximately 20-140 Hz).
There is little
musical material with fundamental frequencies belovy
about 60 Hz, and what is normally perceived as low bass
material is actually in the 60-140 Hz range. The very
lowest frequency control can be used to enhance output
for the few instruments in that range (organ, contra-
bassoon, etc.) or it can be used to reduce rumble,
acoustic feedback and other low frequency aberrations.
The 60 Hz control will cause the greatest perceptible
changes in "bass response".
Approximate Frequency Ranges for Musical Instruments and Voice
Elm —
Approximate fundamental range (and lower harmonics)
— Approximate range of relatively important harmonics (subjective by necessity)
20000
— Hz
=
FREQUENCY EQUALIZER CONTROLS
20

40 1601 100

240

500

2000 1 3500 1
Figure 6

The Mid-Bass (approximately 140-400 Hz). An over-accentuated
mid-bass region will yield a very muddy and "boomy" quality to the
music. A system shy of mid-bass will sound hollow and thin. The 240
Hz control is important for good overall balance.
The Mid -
Range (approximately 400 -
2600 Hz). As the area where
the ear is most sensitive to tonal balance, the mid-range is important
in adjusting the qualitative sonic characteristics of your system.
There is controversy among engineers and audiophiles as to what the
proper balance should be in this range. Moreover, you will find some
1000 Hz control settings optimum for certain types of music with
other settings just right for different types.
The Upper Mid - Range (approximately 2600
-
5200 Hz). Speaker
designers often boost output in this range to effect a quality of
"presence" to the music. Too much energy, on the other hand,
sounds overbearingly harsh and strident. A good balance should be
achieved between this and a more muffled sound. Use the 3500 Hz
control for this effect.
The High End (approximately 5200
-
20,000 Hz). The region up to
only about 12,000 Hz or so is what is normally perceived as high
frequencies. Adjustment in this range affects the brilliance of music.
with too much boost in energy yielding an unpleasant and piercing
quality.
The last 8000 Hz contains very little musical material. And most
adults have hearing which rolls off rapidly above 13,000 to 15,000 Hz.
As a consequence, the 10,000 Hz control will have a very subtle
effect. It can be used to add a little more dimension of the sound or
as a very high frequency noise filter.
Note for European and Australian Models
European and Australian models are equipped with both DIN Sockets
and PHONO Sockets.
Depending on your Amplifier/Receiver you may use either the DIN
type or the PHONO type but never try to use both at the same time.
If you connect a Tape Recorder to the Equalizer you must use the
same type connections as used to connect the Equalizer to the
Amplifier/Receiver. If the Equalizer-to-Amplifier/Receiver con-
nection is DIN, the Tape .
Recorder-to-Equalizer connection must be
DIN also (or both connections must be PHONO only).

TRIM 2SC1222 (F)
or 2SC1313 (G)
R107 3.3K
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R101
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1K
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R108 3.3K
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R110
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390 (2W) C113  1K
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C105
10P
TR103, TR105
2SC1222(F) y
or 2SC1313(G)
-
TR107 2SA953 (L, K)
or 2SA 954 ( L,
MAIN AMP & DC
POWER SUPPLY
P. C. B.
10
12
C109
33/25
R113
TR104 22K
TR106
2SC 1222( F)
L
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R
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C109
3 3 /
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4

FREQUENCY GAIN CONTROL
P. C. B.
60Hz t 
240Hz

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. 
3.5KHz 
10KHz
D105
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100-1 15
D101
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16
17
L.E.D. (RED)
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FOR EUROPEAN MODELS
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FOR AUSTRALIAN
MODELS
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SCHEMATIC DIAGRAM (For European and Australian Models)
V R 2 0 1 ^'VR210 50K (B) x10
NOTE
( 1 ) 
ALL RESISTANCE VALUES ARE INDICATED IN "OHM" ( K =10
3
0HM)
( 2)

ALL CAPACITANCE VALUES ARE INDICATED IN “pF " ( P = 10
6 pF )
( 3 )

X R117,R118 RESISTANCE VALUES ARE SELECTED FOR 9 VOLT NONCL IPPING
INTO 10K OHM OUTPUT LOAD.
(  ) 
X R201^ ,
R210 RESISTANCE VALUES ARE SELECTED FOR EQUALIZER RANGE
AT 
±12 dB
-10-

TR107
2SA953(L,K)
or 2SA954(,K)
•
C105
C109
33
/ 2 5
C107
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2.2K(1W)
TR108
2SA953(L,K)
or 2SA 954(L,K)
MAIN AMP & DC
POWER SUPPLY
P. C. B.
R121 
R122
390(2W) C113 1K
100/25 (
1
/
2 )
43V
R301 220K
R101
1K
C103 4-
47/50
r.7/

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
TR103,TR105

2SC1313(6)

2SC1222(F) x 2

R107 3.3K 
or 2SC1313(G)
C101
2. 2 / 2 5
R105
270K
TAPE MON SW
( PUSH
ON)
R108 3.3K
C104 +
47/50 1 :: 2 
R104
TRIO 2
2SC122 (F)
or 2SC1313(G)
or 2SC 1313 (G) x2
 • 
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II 
R115 3.3K
14
L.E.D. (RED)
C109
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/ 2 5
00
In CO
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30 •
P
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VR201—VR210 50K (B) x10
R111
3.3K
L
MAIN OUT
C302
0.01
R
MAIN OUT
SCHEMATIC DIAGRAM
(For U.S A. and C.S.A. Models)
r
TAPE MON
L TAPE OUT
L
MAIN IN
r
TAPE MON
TAPE OUT
MAIN IN

( 1 ) 
ALL RESISTANCE VALUES
ARE
INDICATED IN "OHM" (K =10
3
OHM)

2) 
ALL CAPACITANCE ,VALUES ARE INDICATED
IN "pF" ( P .10
6 pF )

( 3)

X R117,R118 RESISTANCE VALUES ARE SELECTED
FOR 9 VOLT
NONCLIPPING
INTO 10K OHM OUTPUT LOAD.

( 4 )
 X R201— , R210 RESISTANCE VALUES ARE SELECTED
FOR
EQUALIZER RANGE
AT 
±12 dB
NOTE

RADIO SHACK 2
5
1 A DIVISION OF TANDY CORPORATION
U.S.A.: FORT WORTH, TEXAS 76102
CANADA: BARRIE, ONTARIO L4M 4W5
AUSTRALIA
TANDY CORPORATION
BELGIUM

U
280-316 VICTORIA ROAD

PARC INDUSTRIEL DE NANINNE

BILSTON ROAD, WEDNESBURY
RYDALMERE, N.S.W. 2116

5140 NANINNE

WEST MIDLANDS WS10 7JN
7A0 
Printed in Korea
P-810666