When the predecessor of the 34-5560, the prestigious SA-5550, was ...

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SA- 5560tt/AM stereo FbceirerAmplifier SectlonMassive Power OutputThe 5A-5560 will selve as the powerfulbackbone for any stereo system. ltdelivers 90 watts per channel, minimumRMS. into 4 ohms from 20 Hzto 2O kHz'with no more than 0.1% total harmonic distortion(both channels driven). At '1,000 Hz,this figure rises to 108 watts per channelat 4 ohms.Massive Power SupplyPower-output performance ultimatelydepends on the power supply. The ULapproval accorded the 5A-5560 is partialtestimony to the generous design of itspower supply and more than sufficientomeet the demands of the amplifier. Abridged rectifier circuit helps assureexcellent regulalion of DC voltage in theface of changes in line voltage or signalinput. A 15,000 microfarad filter capacitoris used in either side of the balancedpower supply for the unusual total of30,000 microfarads capacity. This not onlycontributes to the excellent regulation, butalso keeps hum and noise low andimproves power availability at the lowfrequencyend, where it is most oftenneeded.Sophisticated Amplif ler DesignLik'e every Technics receiver ever made,the 5A-5560 employs direct-coupled OCL(output capacitor-less) design. This helpsdssure solid power output and highdamping factor not merely in themidrange around the rated frequency ot1,000 Hz, but also extending into therange of the lowest audible frequencies.This results in clean, well-defined basswith plenty of punch and freedom fromblurring. For example, there is stillsubstantial output at 5 Hz. A differentialamplifier in the first stage employs asinirle-packaged, matched transistor pair,to ensure stable performance against DCvoltage and temperature fluctuations. Apure complementary design, large gainand sufficient negative feedback ensureextremely low 0.1% distortion.Multiple Circuit/Speaker ProtectionThe care used in component selectionand circuit design makes speakerdamagingbreakdown most unlikely, butmany audiophiles are neverthelessconcerned about possible damage totheir valued speakers in the event ofamplilier failure or DC leakage throughthe direct-coupled output. To set theirminds at rest, both an automaticelectronic circuit with relays and fusingare used to safeguard speakers andamplifier circuitry. In addition, an antishocktiming circuit helps eliminateannoying thumps in the speaker afterturn-on by delaying turn-on of the speakerterm inals.Glick-Stop Volume ControlThis control offers 41 discrete steps,providing accurate resetting, at anyfuture time, of adjustments found to bemost suitable for any particular source orrecording.Low-Distortion Click-Stop Tone GonirolsClick-stop settings guard against inadvertentmisadjustment, making itpossible to return precisely to anypreviously used setting, without guesswork.Bax-andall type NF tone controlcircuits are employed, utilizing speciallyselectedvariable resistors, to obtain flatfrequency response at center positions.Distortion is kept to minimum, too.Low-Noise Phono EqualizerThis is a direct-coupled circuit consistingof three stages. Thus low distortion andwide dynarnic range (relative immunityto high-amplitude signals) are assured.This carefully worked-out design hasbeen incorporated into an integratedcircuit for the usual lC reliability andprecision. Special ly-selected low-noiselC is employed to obtain superb phonoS/N ratio of 65 dB. Precision metal-filmresistors (1% tolerance) and polypropylenecapacitors (2oh lolerance) rigidlykeep equalization within +0.2 dB of theRIAA curve.EqualizerMPXcircuitFM lF stageAM lFstageVariable tuningcapacitorsHioh-Cut and Low-Gut FiltersTh-ese filters eliminate or, at least, reduceannoying hiss and scratch noises as wellas hdm that aff lict some records andtaoes.Loudness SwllchAt low listening levels, sensitivity of thehuman ear to low frequencies tends to falloft. throwino the bass out of balance.Wiih the loddnes switch engaged, lowfrequencies are boosted proportionatelyas volume is reduced to restore a natural.audible balance.Two Tape MonllorsComplete input/output terminals are providedfor two tape decks, with front-panelpushbutton switches for instant monitoringof either one. Both may be activatedat the same time for simultaneous copyingof the same source material, or the usermay dub from the Tape 1 to the Tape 2position.Mode SwltchStereo or monophonic mode may beselected by a front-panel pushbutton.Maln/Remote Speaker FaclllllesTwo pairs of speakers may be connectedand fed separately or together. Twopushbutton selectors permit operation ofmain speakers only, remote speakersonly, both pairs simultaneously, or bothoff (as for headphone listening)Front endTwo 15,OOOpFtilter capacitorsPower transformerPower transistors
Tuner SectionTwo Tuning MetersA zero-center meter indicates precisecenter-of-channel tuning on FM. A siqnal_strength meter functions for both FM;ndAM. In conjunction with the carefullvcalibrated dial scales, they facilitatdtuning for lowest distortion and bestnoise rejection. In addition, the ;nnovativesignal-strength meter exhibits linearIndrcation relative to signal strength onsignals below the highest levels,lorpartrcutarty accurate tuning and as an aidin antenna adjustment or oiientation.Floating Wire in Local OscillatorThis f rees the FM oscillator circuit fromunwant.ed coupling through the printedcircuitboard, which would prodi.rce somedegradation in performance. Highlystablealuminum core coil and -temperature-compensating titaniumcapacitor are employed to keepfrequency drift to mihimum.FM lF with lC and "Flat Group Delay"Ceramic FilterOf the seven stages in the lF section(which include six differential amplif iers).three are 2-element ceramic filteis of thenew Flat Group Delay typ6. Flat GroupLJeray means that phase inaccuracies(and the resultant sound distortions) havebeen avcided. The result is claritv.transparency and definition of FM sound.AM suppression is large enough toettmtnat external noise, thanks to thelimiter effect of seven lF stages.Sensitive 3-Gang Fl\tt TuningIne tecnntcs-devetoped 4-pole dual-qateMOS FET is used in the f roni end for-hiohsensitivity and selectivity. In combinatio"nwith a 3-qang variable tuning capacitorfor FM, th;s resuits in a selectivity f igureof 70 dB and a high sensitivity of 1.8microvolts (S/N 30 dB, 300 O).INPUT SIGNAL LEVEL VS OUTPUT LEVEL.S|/N &THDoE,FM SELECTIVITYMcalqine haqomy : !'EMH:1ii-i'"or-'r-i' j'lifr,tsrffilrHrlFM Muting SwitchWhen engaged, this switch suppressesannoying inter-station hiss as'ybu tunefrom one station to another. ltd basicailvsmooth action is enhanced further bv aiAND circuit to eliminate the harsh. 'transitional noises heard in some hutinocircuits as they change from the mute to"non-mute conditions, or back aqain. Aswitch permits defeat of the mu-te actionfor reception of distant, marginal transmrssrons.Quality FM Discriminator]9.preser.ve the exceptional quality ofFM.signal processed through the tiighperformancelF section, a Comparab-lvimproved detector is used. lt id aquadrature discriminator with excellentlinearity and broader peak-to-peak ranoe.It thus contributes to full audici-frequen6vbandwidth. lower distortion and tolbranc'eto high-level signal modulation.FM MPX Section with pLL lCIn stereo FM, PLL (Phase Locked Looo)circuitry helps maintain precise phasihbbetween the pilot signal and the'sub- -carrier. This results in low distortion andthe maintenance of desired seoarationthroughoutthe entire spectruni of audiblesound. In addition, the PLL circuitmaintains stable performance despitechanges in temperature, humiditv and thepassage of time. lt has been incdrooratedinto a high-reliability lC that replaies 57transrstors and 4 diodes. DoubLe differentialswitching circuit ensures stable andexcellent separation.Other Premium FM FeaturesOverall care in circuit design hasresulted in exceptionally flat audiotrequencyresponse right up to the upper_most limits of standard sionaltransmissions. Chebyshevltype low-passIrtters suppress pilot and subcarriersignals without impairing performance atthe higher audio frequencies. phase delavat 15 kHz is a mere 5.5 microsec.Response is *0.2 dB, -0.8 dB over thef ull bandwidth from 20 to 15,000 Hz. AnMPX high-blend switch reduces notseon marginal signals in the FM mode,without essential sacrifice of audibleseparation. The audio output circuit isdesigned for quality performance not onlyunder properly modulated signals, buteven under 300% modulation. This isparticularly important as overmodulatedFM transmissions are not unusual.Quality AM section with lCWe of Technics feel that, when the ownerof a good highJidelity system turns toAM listening for any redson, he isentitled to the reasonable sound oualitvof which AM, at its best. is indeedcapable. Although the results cannotmatch FM, in any case, the 54-5560boasts of double tuned LC filter in the lFcircuit, along with a precise and stablelC incorporating most of the importantcircuitry. The result is better sensitivity,noise f igure and interference reiection'than.found in perfunctory "add-on', AMsecltons.Other Features. Wide Linear FM Dial Scale. FM MPX Output TerminalFor adaptor for future discrete 4-channel broadcasting.Comparison Between "Flat GroupDelay" Filler and Flat Amplitude Fitter"Flat group delay" lilter. kHz kHz(lO,7MHz)Flal amplitude tilterAnplltude ---ChoracterirticGroup DglayCharacteri!ticAmplitudeCharacterirtic. Group DelayCharacterl!tic(tO.7MH2lSquare Wave and Tone Burst Response5A-5560 using" Flat croupDelay " filterII InourConventionalreceiver using flalamplitude filtern n n [ (rrxz) tt [l t--Tl- - .- | ou,ou, ---'--'-I L_r LJ L | (lkH't L! ]r !]f*T",*j+rl--{il/.1I J,rill-llih, I oured | {t!--riilr,, I
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