Fisher 70 A Owners Manual

Page 1

THE 7?)
FISHER

AUDIO AMPLIFIER

INSTALLATION AND
OPERATING INSTRUCTIONS

MODEL 70-AZ

WITH -MATIC

PRICE- 300

FISHER RADIO CORPORATION ' NEW YORK

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(\
77a
T H E

IF CHER

AUDIO AMPLIFIER ' Model 70-AZ

GENERAL INFORMATION

THE FlollER ALI-Ill) Ampllfiu. hlodel ~ll.r\z. will meer rhe rcqnucmenu
or rhe morr (Lung urer. Complere ndeliry or reprodurnon and ibrenee
on lorener loriuue .u: 1 direer run]: or rhe cxxlcmcly low hormonu- inrl
inrermodularion dororrion n all pawn lerelr. n well do LXLcllunl rrrnrienr
responie. unie Ilcquumy ronee ond ooon lineirriy Hum rod nooe ire
unuzlly mn-merrurablo. (huh Allowing operarroo n all Ilslcnlm: lu'eh
Iuhuul rhe dirrrarrron ol exrraneour nun: The gm reserve powchlm»
dlrne raparrry oI rhe Model 'ornz maLe: rr uprble or reproduerny rhe
Lomplcu: dynamie unge eyen or a lull symphony omheslu AZ] (umpur
nenrr rn lIm eompaer unir have been stlcucd ior long lrie 2nd inrulled
Wllh mulmum .Iucsxlblllly In rnrnd. lor enry oeryleing.

THE FISHER Z-MATIC CONTROL
The loudspcdker ryrrem has long been lacogmlcd as one or rhe rnorr
.mporranr Ilmmng lorrorr in rhe lairhrul reproduenon or high hdehry
\ound. Where a loudxpnkcr bears th: rypierl ipeerrrrarion - "Vorre Cox]
lmpedanre. lo ohmT"-lt rhould be nored rhrr rhir speufiunon realiy
jppllcs only lo a IIImIrJ pumuu oi rhe roral lrequenry unge. The reason
rr rhir i rpea'rer i-oiee roil rmpednnre orrunlly vanu ourre marholly, ind
nieordinie ro rhe pnrrieulae pornr oi rhe audible rpeerrurn inioli-er" TIN).
n rypieol 1" rpmkcr rared ar ls ohmr nruolly has rhar l5-ohm impedmle
ar 400 -eler. AI 55 Lydu rhe yorre eoil impchnLe eouid be onywhere
rrom no lo 90 ohm. and or lodmu (yclrs lrorn 3K) ro so ohrnr. See Figure 3.

The rreep roe in yorre eoil imptdanc: In rhe >l0>m~100 punculzrly eerrour. ror rr n cxauly in rhir porrion oi rhe audible rpeerruin
rhar we nml i .rood impedanre Hutch berween yoiee eorl And amplilier
In order ro reproduce wnh lull "(Imus rueh lnslmmcnn .o rhe ryinponurn.
bus yiol. rello, arsm. and rhe borronr oeroye oi rhe piano. nod rhe sleep
roe in me ioil impedance at rbe high end derreerer rreble response.

MI rypiral ampllrierr of berrer quzllry bulIl rodiy have nor lakm rhe above
impedanre muthlng problem rnro aeeounr. Thus. :Ilhuugh rhe eleerrienl
rharorrernrnr ol rhe usual up ro rhe yoire eod rnry hm a unilorrn r:-
sponse. lhls u promprly erleered by rhe rmpedrnre varrorronr ol rhe loud.
rpeolrer Tynan. nlrhourrh rhe VOLTAGE delivered ro rhe loudrpealrer
lcmllm ronrranr regardlexs oi ireoueney. rhe POWER :bmrlxd by rhe
loudspcaker will rm! be ronrrrnr because rr ii i runenon oi borh voltage
aed Imd rernranee.

AT in example. ler us auume rhor a idaeyele rone (Middle A on rhe
pianol ii inrrodoeed ro rhe loudxpeaker. M rhu IthuenLy rhe yoire eoil
impedanee .r auuzIIy I6 ohrnr, n rpeerried by rhe rpeelrer rnanulaerurer.
Ler ux .13)qu lurrher rhar rhe vohaxc reaming rhe voice coil is 4 volts.
under rhtsc rondirionr elerrneal power Illl be l warr. Ler us now arrernpr
ro reproduee an Oman tone 3 lxtzves lower (55 (psi ind ol 1th inren.
riry. The impedonee oi rhe loudspeaker ar lhls ieeoueney would n Ihls
me be .Lboul on ohmr um! in many rorer loudrpeokerr have even Illghct
\mcc \oll rrnpedrneer is one approuher rheir reronrnr lreoueney.l inas-
rnueh or power. nor a column: volrzgc. vanes inversely wirh rhe lord lm~
pedonre. rhe reiulr |I rhar only 4. o) l u-orr ol power will :Llually be
xbmrbcd ood urrloed by rhe speaker on rhe aiorernenrroned oryn rone.

lr rherelore lollowr lIm rhe ideal goal is ro produee an amplifier eonraining
rpeeral eueuirs rhar reeogniae rhe nonumlarm impedanre ol loudrpealrerr
and provide rhe mum ol eliminanng rho inherenr mlxmaKIL We are
proud ro announee rhar (his long-wunhballer norl had now been reaehed
in an Amplmrn. These rpeeial erreurrr rre whar eornprrre THE
FISHER Z~i\hlic Conuol.

THE FISHER z-.\lorie louxpezkcr mun/lore oi in lood impedonee bur. lurrher. will u rhe mere
rurn or i cohrml knob provide .nlrlrrrornri ulmpcnulmll ro IulJm'c lhe
dtliucnucl ol rhe qudapcaL-er or in endusure.

WHAI THE FISHER z-MAIIC CONTROL DOES

The unuuul (immry on THE FISHER 2.24am Conrrol aurenrnrienuy
eorreerr rhe Impedance nurrnarrh (omllliun dmnbed earlier. The mini:
conrrol o eonrrnuourly variable and ean be rer at zny derired poinr in
run rhe reouirernenrr ol rhe parrrrular program Ixinu reprodueed. a:
oileered by lhe :xipnng rpealrer ryrrern. rpealrer enrlroure-rn (an. rhe
enrire elerrrreal ind .Koumul ryrrem. See Figure 9.

The z \lurru Lirnmll unrmno .4) mile-i rhe «Infill-In) lor y.rryino load
unpodimr . we ourr r e . .ru-rrrrd ' r. our In flux-I hr. pullKuI."
aroiorrr mil enyuonrnenul umdllmlh l n rerolrr .rre rruly revolur uly
and rhrrllinr; rr. heir. Xur 7.».\I.-lu own, .r wide. nev. door on hiuh hdelrry
)nulld repronuuron,

IMPORTANT xm l: IHli l I>IIIER Z-.\lulL lzonrrol dues whAl an oldi-
niry Bari Tune conrrol. or LIIulIncn Delanre Conrrol. (.Mrml do. The
Z-Malir Cumm mm lo lu.ll Iuh'nufl' only more quI Itequencin rhar
ruflered arrenualion bcuuhc ol yptukcr iyrrem ehaurrerririer Fur (his
reneon. rm barrel' hm ii rrr-nred. Prom or rhir dnllabk uhicvcmenl
n lmunLIy apparenr on Iulenllll: ro rhe nulc xpezkml, yoire. rhe mosr usual
rource ol barrel" bars

THE FISHER Model o-Az mn be uhcd direrrlr wrrh .m Thwlhl inner.
and. as THE FISHER .\lodel 1! RT. i leyrral phonoguph unridgc or
any mher deyne Ihuh ir rapiblr» or pmeiuung i oneyolr lluuld where
moenerir phonoemph allndgcs. mrerophoner or rrnirlar Iow~lcvcl devnces
Ale employed. preornplrrirairon o neeeoirr. EwcnaIIy ruired ro rhere la
re: Jpphulmm o THE FISHER Morer Audio Conrrol. Series soc. ayai
able 1: a eompanroh unrr ro THE FISHER Audio Am er. Model 7042.

The .\lodel 'o-nz har lour repuore Icedbzd: loopr. resullmg in low in.
rernal impeoanee. erxrernely low Jiuollmn and :x(el|cnl lnmicnl rerponre.
Two type soul-robes. ronneered u r es, in employed in rhe power
rrage. The unique rarhode 1nd sclecn eedbnrl (mun oileri all rhe advan-
nuts or rrrode periorroonee. royerher wrrn eiheienry oi leuodzs. The (1::-
rully ' iened ourpur rranrlormer (onusls ol nlreen inrerleaved windings
in ron nrrron wrrh i erurnorrenred rreel eore. usuring rhe final (nulls.

INSTALLATION
sinre THE FISHER .xlodel 'O-AZ ir derigned Iol' ure ar a barre ernpliher
1! (an be mulled whelzvu rhere u ideouare \tmllalmn. 0nre properly
lmulled and our-med. mess ro xlx «much will noe he required lor nur-
m2] opemuun ol rhe equipmcnh Chum mounung dimemlons ere shown
in noun: 6. THE FISHER Model O~AZ power line eord should be eon-
neered :0 an arorrlrary AC rerepraele working orl r rnarrer wildl. Thur rbe
amplifier n rorned on lagethcr wrrh rhe runer or preamplifier used. THE
FISHER Model 'a-nz Ktqullfl ID worn or los-lzs volts. 5060 eyeler AC.

The z-hlirie Conn-u! And Coble rlrrembly wllI be found pulled in (h: rop
liller' ol rne arnplrr'rer earron. The i-prohe eonneerron plug rhould be
rnrralleri m rhe proper rerepurle on rhe amplirier rhasru.

l. Nore rhrr rhe middle leimuul oi rhe rhree rpealrer rerniinnlr on
rhe amplirrer has been dirronrrnued. Conneer rhe qudspflker lads

ro rhe two remaining terminals «here are labeled "a or 16" and

'Gnd".l The larrer ground muTt nor be law-I as pain ol rhe baiie

ground of the cm": clamuI syueme

To releer rhe proper nonunal mxchlng nnpedanre lor rhe rpealrer

o-rrem beine used. gel rhe impedrnee :Iilth (OHKLIy.

5. The Lola-r Conrrol rhalr ran be moonred on your main eonrrol
panel by dillling a 9/." hole rherein.

or Remove all rhe clemcnn irorn rhe z..\l.r.e ConlmI rhalr. ereepr
rhe linal hex-nu! lnren rhe Conrrol in rhe pinel iroin rhe rear.
and adruer rhe olorernenrioned hex-nu! w rhai rulheienr rhreodr
prorrude pm rhe lronr suriire lo ummmodue rhe z-Marie den;-
narion plore ar well no rhe Icmzmln hurnur. aelore tightening,
mounr rhe Conrrol knob on rhe Thlfi'r rurn ir ro rhe lelr As lar a.
ir will go. and rheo rorare rhe porrion oi rhe Conrrol on rbe In!
oi rhe panel yo rhar rhe while dot on rhe knob iallr ar rhe (on:-
spending min" dor on the designauon plare. Now remove rhe
knub. riehren rhe rinal hexnur and rlip rhe knob buk on again.

INPUT CONNECTION

Conncdlun to the INPUT OI The Model O-AZ is made by means III a
rrandord RETMA phono plup rupplied wirh rhe equipmenr. ll rhe signal
wurle n Jppmxmulely one yolr. m: LEVEL ADJUSTMENT conlxol lhould
be {cured IulI) (IOCkWIK. Fur xlgndl wultfi in cuts; cl one VOII. mm
rhe LEVFL ADJUSTMENT (unnpun-Imglv Iowa leounrer-ehxlrwlse) de-
pending on m: mdxlmum vnlugc 0' the 3:5an source. When using THE
FISHER Mum Audio Conrrol u n preamplifier. Kl llle LEVEL ADJUST-
MEN! ul lhe Model TO-AZ Io mulmum (dekwiseJ

now IO AcmrvL MAXIMUM Imovunu 0!
THE FISHER Z-MA'IIC CONTROL

\thn (he Z-.\l.m< Control is m a! Minimum. Ihe amplifier will opente
in The roni-enrronrl minner. produrlng ronrranr volugc ngudlus or load.

Ler or nnw ubguully KI rhe Conrrol wlIIl rhe ile ai rhe rop. ln this
i-nrnirr- oinrranr power will be led ro rhe loudspukcr «gardlcn oi variar
llllm rn rpealer impedinre. High ouahry speaker syslemx wirh good. oyer.
:Il clfiucmy wrll perrornr berr when rhe Conrrol n in rho poririon.

\hcr: upulllum xpeALev synemx :II-I spake: cmloxuru :1: m zvzilzble.
lire aeuunlr. sIIuHulmlng! ol lhc mum on be uvummc in gml manure
lw rornunu rhe Z-Morir Conlrol roward maximum. cording lo rhe needs
or rhe irruarion. [\ny roranon pair rhe rop pod-ion produrer intrming
mulnplnumn ol rhe eleerrlral Izuuls nererrary lo ovumme lhe deficien-
uu ol lllc spake! Iynem .1an speak enclosure.

The Zr.\l.llln erIcLI wulL or eourse. he reorr oppdrenr in rhe maximum poii.
rron and. in nuny «hrs. lepluems rhe don approneh ro rruly unilorm
response in (runs 0' Jib/u purrer. nhieh n arrer .llI rhe ulrimore errrerron.