What is stereo?

There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.

H.H. Scott '59

Spica TC-50

The TC-50 is a decaptively simple two-way loudspeaker based on a 6-1/2 inch acoustically suspended woofer and a 1 inch dome type tweeter. Its crossover network is truly state-of-the-art., in parts quality, circuit layout and, of course, design. The compact speaker is the result of exhaustive research and the latest technology in computer assisted optimization.

As a music lover, you need not be concerned with woofers, tweeters, crossovers or computers. All you have to do, to really appreciate the TC-50's  advanced design, is go to yoour nearest Spica dealer and listen.

Magnitude Response:  the TC-50 exhibits excellent tonal balance. No external equalization is required.
Phase:  Phase response is the most talked about, but least understood consideration in speakers. Simply put, the phase response shows how well a speaker can preserve complex timinng relationships when reproducing music.

System Type:  Sealed box
System Resonance:  56 Hz, total Q .78
Freqiency Rsponse:  60 Hz - 17 kHz (-3 dB)
Woofer:  6,5 " treated paper cone
Tweeter:  1" impregnated cloth dome
Woofer Crossover:  4th order bessel response
Tweeter Crossover:  Computer deriver, approx. 1st order response
Input Impedance:  4 ohms nominal, minimum 3,6 ohms at 4 kHz
Polarity:  both drivers positive
Sensitivity:  84 dB at 1 watt/1 meter
Power Handling:  50 watts continuous  program, 100 watts peak
Dimensions (W x H x D):  330 x 394 x 295 mm (13" x 15,5" x 11,6")
Weight (Net):  9,07 kg (20 lbs)

Linn Axis turntable

For many years the Linn Sondek LP12 has set the standards by which all other turntables are judged.
Now Linn engineere built the new LinnAxis with the same precision as the Sondek,  but they've made it more afordable. In fac, for a lower price, we/ve given the Axis advanced features you won't find in any other turntable at any price.
Exceptional precision is provided by a pair of low distortion, class A amplifiers driving each of the motor phases. A "smart" controller senses the motor load and provides higher voltage during sterup and reduces the voltage (and noise) once the platter reaches speed.
Electronic switching turns the Axis on or off and provides a smooth transition from 33 to 45 rpm.
An ingenious self-aligning suspension system isolates the armand platter from the motor, base, and external disturbances.

"Of course, the Linn Sondek Lp12 remains the reference, but we know you won't be disappointed with our second best. We haven't cut corners on our legendary engineering, only on the price."

The Axis is a precision built, twin speed (33.3 rpm and 45 rpm) transcription turntable. It is
mounted in a black veneered medite plinth, with a dark grey top-board and equipped with a
moulded, hinged dustcover.
Motor Power Supply:
Linn-designed 2-speed electronic ‘Class A’ power supply incorporating a stall detect circuit.
This monitors the load on the motor from start-up and reduced the power supply to the motor
once the correct speed has been achieved. It will also increase the power to the motor as
required. When this happens the relevant LED on the switch will brighten to show increased
power, and dim once power is reduced. Easily changed (internally) from 110V to 240V and
will run on 50Hz or 60Hz without modification.

AXIS Specifications
Platter:  12” diameter (305mm) aluminium diecast and accurately machined on all matching and visible
surfaces. Weight approximately 1.5kg. The platter is supplied with a felt mat.
Bearing:  Single point system running in an oil bath. The thrust pad which must support the weight of
the platter on a single point is top grade steel, machined, hardened, ground and lapped to a mirror finish.
Motor:  24-pole precision synchronous low noise, high torque motor. Fully shielded and mechanically
isolated from the main bearing assembly by resilient mounting and a damped, uniquely designed suspension system.
Speeds:  33-1/3 rpm and 45 rpm.
Speed Accuracy:  0.1%
Suspension:  Three silicone, custom moulded rubber mounts, providing isolation for both the turntable/arm from the motor/plinth, and the feet from the plinth. Easily adjusted to keep record platform
Drive:  Flat, precision ground neoprene rubber belt driven by a concentric drive pulley; concentricity
Top-plate:  Heavy medite wood, laminated on both sides.
Power Consumption:  8 Watts
Dimensions (W x H x D):  445 x 140 x 349 mm (with lid open 400 mm high)
Weight (Shipping):  8 kg

Bell HF-2240

High Fidelity sound at moderate cost.
Bell Coaxial Loudspeaker - to hear it is proof conclusive that you can have.
Here is the long sought for ideal. A twelve-inch coaxial speaker in which top-flighy electronic engineering, acoustical designing, and the best of materials are combined, to satisfy the high fidelity enthusiast's ear, at a price he can afford.

In this Bell Loudspeaker an efficient low-frequency driver cone is teamed with a high frequency radiator, coaxially mounted, to reproduce both voice and music with unusual audio faithfulness. Cone and radiator are acoustically arranged for distribution of sound over a wide room area. From felt buffer mounting rim to its heavy Alnico Vmagnet, the Bell Model HF-22440 is engineered for output which  - measured by ear or instrument - is uniformly smooth and flat in the "presence" region.
This speaker has been carefully designed for use with any one of Bell's High Fidelity Amplifiers.

Rated Wattage:  30 watts
Voice Coil Diameter:  2"
Frequency Response:  38 - 13,600 kHz ±6 dB
Voice Coil Impedance:  8 Ω
Crossover Frequency:  2400 kHz
Magnet:  Alnico V
Weight:  1 lb
Overall Size:  12-1/8" diameter
Depth:  6-1/2"
Baffle Opening:  11" diameter
Shipping Weight:  9 lb

BSR McDonald 810

The BSR McDonal 810 Transcription Series is available as a Total Turntable that includes a matching custom walnut wood base, a deluxe tinted dust cover, and rhe superb Shure M-91ED magnetic cartridge with elliptical diamond stylus. All in one carton. All included in the price. Complete, ready to plug in and play, with all critical adjustments precisely pre-set on BSR laboratory equipment.
The BSR 810 was designed without compromising quality, technical specifications or performance features - regardless of the ultimate cost. Yet, the result is an instrument offered at a price consistent with our reputation for producing turntables that are unsurpassed values in every price range.

Sequential Cam System
Replaces the conventional cam gear and swinging plate used in every other automatic turntable. This revolutionary engineering breakthrough results in a smoothness and quietness of operation and an overall reliability never before achieved. The utilization of eight independent pre-programmed cams eliminates the multiplicity of light stampings and noisy moving parts required in all other automatic turntable mechanisms.

Synchronous Power Unit
As one of the world's largest designers and manufactturers of subfractional horsepower motors, BSR set its resources to develop a motor to match the performance of the Sequential Cam System. The result is the new high torque ultra-quiet synchronous induction power unit, which achieves an unwavering constancy of speed indepemdent of voltage input or record load.

Transcription Tone Arm System
The longer the tone arm the less the tracking error. The 8,6562" pivot-to-stylus lenght reduces tracking error to less than 0,5° per inch. The low-mass aluminum tone arm assures extremely low resonance and is counterbalanced in both horizontal and vertical planes.

Concentric Gimbal Arm Mount
Gyroscopically pivoted on four pre-loaded ball-bearing races to assure virtually no friction in either the horizontal or vertical planes. This design gives the 810 a tracking capability of 1/4 gram.

Viscous-Damped Cue and Pause Control
Provides gentle silicone oil-damped tone arm descent. In all other automatic turntables, the anti-skate system tends to move the tone arm outwards while it descends. BSR designed an exclusive positive friction Cue-Clutch that prevents this. After a pause, the 810's tone arm returns to the identical groove, every time. The cueing control can be operated in both automatic and manual modes.

Viscous-Damped Tone Arm Descent
The same gentle viscous controlled descent provided in the cueing operation also functions during automatic and semi-automatic play.

BSR makes more automatic turntables than any other manufacturer. More in fact than all other manufacturers in the world put together. But of all the turntables we make, the BSR McDonald 810 Transcription Series is the most unique. It is a triumph of years of painstaking efforts and research in our Engineering laboratories in Warley, Worcestershire, England.
Our enigineers sey out with a single objective. To design an automatic turntable that could effectively offer advantages in performance and features over the finest competitive units made. We sincerely believe our 810 equals, and in many instances exceeds, the performance of any automatic turntable presently available.
 The 810 offers an impressive group of technical innovations for serious music lovers … for collectors of sophisticated high fidelity equipment. Its pre-programmed sequential cam system introduces a new experience in smoothness, quietness and featherlight operation over the widest range of operating modes. The low mass transcription tone arm system virtually eliminates tracking error and offers precise zero balance adjustment over the full range of cartridge and stylus masses. These and the other important engineering features described in this post result in complete freedom from distortion and maximum preservation of your records.

Wow and Flutter (measured on Gaumont Kalee Wow and Flutter Meter type 1740 using Decca LXT5346 record):
Waw at 33-1/3 and 45 RPM :  less than ,1% rms
Flutter at 33-1/3 and 45 RPM :  less than ,05% rms
Wow and Flutter DIN weighted (measured on a ME102B Mini Flux meter manufactured by Technisch-Physikalisches laboratorium):
Wow/Flutter :  ±0,15 peak
Rumble :  less than 55 dB relative to a 1 kHz 10 cm/sec peak recorded signal (record to DIN 455544). The weight curve having a roll off of 12 dB per octave above and below 315 Hz
Tracking Error:  less than 0,5° per inch of redius
Arm Pivot to Stylus Distance:  8,562"
Arm Type:  Concentric gimbal arm mount gyroscopically pivoted on 4 pre-loaded ball-bearing races
Minimum Tracking Force:  1/4 gram
Arm resonance:  7 cycles
Stylus pressure Range:  0- 4 grams
Turntable Platter:  12" Dynamically Balanced die-cast, weight approx. 7 pounds
Motor Type:  Dual range synchronous power unit 100-130 V AC 60 Hz easily convertible to 220 V AC 50 Hz operation
Speeds:  33-1/3 and 45 RPM
Pitch Control: Variable ±3%
Platter Diameter:  12"
Platter Weight:  approx. 7 lbs
Drive Mechanism:  Sequential cam system
Suspension System:  Four foam damped helically wound coils on rubber shock mounts
Record Sizes:  12" 10" or 7"
Record Stack:  6 records
Muting Switch:  provided
Pop Filter:  provided
Dimensiond (W x H x D): 
810 Turntable:  15-1/8" x 4-1/2" x 12-1/8"
With  base and dust cover :  17-1/8" x 9-1/4" x 15"
Only 810 :  17 lbs
With base and dust cover :  22 lbs

Martin Logan Aerius i

 Twenty years ago (from the past 1996) Martin Logan presents "Aerius i" one of the ESL series, a wonder in dimension, technology and price. The Aerius i requires only 1 square foot of floor space making it an outstanding addition for small apartments and dedicated home theaters. Available in matte black with a variety of handfinished hardwood trim. Single and bi-wire capable.
 At the heart of every Martin Logan speaker -  the patented curvilinear electrostatic transducer -lies an ultrathin transparent diaphragm. Driven by charged electrons and weighing less than the air it moves, the diaphragm is so responsive it reproduces sound at levels only associated with the finest audio electronics.
With indistinguishably low distortion, the patented Martin Logan diaphragm precisely tracks the input signal, engages the air, and transmits the audio signal to your ear - flawlessly. The ESL’s low distortion and curvilinear line source combine to provide minimal room interaction, detail, power, and clarity; unavailable any other way.
Frequency Response:  40 - 22,000 Hz, ±3 dB
Horizontal:  30 degrees
Vertical:  3.5’ (106 cm) line source
Sensitivity:  89 dB [2.83 volts/meter]
Impedance:  4 Ω , 1.7 at 20 kHz
Crossover Frequency:  450 Hz
Components:  Custom-wound audio transformer, polypropylene capacitors, air core coils
Woofer Type:  8" (203 mm) high excursion, high rigidity cone with extended throw driver assembly; non-resonant chamber format
Power Handling:  200 watts/channel
Dimensions (H x W x D):  1410 x 270 x 320 mm (55,5" x 10,5" x 12,5")
Weight:   24.9 kg each, (55 lbs)

Onkyo TA-2050

The Onkyo TA-2050 is the most exciting stereo cassette tape deck in its price range. Nothing elde provides the brilliant purity of its sound, or gives you so much control over the quality of your recording and playback.
The Onkyo TA-2050 provides all the features you'd want in a precision tape deck … and more.
Onkyo's exclusive Accu-Bias system lets you "fine tune" your recording bias to customize sound. Peak reading meters (with decay) let you set more precise recording levels. Fade out/fade in controls, record/mute controls, and soft-touch switches with IC-logic / Memory-stopand memory-play.
Two motor direct drive precision and full metal tape compatibility, large illuminated "peak-hold" meters for greater precision, … are just a few of the other important features the TA-2050 offers.

The Onkyo TA-2050 is an outstanding example , it goes further than other tape decks, to harness the full performance potential of new metal tapes. One reason is Onkyo's exclusive "Accu Bias" control system, which guides you to far more precise tape bias adjustments. Brighter cleaner high notes are the reward.
The Onkyo TA-2050 also utilizes a full logic direct drive motor transport for extremely high reliability with minimum wao and flutter. A second motor handles fast forward and rewind functions. A special Hard-Permaloy record/playback head, and ferrite erase head, provide optimum performance  with all types of tape, both metal and conventional.
Styling is superb. Brushed silver metal with elegant appointments, in a dramatically handsome new slim-line design.

Track System: 4-track, 2-channel stereo
Motor:  PLL DC motor (capstan);  DC motor
Heads:  Special hard permalloy heads
Recording System:  AC bias
Erasing System:  AC erese
Tape Speed:  4,8 cm/sec.
Wow and Flutter:  0,045% (WRMS)
Frequency Response:
Normal positionn Tape :  20 - 17,000 Hz (30 - 16,000 Hz ±3 dB)
High position Tape :  20 - 18,000 Hz (30 - 17,000 Hz ±3 dB)
Metal position Tape :  20 - 29,000 Hz (30 - 18,000 ±3 dB)
Signal-to-Noise Ratio:  60 dB (Dolby NR out, Metal position Tape)
A noise reduction of 10 dB above 5 kHz and 5 dB at 1 kHz is possible with the Dolby NR In.
Input Jack:
Microphone Jacks :  2
Minimum Input Level :  0,3 mv/600 Ω
Input Impedance:  5 k Ω
Optimum Mic Impedance :  600 Ω - 50 k Ω
Line IN : 2
Minimum Input Level :  50 mV
Input Impeance :  50 k Ω
Line Out :  2
Output Level :  350 mv (at 0 dB)
Optimum Load Impedance :  over 50 k Ω
Hedaphone Jack :  1
Impedance :  8 Ω/ 200 Ω
Components:  53 Transistors; 29 Diodes; 6 ICs; 4 LED
Power Supply:  AC 120 V, 60 Hz;  220 - 240 V 50/60 Hz
Power Consumption:  35 W
Dimensions (W x H x D):  418 x 120 x 270 mm (16-1/2" x 4-3/4" x 10-5/8")
Weight:  6,4 kg (14,1 lbs)

Onkyo TA-200

Type:  2-head, single compact cassette deck
Track System:  4-track, 2-channel stereo
Tape Speed:  4.8 cm/s
Heads:  1 x Record/Playback, 1 x Erase
Motor:  DC servo motor
Tape Type:  Normal, CrO2, Metal
Noise Reduction: HX-Pro, B, C
Frequency Response:  20 Hz to 17,000 Hz  (Metal tape)
Signal to Noise Ratio:  78 dB  (with Dolby C)
Wow and Flutter:  0.07%
Line Input:  60 mV
Line Output:  0.5 V
Power Requirements:  AC 220 V 50 Hz ; 22 W
Dimensions (W x H x D): 435 x 122 x 264 mm
Weight:  3.9kg

Advent 2

 Advent 2
If your budgett for stereo equipment is limited, and you would like the highest possible quality for what you spend, we believe a stereo system built around the Advent/2 loudspeaker may well be the best buy you can make.
We make that statment out of a conviction that the Advent/2 is a genuinely new kind of low-cost loudspeaker. Its sound quality is very close to that of the best speakers available at any price. It can fill a big living room with more than enough low-distortion sound to satisfy most people's greatest demands. And the bargain it represents is further increased by its efficiency, which is high enough to provide satisfying performance in average use with low-cost, low-power amplifiers and receivers.
The Advent/2 is the product of many years' experience in the design of speakers intended to offer better and better performance at lower and lower cost. Its overall design is based on evertything we have learned about talking the most simple and direct route to high performance, and we have put everything we can into it - including far more expensive basic loudspeaker components than ever before used in a system of its cost. Because it is intended to be first-quality in every sense, we have given as much attention to its appearance as to its performance, replacing the usual low-cost imitation wood cabinet with a distinctive  molded enclosure that we believe will look fresh and appealing for years to come.
The Advent/2 represents our best effort to provide absolutely eveything we believe important in a speaker for the lowest possible cost - and to bring genuine component stereo of very high quality to many people who otherwise might have to settle for something that only looks like the real thing.

Kenwood KR-9400

Kenwood KR-9400 AM/FM Stereo Receiver
Thr Kenwood KR-9400 stands as one of the truly great stereo receivers of the world, meeting the demands of th emost critical purist with the power, performance, and flexibility usually found only in the most expensive of separate components. The KR-9400 is the culmination of years of research and development on the part of Kenwood's engineering team, who have designed this very special unit with but one purpose in mind; to achieve the highest possible performance, regardless of cost.

A masterpiece of engineering with features never before incorporated in a stereo receiver.
Unique Kenwood Triple-Function Meter converts from Signal Strength Meter to Multipath detector to Deviation Meter at the touch of a button.
New Tape-Through Circuit permits tape-to-tape dubbing while you listen to another program source
New kenwood Injection Circuit mixes sound from any source into tape-to-tape dubbing
Triple Tone Controls provide full Bass, Treble, and Mid-range tonal compensation, with Defeat Switch for completely flat response.
Phase-Lock-Loop MPX Circuit; delivers exceptional FM-stereo separation for vivid directionality
Dolby FM Switch ; provides for the addition of a Dolby FM Adapter for best reception of Dolbyized FM broadcasts.

The Tuner Section
Famous the world over for the exceptional performance of its tuners, Kenwood outdoes its own reputation with the superb performance of the AM,FM and FM-stereo tuner section of the KR -9400
The FM Front End. To achieve the theoretical limit in FM sensitivity (1,7 µV), the KR-9400 incorporates an insulated dual-gate MOS-FET, combined with four separate tuned circuits. The extremely linear input of the r.f. stage is virtually impervious to cross-modulation and other forms of overload distortion.
The FM-IM Section. The high alternate channel selectivity (*) dB) and the remarkable capture ratio (1,3 dB) of the KR-9400 are the direct result of the permanently aligned solid state i.f. filter, a multi-function IC and five bi-polar transistors in the i.f. stage.
The Phase-Lock Loop Stereo Multiplex Decoder Section.
The kR-9400 provides extremely high FM-stereo separation throughtout the audio spectrum, thanks to the newly  developed phase-lock-loop IC circuit incorporated in the stereo FM decoder section, achieving more than 45 dB separation at 1 kHz; better than 35 dB at all frequencies from 30 Hz to 10 kHz.

The amplifier Section
The KR-9400 is the most powerful stereo receiver Kenwood has ever built, delivering a minimum of 120 watts of contiuous power per channel into 8 ohms speakers, both channels driven, 20 Hz to 20 kHz, with no  more thn 0,1% Total Harmonic Distortion
Direct-Coupled, Pure Complementary Symmetry Output Circuit
Kenwood;s advanced engineering eliminates the coupling capacitor between  output and speakers, so no distorting element stands  between you and the music. As a result you enjoy flat frequency response from ultra-lows to highest highs, a high damping factor (50 at 8 ohms), faithful bass response throughout the audio spectrum.
Large Power Transformer, Oversize Heat Sinks. A cool-running power transformer and massive heat sinks form the heart of a dual positive-negative power supply to the high-output transitors stages. This nocompromise design assures safe, cool operation even under continuous full-power output.
ASO protection Circuit. Kenwood 's "Area of Safe Operation" protection circuit will not interrupt your listening as long as the KR-9400 is operating within safe limits.shopuld those limits be exceeded, however, the sensitive electronic circuit with relay instantly disengages speakerrs.
Unique " Tape-Through" Circuit. The double tape monitoring facilities of the KR-9400 permit recording simultaneously onto two tape decks or dubbing from ona deck to the other. A unique "Tape-Through" cicruit carries recording convenience a step further by permitting the dubbing process to continue uninterrupted, even while the KR-9400 is being used to play another program source. Its's like owing two stereo systems in one.
The Preamplifier Section
The precision  equalizer-phono preamplifier section of the KR-9400 uses low-noise metal-encapsulated transistors to deliver an exceptionally high Signal-to-Noise ratio and assure utmost circuit reliability. Up to 300 mV (P-P) of input signal can be accomodated at less than 0,1% total harmonic distrotion, from a mere 2,5 mV phono input sensitivity.

FM Tuner Section
Usable Sensitivity (IHF):  1,7 µV
Quieting Slope ( at 5 µV / 10 µV / 50 µV):  56 dB / 63 dB/ 72 dB
Signal-to-Noise Ratio:  72 dB
Capture Ratio (IHF):  1,3 dB
Selectivity Alt. Ch (IHF):  80 dB
Stereo Separation ( at 1 kHz / 10 kHz):  45 dB / 35 dB
Total Harmonic Distortion:
Mono :  0,3%
Stereo :  0,5%
Image Rejection Ratio:  80 dB
IF RejectionRatio:  100 dB
Harmonic Spurious Rejection:  90 dB
AM Suppression:  55 dB
Sub-Carrier Suppression:  62 dB
Antenna Impedance:  300 Ω balanced; 75 Ω unbalanced
AM Tuner Section
Uasble Sensitivity (IHF):  15 µV
Signal-to-Noise Ratio:   50 dB
Selectivity (IHF):  35 dB
Image Rejection Ratio:  70 dB
IF Rejection Ratio:  70 dB
Main Amplifier Section
Power Output: 120 watts per channel
Intermodulation Distortion:  0,1%
Preamplifier Section
Input Sensitivity/Impedance
Phono 1 and 2:  2,5 mV / 50 k Ω
Aux, Tape Play A, B:  150 mV/50 k Ω
MIC :  2,5 mV / 50 k Ω
Hum and Noise
Phono 1 and 2 :  70 dB
Aux and Tape :  93 dB
Mic :  65 dB
Output Voltage/Impedance
Tape Rec A, B
PIN :  150 mV/ 100 Ω
DIN :  30 mV/80 k Ω
Tone Controls
Bass :  ±10 dB at 100 Hz
Midrange :  ±10 dB at 800 Hz
Treble :  ±10 dB at 10 kHz
At 100 Hz :  8 dB
At 10 kHz :  5 dB
High Filter:  12 dB/oct turnover 7 kHz
Low Filter:  12 dB/oct turnover 100 Hz
Power Requirements:  110/120 V 50/60 Hz
Power Consumption:  415 watts at full power; 60 watts at no signal
Dimensions (W x H x D):  21-15/16" x 6-9/16" x 15-9/16"
Weight:  45,4 lbs

Pioneer SA-5200

Pioneer SA-5200 - A compact, value-priced stereo integrated amplifier with advanced solid state circuitry and top versatility.

In the medium power and price range, few stereo amplifiers can match Pioneer's  SA-5200 for value and versatility. Designed for the person who is building his first set of home stereo components, this solid state amplifier offers the very latest circuit technology distinguished by superior stability and versatility. From the equalizer section to the power amplifier stages, the SA-5200 offers improved circuit design. The equalizer is unmatched in this price range for its precise RIAA equalization within +_0,5 dB as well as its ability for handling large inputs. In the power amplifier section, Pioneer has chosen complementary SEPP (Single-Ended, Push-Pull) ciruit with silicon transistors, offering ghigh efficiency and low distortion while delivering 13 watts + 13 watts of continuous power, both channel driven at 1 kHz into 8 ohms. The outstanding sound character of the SA-5200 makes it a value and a half, and the extent of this value is more than apparent when you price this amplifier. Another dynamic difference in true hi-fi components from Pioneer.

Circuit Description
Equalizer Amp
The signal from the Phono input terminal is fed to the input terminals of the equalizer amplifier stage, which employs a two-stage direct coupled circuit.
Since sufficient negative feedback from the second-stage collector is fed to the first-stage emitter, characteristics accurate to within ±0,5 dB on the RIAA curve can be provided. Compared with previous two-stage direct coupled circuits, this system makes for greater stability in the bass range and provides a surplus dynamic margin.
The amplified signal from the second-stage collector is fed to switch circuit-A ass'y through the Function Switch.

Control Amp
The signal selected by the Function switch is fed to the control amplifier through the Tape Monitor switch in switch circuit-A ass'y the loudness compensator circuit in switch circuit-B ass'y, and a potentiometer. The Tone Control circuit employs the nominal CR type configuration, and is connected after the one-stage amplifier. As in the bass and Theble tone controls, click-stop volume controls are employed, which provide high accuracy for flat frequency characteristics at the middle point of control knobs. The output of the control amplifier is fed directly to the power amplifier.

Power Amp
The power amplifier stage consists of seven transistors for each channel. It is composed of the thruout direct coupled  circuit with differential amplifier.
The signal from the control amplifier ass'y is fed to one base in the differential amplifier. The AC and DC negative feedabck from the output junction is fed to another base in the diffecrential amplifier so that overall stability is improved.
The differential amplifier output connects directly with the pre-driver base and amplifier. The signal from the pre-driver is amplifies by the driver and the power output stage, and fes to the speaker terminals through the Speaker switch in switch circuit-A ass'y.
Temperature compensation in the power amp ass'y is accomplished by a three-element varistor and the idle current adjustment by a semi-fixed variable resistor connected in series to the varistor.
Power transistor protection is accomplished by the fuse installed in series at the B-power circuit.

Power Supply
A full-wave rectifier circuits aupply all DC power. The rectified DC, with the ripple component eliminated by means of a 4,700 µF capacitor, is supplied for the output circuitry of the power amplifier circuit, and through CR filters for the other stages. The muting circuit eliminates the unpleasant noise usually heard when the power switch is turned On or Off. When the power switch is turned ON, the first-stage transitor Q1 in the power supply circuit is cut off immediately by the reverse bias caused  by a diode associated with the base.
When the power switch is turned OFF, the negative bias which has kept the first-stage transistor cut off is turned over to positive bias, and current entering the driver-stage transistor makes the second-stage transitor base connect to ground, the transitor cuts off the bias current entering the driver stage in the power amplifier ass'y. thus the amplifier stops working and unpleassant noise is eliminated.
A diode connected between the base and the emitter of the second-stage transistor permits discharge of the current charge in the power amplifier ass'y when the second-stage transistor is cut Off (when the power switch is turend Off).

Power Amplifier Section
Circuitry:  1st Stage Differential Amplifier, Dirct Coupled Quasi-complementary
 Continuous Power Output (both channel driven at 1 kHz):
15 W + 15 W at 4 Ω
13 W + 13 W at 8 Ω
Continuous Power Output (each channel driven at 1 kHz):
20 W / 20 W at 4 Ω
16 W / 16 W at 8 Ω
Power Output in 20-20,000 Hz (both channel driven):
10 W + 10 W at 8 Ω
Total Harmonic Distortion:
At continuous  Power  Output :  less than 0,8%
At 1 W + 1 W Power Output :  less than 0,2%
Intermodulation Distortion:
At Continuous  Power  Output :  less than 0,8%
At 1 W + 1 W Power Output :  less than 0,4%
Power Bandwidth (both channel driven IHF):  10 Hz - 40 kHz (THD 0,8%)
Output Speaker:  A, B, A+B (4 - 16 Ω)
Output Headphones:  4 - 16 Ω
Damping Factor:  more than 30 (1khz, 8 Ω)
 Preamplifier Section
Equalizer-amplifier:  2-stage Direct Coupled NFB type
Control-amplifier:  CR type
Frequency Response:
Phono (RIAA equalization):  30 Hz - 15 kHz ±0,5 dB
Tuner, Aux 1, 2; Tape Monitor :  15 Hz - 30 kHz ±1 dB
Hum and Noise (IHF, Shsort-circuited, A-Network):
Phono :  more than 70 dB
Tuner, Aux 1,2; Tape Monitor :  more than 90 dB
Input Sensitivity/Impedance:
Phono Mag :  2,5 mV/50 k Ω
Phono Overload Level :  100 mV/280 mV (rms/p-p)
Tape Monitor:  150 mV / 100 k Ω
Tape Rec/Pb (DIN  connector):  150 mV/100 k Ω
Aux 1, 2  :  150 mV/100 k Ω
Tuner :  150 mV/100 k Ω
Output Level/Impedance:
Tape Rec :  150 mV
Tape Rec/Pb (DIN connector)  30 mV/80 k Ω
Bass Control:  +12 dB; -10 dB at 100 Hz
Treble Control:  +9,5 dB; -10,5 dB at 10 kHz
Loudness Contour (-40 dB position):  +10 dB at 100 Hz ; +6 dB at 10 kHz
Power Requirements;  AC 120 V 60 Hz or AC 110 V , 120 V, 130 V, 220 V and 240 V 50/60 Hz (switchable)
Power Consumption:  85 W max
AC Outlets:  1 Switched, 1 Unswitched
Semiconductors:  22 Transitors; 7 Diodes
Dimensions (W x H x D):  415 x 132 x 328 mm (16-5/16" x 5-3/16" x 12-15/16")
Weight:  7,2 kg (15 lb 13 oz)

Harman/Kardon Citation Eleven

 Harman/Kardon Citation Eleven
Professional Solid State Stereophonic Preamplifier/Audio Equalizer

When Harman/Kardon introduced the Citation  A preamplifier  several years ago, it represented  a major breakthrough in solid state design. Within a short period of time, it became the audiophile's standard of excellence. In fact, the "A" is still recognized today by many audio authorities as the finest stereo preamplifier ever designed.
With the introduction of the Citation Eleven, Harman/Kardon has once again innovated a major change in the design and function of high performance solid state stereo preamplifiers.
The Citation Eleven uses the potential of transistors more completely and creatively than any other preamplifier in existance. It is a computer-crafted instrument that easily meets or exceeds every performance parameter ever established for a preamplifier. The simple truth is that the Citation Eleven is the best stereo preamplifier ever made.
 Total Flexibility and Control Over Acoustics
An important new design concept has been incorporated into the Citation Eleven to make it the most versatile stereo preamplifier ever created for home use. H/K engineers have determined that standard tone controls, even professional switched types, limit flexibility for they do not permit precise adjustment of program material over the entire audio range.
The Citation Eleven employs a professional type audio equalizer which gives the user complete control over program material, room acoustic and deficiencies within the speakers. Operating at predetermined hinge points, the audio equalizer adds or deletes audio energy to any of five points within the audio spectrum to compensate for inaccuracies in program material or within the playback system. It is no longer required to match room acoustic to the speakers by re-positioning furniture or by adding draperies and rugs to the room. The Citation audio equalizer controls room acoustics by permitting the user to set the five controls to suit his own personal requirements. Hot spots, ear-piercing high, frequency response drop out, excessive bass and even mid-frequency harshness can now be cancelled out by adding or deleting audio energy at the specific points in the audio spectrum where these probllems occur.

Below: another version of H/K Citation Eleven
 Listening quality of the Citation Eleven is superb , and not easily described in terms of laboratory measurements. The preamplifier offers solidity combined with an openness that sets it apart from all others. The more you listen to the Eleven , the more you become aware of the great achievement it represents. Anyone who wants the very best and will not be satified with anything less than the finest, will be well-advised to see and hear the new Citation Eleven.
Audio Output:  up to 6 volts RMS into 10 k ohms
Frequency Response:  below 5 Hz to beyond 125 kHz ±0,5 dB
Square Wave Rise Time:  less than 1 ms at 20,000 Hz
Square Wave Tilt:  less than 5% at 20 Hz
Total Harmonic Distortion:  less than 0,05% at 6 volts RMS from 10 to 30,000 Hz
Below residual level of most test instrumentation at 2 volts RMS and below
Intermodulation Distortion:  less than 0,05% at the equivalent 6 volts RMS output
Noise (Unweighted):
Low Level :  65 dB below 6 volts at 10 mV input reference
High Level:  80 dB below 6 volts  ( volume control wide open)
Residual:  900 dB below 6 volts
Low Level :  1,5 mV for 2 V output
High Level :  150 mV for 2 V output ( in all auxiliary positions except Aux 3, which is 300 mV for 2 V output)
High Cut Filter:  -8 dB at 10,000 Hz, 6 dB /octave slope
Subsonic Filter:  -12 dB at 15 Hz, 6 dB/octave slope
Input Impedance:
Phono :  47  k Ω
Aux :  20 k Ω
Output Impedance:
Source Impedance :  less than 500 Ω
Recommended Load :  10, 00 Ω or greater
Phono Overload:  Greater than 115 mV
Audio Equalizers:  Five sliding controls operaating at the following hinge points; 60, 320, 1k, 5 k, 12k Hz. Boost and cut ±12 dB, each position
Phono Equalization:  RIAA curve ±0,5 dB
A.C. Convenience Receptacles:  Three switched. One unswitched
On/Off Switch:  Pushbutton, heavy duty rating
Function Selector:  Mag. Phono 1, Mag. Phono 2, four high level positions
Mode Selector:  Stereo, Stereo Reverse, Mono, LeftChannel only, Right Channel only
Balance Control:  Zero to infinity type
Volume Control:  Close tracking dual potentiometers, frequency insenstive within range of frequency response specifications
Speaker Selector:  Permits choice of speaker system 1, system 2 or both at once when preamplifier is connected in the manner described in the instruction manual
Headphone Receptacles:  Two low impedance headphone receptacles controlled by front panel speaker selector switch. May be switched in or out at user's discretion.
Output Receptacles:  Four main preamplifier outputs. Four outputs for tape recording
Two pair for low level phonograph
Four pair for high level equipment
Two pair for tape monitor
Two grounding termnals
Power Requirements:  117 volt, 50/60 Hz or 220 volt operation, AC line fuse
Dimensions (WxHxD):  16-1/16" x 4-3/4" x 12"
Weight:  20 pounds