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SOUND
PICTURES
LESSON NO.
P-1+
THEATER
SOUND EQUIPMENT
THE PURPOSE
OF THIS LESSON IS TO FAMILIARIZE YOU HITH THE VARIOUS
AMPLIFIER
CIRCUITS AND SYSTEM HOOK-UPS AS USED IN THE CONVENTIONAL
THEATER-
YOU HILL
FIND THE FIRST PART OF THIS PARTICULAR LESSON TO BE BASED
UPON
WESTERN ELECTRIC EQUIPMENT HHICH IS MANUFACTURED AND INSTALLED BY
ELECTRICAL
RESEARCH Pnooucrs, Inc. Nesrsnu ELECTRIC EQUIPMENT as VERY
POPULAR IN
THE SOUND PICTURE FIELD; AND CAN BE USED HITH ALL TYPES OF
WELL KNOWN
PROJECTORS- THE LATTER PORTION OF THIS LESSON I5 DEVOTED TO
0
5%!-
PAGE 2
souuo PICTURES
R.C PHOTOPHONE SOUND EQUIPMENT AND WHICH ALSO IS
USED A GREAT DEAL.
DURING THE
FEW YEARS wE HAVE HAD SOUND MOTION PICTURES, PRACT!C-
ALLY ALL
souun SYSTEMS vznz DEVELOPED HERELY WITH THE IDEA or souuo RE-
PRODUCTION
IN MIND, GIVING LITTLE OR no CONSIDERATION To THE quAL|Tv OF
souuo
PRODUCED. UNTIL REcEuTLY,A SERVICE ENGINEER wAs CALLED unou To R5
PAIR souuo
EQUIPMENT wusuzvsn TROUBLE OCCURRED- Tans wAs VERY EXPENSIVE
AND LED To
MANY DELAYS AND POOR PERFORMANCE. THE PUBLIC NOV DEMAND$ THE
BEST |~
BOTH EQUIPMENT AND OPERATORS, IT |s FOR THIS REASON THAT we ARE
anvnne YOU
A THOROUGH TRAINING vu SOUND'AND REPRODUCTION. BEFDRE we
TAKE UP THE
PRACTICAL woax AND TRAlN|NG,|T IS NECESSARY TD ACQUAINT YOU
w|Tu THE
DIFFERENT SYSTEMS AND EQUIPMENT USED an MOTION PICTURE WORK-WE
SHALL START
WITH WESTERN ELECTRIC EQUIPMENT, s|v|ns YOU A BRIEF DESCRI-
_ PTION AND
DISCUSSION
LESSON NO-
L PAGE 3
THIS
ILLUSTRATION VERY CLOSELY, YOU WILL DISCOVER MANY IMPORTANT FACJS.
FIRST, YOU
HILL FIND THAT AT LEAST THO PROJECTORS IAIITH BUILT-IN P.t.
CELL
AMPLIFIERS ARE REQUIRED IN ORDER TO OBTAIN CONTINUITY OF REPRODUC-
TlON- A
METHOD OF SWITCHING THE OUTPUT OF EITHER MACHINE T0 THE I-I-IA ,A_h_1_
PAGE R
SOUND PIcTuRE§
IN us: AND
A REcTIrIER wHEN THE AL.PowER SUPPLY Is IN usE. IN THIS IN-
sTALLATIoN,
wE FIND THAT A D.C. POTENTIAL Is REquIREo FOR THE EXCITING
LAMP,
PHOTO—ELECTR|C CELL, FIELD MAGNETIZING cuRRENT FOR THE LOUD sREA5
ERs, AND
FOR THE MIA AMPLIFIER wHIcH Is COMPLETELY_D-C- OPERATED. WE AL
so FIND
THAT A D.C. PQTENTIAL FOR THE REA AND U}A AMPLIFIERS Is REQUIR:
ED.
TRACING THE
SIGNAL
BEFORE
BREAKING THE BLOCK DIAGRAM DOWN INTO ITS COMPONENT PARTS,
LET US
TRACE OUR SIGNAL THROUGH THIS COMPLETE S‘fSTEM-
THE HEAVY
BLACK LINES IN FIO.I INDICATE "s|aNAL LINES". STARTING
AT THE
LEFT’WE FIND THE OUTPUT or oNE FILM PICKUP AND oNE MAGNETIC RE-
105-O
IN THE
THEATER. IN F|G- 2 YOU WILL FIND A PHOTOGRAPH 0; THE AMPLIFIERS
AND CONTROL
SYSTEM .
P.E. CELL
AMPLIFIERS
THE WEsTERN
ELECTRIC SYSTEM uszs Two DIFFERENT
EcTRIc CELL
AMPLIFIERS. THE OLDER TYPE MACHINES USED
TUBE BEING
LOCATED IN THE CELL HOUSING AND THE OTHER
SUSPENDED
ON THE MACHINE AT SOME coNvEN|ENT POINT.
IN
CONNECTION WITH
PLIFIER wE
BUILD up
THE SIGNAL
CURRENT
THROUGH THE
HZA AND
UjA
AMPLIFIERS, THUS
SECURING
SUFFICIENT
AMPLICATION
or Wyoua
SlGNAL- OuR
AMPLI-
FIED
SIGNALTHEN GOES
Te THE
OU??UT ca»-
TROL
PANEL,WHERE IT
Is FED To
THE VAR-
Ious LOUD
SPEAKERS
TYPES or
RuoTo-EL-
THREE
STAGES, oNE
Two STAGES
BEING
THE NEWER
MODELS
USE ONLY
TWO STAGES AND BOTH OF WHICH ARE SUSPENDED BELOW THE CELL HOU§
ING-
THE P.E.
CELL AMPLIFIER uszo WITH THIS LATTER SYSTEM '5 THE
LESSON no U
PAGE 5
D-859k} OR
D~86Y29 AND ITS DIAGRAM APPEARS IN FlG- 3- UPON LOOKING AT
THIS
oIAsRAM,vou WILL FIND THAT THE P.E. CELL I5 RE$|5T*"°E'°*P*¢'T*
COUPLED TO
THE FIRST STAGE. Tu: ACTIVE SURFACE or THE CELL, wH|cH Is Tu:
FILM ON THE
INNER SURFACE OF THE GLASS IS CONNECTED T0 THE MINUS SIDE OF
THE BATTERY
AND THE COLLECTOR RING Is couuscrso THROUGH A TWO MEGOHM as-
SISTOR TO B
PLUS. ALL STAGES EMPLOY rue W.E. 239 TYPE TUBE AND THE FIL-
AMENTS ARE
WIRED IN sznnss. THE OUTPUT FEEDS INTO A 500 own LINE WHICH
CONNECTS TO
THE FADER.
A CIRCUIT
DIAGRAM or THE kl-A AMPLIFIER APPEARS In FIG. 3-
BY
REFERRING T0
FIs.2 AeAI~,You
WILL W
NOTICE THAT
THE REA
AMPLIFIER
Is MOUNTED
DIRECTLY
BELOW THE HIA
AMPLIFIER,
THIS NZA A!
PLIFIER
CONSISTS or A
SINGLE
TRANSFORMER cog
PLED
PUSH-PULL OPERAT-
zo STAGE
EMPLOYING A
PAIR OF
TYPE W.E. 205D
rua:s.(THE
CHARACTERIE
TIC or
THESE TUBES ARE
cnvzn IN
one or YOUR
TUBE
cHARTQ.THz F|LA-
MENTS ARE
OPERATED on
A.C. FROM
STEP—DONN
TRANSFORMERS.
PLATE
VOLTAGES
ARE OBTAINED
FROM A PAIR
or 205D
TUBES WHICH
OPERATE As
RECTIFIERS
wusn conn-
ECTING THE
GRID AND
PLATE or
EACH TUBE 10-’
GETHER.
Tn|s AMPLIFIER
HAS A GAIN
OF 25 D-5-
Anu Is
CAPABLE or oc-
LIVERING
2.5 WATTS or
UNDISTORTED
ourpur PO!
ER. SEE
FIc.5 roa A
CIRCUIT
DIAGRAM OF THE
UZA
AMPLIFIER.
To PERMIT
THE
FILAMENTS
TO LIGHT ec-
FQRE THE
HIGH PLATE
VOLTAGE Is
APPLIED TO
THE
TUBES,THE CONTROL
SWITCH Is
szr so THAT
ITS FIRST
POSITION,
rue POINTS
A-B AND D-E
ARE
CLOSED,THUS LIGHT-
ING THE
FILAMENTS or
THE 742-A
AMPLIFIER
m SWIYCH
FOR AR
_ nzsuun
Ann UICIIR
Q [HERSHEY
gymuils
IIIPUT
SPEAKER
VOLUME CONWOL
MULYI-TAPPED
MD IMPEDANCE MARI‘
AUTDYIAIISFORHII
YA? SWIYClI.$
F01}
EXIHIN.
PAGE 6
souuo PICTURES '
THE TUBES.
AFTER THE FILAMENTS ARE HOT, THE CONTROL IS MOVED TO POSI-
TION NUMBER
TVO AND THE AMPLIFIER THEN GOES INTO OPERATION
THE h3A
AMPLIFIER
Tu|s
AMPLIFIER us SIMILAR T0 tn: REA, AND CONSISTS OF A SINGLE
TRANSFORMER
COUPLED PUSH-PULL STAGE. THIS AMPLIFIER USES Two 211E TYPE
TUBES,
snvnnc A PowER output or ABOUT 12 wArrs, 0R A GAIN or 6 D.B. IT_
LESSON No R
PAGE Y
AMPLIFIER
IS SHOWN IN FIG-6A AND WE ADVISE YOU TO STUDY IT THOROUGHLY
BEFORE
CONTINUING WITH THIS LESSON-
OUTPUT
CONTROL PANEL
THE OUTPUT
or THE U§A AMPLIFI-
ER GOES To
THE 200A CONTROL PANEL
TH|s UNIT
rs THE DISTRIBUTING SYSTEM
ANo us
sHowN AT THE TOP OF THE RACK
IN F|e.2 A
REAR-v|Ew or THE 200A
CONTROL
PANEL |s sHowN IN FIGURE 6B.
THE
PRINCIPLE PART or THIS coN
TROL PANEL
coNs|sTs or A sTER-oowN
AUTO-TRANSFORMER
WITH A NUMBER or IN
TERMEDIATE
TAPs, wH|cH ARE coNNEcTEE
TO sEvEN
DIAL sw|TcHEs. TH|s PERMITS
THE CONTROL
OF sax SPEAKERS AND oNE
MONITOR
SPEAKER- THE MONITOR SPEAKER ;¢_.
HAS A PAD
WHICH DROPS THE'POw£R ’ To ““‘“ " ’ ”'*
A
COMFORTABLE HEARING VALUE.
Fza. 9
The It/.5.
49-A Amp//'7‘/'¢rfl
OTHER W.E.
INSTALLATIONS
THERE ARE
SEVERAL OTHER cou-
PLETE
WEsTERN ELEcTR|c INSTALLATIONS
usEo FOR
VARIOUS PuRRosEs. ONE or THE|R PRODUCTS, THE h6A sYsTEH, |s
VERY
POPULAR AND uszo EXTENSIVELY IN THE SMALLER THEATERs. FoR THE LAR
GER sHow
HOUSES THERE IS A cHo1cE or SEVERAL INSTALLATIONS, EACH BUILT
UP FROM
STOCK AMPLIFIERS- THEsE srocx AMPLIFIERS ARE THE 8B,9A AND IOA
PAGE 8 SOUND
PICTURES
THE 119A
AMPL lT>'|ER
Tn: U9A, A
new HIGH-GAIN AMPL|F|zR,HAs azzn BUILT FOR use WITH
THE h6A
AMPLIFIER. IT uses THE 3A PHOTO—ELECTRlC CELL AND Two STAGES or
W.E. 26hA
Tuacs. THE 59A IS usso BETWEEN THE PHOTO—ELECTRIC CELL AND
THE MAIN VOLTAGE
AMPLIFIER. |T us MOUNTED |n A RUBBER cusnnonco CRADLE
LESSON
No.14 PAGE 9
ES
OPERATING AT A PLATE VOLTAGE OF 350 VOLTS AND A anon VOLTAGE or -21
voLTs._lT
HAS A GAIN or 16 D.B. AND WILL PRODUCE 1.36 WAYTS or uNo1sTQ3
TED woven.
OTHER FEATURES or THIS AMPLIFIER AR: SHOWN IN THE CIRCUIT
DIAGRAM or
F1s.12.
THE 10A
AMPLIFIER
THIS I5 A
HIGH-POWER AMPLIFIER USING FOUR 211E TUBES IN A SINGLE
PUSH-PULL
STAGE, OPERATING AT A PLATE POTENTIAL OF 150 VOLTS raom A
sPccrAL
RECTIFIER on MOTOR GENERATOR,AND A ennu a|As or -36 VOLTS QB-
TAINED FROM
BATTERIES. A BLOCK DIAGRAM or A nzcn POWER INSYALLATION qg
ING vac 8B
AND 10A AMPLIFIERS IS suowu IN FIGURE I}. Tn: SAME svsrcm
IN RACK AND
PANEL roan us suowu IN F!GURE IN.
<(I|1—\uu
‘ n H I ! __
Lag/cuf of
M E. Sauna’ Prafecfar S5/$7‘e/-r1
THE 6000A
RECTIFIER
THIS as THE
UNIT THAT SUPPLIES THE PLATE AND FILAMENT VOLTAGE roa
THE LARGE
INSTALLAT|ONS- As MAY as scan FROM FIGURE 1%, IT CONSISTS or
THREE
QISTINCT PANELS, WHICH ARE THE 519A, on FILTER UNIT FOR Tn: HIGH
voLrAcg
RECTIFIER 520A,ANo THE PANEL CONTAINING THE PLATE cunnsur MET-
cas. _
TH: 520A
PANEL SUPPLIES 1§0;}50; AND 150 VOLTS FOR THE VARIOUS A5
PLIFIERS.
I1 EMPLOYS "Two TYPES W.E. 219 RECTIFIER ruazs IN A FULL-
wAvs
RECTIFYING CIRCUIT. A runs: POSITION sw|1cn ENABLES THE FlLA-
MENTS or
ALL TUBES TO LIGHT acroaz THE PLATE VOLTAGE IS APPLIED.
FILAMENT
VOLTAGE roa THE vAR|ous AMPLIFIERS |s OBTAINED rnom THE
521A PANEL
WHICH ls ONLY A STEP-DOHN TRANSFORMER FOR EITHER 110 on 220
VOLTS A.C.
THIS PANEL ALso CONTAINS A METER FOR MEASURING FILAMENT cug
RENT.
PAGE IO
SOUND
PICTURES
W.E.
MISCELLANEOUS EQUIPMENT
THERE IS
STILL ANOTHER VERY IMPORTANT ITEM To COMPLETE oun INSTA-
LLATION,
AND THAT Is THE FADER. FIGURE 15 sHows A FRONT vIEw or THE
FADER AND
FIs.16 A cIRcuIT DIAGRAM. BY STUDYING THE D|AGRAM You wILL
FIND THAT
THIS FADER Is A D.B. VOLUME CONTROL THAT wILL ATTENUATE THE
SIGNAL rnom
Two CHANNELS- THE RESISTANCE NETWORK on THE INPUT AND ouT-
PuT SIDES
or THE FADER ARE H PADS.
SOUND HEAD
THE SUBJECT
OF THE SOUND HEAD WAS TAKEN UP IN A PREVIOUS LESSON,
BUT TO MAKE
OUR DISCUSSION COMPLETE WE ARE SHOWING YOU THE w.E- SOUND
HEAD IN
FIGURE I7. BY LOOKING AT THIS PICTURE HE CAN TRACE THE PATH OF
T (— _ THE
FILM THROUGH THE PROJECTOR
5I9~A
FILTER
PANEL
A-STAGE
:1-1:2
B'SIAGl 3
B"!
AHPLIFIR
PLAY! SUM.‘
SWITCHES
' 5201
n:cTIr|E|=
PIN EL
SZITA
FILAHEIIY
SUPPLY
PA|\U~
I AND suuuu
HEAD. NOTICE THE
,§§flmR ‘ scnzws on THE EXCITING LAMP
vHIcH
ENABLE one To ADJUST THE
‘ LAMP TO
ANY DESIRED POSITION-
R.C.A.
PHOTOPHONE
SOUND EQUIPMENT
BOX
LIKE THE
ELEcTRIc RE-
SEARCH
Pnooucrs Co., THE R.C.A
PHoToPHoNE
Co. BUILDS AND IN-
STALLS
SEVERAL TYPES or souno
°flf§fl§P SYSTEMS. THEsE ARE CLASSIFIED
""“
INTO THE A TYPE, wH|cH Is no
LONGER
MANUFACTURED, THE B syg
TEM WHICH
IS uszn FOR HOUSES
OF 2,500 on
MORE SEATS AND THE
FUNDAMENTAL
UNIT FOR THE SMALL
ER
INSTALLATIONS svcn AsC svq;
TEM FOR
HousEs BETWEEN 800 AND
MUgm:§MMT‘
2,500; D SYSTEMS FOR HOUSES OF
800; F
SYSTEMS FOR HOUSES or
”700; AND G
SYSTEMS FOR HOUSES
OF 500 on
LESS. Anonc THE NE!
E51 R,¢
A,|NsTALLATIoNs IS THE
HIGH
FIDELITY souuo SYSTEM
WHICH WILL
aE oIscussE0 on THE
I FOLLOWING
PAGES. ALL or THEsE
‘I usu
svsvzms OPERATE FROM THE
A.C. POWER
SUPPLY LINE.
TYPE A
AMPLIFIERS
THE TYPE A
AMPLIFIER IS
A VERY
LARGE UNIT, CONSISTING
I-v or Two
COMPLETE SYSTEMS 'lN
1=;¢.,.14
mans, s|oE av sIoE, AS suown
7776 Com
/e7¢e pane/. IN FIG. I8. THE AMF'I_IFIER$
P WOULD BE
IDENTICAL WERE IT NOT
LESSON No.U
PAGE I1
FOR ONE
RACK WITH A LOUD SPEAKER DISTRIBUTING PANEL ON IT.
VOLTAGE
AMPLIFIERS
UNLIKE
OTHER SYSTEMS THE R.C.A.PHOTOPHONE EQUIPMENT uozs NOT us:
SPARE
EICITER LAMP5
FADER
TOME
ccNTR¢L.
FIG.15'
735 Fiacflzrt
ARE JUST
ADDITIONS OR
THE SOUND
HEAD
BY STUDYING
Fne.
I9 vou WILL
NOTICE now
THE FILM ls
THREADED
IN A
SIMPLEX MACHINE
AND THE PARTS
THAT
MAKE UP THE
souuo HEAD.
Tues: PARTS
CONSIST or
THE EXCITER
LAMP, THE
P.E. CELL, THE souuo
GATE, THE
LENS SYSTEM,
THE
ROLLERS, AND THE
CONSTANT
SPEED SPROCK-
ET5. Fen
THE OPERA-
TION OF THE
VARIOUS
PARTS,
REFER To THE
PRECEDING
LESSONS.
A HEAD AMPLIFIER,
on P.E. CELL AMPLIFIE&
As IT IS
CALLED. THE P.E. CELL IS TRANS-
FORMER—COUPLED
To A STAGE USING A UX-210
TUBE AND
THEN INTO A UX-8M1 TUBE AND FIN-
ALLY INTO A
210 As THE LAST STAGE. GRID
VOLTAGE us
OBTAINED FROM new BATTERIES
AND PLATE
VOLTAGE FROM A VOLTAGE TAP ow
THE 1000
VOLT D.C. GENERATOR.
POWER
AMPLIFIER
THIS
AMPLIFIER, WHICH IS DRIVEN av
A VOLTAGE
AMPLIFIER, CONSISTS or A PUSH-
PULL STAGE
EMPLOYING TEN UV-8H5 TYPE Tus-
ES. IT
OBTAINS PLATE AND GRID VOLTAGE
FROM D.C.
GENERATORS. As THIS |s AN OLD
INSTALLATION,
we WILL LEAVE IT AND STUDY
THE NEW
TYPES or souuo SYSTEMS.
TYPE B
EQUIPMENT
VERY
CAREFULLY As THE OTHER INSTALLATIONS
. L-
TAGE IS
OBTAINED FROM A FUL£
WAVE
RECTIFIER EMPLOYING TY-
PE BI
Tuezs. Tfie I4/.E. Sou/10' /‘/E50’
BY LOOKING
AT Fla. 21
vou CAN
FORM A coco MENTAL
PICTURE or
THE CIRCUIT DIA-
GRAN. THE
g;RsE_ REC-
TIFIER
SUPPLIES THE VOLTAGE
AND CURRENT
FOR THE MAGNETI-
ZING OF THE
SPEAKER FIELDS.
TYPE C
SYSTEM
THIS
INSTALLATION con
SISTS OF
THE SAME VOLTAGE
AND POWER
AMPLIFIERS THAT
ARE USED IN
TYPE B SYSTEMS,
EXCEPT ONLY
TWO POWER AMP-
LIFIERS ARE
USED.
TYPE D
SYSTEM
TH|s SYSTEM
|s ALMOST
IDENTICAL
To THE TYPE C sys-
TEH, THE
ONLY DIFFERENCE BE-
nnc THAT
TYPE D EMPLOYS ONLY
one VOLTAGE
AND POWER AMPL|—
FIER, AND
IT noes NOT EMPLOY
THE TONE
COMPENSATION THAT
|s USED |n
TYPE C.
TYPE F
AMPLIFIERS
FI6.17
PAGE In
souun PICTURES
USED IN
OTHER HEADS HAS BEEN REMOVED THE.OPTICAL SYSTEM HA5 ALSO BEEN
SIMPLIFIED.
THE MECHANICAL SLIT HAS BEEN MOVED TO THE REAR END OF THE
OPTICAL
SYSTEM, AND ADJUSTMENTS ARE MADE AT THAT POINT» FOCUSING IS DONE
BY ACONTROL
WHICH
Cfrcu/"Es
of Pawer Amp/1'7‘/'er,
HIGH
FIDELITY SYSTEMS
THE DEMAND
FOR HIGH FIDELITY HAs BEEN MET av THE R.C.A.PHoToPHoNE
Co , IN
SEVERAL INSTALLATIONS- THEsE SYSTEMS ARE COMPLETELY.A.C. QPERAT
ED AND ARE
MOUNTED IN RACK AND PANEL FORM- ALTHOUGH THEY WERE DESIGNED
FOR USE
WITH S|MPLEx PROJECTORS, THEY MAY BE OPERATED w|TH OTHER TYPES.
To OBTAIN
HIGH FIDELITY, A NEw TYPE SOUND HEAD wAs BUILT AND IS Now
STANDARD EQUIPMENT.
.
THE Ps-2h
SOUND HEAD
THIS NEW
SOUND HEAD IS CALLED THETHOTARY STABILIZERHBECAUSE A RO-
TARY DRUM
IS EMPLOYED FOR THE SOUND TAKE-OFF INSTEAD OF THE USUAL GATE.
THE
CONSTANT SPEED CONTROL CONSISTS OF A SMOOTH DRUM PULLED BY THE FILM
MOUNTED ON
A SHAFT HAVING A LIGHT HOLLOW CASE ON THE OUTER END OF
SHAFT. THIS
SHAFT RUNS ON
THE
BALL
BEARINGS. INSIDE THE
cAsE IS A
FLYWHEEL coNcENT-
nnc VITH
THE SHAFT BUT RUNN-
ING on A
EALLBEAHTNG so THAT
IT IS
ENTIRELY FREE To RD-
TATE AROUND
THE SHAFT- THE
cAsE IS
THEN FILLED w|TH OIL
-N“
mm»
--.....
D...“
TIIZTIHIZ
Oi
TD DAMP OUT
THE OSCILLATIONS
WHICH WOULD
OCCUR IN THE MO-
TION OF THE
DRUM WERE THE
gILEIiL:_=
I
IIl|Hi'I
E =aI
vi.
"~"““;: "‘ ‘ E.
FLYWHEEL
CONNECTED TO THE
SHAFT. WHEN
THE SHAFT IS RO-
TATEo,THE
HOLLOW cAsE WILL
F516. 2111
7H5 Tigoz F:.4n@ufijZern
LESSON uo.h PAGE 15
PoTAT:,cAus|ua
THE FLYWHEEL TO TURN nu: To THE VISCOSITY or THE OIL
Tnus new
souno HEAD IS SHOWN IN Fun. 2“, WITH ALL PARTS LAa:L:o-As THE
MOTOR 1s
BUILT INTO THE souuo HEAD CASTING, IT ELIMINATES THE us: or
BELTS OR
CHAINS FOR DRIVING PURPOSES-
TYPE PG-}2
SYSTEM
THIS
svsrem, IS COMPLETE FROM PROJECTORS To SPEAKERS AND Is usso
ONLY wntu
SIMPLE! MACHINES Tu: SYSTEM INCLUDES SEVERAL NOVEL CHANGES
rnon OLDER
EQUIPMENT, A SEPARATE zxcnrsn LAMP SUPPLY VOLTAGE,PHOTO—CELL
EQUALIZING
POTENTIOMETER, REMOTE VOLUME CONTROLS AND THE NEW souun HEAD
ausr
usscn|s:u- A SCHEMATIC DIAGRAM or THE COMPLETE INSTALLATION |s
snow» nu
F|e.25. BY STUDY|NG F|e.25, You WILL rnun THAT THE 868 P.E.
CELL |s
COUPLED TO THE VOLTAGE AMPLIFIER av AN IMPEDANCE MATCHING TRAN§
FORMER
THROUGH THE SWITCHING PANEL AND FADER.
Tn: FIRST
STAGE EMPLOYS A TYPE 22h-A TUBE wnncu us RESISTANCE couf
LED To THE
56 TUBE |u THE szcouo sTAs:. THE FILTER UNIT IN THE PLATE
CIRCUIT or
THIS STAGE PROVIDES A SHARP CUT-OFF AT 9500 CYCLES. Bv PARA-
LLELING THE
950 MMFD- connsuszn WITH A 550 unro. connzuszn AND CHANGING
TAPs on THE
co|L, A CUT—OFF or 1000 CYCLES MAY as HAO. TH: 56 STAGE |s
COUPLED TO
A PUSH—PULL STAGE EMPLOYING Two 2N5 TUBES As A VOLTAGE AMPLl
FIER. '
Tn: POWER
AMPLIFIER vs A PUSH-PULL STAGE usnua B45 TYPE ruazs. A
PICTURE or
oun COMPLETE AHPLIFYING svsrzu MAv as rouun an F:e.26. Tans
AMPLIFIER
SYSTEM |s ALSO KNOWN As TYPE PA-52. PLAT: VOLTAGE ron THE vqh
TAGE
AMPLIFIER AND POLARIZING VOLTA
LESSON Ho.
U PAGE I7
OBTAINED
FROM A VELL FILTERED RECTIFIER EMPLOYING A TYPE 80 TuaE. THE
POWER
AMPLIFIER REcE1vEs ITS PLATE SUPPLY FROM A HIGH VOLTAGE RECTIFIER
CONTAINING
Two TYPE 866 MERCURY vAPoR TUBES. To PREVENT DAMAGE T0 THE
TUBES, A
TIME DELAY CIRCUIT PERMITS THE FILAMENT To HEAT UP BEFORE THE
HIGH PLATE
voLTAeE IS EMPLOYED.
BECAUSE OF
THE HIGH VOLTAGE; EXTREME CARE MUST BE TAKEN T0 PREVENT
PERSONAL
INJURY. A SAFETY SWITCH IS CONNECTED IN THE CIRCUIT WHICH TURNS
OFF THE
HIGH VOLTAGE, HHENEVER THE COVER-
ING FOR THE
POWER AMPLIFIER IS REMOVED. _,ii
THE EXCITER
LAMPS RECEIVE DIRECT
CURRENT
FROM SEPARATE DISC RECTIFIERS; amen“
ONE BEING
EMPLOYED FOR EACH LAMP. THE “"55
CURRENT IS
VERY WELL FILTERED TO OBTAIN
A PURE
DIRECT CURRENT.
VOLUME
:nnI|0L
OPERATING
INSTRUCTIONS lAbV|£:Y.k(;|0s/
To sTART
THE EQu|PHEHT,TuRN "DH" ~"w"fl»“
THE A.C.
LINE sw|TcH AT THE ToP OF THE
RACK on:
MINUTE BEFORE THE svsTEH IS To
as usED.
AFTER 30 SECONDS, THE TIME DE-
LAY APPLIES
THE PLATE VOLTAGE To THE
TUBES AND A
BLUISH eLou v|LL APPEAR
AROUND THE
PLATEs OF THE 866 RECTIFIER .
TUBES. FIG
AFTER THE
MACHINES HAVE BEEN CLEAN— {gar L§gM/ 3/'Ayqp[ £2;k
ED AND
o|LED, THREAD THE FILM THROUGH THE
PROJECTOR
AND souun HEAD,LEAv|He THE REQUIRED LooPs. TDRH on THE EXCITER
LAHP av
THROHING THE sH|TcH on THE BACK or THE souuo HEAD To THE "on"
POSlTl0N-
START THE PROJECTOR BY TURNING THE HDTDR sv|TcH T0 THE "on"
POSITION.
AFTER THE MOTOR HAs GAINED SPEED (AsouT THO sEcoHDs) FADE THE
souuo
c|Rcu|T on THIS PROJECTOR av DEPRESSING AHD RELEAs|He THE FADER
sH|TcH
HANDLE on THE souuo CONTROL UNIT- WHEH THE souuo CIRCUIT |s com-
PLETE, THE
INDICATOR LAMP on THE CONTROL UNIT HILL LIGHT. THE INPUT cog
TROL UNIT
IS NOT USED As THE VOLUME coHTRoL. IHsTEAD, A GAIN CONTROL |s
EMPLOYED
FOR EAcH AMPLIFIER AND IS CONTROLLED BY REMOTE CONTROL BUTTONS.
To sToP THE
EQUIPMENT; |T IS ONLY NECESSARY To TURN "OFF" THE A.C. LINE
sv|TcH on
THE AHPL|P|ER RAcx.
THE PG-65
SYSTEM
_ TH|s as A
SMALLER INSTALLATION THAH THE PG-32 EQUIPMENT. IT as
SUITABLE
FOR HOUSES HAVING A cAPAc|TT or 800 sEATs. A PS-24 TYPE SOUND
HEAD IS
EMPLOYED, THE ouTPuT or wH|cH |s IMPEDANCE MATCHED To THE GRID
OF A 51
TYPE TUBE. THE 57 TUBE |s RESISTANCE couPLED To A 56 TUBE EM-
PLOYING A
500,000 OHM v0LuHE LDHTRDL IN THE GRID CIRCUIT-_ TH|s IS USED
As THE MAIN
GAIN CONTROL.
FRQM THE 56
sTAeE, THE SIGNAL FEEDS To Two 56's an A PUSH-PULL
STAGE uH|cH
IN TURN DRIVES A PusH-PuLL PowER STAGE or 2A§‘s DEL|vER|H§
APPROXIMATELY
IO wATTs or UNDISTORTED POVER- A PANEL HIRING DIAGRAM or
THE
AMPLIFYING sYsTEM,KHoHu ALsD As TYPE PA-96Ab as suouu IN Fne. 27.
PAGE I8
souwo PICTURES
PLATE
VOLTAGES FOR THE AMPLIFIER AND THE POLARIZING VOLTAGE roa
THE P.E.
CELL ARE OBTAINED FROM A FULL HAVE RECTIFIER CONSISTING or Two
TYPE 80
TUBES IN PARALLEL. Tu: STAGE LOUDSPEAKERS ARE cuznerzzo av
usrue THE
FIELD COILS AS THE FILTER cnoxzs |u THE RECTIFIER SYSTEM-
TT:::::\21]
-%#§$E€1 I55‘:
DIRECT
CURRENT FOR THE EXCITER LAMPS I5 OBTAINED FROM A HELL FIL-
TERED DISC
TYPE RECTIFIER, ONE BEING EMPLOYED FOR EACH LAMP. A5 THERE
IS NOT
SUFFICIENT POWER FROM THE MAIN AMPLIFIER T0 OPERATE A MONITOR
SPEAKER
BESIDES THE STAGE SPEAKER$,A SPECIAL POUER AMPLIFIER IS PROVIDED
TO SUPPLY
POWER TO THE MONITOR SPEAKER. THIS AMPLIFIER CONSISTS OF A
PUSH—PULL
STAGE EMPLOYING H5 TYPE TUBES- THE OPERATING VOLTAGE IS OB-
TAINED FROM
A 80 TYPE RECTIFIER; WHICH TOGETHER HITH THE AMPLIFIER STAGE
AND SPEAKER
IS MOUNTED IN A STEEL CABINET- THE OPERATING VOLTAGE AND
CURRENT
ARES
GRID Scnszn
PLATE PLATE FILAMENT
THE TOTAL
PLATE CURRENT DRAIN IS ABOUT IMO MlLL|AMPERES- THE Fl-
DELITY
CURVE axrzuos FROM 50 TO I0,000 CYCLE$- THE AMPLIFIER I5 counsel
so wuzu
BUILT so THAT IT covzas THE RANGE HITH A RISING CHARACTERISTIC
TO 5000
CYCLES AND THEN onops OFF AT 5000 CYCLES. THIS cuavz MAY as
VARIED sv
MAKING nunon CIRCUIT CHANGES, A FLAT RESPONSE asaue oaTA:~"
LESSON Mo.
A PAGE I9
WHEN THE
BYPASS CONDENSER ACROSS THE BIAS RESISTORS or THE FIRSW THO
STAGES IS
REMOVED. A SLIGHT RISE UP T0 3000 CYCLES MAY as HAD av SHUNT-
ING THE
BIAS RESISTOR 0F THE szcouo STAGE WITH A .I MFD CONDENSER AND
l,OO0 OHM
RESISTOR IN SERIES. HIGH FREQUENCY RESPONSE MAY a: OBJAINED
av SHORTING
OUT RESISTOR R-27, on REMOVING tn: BYPASS CONDENSER FROM THE
BIAS
RESISTOR or THE SECOND STAGE AND SHUNTING THE 57 Tuaz's BIAS RESIS-
TOR WITH A
.2 MFD counsussn. AM INCREASE IN Low FREQUENCY RESPONSE MAY
BE OBTAINED
BY REMOVING tn: 60,000 OHM RESISTOR R-32 AND R-3} IN THE
GRID
CIRCUIT OF THE 2Aj's.
TABLE I
CHARACTERISTICS
OF WESTERN ELECTRIC TUBES
_ I , I , ,
I I _ -.
PLATE PLATE
FILAMENT FILAMENT PLATE I Buns I
VOLTAGE
CURRENT VOLTAGE CURRENT Mu. RESISTANCE VOLTAGE
—ro;-5
4:--—
WESTERN
ELECTRIC TUBES
IN TABCE I
YOU ARE GIVEN THE MORE IMPORTANT OPERATING CHARACTERIS-
TICS OF THE
MOST POPULAR SERIES OF WESTERN ELECTRIC TUBES.
FROM WHAT
YOU HAVE ALREADY LEARNED FROM YOUR PREVIOUS STUDIES IN
THIS
COURSE, YOU SHOULD EXPERIENCE NO DIFFICULTY IN ACQUIRING A GOOD
UNDERSTANDING
OF THE EQUIPMENT WHICH IS DESCRIBED IN THIS LESSON. MUCH
OF THIS
SOUND PICTURE AMPLIFYING EQUIPMENT IS IDENTICAL TO THAT USED FOR
OTHER
PURPOSES,VlTH CERTAIN CHANGES AND ADDITIONS UHICH SERVE TD BEST
ADAPT IT TD
SOUND PICTURE WORK-
J. A.
ROSENKRANZ
DRAW A
DIAGRAMMATIC SKETCH WHICH ILLUSTRATES THE LAY-
OUT OF THE
SOUND PICTURE EQUIPMENT IN A TYPICAL THEATER
NAMING ALL
OF THE VARIOUS UNITS-
DESCRIBE A
WESTERN ELECTRIC SOUND INSTALLATION FOR A
MOTION
PICTURE THEATER-
DESCRIBE AN
R.C.A. PHOTOPHONE souno INSTALLATION FOR A
MOTION
PICTURE THEATER.
MAKE A
SKETCH OF A TYPICAL SOUND HEAD AS EMPLOYED ON A
MOTION
PICTURE PROJECTOR AND NAME ITS PARTS.
DESCRIBE
some OF THE MORE IMPORTANT FEATURES or THE 43A
WESTERN
ELEcTRIc AMPLIFIER.
EXPLAIN How
YOU wouLn OPERATE THE TYPE PG-32 PHOTOPHDNE
EQUIPMENT.
NHAT ARE
THE OPERATING CHARACTERISTICS OF son: or THE
MORE
IMPORTANT TYPES OF WESTERN ELECTRIC TusEs?
DRAW A
CIRCUIT DIAGRAM OF THE M6-A WESTERN ELECTRIC
AMPLIFIER
AND EXPLAIN How IT Is USED.
DRAW A
CIRCUIT DIAGRAM or THE R.C.A. VOLTAGE AMPLIFIER-
DRAw A
CIRCUIT DIAGRAM or THE R.C.A. POWER AMPLIFIER-
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