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





Sanyo Plus 55


Stereo Reciver with SQL Quartz-Locked Tuning and High Speed DC amplifier
The Sanyo Plus 55 is elegant proof that moderate power and reasonable price in a stereo receiver do not inevitably mean compromise in  performance or features. Every aspect of its design, both internal and external, has been painstakingly worked and reworked to achieve a harmony seldom found even in far more to operate without being oversimplified. The controls are logical and responsive. The front panel gives visual display of a wealth of important information. And the internal circuits are the best that today's technology has to offer. The Sanyo Plus 55 is truly the perfect rceiver for the audio connoisseur with power requirements in the 50-60 watt per channel range.

Tuner Section
Digital Plus Tuning
Unquestionably, the most striking feature on the Plus 55's handsome front panel is its unique dual-mode frequency display. Sanyo engineers knew that digital frequency readout was a necessity for completely accurate, unambiguous tuning. At the same time, they realized that many people do not know the exact frequencies of their favorite stations, and find it easier to remember the approximate dial pointer location for each station. So sanyo Digital Plus tuning includes both a conventional dial scale and a bright fluorscent digital frequency display, which travels with the illuminated pointer along the dial scale as the receiver is tuned. Digital Plus thus combines the convenience of analog tuning with the precision of digital, and is a Sanyo Plus series exclusive.

SQL Quartz-Locked Tuner Circuitry
The Plus 55 incorporates Sanyo's unique Sampling Quartz-Locked tuning system, which provides accuracy impossible to achieve with conventional tuner designs. The special AT-cut quartz crystal locks in stations, with no significant drift due to time or temperature changes.

LED Signal Indicators
Conventional tuning meters are replaced in the Plus 55 by an array of light emiting diodes. Signal strength is indicated by a 5 LED 'bar graph' display, while a separate LED indicates when the SQL system has achieved 'lock' on a given FM frequency (equivalent to a center-channel indicator). Both displays use high gain, DC-coupled voltage comparators for precise indications.

Dual-gate MOSFET RF amplifier
Sanyo solves the problem of FM front-end overload by using a dual-gate MOSFET (metal-oxide-silicon field effect transistor) in the front end circuitry. One of the device's gates recelves the antenna signal, while the second is driven by a DC voltage from the tuner's Automatic Gain Control circuit. Thus the RF gain is automatically reduced in the presence of strong signals, avoiding overload and cross-modulation distortion and keeping other stations from interfering with the one you want.

Advanced IF design
Outstanding performance in the Plus 55 's IF section is achieved by a combination of Sanyo IC's and 3 sophisticated ceramic filters. These solid state resonators provide extremely good rejection of unwanted signals, plus 'linear phase' characteristics in the passband (essential for low distortion in the audio program). A quadrature FM detector and Phase Locked Loop multiplex decoder assure outstanding stereo separation without the need for periodic realignment. The result is clean, clear listening and years of trouble-free reception.

Combined muting/mode switch
When stereo mode is selected, FM muting is automatically engaged to screen out stations which are too weak for enjoyable stereo listening. Muting is defeated in mono mode.

Dolby FM demphasis switch
A rear panel switch changes the tuner's FM deemphasis characteristic from the standard 75 µs to 25 µs for proper decoding of Dolbylized broadcasts with an external Dolby adaptor.

Preamplifier Section
High performance phono preamp
After years of intensive development Sabnyo has perfected an integrated circuit with ideal characteristics for handling low level phono cartridge signals. The Plus 55 phono circuit easily achieves an astonishing 87 dB Signal-to-Noise ratio (re10mV input), frequency response to 150 kHz , and distortion below 0,01% under most conditions. The differential first stage has anexceptionally wide overload margin (150 mV at 1 kHz) to easily handle high output cartridges and the extremely demanding transient peaks found on direct-to-disc and digitally mastered recordings. The differential configuration also isolates the RIAA equalization network from the phono input, to avoid frequency response errors caused by interaction of cartridge impedance with the network. Precision resistors and capacitors are used to hold RIAA equalization eror to a maximum of ±0,2 dB. Records sound the way they should, no matter which cartridge you prefer to use.

Versatile tone controls and filters
Bass and treble controls on the Plus 55 are of the Baxandall feedback type, and combine wide adjustment range with an almost total absence of interaction; even at maximum cut or boost, their effect on th emiddle of the spectrum is less than1/2 dB. You can adjust bass and treble without upsetting the tonal balance of the rest of the music.
The Plus 55 is provided with an 8 kHz high filter useful for removing hiss and scratches from noisy programs, and a 12 dB/octave subsonic filter to remove record warp and arm resonance signals.
These inaudible signals can consume large amounts of amplifier power, creating distortion of audible bass and putting a severe load on woofers. The loudness control provides moderate bass and treble boost at low volume settings to compensate for the ear's reduced sensitivity to these frequencies.

Two tape deck inputs with dubbing
The Plus 55 allows recording and monitoring with two tape decks, as well as dubbing from one to the other at the push of a button.

Power Apm Section
High Speed DC amplifier
Except for the DC blocking input capacitor, the Plus 55 power amplifier is totally direct coupled from first stage to speaker terminals. Frequencies from 5 to 150,000 Hz are reproduced with virtually no phase distortion. Musical signals are reproduced exactlly as recorded, for the ultimate in realism.

Exclusive Sanyo Hybrid IC power stage
Sanyo's pioneering work in high power integrated circuit design now makes it  possible to put the entire power output stage of one channel of the Plus 55 in a single compact hybrid IC. Using a fully complementary, Darlingto-connected circuit configuration, the power stage achieves ultra-low distortion, outstanding waveform symmetry, plus a fast 60 V/µs slew rate to prevent transient distortion. Close mounting of the hybrid components on a copper plated aluminum substarate assures ideal thermal tracking of all components, for better bias stability and greater reliability  than an equivalent discrete circuit.

LED power indicators
These attractive 5-LED 'bar graph' displays give instantaneous indication of right and left channel output level. The LED's response time is far faster than any mechanical meter, and special 'peak-stretching' circuits make sure that even extremely short transisnts are visible to the eye. Amplifier output and possible overload canbe monitored precisely and easily. A range switch increases the sensitivity of the indicators by 10 times, for useful readings at low listening levels.

Speaker A/B switching
Allows connection and operating two pairs of speakers separately or simultaneously. Ecxcellent performance with 4 Ω loads permits running most popular speakers in parallel without loss of power or sound quality.

4-way output protection
A protective relay locked between teh amplifier output and the speaker terminals operates to disconnect the load under any of the following conditions.
When the unit is first turned on ( after a 5 second delay for the circuits to stabilize the speakers are reconnected)
When the heat sink temperature becomes too high for safe operation ( due to inadequate ventilation or sustained overload)
When special protection circuits sense the presence of a DC voltage at the outputs (which can quickly damage speakers)
In addition, current monitoring circuits operate to instantly shut down th epower stage if, for any reason, the output current should reach an unsafe level.

Specifications:
Amplifier Section
Continuous Power Output (minimum sine wave RMS per channel at 8 Ω, 20 - 20,000 Hz no more than 0,04% T.H.D.):  55 watts into 8 Ω; 60 watts into 4 Ω
Maximum Total Harmonic Distortion (from 250 mW to rated power into 8 Ω, 20 - 20,000 Hz, Aux input):  0,04%
Intermodulation Distortion (rated power, Aux input, 60 Hz : 7 kHz= 4 : 1):  0,04%
Input Sensitivity/Impedance:
Phono :  2,5 mv/47 k Ω
Aux, Tape 1 and 2 :  150 mV/47 k phm
Frequency response:
Phono (RIAA standard curve):  ±0,2 dB
Aux, Tape :  ±0,5 dB (20 - 20,000 Hz);  ±1 dB (10 - 40,000 Hz)
Signal-to-Noise Ratio (IHF-A weighted)
Phono (at 10 mv):  87 dB
Phono (at 2m5 mV) :  75 dB
Aux,  Tape :  95 dB
Damping factor:  40 (1 kHz, 8 Ω)
Residual Hum and Noise at Speaker Outputs:  0,6 mV
Transient Response (Slew Rate):  60 volts  per microsecond
Phono Maximum Input Capacity (1 kHz):  150 mv RMS
Tone Controls
Bass :  ±10 dB at 100 Hz
Treble :  ±10 dB at 10 kHz
Loudness Control (Vol. -30 dB)
100 Hz  / 10 kHz :  +8 dB /+3 dB
Filters
Subsonic (30 Hz) :  -12 dB/oct
High (8 kHz) :  -6 dB/oct
Output Voltage
Tape Rec 1 and 2 :  150 mV
 FM Tuner Section
Frequency Range:  88- 108 MHz
Usable Sensitivity [mono]:  10,8 dBf (1,9 µV)
50 dB Quieting Sensitivity
Mono :  13,7 dBf (2,7 µV)
Stereo :  37 dBf (39 µV)
Maximum Signal-to-Noise ratio
Mono :  75 dB
Stereo :  70 dB
Total Harmonic Distortion [Mono]:
At 100 Hz :  0,2%
At 1 kHz :  0,2%
At 6 kHz :  0,35%
Total Harmonic Distortion [Stereo]:
At 100 Hz :  0,35%
At 1 kHz :  0,3%
At 6 kHz :  0,4%
Frequency Response:  20 Hz - 15,000 Hz, +1 -2 dB
Alternate Channel Selectivity (at ±400 kHz):  75 dB
Capture Ratio:  1,2 dB
AM Suppression Ratio:  55 dB
Stereo Separation [1 kHz / 10 kHz] :  45 dB / 35 dB
Spurious Response Rejection (98 MHz):  80 dB
Image Rejection ratio:  70 dB
IF Rejection Ratio (98 MHz):  90 dB
Muting Threshold:  5 µV
AM Tuner Section
Frequency Range:  525 - 1620 kHz
Usable Sensitivity (Ferrite External Antenna):  300 µV/m - 30 µV
Signal-to-Noise Ratio (at 5 mV/m):  45 dB
Selectivity:  35 dB
Image Rejection ratio (1000 kHz):  50 dB
IF Rejection Ratio (1000 kHz):  45 dB
General Section
Power requirements:  AC 120V, 60 Hz / Ac 220 - 240 V 50/60 Hz
Power Consumption:  200 W
AC Outlets [switched/unswitched]:  1 x 100 W max./ 1 x 100 W max.
Dimensions (W x H x D):  18-7/8" x 5-1/4" x 11-1/2"

Wadia 7 Transport


If the essence of music is art, then th eessence of music reproduction is technique. And the quintessence of that technique is Wadia.
As we continue to make pioneering advances in digital reproduction, by applying advanced computer technology and patented programming to leading-edge signal decoding, we place increasingly greater demandads on th eelement of digital technology first in the reproduction chain; the transport.
For, while the New Generation of Wadia Decoding Computers has been engineered to achieve faithful reproduction of the very life of recorded music, the broad symphony of instrumental and vocal nuance, the aural ambience of soundspace, the audibly influential presence of the artists themselves, reproduction comes to naught lest the recorded signal is sent, intact, to these brilliant instruments of sonic  reproduction.


Enter the new generation of Wadia transports - designed, foremost, to ensure absolute mastery of signal recovery in the time domain; the genesis of optimum reproduction.
Wadia's proprietary clocking technology initiates digital timing accuracy at the LSI chip, setting the standard for accurate time-base relationships throughout the chain of digital reproduction equipment.
To isolate signal topology from power-supply generated noise, the Wadia 7 Transport has been engineered with a completely redesigned power supply, housed in its own substantial chassis. A state-of-the-art regulator stage ensures constant voltage sophisticated line filtering delivers a pure AC line feed to two toroidal transformers - the very best of current manufacture as is every component in the Wadia 7.
Enclosure design, too, is an essential element of distortion control and, as a result in a loss of information  which cannot be recreated by improvements later in the system.


Wadia's exclusive rounded-corner design detunes the enclosure from resonant frequencies which would have a negative impact of critical clock and program signals.
As the foundation for fautless signal recovery, the chassis of the Wadia 7, constructed of massive body plates, provides a profoundly stable platform for that most critical of all transport components, the spinning mechanism itself.
To expect near- perfect accuracy from heavy-handed servo-feedback corrections would seem folly. Thus, at the heart of the Wadia 7 Transport is the critically acclaimed P-2S spinning mechanism - an acknow ledged industry standard, utilized outside  the manufacturer's realm only within the Wadia 7.
Its full-size die-cast zinc/bronze disc turntable and stabilizer clamp keeps disc and laser pickup in their precise relative positions. With this dimensional stability and interial damping, servo corrections need only deal with tracking the variable disc rotation speed.
Combine full-disc clamping with a floating suspension system, sophisticated resonance damping design and the use of non-resonant metals - not plastic - throughout its understructure, and the result is a mechanical treatment which has risen to worldwide critical acclaim..

Function selection of the Wadia 7 is equally sophisticated. Sculpteed from a solid block of aluminum, the full-functions remote controller promises a lifetime of faultless service, reducing control intrusions into both cosmetics and mechanical integrity.
It is also your fully remote acces to the Wadia 7's matchless companion in unrivaled digital reproduction, the Wadia 9 Decoding Computer.
Truly, the Wadia 7 Transport brings unerring digital transport to reality, presenting, through Wadia's pioneering use of the Glass Fiber Optical Transmission System, the world's most accurate digital output, and offering for  your audition the essence of the art of music, through the twenty-first centry technique that is Wadia.
The Wadia 7 Transport  feature a complete array of output choices. Un mistakably, our prime choice is Glass Fiber Optics. To maintain compatibility between Wadia transports and all possible subsequent system components, we have included a plastic optics output, a Coax output via BNC, and an output in the AES/EBU  connection system.
Additional user-selected options are adjusted from the real panel of the wadia 7 Transport. Separate adjustments can be made for disc drawer insertion speed and ejection speed, and for display intensity.


Wadia 7 Transport Specifications:
CD Stability:  Vibration-Free Rigid Disc Clamping System (VRDS)
CD Pickup Mechanical:  3-beam, objective lens drive, 780 nm wavelength
2-dimensional parallel drive
Machined Cast-alloy turntable
Precision Servo-sled tracking mechanism
Floating suspension system
Pickup Drive Metod:  Linear motor drive
Disc Diameter:  120mm/80mm
Quality Level:  Level 1, High Accuracy ; EIAJ CP-340 Specification
Four Outputs :
Glass Fiber Optic (850 nm) :  -16dBm
EIAJ Standard Plastic Fiber Optic (665 nm):   -15 to -21 dBm
S/PDIF Coaxial via BNC Connector:  0.5V p-p, 75 Ω
AES/EBU Standard via XLR Connector:  3V p-p, 110 Ω
Power Supply;  2 Toroidal Transformers; 100, 120,2 20, 240 V AC
Enclosure:  Airborne computer quality aluminum plate.
Detuned for Lenz's Law and package parasitic resonances.
Side panel skin effect transitions @ < 20 Hz.
Dimensions: 
Main Unit: 9.625" Wide, 17.875 'I Deep, 6.063" High
Power Supply: 7.375" Wide, 17.875" Deep, 6.063" High
Wright: 
Main Unit : 32 Ibs.
Power Supply :  23 Ibs

KEF Cantata SP1056


KEF loudspeakers are designed to reproduce natural sound, free from exaggerated effects of balance and with the lowest possible distortion. Many hundreds of separate items are used to build a loudspeaker system and the electrical and machanicl interaction of the components will significantly affect the reproduction quality

Loudspeaker drive units.
Every KEF diaphragm is manufactured from plastics or, in the case of larger units, from metal and plastics. These special constructions obviate the wide variations in performance associated with ordinary loudspeakers, and considerably reduce colaoration due to the absence of unwanted resonances in the diaphragm itself.
KEF engineers work with radically new techniques to explore the truth about sound coloration, its causes and prevention. Computer based analysis techniques unfold a more precise and detailed insight into speaker behaviour than was previously possible using conventional research techniques.
To make loudspeaker systems which optimise the performance of individual KEF drive units, recent research has concentrated on the interaction of other critical components with the drive units - the dividing network and the enclosure.

Loudspeaker Enclosures
Resonances in a loudspeaker enclosure are known to cause unwanted acoustic radiation which can ruin the clarity of sound from even the finest drive units. The impulse response compares signals from a single drive unit measured in a simple undamped enclosure and from the same unit in a box to which optimum dampinghas been applied using layers of bituminous damping material.
Enclosure analysis is part of loudspeaker engineering. KEF are noe able to assess objectively the audible effect of enclosure resonances and consequently, each KEF system is critically and consistently damped to minimise resonances and reduce audible coloration.

Dividing Networks
Conventional filter designs assume that the load is a simple resistance, whereas in fact, loudspeakers present complicated loads with frequency dependent impedance characteristics. As a result, traditional loudspeaker dividing networks rarely satisfy the conflicting requirements of smooth amplitude frequency response and desirable impedance characteristics.
An entirely new approach to dividing networks has been developed by KEF. The new technique improves transient behaviour giving a smoother, more transparent sound quality, increased depth perspective, and sharper stereo imaging.

System Study
Detailed objective analysis of the comleted loudspeaker system is aided by another sophisticated KEF computer programme. Three-dimensional plots of cumulative spectra - provide "in depth" displays of speaker response in terms of amplitude, frequency and time. At last it is possible to see the effects of speaker design changes and relate them to sound quality.

Quality assurance

The quality of a KEF speaker is under surveillance and control at all stages of production, commencing with the critical inspection of incoming raw materials and components. Frequent inspection of subassemblies at many subsequent stage ensures a very high standard of consistency and reliability. Final testing is carried out using the most sophisticated techniques. Stringent and effective quality controls enable KEF to offer a Five year warranty on all its products.

Specification:  Cantata
System Type:  Three-way, floor standing
Enclosure Type:  Closed box
System:  SP1056
Drive Units: 
Bass Unit :  B139 (SP1044),
Bass  Unit :  B110 (SP1057),
Tweeter :  T52 (SP1049)
Crossover:  SP1058 and SP1064
Input Impedance:  8 Ω
Rated Maximum Power:  150 W programme
Amplifier Requirements:  15 - 150 watts per channel into 8 Ω
System Resonance:  38 Hz, Q=0.7
Frequency Range:  35 - 20,000 Hz, ±3 dB
Sensitivity:  8 watts for 96 dB at 1 m and 400 Hz in anechoic conditions
Crossover Frequencies:  250 and 3000 Hz
Internal Volume:  60 litres
Finishes:   Walnut or Teak
Grille:  Mokka brown cloth
Dimensions (W x H x D):  815 x 340 x 392  mm (32.1" x 13.4" x 15.4")
Weight:  31.7 kg (70 lb)

KEF Calinda SP1053


The Calinda three-way loudspeakers are among the first KEF model to benefit from the technological innovations introduced by the Company during the early and mid 1970s - in particular the application of computer-based test methods in both design and quantity production and the use of the "Target Function Concept" in the synthesis of crossover networks. These advances have made it possible to produce loudspeakers in the domestic size and price range with a standard of performance hithero associated with professional equipment. Like most other loudspeaker, Calinda have been designed to meet aesthetic requirements imposed on them as articles of furniture, and as a result, the outward appearance shows no sign of their special technical features. 

Howev, with the grille covers removed, as shown above, certain differences in the type and positioning of the drive units, and it will also be noticed that in Calinda and largest KEF Cantata, the conventional placing of the mid-range and high-frequency units is reversed.
These features, the reason for which may not be immediately clear, are in fact part of an overall system-engineering approach, in which the various components of each model - drive units, enclosures and filter networks - are developed together and optimised to fulfil a particular need; both designs are based on practical considerations of performance and cost-effectiveness, avoiding the kind of over-specification that may look impressive on paper but is irrelevant to the listeners requirements.
 

Calinda was an 8 inch two-way system with an auxiliary (passive) radiator augmenting the low frequency response. This format was used previously in the Cadenza and Reference 104. In the Calinda system the driver layout was adjusted to allow an elegantly slim floor standing cabinet. 

Specification:  Calinda
System Type:  Two-way, floor standing
Enclosure Type:  Passive radiator
System:  SP1053
Drive Units:
Bass Unit : B200 (SP1054),
Passive Radiator :  BD139 (SP1042),
Tweeter :  T27(SP1032)
Crossover:  SP1055
Input Impedance: 8  Ω
Rated Maximum Power:  100 W programme
Amplifier Requirements:  15 - 100 watts per channel into 8 Ω
System Resonance:  28 Hz, mechanical reflex
Frequency Range:  40 - 30,000 Hz, ±3 dB
Sensitivity:  12.5 watts for 96 dB at 1 m and 400 Hz in anechoic conditions
Crossover Frequency:  3,500 Hz
Internal Volume:  45 litres
Finishes:   Walnut or Teak
Grille:  Mokka brown cloth
Dimensions (W x H x D):  700 x 280 x 350 mm (27.5" x 11" x 13.8")
Weight:  19.1 kg (42 lb)