Altec Lansing 9473A User manual

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SPECIFICATIONS
Type:
Scan
Frequency Response:
ower Output:
Distortion:
Noise Level:
Source Impedance:
Load Impedance:
Maximum Compression:
Atteck Time:
Release Time:
OR
OR
OR
Threshold:
Compression ratio:
Controls:
Power Syoply:
Dimensions:
Color:
Weight:
| ALTEL
LANSING:
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OPERATING
INSTRUCTIONS
abot to 47
Figure 1. 9473A Limiter Amplifier
Limiter Amplifier
50 dB
=1 dB 20~ 20,000 Hz
+24 dBm maximum output level
Less than 1% at 20 dB compression
32 Hz to 20 KHz (Typical 0.5%)
74 dB below rated oviput
150 ©: 600 ohms
150 or 690 ohms
40 dB
10 ps
C.4 sec. above 250 Hz, 3.6sec.
below 250 Hz
C.4 sec. Single Band
3.6 sec. Single Band
Dia. Releose as 9 function of con-
trolling freauency
+15 dbmwith output level contro! ot
maximum
Selectable 4:3, 12:1, or 20:1
INPUT Level Corirol, 20 step at-
tenvater 2 dB/step
OUTPUT Level Controf, 20 steo at-
terivator 2 d8/ step
Dual Band Dual Release
Single Band Dual Release
Single Band 0.4 sec. Release
Single Bond 3.6 sec. Release
Compression Ratio interlocked 20:1,
12:1, 4:1
POWER SWITCH
120/240V o- 50/60 Hz at 15 watts
5-1/4" Hx 19" Wx 7-3/16" D
ALTEC Greer.
14 pounds
1515 S. Manchester Ave., Anaheim, Calif. $2803
DESCRIPTION
The ALTEC 9473A Limiter Amplitier, designed primarily for re-
cording studios, cherocterizes the concapt of spectral sepera-
tion, through the technique of a> Internal crossover network.
The classical problems of envelope distortion cavied by 120
short a release timeand lossaf program followings nign energy
peak
when
release
t'me
is
too
long
ore
eliminated.
A
soiid-
state, 100% silicon transistor amplifier, the ALTEC 9473A,
separates the incoming progrom materia! into two bands, eect
band controlled by o separcie limite: circuit. The distortior
floure, allowable ot the lowest frequency of the’ bend deter
mines the release time, from 250 Hz up at 0.4 seconds, are
below 250 Hz at 3.6 seconds. The ALTEC 94724 Limiter Am-=
plifier utilizes ‘wo ‘ront panel meters to indicate dB of com-
pression within the respective frequency spectrum, The usa of
an insulated gare Field Effect Transistor, provides instantaneous
attack with no thump or oversmoot.
The Qual Band Dual Release position operates on each tana
separateiy, compression in one band no: aifecting the other.
The Single Band Dual Release position contral volteges ore
sleved together, with the largest signa! cantroiling both sides.
In this mode, the ALTEC 94734 is a standard wideband com-
pressor with the added advantage of allowing the release time
to vary fron: 0.4 seconds to 3.6 seconds, as a function of the
frequency of the largest signal presen}. Forexample, high
frequency
passages
may
be
severely
compressed
by
peaks
with
a rapid release thus eliminating prolonged toss of audio, wile
low Frequency passages are released slowly te eliminate envelope
distortion.
Two
ALTEC
94734
Limiter:
provide
stereo
control
in
a'l
modes
of
operation
for
both
highand
!ow
frequency
bunds, via
'ste-eo
inferconrect’
jocks
on
the
rear
penel.
When
connecred
to”
stereo
operation,
compression
in
either
ALTEC
94734
Limiter.
Specifications and componente subject to change without
notice. Overal! yerfearmance will be maintained er improved.
42-02-04 1697~02 Price 56.21

will
dausea
carresponding
degree
of
compression
in
the
other,
thereby
maintaining
channel
gain
baience.
Wel
positioned
controls
provide
unobstructed
vision
for
ease
of
operation,
and
o
hinged
front
panel
facilitates
servicing.
INSTALLATION
Tne ALTEC 9473A Limiter Amolifier will flush mount into any
standard 19" reck orcabinet rackand requiresenly three verti-
cat mourting spaces (5-1/4") and is 7-3/16" deep.
A screw type terminalblock is provided at the rear of the chassts
for input ond output connections. Stereo control in all moces
of eperction for high ena low frequency bandsare provided via
the stereo interconnect jacks also on the rear of the chassis.
Terminels 6, 7, 8, and 9, located on the input side of the ter-
minal strip provide sroper termination fer 150 or 600 chm driving
source. Strapping combinations ond input connections are dia-
grammed ir Figure 3.
Termincts 1, 2, 3, and 4 on the output terminal strip are for
vads of 150 or 600 ohms. Proper stracping combinations and
output connections are diagrammed in Figure 3.
Figure 2. Rear View 9473A Limiter Amplifier
APPLICATION
The ALTEC 9473A Limiter Amplifier is intended foruse in auto-
matic level control applicctions fulfilling the requirements of
professional broadcast, recordingand motion picture industries.
Figures 4 and 5, illustrate twe of several system arrangements .
Figure 4 iflustrotes the use of the 9473A Limiter Amplifier in
controlling peak levels from live recording microphones in a
typical recording studio application, eliminating system over-
drive im the tape recording urit.
Figure 5 Ulustrates the S473A Limiter Amolifier used ina typi-
cal broadcast studio application to peak limit the signal frem
the program mixing console prior te distribution to the trans-
mitter moduistor. This allows the station to operate with high
modulation efficiency while preventing over nodulation. The
9473A Limiter Amplifier provides an output of +24 dBm for
_ driving remote lines to the modulator.
OPERATION AND USE OF CONTROLS
The input level control is used to adiust degrees of limiting with
varying input levels. With the control in the fuily clockwise
position (0), limiting takes ploce with an input of -35.
The input level required to reach limiting threshold increases
2 dB for every counterclockwise position cf the input level
control te a maximum of 40 dB, f.e.; an input of +5 dBm. The
output level control adjusts the ourput from the Iimiter over a
40 dB range. With theautput level contro! set fully clockwise
(0},
an
input
signa!
causing
threshoid,
produces
an
output
of
+15dBm. This output may bereduced 2 dB per counterclockwise
step
of
the
output
level
cortro!
for
a
maximum
cf
40
dB,
j.e.;
~25 dBm output at threshold .
COMPRESSION AND RATIO CONTROLS
The 20:1, 12:1 and 4:1 compression ratio controls are used to
change
the
transfer
slope
of
the
limiter
above
limiting
‘hreshold
.
In
the
20:1
sosition
a
20
dB
increase
in
the
input
level
above
threshoid causes only 1 dB increase in the output. The slope is
12:1 or 4:1 in the other two positions, respectively .
weno imam
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Figure 3. Input ond Output Stragpings
SINGLE AND DUAL BAND RELEASE FUNCTIONS
In the Duel Band, Dual Release position, the limiter operates
oneack band seperctely, compression in cne band nor cffecting
the other.
In the Single Band, Dual Release position, the control vo!tages
oresiaved together with the largest signal contralling both sides -
in this mode the limiter is astandard wideband compressor with
release time varying from 0.4 seconds to 3.6 seconds, as
function of the frequency of the largest signal present.
In the Single Band 0.4 second release or Single Band 3.¢ release
positions the limiter operates as a standard wideband limiter,
with a release time of 0.4 seconds or 3.4seconds, respec? vely.
CALIBRATION PROCEDURE
t. See Figure 4 for location of conirols and sirec tion o rota-
tion, Thesrrows indicate rhe direction of rotation toward
meximum or eack control.
2,
Set
HIGH
ond
LOW
BAND
LINEARITY
controis
to
their
MIN.
positions.
3.
Set
RIGH
and
LOW
BAND
SENSITIVITY
controls
to
their
MID.
positions.
4,
Set
RIGH
ond
LOW
BAND
THRESHOLD
controls
to
tneir
MIN.
positions.
5. Set INPUT level control to "0".
6. Set CUTPUT level control to "12".
7.
Push
the
12:
COMPRESSION
RATIO
selector
switch.
&.
Simu!tonecusly
press
the
DUAL
BAND
DUAL
RELEASE
and
SINGLE
BAND
0.4
SEC
.
RELEASE
buttons,
thereby
locking
both
down.
Jumper
point
A
te
point
B.
(See
Figure
9
for
iocation).

94794 LIMITER AMPLIFIER
i
|
{
a as Gees at me a
Figure 4. Typical Recording Studio Application
9, Apply 117V ac power to the unit and press the POWER
switch "ON".
10. Apply a 1 KHz input signal of -36 dBm to the input termi-
nals.
11. While observing the output on the oscilloscope, increase
the HIGH BAND LINEARITY contro! toward maximum until
the output wave form just starts to decrease. Any further
increase would cause a definite raduction in the level of
the output wave form.
Repeat Step 11, but this time adjust the LOW BAND LINE~
ARITY control for the start of wave form amplitudereduc-
hion.
With the -36 d8m signal still applied to the input termi-
nals, increase both the HIGH BAND and LOW BAND
THRESHOLD adjustments until thelr respective meters jus!
start to indicate to the left. The reaction to this adjust-
ment may be slow and overshoot is common. If overshoot
results and the meters peg to the left, slowly back the
threshold controls down until the meters just indicate "0".
From the -36 dB input leve', slowly incrsase the input
level until one or bothmeters just start to indicate. |f one
meter starts to indicate First, back off on its threshold con-
trol whilestill increasing rhe input ievel, unti! both meters
just start to indicate at the same input, i.e., threshold
= -35 dB.
tZs
3.
14,
FAT ZA LIMITER AmPLiFER
_
MN
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a
!
rb
a
ae
|
ne
4
PY
epniareae—
Ss
FROGRAM
j
MIXING I i
CONS CHE
Figure 5. Typical Broadcast Studio Applicerion
From the threshold level established in Step 14, advance
the input level by 22 dB.
Simultaneously press the SINGLE BAND 0.4 SEC. RELEASE
and SINGLE BAND DUAL RELEASE buttons, thereby lock-
ing both down.
Adjust both the HIGH BAND and LOW BAND SENSITI-
VITY controls for a reading of 20 dB on their respective
meters .
Simultaneously
press
the
DUAL
BAND
DUAL
RELEASE
and
SINGLE
BAND
0.4
SEC,
RELEASE
buttons,
thereby
lock-
ing
both
down.
Drop the input level by 11 dBand adjust the HIGH BAND
and LOW BAND LINEARITY controls For o reading of 10
dB on their respective meters.
20.
Inerease
the
input
level
by
11
dB
and
repeat
the
Step
16
through
20
sequence
as
necessary.
21.
Recheck
Step
14
to
=1
dB.
Hf
reodjustment
of
either
thres~
hold
control
is
required,
recheck
steps
15-20
also.
22.
Remove
jumper
from
point
A
end
B.
(See
Figure
9}.
23.
Press
front
pane!
POWER
switch
to
“OFF"
and
remove
line
cord plug from 120V supply.
HIGH LINEARITY LGW THRESHOLD |
eS evened |
LOW LINEARITY HIGH SOD | |
Hy
=]
|
MUGH SENSITIVITY
ble
LOW SENSITIVITY
Figure 6. Location of Catibration Controls
STEREO OPERATION
Two
ALTEC
9473A
Limiter
Amplifiers
provide
stereo
control
in
all
modes
of
operation
for
both
high
and
low
frequency
bands.
When
connected
for
stereo
operation,
compression
in
either
ALTEC
9473A
Limiter,
will
cause
o
corresponding degree
of
compression
ir
the
other,
thereby
maintaining
channe'
gain
balance.
Multiple
jacks
ore
provided
for
each
bend
to
allow
peralleling
additional
limiter
amplifiers.
Figure
7
illustrates
stereo
interconnection.
f oTEREG IM TERICOCMNECT i I CABLE
1] j alow al ie
[280 He mee: , |
14 + Cute: RAT Oh
t 3
if a)
LEFT CHANNEL == | | ine
PRE AAP
1] ? LEFT CHANAEL
ar it DRIVER AME
‘ a
t
LO rorcrre oe
caine! a Me apn oi
Ses
Sew,
cae
“ere
ie
aly
;
i}
=
ORG:
+
=.
C4 1
EXTERNAL STERO
INTERCONNECT SUBTCH
STE ES IH TERICONNE CT
} oy t AEM
2S He OSS 355
LIT CHAN NES
ANP
AKDT CM aAnNEL
DRIVER ane
Figure 7. Stereo interconnect
SERVICING
All circuit components are easily reached by opening the hinged
front
panel
of
the
unit.
Normel
servicing
may
be
done
with
a
volimeter. All pertinent information is shown on the schematic,
Figure 10.

Figure 8. Typical Limiter Characteristics
PARTS LIST
Reference
Destignator
Ci
C2, 25,32, 33,34
C3,4
CS76
67,8; 1120
C9,10
C12, 13
C14,15,36,37
C2)
a
CRI
CR2,3,4,5,6,7
TRE
CRY
CRIO,11,13, 14
RZ
Q6,7,8,9, 14,15,
16,17,21,24
10, 11, 42, 13,20
218,19
Q22
Q23
R1,73
R2,o4
Ordering
Number
:5-0°-108579--01
15-06-107426-01
15=06-10013 1-91
15+ 06-051 240-02
1$-O07-107343-01
15-03 -106218-O7
T5-01-168635-01
15-02-108584-0}
15-06- 106204-0%
15-06-108629-01
15-01-108580-0)
15-01-107523-01
15-01-100255-01
15-01 -108581-01
15-01-108578-01
35-02-107455-01
4B8~01-108576-0'
48-01~102592-01
48-01-108575-01
48-01 -109738-0}
48-01-10701 7-01
48-02-108577-90}
31-04-100464-01
29-01-041819-01
48-03-167318-01
48-03-108575-01
48-03-04) 440-01
46-03-101098-01
46~03-108574-0}
45-03 -04046 i-G2
48-03-1017 111-9)
10-05- 26-487
47~01-104541-0)
Nlame ond
Description
Cap., 50 pF 30V
Cap., | wF 210%, 50V
Ceop., O11 pF 210%, 100V
Coo,,, ©.025 pF £5 6}
yOoV
cap., 25 pF 25V
Cap., lyr 15V
Cap., 200 wF 15V
Cap., }O pF 30V
Cop., 0.047 pF +10%,
OOV
Cap., 0.47 pF 10%,
100V
Cap., 25 wF 6V
Cap., 50 pF 15V
Cap., lOO ur 20V
Cap., 50 pF 50V
Cup., 3103 pF 40V
Cap.,47 pF +10%, 100V
Diode, Zener +15%, 5V
Disde
Dinge, Zener 30V 5%
Diode, Zener 27 10%
Diode, IN456A
Diode, Rectifier, SCBR~]
Fuse, IA 3AG
Meter
Transistor, 2N5308
Transistor, MAFESO0Z
Transistor
Transistor (AL2712)
Transistor, 2N4639
Transistor
Transistor, 2N4036
Attenuctor, 25K
Res. , 330K 0 25%, 1/4W
JDOPER PORT ay
TS ROINT B
Figure 9. Input Switchboord Asembiy
PARTS LIST (Continued)
Name ond
Desertation
48,76, 77, 78,87,88 47-01-102127-0) Res., WOOKR 45%, 1/4W
Reference Ordering
Designotor Number
R3,10,32,33,44,4546,
k4,5 47-0} -102086-01
R6,8 47~01=102097-91
R7 APF -CF~-1021 12-0)
R? 57,60 47-013-102082-01
Ri] 47~91-192115-0'
R12,13,42,43 47~O1-10Z094~01
R14,16,34,35 47-04-1021 00-03
R16,17,52,
54,56,59 47-05-100813-01
R18, 19,22, 23,40,
41,55,53,67,
69,83, 84 47-01-102102-01
R20,21,24,
25,26,27 47eO1+102)10-01
R28, 29,49 ,50 47~01+102114-0)
R3G,33 47~01-102066- 01
R36 ,37,62,75
80,81 47~(j1-10207&-C"'
R38 ,39 47-01~102079-91
R51,52 47-01-1085B6- 01
R56 ,61,70 47-01 -192090- 0)
R65 47=0)~10213 1-01
R66 68 47~-C4~102098- 01
R71,72 A7~-O}-102030-0)
R74,75 47-03-102346-Ci
R82 47~01~-102073-01
R85 ,86 47=-01-102038-01
RES 47=91~102351+01
5] 51-02~108588-01
$2 51-02-106589-01
TI 56-04-004833-01
12 56-08-007375-01
T3 56-07-0115 298-01
Res., 2.2K 2 29%, 1/4W
Res., 6.2K 07 25%, 1/4W
Res., 27K 2 45%, 1/4W
Res., }.SK 225%, I/4w
Res., 36K 2 45%, 1 /4W
Res., 47K 02 £5%, 1/4W
Res., 8.2K 245%, 1/4W
Potentiometer, 1OK &
Res., 10K © £5%, 1/4W
i /4W
as
Van
Res., 22K C2 +596,
Res., 33K & +5%,
Res., 3302 «5%,
—
Res., 1K 45%, I/4W
Res., 7 5KQ 25%, 1/4
Res, 8.245%, 1/4
Res.,3.3KQ 45%, 1/4W
Res., SOK 45%, 1/4
Res., 6.8K 245%, 1/4W
Res., 19 45%, 1/4W
Res., 3302 =10%, 1/4W
Res.,6202 25%, 1/4W
Res., 222 45%, 1/4W
Res. , 470 2210%, 1/2W
Switch assembly
Switch assembly
Transformer, input
Transtormey, power
Transtormer, output

Ty
=
8
wif
|
&
QUTPUT
STRAPPING
INFORMATION,
FOR
600a, STRAP
2-3 AND
CONNECT
TO
+4,
FOR
1900,
TRAP
1-2
4
3.4
AND
COonnecr
1-4,
&
INPUT
STRAPPING
INFORMATION.
FOR
$0Ca, STRAP
7-6
ANT
COMNECT
‘Te
6-9
FOR
159m.
STAL®
6-79
8-9
AND
CONNECT
TO
6-&
SAL
OCES
WE
TS.
2.
aL
CAPECITOR
VALLES
ARE
IN
micaranads
4
MLL
RESSTOR
vacuts
ake
%
Ones,
‘Abwatt,
28%
:
MOTE:
UNLESS
CTwEawiSE
SPECHHO
1
wis
8
1]
t
=
CL
Figure
10.
Senomer'c,
473A
Limiter
Amplifier
eck
a
M27 >>
Mas
Sata
ca
eae
es
ee
OR
ERLE
Se
ph
eo
LIMITER