Stromberg-Carlson ASR-220C Guide

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instructions for installation of your:
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STEREO PRE-AMp/pOWER AMpltFtER COMBINATTON
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Considerable care has gone into the pack-
aging of this equipment. If alter unpacking
you discover signs of damage, notily your
dealer at once. Before putting your equip-
ment into operation, make sure that all
tubes are set firmly in their sockets and
that the circuit breaker (the red push-
button at the rear of the amplifier chassis,
on your left i,vhen viewing amplifier from
the rear) has been pressed in.
uentilution,
Good ventilation is required {or long life,
trouble {ree operation. Be certain that air
flow around the amplifier is not obstructed
by such objects as cabinets or books.
TnoLL\LLin,g
For panel or cabinet mounting make a cut-
out measuring 133/a inches by 47/a inches.
An attractive cover is available as an op-
tional extra if you wish to set the amplifier
in an open location. When used in this
manner, insert the ieet packed with the
amplifier into the holes in the bottom cover
of the chassis and press them home.
i)j'iler
The AC cord should be plugged into a wall
socket supplying between I05 and I25
volts, 60 cycles. One switched AC outlet is
provided on the amplifier for connecting a
tuner, phono, or tape player. Another out-
let provides 6.3 volts AC for possible instal-
lation of a pilot lamp that lights when the
amplifier is switched on.
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Illustration 2 suggests a number of pos-
sible components you may wish to connect
to your ASR-220C, either initially or step
by step. Connections are easy to make, par-
ticularly if you use the shielded cables
with skirted single pin connectors provided
with all Suomberg-Carlson components.
Shielded cables are also obtainable in vari-
ous lengths at any high fidelity dealer.
General Rule: Connect A OUTPUT of the
program source to A INPUT of the ampli
fier, and B OUTPUT to B INPUT.
Which is A and, which js B: A is usually
the channel oriented at the left of the lis-
tener (Right terminal oI any pair when
viewing amplifier from the rear), and B on
the right (Left terminal of any pair when
viewing from the rear). All Stromberg-
Carlson and most other manu{acturers'
components have channel connections
clearly marked A and B. If you cannot
find any markings, a simple experiment
may give you tlre answer. With most sym-
phonic stereo recordings the violins should
sound from your left speaker system. II
they do not, chances are your channels are
reversed.
Phono Insta,llation: Yorr ASR-220C pro-
vides you with two phono inputs for maxi-
mum flexibility. The MAGNETIC PHONO
input circuit of your ASR-220C presents a
47K load; the CERAMIC PHONO input a
1.0 meg. load. These values were chosen to
suit the majority of modern cartridges. A
few magnetic cartridges, however, require
a special additional load resistor across
their terminals to give optimum results.
Check the information supplied with your
cartridge.
Magnetic Phono: This designates the input
suitable for all types of low output mag-
netic and variable reluctance cartridges.
This is the input to use if your changer or
turntable has a magnetic cartridge.

Ceramic Phono: Use this input i{ your
changer or turntable has a higher output
ceramic or crystal cartridge.
Tuner Installation: Any monophonic tuner
may be connected either to the channel A
TUNER INPUT or the channel B TUNER
INPUT. Because of the versatility of the
ASR-220C, this tuner immediately becomes
a two speaker system operation when the
MODE SWITCH is clicked to the Mono-
phonic position. AM,zFM stereo tuners
should have the AM section connected to
channel B and the FM section to channel
A. This is recommended because the left
hand channel generally carries the. violins
and other instruments in the higher fre-
quency range. It is normally broadcast on
FM {or better broadcast quality and less
interference.
T ape Record,er I nstallation .. There are
three principal types:
1) The Tape Recorder-This includes
either a complete pre-amp,/amplifier or a
pre-amplification section and has full re-
cording facilities. It may be a 'packaged'
machine or a unit designed {or panel
mountrng.
2) The Play-Back Tape Deck-This unit
is designed only for play-back o{ pre-
recorded tapes, and will have NARTB
equalization and at least a pre-amplification
stage.
3) The Tape Transport - This mecha-
nism has neither recording nor NARTB
equalization nor a pre-amplification section.
Only the first two units can be used with
the ASR-220C. For playing pre-recorded
tapes, connect by running shielded cables
from the output jacks of your tape re.
corder or tape deck to the inputs (CE-
RAMIC PHONO or TUNER/AUX) of
your amplifier. Do not make the mistake of
connecting directly to the TAPE OIITPUT
jacks (located in the center of your ampli-
6er chassis), as these can only be used for
recording purposes with a tape recorder
having {ull recording facilities.
mxportant ruote-
power supply
When your tuner is connected
to the switched AC socket at
the rear of your amplifier, it is
switched ofi with your ampli-
fier. However, if you use this
socket to connect a turntable,
a changer, or a tape machine,
that instrument should always
be turned ofi separately with
its own switch. Most of these
machines are driven by idler
wheels. When not in use, these
wheels must be properly dis-
engaged to a neutral or ofi po-
sition, or serious damage may
result.
muke your own tape record,ings
If your tape recorder has full recording
facilities, you can connect it to the ASR-
220C and record while listening to any
recorded or broadcast program. Two out-
lets, one for each channel, are provided in
the center of the amplifier chassis. The
signal supplied to the tape recorder is es-
sentially flat and uncorrdcted, being tapped
ahead of the controls of your amplifier.
However, you can enjoy the program using
the full faiilities of your amplifier controls,
including volume, without afiecting the
correct recording characteristics or record-
ing volume as adjusted at the tape re-
corder itself.
The monophonic recorder can be connected
to channel A or B; a stereo recorder to the
appropriate A and B channels.
Standard 18-gauge lamp cord is recom-
mended for making your speaker connec-
tions, although there certainly is nothing
wrong with using single strand colored
wire. Note that there is a fine ridge on one
side o{ the lamp cord to help you in the
proper identification of connections.
Monophonic: Speaker or speaker system
terminals are usually marked in some way.
A color, a numeral, a letter, or a sign such
as a cross may be used. First connect the
ridged wire to the "positive" or '\ight"
speaker terminal (+). According to the

impedance of the speaker you are using,
attach this same wire to the 4 or B ohm
OUTPUT terminal of either channel. Con-
nect the other wire from the "common" of
the speaker to the "common" of the same
channel OUTPUT (C). t6 ohm speakers
are attached to the 8 ohm tapping. You
should now connect a ]oad resistor across
the amplifier output terminals o{ the chan-
nel that you are not using to "load" this
channel. Choose a 10 watt resistor of the
same ohm rating as the speaker you are
using and connect it to the free channel,
duplicating the speaker connections. How-
ever, if you wish, you may attach an ex-
tension speaker for use in another room
instead of a resistor. It is very important
throughout your speaker wiring that you
make absolutely certain that no loose
strands of wire are shorting out (touching)
adjacent terminals.
Stereo: Use the same code designation to
make identical connections for the two
channels. Proceed exactly as ahove. First
wire the channel A speaker system to
channel A OUTPUT; then similarly wire
the channel B speaker system to channel
B OUTPUT (See illustration). Nothing
more need be done.
Phasing: If one or both of your speakers
have no identification markings you will
have to phase the speakers correctly in the
following manner. Connect the speakers to
the correct impedance output terminal of
each channel. Choose a good monophonic
record containing sustained, deep bass
passages. While you listen to these pas-
sages, reverse the two connections of one
channel only. In one of the two positions
the bass will be out of phase-the speakers
will counteract each other and bass re-
sponse will lose both quality and volume,
In the other position the speakers combine
their bass energy and reproduction sounds
better and fuller. This efiect is most ap-
parent if the bass control is at maximum
(both channels) and the speakers are
placed about two feet apart, facing each
other. Fasten the wires down in the cor-
rectly phased position.
Center Channel Stereo: First connect the
two main channels as outlined above. Cor-
rect phasing if speaker terminals are un-
marked. Then connect the center channel
speaker, one lead to the 4 ohm terminal of
channel A and the other to the 4 ohm ter-
minal of channel B. Reverse terminals to
determine the best phasing position.
In many cases it is desirable to reduce the
volume of the center channel speaker. The
best way to do so is to use a "T" ot "L"
pad, easily mounted at the rear of the
speaker baffie. Ask for a connection dia-
gram when you obtain either one at your
local high fidelity or radio parts dealer.
If you use this A plus B'signal speaker for
monophonic reproduction in another room,
you do not have to check for phasing.
hunt,
Hum happens in the best of circles, par-
ticularly in ground loops. Every program
source should be grounded to the ampli
fier. And all of them in turn should be
grounded. Disconnect all sources and out-
puts from the amplifier except the speakers.
If there is hum, reverse the AC plug. Then
re-connect one program source at a time to
locate which, if any, induces hum. If one
does, and it is well grounded, move its con-
necting cables, even the whole piece of
equipment to various positions. You may be
troubled with hum induced by a strong AC
field. Phono pickups are especially sus-
ceptible to this type of field and should be
well shielded from the transformers or
motor of other audio equipment. If phono
hum persists, check installation instruc-
tions provided by the cartridge manufac-
turer. There are some general rules here
that you may wish to follow. The ground
side of the shielded cables {rom the car-
tridge should not make contact with the
turntable chassis, nor should the two shields
make contact except at the amplifier. Use
insulated shielded cables. The tone arm
should be grounded to the turntable chas-
sis and the latter to the motor. Tone arm
grounding, which is often efiected only
through the bearings, can cause hum. If
all other attempts to cure phono hum have
failed, try to achieve better grounding by
the use of fine braided wire.

6.3 P|LOT
TAMP OUTLET
AC
SWITCHED
OUTTET
CIRCUIT
BREAKER
AM/FM STEREO TUNER
OR
STEREO TAPE RECORDER
WITH PRE.AMP
OR
MONOPHONIC
TAPE RECORDER
STEREO TAPE RECORDER
WITH PRE-AMP
OR
STEREO CERAMIC CHANGER
OR TURNTABTE
STEREO MAGNETIC CHANGER
OR TURNTABI-E
MONOPHONIC
AM, FM, OR
SHORT WAVE
TUNER
OR
MONOPHONIC
MAGNETIC CHANGER MONOPHONIC MAGNETIC
TURNTABI.E
MONOPHONIC
CERAMIC TURNTABLE MONOPHONIC
CERAMIC CHANGER
TAPE
OUTPUT
OR

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STEREO PRE-AMp/pOWER AMpLIFtER COMBTNATTON
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STEREO PRE-AMP/POWER AMPLIFIER COMBINATION
You now own one of the finest, most advanced stereo
amplifier-s. Every refinement contributing to high quality
stereo reproduction has been included.
The flexibility of the amplifier enables you to compen-
sate for different room acoustics, make use of a wide
variety of program sources, correct recording or broad'
cast deficiencies. It allows you to adjust tone quality,
volume and dimension of sound so that to your own ears,
in your own room, music and voice are reproduced with
complete realism.
Turn this control to the program source
you wish to select . . . phono, radio tuner,
or tape recorder.
Tuner/Aux: Depending on the radio tuner
you are using, this control position selects
either AM/FM stereo, FM multiplex or
monophonic AM or FM programs. If you
are not using a radio tuner, this position
permits you to select auxiliary program
sources such as television or tape.
Mugnetic Phono: If you are using a mag-
netic phono cartridge, this is the RIAA
(Record Industry Association of America)
compensated control position you will use
for playing all your records. RIAA is
the equalization characteristic universally
adopted by record manufacturers since
mid-1954. On play-back, your amplifier
compensates for the recording character-
istics and restores the original sound.
Ceramic Phono: If you are using a ceramic
(high output) cartridge, this is the setting
you will use for playing all your records.

You will note that both the treble and bass
controls consist of a'clutch'type arrange-
ment. The smaller knob (Channel A) will
move together with the larger one (Chan-
nel B)-unless one is held firmly while
the other is turned. Thus each stereo chan-
nel has its own, independent bass and
treble controls. This valuable {eature
allows you to compensate for a difierence
in tonal values that might occur between
the two channels of an AM/FM stereo
broadcast or with poorly recorded stereo
records and tapes. Where two difierent
model speaker systems are used, separate
tone controls are invaluable in obtaining
closer ]ikeness of sound. If one of the
speaker systems faces a heavily draped
(high frequency absorbent) area and the
other does not, separate controls again
permit you to equalize the two channels.
Ideally these controls should be set mid-
way - in the I2 o'clock position. This
assumes perfect balance between the
channels and ideal room acoustics.
If you listen in a very 'live' room, one that
has few drapes, carpets and comparatively
little upholstered furniture, high frequency
or treble response will be exaggerated ow-
ing to the large number of reflecting sur-
Iaces. Turning down (counter clockwise)
the treble control will re-establish the cor-
rect relationship between the high fre-
quencies and the rest of the audio spec-
trum. Conversely, increasing this control
setting will compensate f or a so called
"dead" room - where an abundance of
drapes, carpets and upholstered furniture
absorbs too much treble.
A similar situation arises with the low fre-
quencies. Bass is afiected by the size and
shape of your room, the height of the ceil-
ing and the response of your ears. Gen-
erally speaking it can be said that the more
wall area surrounding a speaker, the better
the bass response. A corner placement,
close to the floor, provides most efficient
bass response; free standing, away {rom
any wall, least efficient.
Adjust treble and bass so that in your own
room, in your favorite listening area, the
sound appears most realistic and true to
your ears. And don't hesitate to re-adjust
the controls when a record, radio program
or tape does not sound right. Your Strom-
berg-Carlson 220C amplifier has a variety
of controls so there need be no compro-
mise in listening quality.
Your 220C amplifier features independent
volume adjustment for each of the two
channels - combined on a dual 'clutch'
type control. Operate this flexible arrange-
ment as follows: With perfectly balanced
speakers and program material, line up
both volume controls by holding one knob
and turning the other until their center
markings coincide. Once set, operating one
will automatically move the other, thus
controlling equally the volume of both
channels simultaneously.
You may, however, be listening to unbal-
anced program material-such as an AM/
FM stereo broadcast. One channel sounds
Iouder than the other. In this case adjust
the separate volume controls by moving one
knob against the other until you obtain
correct balance between the two channels.
Once set, they will move together to raise or
lower the overall sound level of the whole
system without upsetting the corrected bal-
ance between the two channels.

Independent volume controls for each
channel make good stereo balance possible
where it is impractical to arrange the main
listening area mid-way between the two
speaker systems. If for example, your main
listening area is slightly left of the ideal
position, increase the volume of the right
channel until the balance sounds right. For
easiest balance adjustment use a mono-
phonic source which provides long, sus-
tained notes.
irnportant note-
circuit breaker
For your convenience, Strom-
berg-Carlson has installed an
'eternal fuse' in the form of a
circuit-breaker. In the case oI
an unusually high voltage surge
or component {ailure, the
circuit-breaker removes power
from the amplifier. Re-set by
pushing the red knob mounted
through the rear of the ampli-
fier chassis. If it continues to
disengage consult your service-
man.
Stereophonic: This position should be used
for all types of Stereophonic material. Both
speaker systems play.
Monophonic : Monophonic program mate-
rial sounds fuller, more realistic when
played back over rhe whole system rather
than one channel only. When you select this
setting, the monaural record, the FM broad-
cast, the AM broadcast, or the monaural
tape is Ied through both stereo channels to
both speaker systems. Therefore, select
Monophonic position for all monophonic
inputs.
This control position simply reverses the
left signal to the right channel and vice
versa. This may he useful for stereo broad-
casts.
A badly worn or in{erior turntable or rec-
ord changer-even a turntable used by
your local FM station-may introduce an
undesirable low frequency noise known as
"rumble." You can eliminate it by moving
this switch to the IN position, without sub-
stantially aflecting the good bass repro-
duction of the amplifier.
In the IN position this cuts out undesirable
high {requen:l:: :"-:}- L"- i::11: z":,""t:},
(particularly on older records) and radio
interferenee

(1)
(2)
(3)
(4)
o lf you can't wait, here is.a quick and easy way to get immediate results.
Switch on amplifier at A. face up. (center or 12 o'clock setting) Switch G, H and I
Turn Program selector B to the program source you wish to left'
to use. (5) Place record on turntable and set it in motion. lf you are
using tuner . . . switch it on and select station.
Turn Mode Selector C to 'Stereo' or 'Mono' accordine
to the program material you,re going to use. (6) Turn loudness control F clockwise to required volume.
For best results study the purpose and function of each con-
Turn Treble D and Base E Controls so that their pointers trol and adjust the implifier accordingly.

ASR.22OC
POWER OUTPUT (Continuous) . . . 12 watts per channel
(24 watts total)
POWER OUTPUT (music power,
IHFM standard). . . . ..14wattsperchannel
(28 watts total)
I NTERMODU LATION DISTORTION
(at rated output: 4:1 ratio, 60 and 7,000 cps) 2%
TOTAL HARMONIC DISTORTION
(at 1 kc, maximum power) .0.7o/o at
12 watts per channel
FREQUENCY RESpONSE . . . .-+0.5 db, 20-20,000 cps
HUM AND NOISE (db below rated output)
RESIDUAL (gain min.) ......80db
MAG. PHONO (gain max.) . . . .55 db
TUNER (gain max.) . . .70 db
SENSITIVITY
TUNER ....0.3V
MAGNETIC PHONO .3.5 MV
CERAMIC PHONO . .0.3 V
INPUT IMPEDANCE
TUNER .....lMeg
MAGNETIC PHONO . . .47 K
CERAMIC PHONO . . .1 Meg
OUTPUT IMPEDANCE 4, 8 ohms
Center Speaker (A+B): 4 and 8 ohms
(across 4 ohm taps)
TONE CONTROL RANGE
BASS (50cps).. ...-F15db
TREBLE(20kc) ....+12db
Front panel cut-out for component
mounting ....L3y8, x4y4,
Part No. 146012-034 GLP 23186 Printed in U.S.A.