Sparta ASC 305 B User manual

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[p~~LF~
ELECTRONIC
CDRPDRATIDN
MODEL
ASC
305 B
Stereo Control Center
TECHNICAL
MANUAL
5851
FLORIN-PERKINS
ROAD
/
SACRAMENTO,
CALIFORNIA
/
TELEX
377-488
CABLE
SPARTA
/
(916)
383
-
5353
A Division
of
Computer Equipment Corporation

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TECHNICAL
MANUAL
MODEL
ASC
305 B
Stereo Control Center .
PROPRIETARY
NOTICE
Sparta Electronic
Corporation
proprietary
data
is
contained herein. Neither this
document
nor
the
information
contained herein shall be disclosed
to
others
for
manufacturing
or
any
other
purpose except
as
authorized in
writing
by
Sparta Electronic Corporation.
'
c1970 098-2150
$5.00
~
~[p~~lJ~
~
ELECTRONIC
CORPORATION
!5B51
FLORIN-PERKINS
ROAD
SACRAMENTO,
CALIFORNIA
95B28
A OI
VISIO
N
o,
CO
MP
UTER
EQUIP
MENT
CO
R
POR
ATION
. .

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DESCRIPTION
ASC-305B
The
ASC-305B
Ste
r
eo
Studio
Control
and
Remote
Unit
consists
of
a
Stud
io
Cont
r
ol
Console
(cabinet)
two
twe
l
ve
-
inch
professiona
l
turn
t
ab
l
es
,
two
TEP-
3S
Stereo
Preamplifiers
,
an
MCA-1
monitor-amp
li
fie
r
and
the
AS-30B
Stereo
Audio
Console
.
CONSOLE
AS
-30B
The
AS
-30B
Console
may
be
used
separate
ly from
the
ASC-
305B
cabinet
by
simply
removing
the
quick
-
disconnect
connectors
from
the
rear
panel
. It
may
be
battery
-
operated
or
the
power
supply
may
be
easily
removed
also
from
the
ASC-305B.
PREA
MPLIFIERS
·--....,'-
Preamplifier
s
are
l
ocated
on
the
lower
sh
e
lf,
one
on
each
side
,
and
feature
separate
l
evel
controls
fo
r l
eft
and
right
channe
l
output.
These
are
preset
for
prope
r l
evel
but
may
be
changed
if
needed
for
new
or
different
cartridges
Additional
information,
plus
maintenance
data
is
i
ncluded
in
a l
ater
section
.
MONITOR AMP,
MCA-
1:
An
MCA
- 1
monitor
amp
is
a l
so
located
on
the
l
ower
shelf
near
t
he
operator's
knee
. A l
evel
switch
su
pp
li
es
either
Cue
or
Program
audio
to
the
monitor
s p
eaker
located
in
the
conso
le
ca
bi
ne
t.
Adequate
power
is
ava
il
ab
le
to
drive
an
a l
ternate
,
externa
l 8
ohm
speaker
if
desi
r
ed
.
Appropriate
schematics
are
included
wi
th
the
A
S-30B
schematics.
ASC-305B
~
Page
1

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DESCRIPTION ASC-305B (Cont'd)
TURNTABLES
The ASC-305B may be equipped with either four-pole or synchronous motor
driven turntables. Another section provides additional information.
TONE ARMS
The ASC-305B is supplied - standard with SPARTA ST-220 Professional Stereo
tone arms and are designed so highly accurate adjustment may be made visually for
optimum overhand and tracking-force. Other tone-arm options are available.
ASC-305B Page
2.

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FEATURES
Portable
Cabinets:
Finish
.
..
.
..
.
.....
.
..
.
..
. .
...
..
...
..............
.
..
. l\'alnut wood
grain
&
Dove
bonded
plastic
laminate
Unit
set-up
Dimensions
•••
••••
•• .
••
.
••••••
•
•••••••
•..
Overall,
including
legs
&
lift
l
eaf
extended
34"
high (
28"
to
work
surface)
51
1/2"
wide,
25
3/4"
deep.
Bench/Lid
Dimensions
.•
• .
.•
•
••••
••
••••••••
. .
•..•.••.
Legs
installed
16
1/2"
high,
49
1/2"
wide
, 19
1/2"
deep.
Closed
Case
Dimension
.•
•••.••
.•.•.•
•
.••••
.
•••
•
•••••
Bench/Lid
installed
14
1/2"
hi
gh
51
1/2"
wide,
19
1/2"
deep.
'
Shipping
Weight
.•••••••••.••
•
•.•••••••••
•
•••
• ••
••
.
>is,?
Pounds
AS-30I3
Console:
9
stereo
pairs
1
each
for
mixers
1
through
4 and 5
for
mixer
5.
Standard
equipment
of
the
AS
-30B
as
supplied
with
the
ASC-3058
includes
a
pair
of
microphone
preamplifiers
in
channel
1,
plus
stereo
equalized
phono
preamplifiers
for
inputs
to
channels
2 and 3.
TONE ARM
The
SPARTA Model
ST-220
Professiona
l
Stereo
Tone
Arm
reflects
the
high
quality
and
scientific
design
needed
for
the
superior
reproduction
of
phonograph
records.
It
permits
the
use
of
lower
tracking
forces
for
which
the
latest
cartridges
are
designed.
The
Tone
arms
can
be
precision
balanced
and
are
so
designed
that
a highly
accurate
adjustment
of
the
tracking
force
can
be
made
visually
.
Some
of
the
outstanding
features
are:
All
cartridges
can
be
adjusted
for
correct
overhang
to
insure
optimum
tracking
.
The
plug-in
head
assembly
is
rigidly
locked
in
place,
but
very
easily
removed
when
necessary.
Precision
ba
ll-
bearings
are
used
throughout
on
a
ll
pivot
surfaces.
ASC-305B Page
3.

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\.
\.
TECHNICAL MANUAL
Model GT-12
Professional Turntable
PROPR . IET ARY NOTICE
Sparta El ec troni c Corporation
proprietary data is contained herein. Neither this docum ent
nor the information co nt ained herein shall be disclosed
to others for manufacturing or any other purpose exce pt
as a uthori zed in writin g by Sparta Electronic Corporation.
~ $~~~LI~
V ELECTRONIC CORPORATION
!5B!51 FLORIN • PERKINS ROAD SACRAMENTO, CALIFORNIA 95828
A OIVISION OF CO MPUTER EQUIPMENT CbRPORATION

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TOTAL
WEIGHT
WEIGHT
OF
PLATIER
DIMENSIONS
BOTTOM CLEARANCE
TOP CLEARANCE
PLATIER
SIZE
SPEEDS
ACCELERATION
RUtvIDLE
WOW
AND
FLUTTER
F I
NISH
POWER
SPECIFICATIONS
1.
18
1/2
l
bs
6 l
bs
1
6"
Wi
de,
15 1
/2"
deep
5 1
/2"
GT-12
-4P
6 1
/2"
GT-
12-SY
2
1/4"
without
tone
arm
2
3/4"
with
ST
-220
1
2"
33 1
/3
and
45
rpm
Less
t
han
1/16
turn
at
33 1
/3
rpm
45
db
below
reference
l
evel
of
1.
4
centimeters
per
second
peak
ve
l
ocity
at
100
Hz,
measured
at
33
1/3
rpm
0
.1
%
or
better
SMOKE GRAY,
textured.
Burnt
orange
turntable
pad.
117
volts,
60Hz, 220
V
/50
Hz
available
GT-12-4P
65
Watts
,
GT-12-Sy
35
Watts.

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INSTRUCTIONS FOR OPERATION
2 SPEED TRANSCRIPTION TURNTABLES
SPARTA
Turntables are shipped completely assembled. Shipping materials such as
blocks, cardboard, etc., should be removed and the table thorough ly checked for
possible damage incurred in transit.
Connect 115V 60 cycle AC (unless otherwise ordered or specified) only to terminals
marked in red.
INSTALLATION: The tab le should be solidly mounted to operating table or desk.
DO NOT USE SPONGE RUBBER OR OTHER RESILIENT MATERIAL BETWEEN
TURNTABLE CHASSIS
AND MOUNTING SURFACE! This is especially important
where reproducer arm is of such length that it cannot be mounted directly on the
turntable chassis.
OPERATION AND ADJUSTMENTS: Turntable speed is c:ontrolled by 3 factors:
(1) speed of motor in RPM, (2) diameter of motor pulley (capstan) (3) diameter
of inside rim of turntable. Diameter of idler has no effect on table speed, hence
no speed change occurs as idler wears. Speed change is made by placing speed change
arm in one of the two slots, top for 33-1/3, and bottom for 45 RPM. A "Neutral'' position
is provided between the slots, and when not in use the shift arm should be left in neutral
position to prevent "flats" on the idler.
Both of the slots have an adjustable stop which limits the travel of the arm.
While a slight change can be made in table speed by adjusting these stops, their
purpose is to limit the pressure between motor pulley-idler and table rim.
INITIAL ADJUSTMENT IS AS FOLLOWS: Screw in (clockwise) (45 RPM) screw until
motor ceases to drive table, then back out screw slowly until just enough pres~ure is
applied to give satisfactory acceleration . Best results will be realized by using the
least possible pressure consistent with adequate driving power. Too much pressure
will cause undue wear on the idler, cause incorrect speed and induce vibration.
LUBRICATION: MAIN TURNTABLE SHAFT: Main turntable shaft should be wiped
clean with clean lintless cloth and bearing well should be cleaned with cloth wrapped
around wooden dowl to remove gummy deposits of dirt and oil. Re lubricate by
applying l ubriplate #3 Special Product Oil. If not available use S.A.E . 30 automot i ve
oil . A small dab of Lubriplate should be applied to the ball on the end of turntable
shaft . This lubrication procedure should be followed every two weeks - - every
week if table is used in a 24 hour operation.
IDLER BEARING LUBRICATIQ'\J: The idler bearing is made of oilite; a material
consisting of small bronze particles pressed together with microscopic passages
between them. These passages are impregnated with oil. This bearing material
contains enough oil for several years of bearing life. Should the idler tend to become
stiff on the shaft and not rotate freely, this would indicate that the bearing no longer
has sufficient oil for lubrication . At this time the idler should be removed, the shaft
and bearing wiped thoroughly with a clean lintless cloth and the bearing relubricated
with a light oil _ such as 3 in 1 oil.

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Page 2
BODINE
SYNCHRONOUS MOTOR:
This
motor
is
equipped
with
oil
cups
located
on
the
side
of
top
and
bottom
bearing
.
The
bearings
on
these
are
of
the
solid
bronze
sleeve
type,
equipped
with
a
felt
wick
to
carry
oil
to
the
shaft.
Ordinary
lubrication
at
two
month
intervals
with
a
couple
of
drop
s
of
oil
per
bearing
is
sufficient
.
Grade
#10
non-
detergent
oil
is
recommended.
UNIVERSAL
ELECTRIC
FOUR POLE MOTOR:
This
motor
comes
equipped
with
oilite
bearings
and
ordinarily
needs
no
lubrication
attention
during
its
life.
If
the
turntable
is
located
in
an
unusually
hot
loc
ation
it
is
possible
for
the
oil
in
these
bearings
to
change
viscosity
to
the
point
where
the
motor
shafts
will
be
so
stiff
that
th
e
motor
will
have
trouble
starting
.
Under
these
conditions,
the
motor
should
be
removed
from
th
e
turntable,
disassembled,
and
the
bearing
and
shaft
cleaned
.
The
be
aring
then
should
be
thorou
ghly
saturated
with
a
light
oil
such
as
3
in
1.
The
motor
then
can
be
reassembled,
reinstalled
on table and
table
restored
to
further
u
sage
.
IDLER ADJUSTMENTS:
Note
that
the
motor
is
attached
to
its
hanger
with
screws
or
bolts
through el
ongated
ho
l
es
.
If,
due
to
wear,
(r
eduction
of
diameter)
of
the
idl
e
r,
it
becomes
impossible
to
secure
adequate
driving
power
with
the
shift
arm
at
the
extreme
l
eft
hand
end
of
the
speed
selector
slot,
moving
the
motor
toward
the
rim
of
the
table
will
give
correct
driving
pressure
more
toward
the
center
of
the
speed
change
slot.
If
a new
idler
makes
it
impossible
to
obtain
a
"n
e
utr
al
",
the
motor
is
simply
moved
away
from
the
table
rim
until
a
suitable
arm
position
in
the
slot
is
obtained.
IDLER
DRIVING SURFACE:
It
is
extremely
important
that
the
driving
surface
of
the
idl
er
and
the
inside
rim
of
the
turntable
be
kept
clean
of
oil
or
other
contaminating
substances.
During
the
first
few
weeks
of
operation,
the
idler
driving
surface
and
the
in
side
rim
of
the
table
should
be
cleaned
with
methy
l
alcoho
l
at
weekly
intervals.
No
further
attention
should
be
needed
unless
these
areas
are
subject
to
oil
overflow
from
the
idler
due
to
over-lubrication.
If
the
idler
or
table
rim
becomes
contaminated
with
oil,
the
only
satisfactory
solution
is
to
cl
ean
the
table
and
idler
thoroughly
with
hot
water
and
deterg
ent
. .
NOISE, HUM, RUMBLE: Many
pickups
are
subject
to
hum
caused
by
the
magnetic
field
of
a
motor.
Before
in
stalling
pickup
arm
on
tabl
e,
it
is
wise
to
move
the
pickup
head
to
variou
s
lo
cations
on
the
platter,
with
the
motor
operating
but
w~th
the
idler
in
"neutral".
This
should
help
in
loc
ating
the
mounting
position
of
the
arm
which
will
cause
the
least
hum.
Noise
is
divid
ed
into
two
classes,
mechanical
and
electrical.
Noise
that
can
be
h
eard
w
ithout
amplifier
or
pickup
in
·operation,
can
u
sually
be
tr
aced
to
its
source
by
comparing
the
noise
with
the
speed
of
the
motor,
idler
or
table
itself.
If
noi
se
is
constant
at
all
speeds
it
probably
originates
in
the
motor.
If
it
increases
with
table
speed
,
but
its
frequency
is
greater
than
table
spee
d,
it
can
usually
be
traced
to
the
idl
er.
If
the
noise
varies
with
table
speed
and
has
the
same
frequency,
look
for
something
on
th
e
table
rim,
such
as
oil,
dirt
or
possibly
a
crack
in
the
table
casting.
In
the
case
of
noise
traced
to
the
idler,
look
for
dirt
on
idl
er
driving
surface,
pits,
or
foreign
material
imbedded
in
idler
driving
surface.
Check
felt
thrust
bearing
under
idler
to
be
sure
id(e.r
is
not
riding
directly
on
metal
boss
at
bottom
of
idler
shaft.
Too
much
idler
tensiori
can
cause
idl
er
to
ri
se
on
its
shaft
and
noise
is
heard
as
the
idler
contacts
the
idl
er
re~ining
ring.
•
..

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,_
Page 3
Rumble more or l ess constant at all table speeds can usually be traced to the capstan.
Again, too much idler tension will aggravate rumbe caused by an out of round or
wobbly condition in the capstan, (motor pulley). Noise caused by "flarn" in the idler
will run out in a few minutes because of the "self-healing" nature of the neoprene
used in the idlers. Put table in 45 RPM position and let run for a few minutes.
SPARTA ELECTRONIC CORPORATION will be glad to assist in any problems in
connection with operation or maintenance of the tables . To insure a minimum of
delay, please give as much information as possible in connection with the problem,
such as serial number of table, date purchased, whether problem is new or of
lo ng standing, type of pickup and arm used, whether problem is different at
different table speeds, whether it is only in evidence when idler is driving table,
etc. The more information supplied, the easier it will be to provide suggestions
to eliminate the difficulty.
IMPORTANT
There are aluminum shipping tabs installed between the
motor hanger and turntable frame to protect the rubber
motor mounts during shipment.
THESE BLOCKS MUST BE RE MOVED BE FORE OPERATION
Each block is secured in place by a 10/24 by l 3/4 "
screw with a red painted head. (The shipping blocks
should be retained for i nstallation in case of future ship-
ment of turntables, or to secure during moving. )
SPARTA ELECTRONIC CORPORATION
5851 Fl
orin-Perkins Road
Sacramento, California 95828

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q~?:~~ot~
ST-22O PROFESSIONAL STEREO TONE ARM
FOR BROADCAST APPLICATIONS
USING HIGH COMPLIANCE CARTRIDGES
FEATURES
CONSTRUCTION: Light alloy arm,
cartridge shelI
·MOUNTING: 7/8" diameter s in gle
threaded shank
with low-mass
hole , 1'' long
ROTATION: Miniature precision ball bearing
LATERAL BALANCE: Adjustable, to compensate for
variations in center of gravity between various
cartridges
TRACKING FORCE ADJUSTABLE: Movable weight,
with lo cking screw, adjusts tracking force for
any cartridge
ARM HEIGHT ADJUSTABLE: Locking screws on
shafts of arm and rest adjust height of arm from
40-60 mm (1-9/16" - 2-3/8")
CARTRIDGE SHELL REMOVABLE: Uses international
standard 4
pin connector
CONNECTING CABLE PLUG - IN : 5' cal)le plugs into
base of arm, has color-coded phono plugs and
ground
wire
SPECIFICATIONS
TOTAL LENGTH ........ . ..... 310 mm (12-13/32")
EF F ECTIVE LENGTH · · ·· · · · · · 220 mm (8-21 /32")
OVERHANG ........ . . . ........... 15 mm (19/32")
OFFSET ANGLE ............ . ... . ........ . . : • 22°
LATERAL BALANCE ..... Adjustable, all cartridges
STYLUS PRESSURE · · · Adjustable,
1-6 grams recom-
mended, depending on cartridge
TRACKING ERROR
...................• +4 0, -1 o
"I
0
-0
I
0
l
15-t- -- ----220 --- ---- ---1- --,s
A DIVISION 0, COlll'IITPI EQUIPMENT CORPORATION
MA IN WEIGHT- -~
MAIN WEIGHT
LOCK SCREWS
t,g·2

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Models
TEP3S
and
TEP3M
Turntable
Preamplifiers

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TEP
3S,
TEP
3M
PHONO
EQUALIZED PREAMPLIFIERS
SPECIFICATIONS
FREQ . RESPONSE:
RIAA
(NAB)
within
typical+
0 .5
db
(±
1
db
max).
OUTPUT LEVEL, PROGRAM:
ff
dbm
into
600
ohms
balanced
,
adjustable
to
below
-20
dbm.
OUTPUT LEVEL,
MAX:
+10
dbm
(12
to
14
dbm
typical)
DISTORTION:
Less
than
0 . 1% (0 .
03%
typical)
THD.
INPUT IMPEDANCE:
47K
ohms
.
Can
be
changed.
SENSITIVITY: 5
mi
ll
ivolts
for
1
dbm
outpu
t
at
1 KHz .
NOISE:
70
db
below
Program
Level
.
More
than
80
db
be
l
ow
max.
output.
HUM
:
Inaudible
and
virtually
un
-
measureable
.
(Below
noise)
SEPARATION:
Stereo:
70
db
typica
l (65
db
min
.)
SIZE:
Width
, 4 .
5"
.
Height
2 .
6",
Depth
6.
5"
WEIGHT: 1
lb
. 6
oz.
POWER:
ll0tol25VAC,
50-60Hz.,
0.25A
MOUNTING:
Rubber
feet
plus
two
single
-
ho
le
"Z"clamps.
A.

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INSTALLATION:
Please
Read
Carefully!
As
with
all
electron
ic
instruments,
best
performance
will
be
assured
by
following
good
wiring
practices
and
proper
in
sta
ll
ation
procedures.
RCA
type
phono
input
connectors
are
provided
pl
ug
a
ground
terminal
for
the
turnt~ble
frame
l
ead
and
tone-arm
she
ll
ground
,
if
part
of
the
tone-arm
cable.
The
tone-arm
cable
l
ength
should
not
exceed
30
inch
es
,
to
avoid
excessive
shunt
capacitance
which
cou
ld
resu
lt
in
lo
sse.s
of
the
higher
audio
frequencies.
Output
connections
are
via
an
Amphenol
91
series
connector.
When
soldering
th
e
output
cab
l
es,
be
certain
not
to
leave
excess
solder
on
the
pins
which
might
distort
the
mating
socke
t,
and
carefu
lly
remove
any
r
ema
ining
flux
or
rosin
before
engaging
the
connector
.
Additiona
l
inform
ation
will
be
found
in
the
following
1
DESCRIPTION
section
under
"output".
A
common
cause
of
RF!
in
l
ow
-l
eve
l
audio
equ
ipment
occurs
when
a
connecting
cab
le
length
repre
sents
a
multiple
of
an
electrical
quarter-wave
at
the
frequency
of
a
nearby
transmitt
er
,
and
thereby
acts
as
an
antenna
.
Connecting
cab
le
l
engths
should
be
chose
n
slightly
longer
than
required
so
they
can
be
re-routed
or
shortened
el
ectrically
by
folding
-
over
and
tying
the
excess
length.
Al
ways
avoid
excess
cable
lengths
and
never
coil
audio
connecting
cables
.
In
strong
RF
fie
ld
s ,
these
same
conditions
may
app
ly
to
the
AC
power
-
cords
in
a
system;
excess
or
critica
l l
engths
s
hould
be
avoided
.
In
extreme
circumstances
it
may
be
necessary
to
experiment
by
adding
or
removing
various
system
grounds
..
t B.

www.SteamPoweredRadio.Com
INSTALLATION (cont'd)
to find the best combination.
The output circuit of the TEP- 3 series is a transformerless para - phase inverter
which avoid~ the problems associated with cascaded output and input transformers.
This contributes significantly to the excellent equalization and freedom from ex-
traneous hum pickup of the TEP-3S. Please read the following description thoroughly
!. to obtain the maximum benefit from this feature .
c.

www.SteamPoweredRadio.Com
DESCRI Pl'ION:
The
SPARTA
TEP
3S
(St
ereo
)
and
TEP
3M
(m
ono
)
preamplifiers
a
re
completely
self-contained
and
equalized
for
us
e
with
any
modern
varia
ble
-r
e
lu
cta n
ce
or
magnetic
cartr
id
ge
. T
he
y
offor
a
co
mbin
a
tion
of
capabiliti
es
and
pe
rform
ance
features
rar
e
ly,
if
ever,
found
in
other
ph
one
-
equa
liz
ed
pr
eamp
lifier
s
for
broadcast
us
e .
Mos
t
significant
is
the
use
of
a
dual
(
stereo
)
integrated-circuit
(I
C)
in
th
e
amplifier
prope
r .
The
ex
tr
eme
ly
hi
gh
ope
n- l
oop
gain
(ty
p.
20,000)
allows
both
t
he
operating
ga
in
a
nd
equa
li
za
tion
to
dep
end
solely
on
th
e
characteristics
of
s
impl
e
passive
components,
which
provides
inh
eren
t
l
ong
-term
stabil
ity
and
reliability
.
In
add
iti
on
,
the
s/n
ratio
of
th
e
IC
is
equal
to
or
better
th
an
can
be
obtained
in
discrete
designs,
which
l
eaves
t
he
noise
performance
primarily
dependent
upon
the
r
esistors
used
in
·
th
e
external
circ
uitry
.
Oth
er
preamplifiers
are
specified
at
10
or
12
mv.
input
for
rated
output.
But
most
modern,
high
-
performance
cartridges
provide
l
ess
than
10 mv .
output
at
normal
program
level
,
with
some
as
l
ow
as
S
mv.
So
th
e
SPARTA
TEP
3S
and
TEP
3M
preamplifiers
were
designed
wi
th
added
gain
fo
r
th
e
n
ewe
r l
ow
-
output
cartridges
with
out
compromising
any
other
performance
feature.
An
int
e
re
s
ting
side
benefit
comes
about
when
gain
is
adjusted
l
ower
to
accommoda
te
high-output
cartridges
;
Th
e
gain
reduction
also
reduces
t~e
noise
, r
es
ulti
ng
in
further
improvement
of
the
a
lr
eady-exce
ll
ent
noise
figure.
Th
e
input
im
pedance
of
eac
h
channel
is
set
at 47K
ohms
by
an
internal
1.
l.

www.SteamPoweredRadio.Com
DESCRIPl'I9N:
(cont'd}
resistor
.
This
is
the
proper
va
l
ue
for
virtua
ll
y a
ll
monaura
l
and
ste
r
eo
car
t
ridges,
but
can
easily
be
changed,
if
need
be,
by
referring
to
the
schematic
diagram.
Care
should
be
taken
to
use
only
deposited-f
il
m,
l
ow-noise
resistors
.
The
self
-
contained
power
-
supply
is
extremely
well
regulated
and
wi
ll
maintain
prop
er
performance
be
l
ow
ll
OV
AC
input
.
This
results
in
an
output
hum-level
that
is
virtually
un-detectable
and
completely
masked
by
normal
11
white
II
nois
e
produced
by
var
i
ous
circuit
resistances
.
OPERATION:
Gain
Adju
stme
nt:
During
fina
l
test
at
SPARTA
,
the
gain
(
sensitivity)
of
the
TEP
3S
or
TEP
3M
is
set
for%
dbm
output
with
10 mv.
input.
If
they
were
set
for
higher
sensitivity
,
then
operation
with
a
high
output
cartiridge
would
provide
more
than%
dbm
output
and
seriously
decrease
the
available
headroom
for
prog
ram
peak
s .
If
the
output
level
of
your
cartridge
is
unknown
and
you
do
not
have
an
NAB
te
st
record
plus
the
means
to
accurately
measure
the
preamp
output
level,
it
is
suggested
that
the
gain
controls
be
l
eft
at
the
factory
setting.
With
a
te
st
record
and
a
suitab~e
meter
,
the
1 KHz
reference
tone
at
7
cm/sec
velocity
(lateral)
can
be
played
and
the
gain
contro
ls
set
for%
dbm
output
across
600
ohms
(774 mv .)
or
for
-6
dbm
(387 mv.)
from
either
plus
or
minus
output
to
ground
(shield).
This
will
assure
the
maximum
program
output
l
evel
while
maintaining
a
minimum
of
10
db
head
room
.
Note
that
the
7cm/sec.
l
ateral
test
ton
e
will
pro
duce
the
same
level
in
ea
ch
chann
el
of
a
stereo
unit
as
a
Scm/sec
left
or
right
c
hannel
only
ton
e
will.
I
2.

www.SteamPoweredRadio.Com
OPERATION
(Cont'd}
Balance.
Since
a l
atera
l
test-tone
should
produce
equal
outputs
from
each
half
of
a
stereo
cartridge
,
th
e
method
described
automatically
assures
a
balanced
output
from
th
e
preamp
system,
for
the
gains
are
being
se
t
also
to
compensate
for
any
cartridge
unbalance.
Further
tests
may
be
made
at
other
frequencies
to
determine
if
the
system
is
retaining
proper
balance
throughout
the
audio
ran
ge
.
Balance
may
also
be
set
by
playing
a
mono
record
and
noting
the
conso
le
VU
meters.
Balance
should
be
accomplished
by
reducing
9ain
of
the
channel
which
is
too
high,
which
again
insures
that
gains
have
not
been
incr
eased
to
the
detriment
of
the
adequate
headroom
.
Input
is
made
via
a
standard
phone
jack
plus
a
separate
front
-
panel
ground
stud
.
Th
e
stud
is
provided
for
the
separate
tone-arm-shell
ground
l
ead
which
is
oft
en
provid
ed
and
is
also
the
proper
place
to
connect
th
e
turntable
frame
ground.
Ton
e
-arm
to
preamp
cables
shou
ld
not
be
much
l
onger
than
30
in
c
hes
sinc
e
excessive
capacitive
loading
will
affect
the
cartridge
high-frequency
resp
onse.
Output
is
taken
from
the
six
-pin
pane
l
socket
using
the
plug-in
connector
provided.
Refer
to
the
schematic
diagram
for
proper
connections,
rioting
that
pins
'1
and
2 a
re
not
used
on
the
TEP
3M
(monaur
al)
and
taking
care
to
note
proper
output
phasing
on
the
TEP
3S
(stereo)
as
indicated
by
the
polarity
indi
cations.
It
should
also
be
noted
that
outputs
are
tru
e
differential
balanced
-
to-ground
in
the
standard
versions,
and
care
must
be
t
aken
that
neith
er
output
is
shorted
to
ground
.
If
single-ended
outpu
t
is
needed
for
testing
purposes,
it
can
be
ta
ken
from
either
plu
s
or
minus
output
and
grou
nd,
with
the
attendant
6db
3.

www.SteamPoweredRadio.Com
OPERATION (Cont'd)
Output
(cont'd)
redu
ction
in
overall
outp
ut
level
.
Output
connections
are
normally
made
with
standard,
twisted-pair
shie
l
ded
audio
cable,
although
separate
single
shielded
cables
wi
ll
work
equa
lly
well.
Th
e
source
imp
edance
of
the
TEP
3S/M
is
quite
l
ow
,
so
cab
l
es
of
any
reasonabl
e
length
may
be
used.
In
the
interest
of
RFI
reduction,
however,
the
cables
should
be
no
l
onger
than
required
and
the
shields
may
be
left
floating
at
one
end
only,
usually
the
source
end
,
to
prevent
magnetic
field
pickup
.
The
best
arrangement
can
be
determined
experimentally
for
the
individu
al
installation.
As
stated
ear
li
e
r,
hum
is
virtually
non-existent
in
the
TEP
3S/M.
If
hum
is
experienced
in
a
final
installation,
it
will
most
lik
ely
be
due
to
pickup
in
the
cartridge
or
tone-arm
leads
.
This
can
be
determined
by
shorting
the
preamp
inputs
with
shorting-plugs.
If
the
hum
disappears,
it
was
introduced
before
the
preamp
.
Similarly,
disconnecting
the
preamp
output
plug
will
determine
if
hum
is
coming
through
or
from
the
preamp
.
If
the
output
cable
shield
was
originally
connected
to
the
preamp
output
shield
terminal
(3),
it
shou
ld
be
disconnected
and
the
plug
then
reinserted
to
e
limin
ate
any
ground
-
loops
through
the
shie
ld.
Also,
it
is
worthwhile
to
determine
if
the
load
(con
so
le)
has
a
grounded
cen
ter-tap
on
the
primary
of
the
input
tran
sforme
r.
If
so
,
this
ground
should
be
broken,
so
the
input
is
isolated
from
any
possible
ground-loops
.
Rumble
filt
e
r.
Both
th
e TEP
3S
and
TEP3M
preamps
incorp
orate
rumb
le
suppression
in
the
form
of
a
controlled
low-fr
equency
characteristic
as
described
in
the
Circuit
Theory
section
.
Response
is
shaped
so
as
to
be
nearly
2
db
down
at
30
Hz
and
3
db
down
at
20Hz
. ,
approaching
a
12db-per-octave
slope
at
the
usual
rumble
frequencies.
The
suppression
thus
obtained
is
more
than
4.

www.SteamPoweredRadio.Com
OPERATION
(Cont
'd)
Rumble
filter
(cont'd)
adequate
for
essentially
rumble-free
operation
with
any
reasonable
turntab
l
e,
without
restricting
low-frequency
reproductim
of
program
material
.
High
frequency
filtering
.
As
indicat
ed
ea
r
lier
,
the
input
impedance
of
the
TEP
3S
and
TEP
3M
preamplifiers
is 47 K
ohms
.
If
a
cartridge
is
term
i
nated
in
a
higher-than-optimum
impedance,
undesirable
high-frequency
peaking
will
result
.
If
a
lower
valu
e
is
used,
however,
the
terminating
resi
sto
r
with
the
cartridge
indu
cta
nce
will
r
esu
lt
in
a
rolloff
of
the
higher
frequencies
.
Filtering,
then
,
can
be
obtained
simply
by
provid
_
ing
a l
ower
terminating
r
esistance
.
The
proper
value
is
be
st
determined
by
trial-and-error
until
the
desired
rolloff
is
obtained.
A
resistor
may
then
be
added
directly
across
the
input
phon
e
jack
(s)
without
altering
components
on
the
circuit
bo
ar
d .
5 •