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STEREO RECEIVER PLUS 55
PLUS 55 Stereo Receiver
SQL quartz-locked tuning High speed DC amplifier 55 watts minimum RMS power into 8 ohms (60 watts into 4 ohms), 20-20,000 Hz, with no more than 0.04% total harmonic distortion.
The new 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 dosign, both internal and external, has been painstakingly worked and reworked to achieve a harmony seldom found even in far more costly components. The PLUS 55 is easy 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 receiver for the audio conneisseur 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 fluorescent 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
SANYO SQL (SAMPLING QUARTZ LOCKED) TUNING SYSTEM Theory of Operation
The Sanyo SQL system is a unique new tuner design that provides the unmatched precision of quartz without the high cost and complexity of other quartz locked systems. Once an FM station is tuned in, SQL takes over to keep the tuner "locked" at the exact point of minimum distortion and interference — with an accuracy measured in parts per million.
With the SOL tuner, initial selection of a station is accomplished manually by turning the multi-gang tuning capacitor. This tunes the front end to the desired station frequency, and simultaneously adjusts the "local oscillator" (LO) frequency. When the LO and RF signals are combined in the mixer, a "difference" frequency is obtained and sent to the IF section for further amplification, filtering, and eventual demodulation into an audio signal.
For best performance, it is essential that the LO frequency be fixed exactly 10.7 MHz higher than the station frequency, since any frequency error due to mistuning or drift will appear in the 10.7 MHz IF section, where even a small error can greatly increase audio distortion. The SQL system makes it impossible for this to happen.
To understand how SQL works, first note that all FM stations broadcast on frequencies that are exact multiples of 100 kHz (or 0.1 MHz). As a result, the correct local oscillator frequency, 10.7 MHz higher, must also be a multiple of 100 kHz.
SOL takes advantage of this fact by generating a quartz crystal-controlled 100 kHz pulse signal, which is used to "sample" the phase of the LO output every 10 microseconds. As long as the two signals are precisely in phase, nothing happens. But if the LO should begin to drift slightly, the next sampling pulse will show an "out of phase" condition, and cause a correction signal to be generated. This signal is used to control a voltage-variable capacitor (varactor) in the local oscillator, which adjusts the frequency of the LO until "lock" is restored. This correction process takes place 100.000 times per second, insuring perfect tuning accuracy at all times.
Sanyo SQL
(see inset for an explanation of SQL operation).
LED signal indicators.
Conventional tuning meters are replaced in the PLUS 55 by an array of light emitting diodes. Signal strength is indicated by a 5 LED "bar graph" display, while a separate LED indicates when the SOL 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 frontend overload by using a dual-gate MOSFET (metal-oxide-silicon lield effect transistor) in the front end circuitry. One of the device's gates receives 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 atate 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 ongaged to screen out stations which are too weak for
enjoyable stereo listoning. Muting is defeated in mono mode.
Dolby* FM deemphasis switch.
A rear panel switch changes the tuner's FM deemphasis characteristic from the standard 75 µs to 25 µs for proper decoding of Dolbyized broadcasts with an external Dolby adaptor.
PREAMPLIFIER SECTION High performance phono preamp.
After years of intensive development, Sanyo has perfected an integrated circuit with ideal characteristics for handling low level phono cartridge signals. The PLUS 55 phono circuit easily achieves an astonishing 87dB S/N ratio (re 10 mV input), frequency response to 150kHz, and distortion below 0.01% under most conditions. The differential first stage has an exceptionally wide overload margin (150 mV at 1kHz) 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 error to a maximum of ±0.2dB. 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 the middle of the spectrum is less than 1/2dB. You can adjust bass or 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 12dB/octave subsonic filter to remove record warp and arm resonance signals.
TM Doitry Laboratories.
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 AMP 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 150,000Hz are reproduced with virtually no phase distortion. Musical signals are reproduced exactly 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, Darlington-connected circuit configuration, the power stage achieves ultra-low distortion, outstanding waveform symmetry, plus a fast 60 V/as slew rate to prevent transient distortion. Close mounting of the hybrid components
on a copper plated aluminum substrate 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 "peakstretching" circuits make sure that even extremely short transients are visible to the eye. Amplifier output and possible overload can be 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 connecting and operating two pairs of speakers separately of simultaneously. Excellent performance with 4 ohm loads permits running most popular speakers in parallel without loss of power or sound quality.
4-way output protection.
A protective relay located between the 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 the power stage if, for any reason, the output current should reach an unsafe level.
Like all PLUS SERIES components, the 55 promises a uniquely satisfying experience to the music lover who is sensitive to the fine points of audio reproduction.
Sanyo Electric Inc. Consumer Electronics Division 1200 West Artesia Blvd. Compton, California 90220
PLUS SERIES philosophy
Sanyo PLUS SERIES ™— a new collection of ultra-high performance audio components designed, literally from the ground up, to excel in every way: outstanding specifications, useful "humanengineered" controls, features combining the best of traditional functions with unique new solutions, and styling of enduring beauty — plus, most importantly, audio reproduction quality that transcends simple formulas and numerical specifications.
This distinguished new series is the result of a unique design and production concept. Within one of the world's largest and most diversified electronics companies, we set up an independent team of audiophile engineers and gave them full freedom to draw on Sanyo's massive technological capability. A major part of their assignment was to devote special attention to eliminating those small but audible departures from sonic reality problems that seldom show up on specsheets or test benches, yet can make the difference between sound that is merely good, and sound that communicates a spine-tingling sense of life, openness, and "nir '
To support the PLUS SERIES group, Sanyo produces virtually every part required by their designs: transistors, capacitors, integrated circuits (both analog and digital), circuit boards, motors, meters, frames, knobs, cabinets — to name only a few. We control our quality to tolerances far stricter than outside suppliers can match. We back up our production systems with 30 years of know-how from our consumer and industrial electronics divisions.
The development of the Sanyo PLUS SERIES was one of the most difficult goals we have ever set for ourselves: to produce true "state of the art" audio components embodying the enlightened aesthetic and technological perspectives of the 1980's, and to make them available at a cost only slightly greater than the best of today's mass-produced audio equipment.
Our success — or failure — in achieving this almost superhuman goal can be evaluated now by arranging an audition with a PLUS SERIES dealer.
SPECIFICATIONS
AMPLIFIER SECTION
|
Continuous PMS Sine Wave Power per
Channel, Both Channels Driven from 20 H to 20,000 Hz at normore than studied Totel Hermonic Clistorium |
z |
|---|---|
| Into Nohms | 52 W at 0.04% THD |
| into 4 ohms | 60 W at 0.04% THD |
|
Measurum Totel Hermonic Distortion
(from 250 mW to sated power into 8 ohms, 20 Hz to 20,000 Hz, Aux input) |
0.04% |
| Intermediatebran Underlann (rated pawer, | |
| Aux input, 60 Hz & 7 kHz, 411 | 0.04% |
| Input Sensitivity/Impedance | Are water and |
| Phono | 2.5 mV/47 % uhms |
| Aux, Tape 1, 2 | 150 mV/47 k-chma |
| Frequency Response | |
| Phono (RIAA standard curve) | 10.2 48 |
| Aux, Taper | 4.0.5 dtl |
| (2014tr - 201kittr) | |
| ±1 dB | |
| 10 Hz 40 kHz) | |
|
Signal-to-Nnise Flatin (IIII - A weighted)
Phono (at 10 mV) (at 2.5 mV) Aux, Tupe |
87 dB
76 dB |
| 1 | 40 |
| Damping Factor (Tkitz, Corns) | |
| Beschull Hum & Noiseant Speaker | |
|
Residual Hum & Notedal Speaker (
Outputs De Notedal Speaker) |
0.6 mV |
|
Residual Hum & Noise at Speaker 11
Outputs 11 - 11 |
0.6 mV |
| Transient Response (Tells, Bahma) |
0.6 mV
GII volts per misso- second |
|
Residual Hum & Noise at Speaker II
Augusts HC Hum & Noise at Speaker II Cutputs HC Hum & Noise (Elektrole) Phano Museman Input Capacity |
0.6 mV
68 wolts per micro- second |
|
Residual Hum & Noise at Speaker (
Residual Hum & Noise at Speaker ( Outputs Transfert Rectioner (Reft rate) Phono Musemani Input Capuely (1 kHz) |
0.6 mV
GB write per micro- second 150 mV HWES |
|
Damping Factor (Tailr, Bapma)
Residual Hum & Noise at Speaker Outputs Introducts (Field rate) Phano Musemani Input Capuelty (1 kHz) Tone Controls |
0.6 mV
68 volts per micro- second 150 mV 1005 |
|
Damping Factor (Tell), Bapmel
Recidual Hum & Noiseal Speaker Outputs Translent Response (Cele rele) Phono Musamani Input Capacity (1 kH4) Tone Controls Bass (100 Hz) |
0.6 mV
Gil units per micro- second 150 mV HWE: ±10 dB |
|
Damping Factor (Traity, Bapme)
Recidual Hum & Noiseal Speaker Outputs Translent Response (Refe rate) Phono Musamani Input Capacity (1 kH4) Tone Controls Bass (100 Hz) Truble (10 kHz) |
0.6 mV
Sil volts per micro- second 150 mV 10VES ±10 dB ±10 dB |
|
Damping Factor (Tell), Bapmel
Residual Hum & Noiseal Speaker Ouputs Translent Response (Stell role) Phono Musemani Input Gapuely (1 kHz) Tone Controls Bass (100 Hz) Truche (10 kHz) I audness Control (Vol30 dP) |
0.6 mV
Gil units per micro- second 150 mV HMES ± 10 dB 1 10 dB |
|
Damping Factor (Teilt), Bapmel
Residual Hum & Noiseal Speaker Outputs Translent Response (Rele rate) Phono Musamani Input Capacity (1 kH4) Tone Controls Bass (100 Hz) Truche (10 kHz) Linutness Control (Vol30 dR) (00 Hz/10 kHz) |
0.6 mV
SII volts per micro- second 150 mV 18VES ±10 dB ±10 dB ±10 dB |
|
Demping Factor (Tell), Bagenes
Recidual Hum & Noiseal Speaker Ouputs Translent Response (Stell role) Phono Musamum Input Gapuelly (1 kHz) Tone Controls Bass (100 Hz) Truble (10 kHz) I autness Control (Vol30 dR) 100 Hz/10 kHz |
0.6 mV
GB white per micro- second 150 mV 1005 ±10 dB ±10 dB ±10 dB |
|
Damping Latter (Tail), Bapmal
Residual Hum & Noiseal Speaker Outputs Translent Response (Step role) Phano Muzemani Input Capueby (1 kHz) Tope Controls Bass (100 Hz) Truble (10 Hz) Laudness Control (Vol30 dR) (00 Hz)(10 Hz) Filers Schoome (10 Hz) |
0.6 mV
Gil unito per micro- second 150 mV 1005 ± 10 dB 1 10 dB + 6 dB/ + 8 dB - 12 dR/oct |
|
Toensient Response (Tell', Bapme)
Residual Hum & Noiseal Spoaker Outputs Transient Response (See role) Phano Musemani Input Capueby (1 kHz) Tope Controls Bass (100 Hz) Truble (10 kHz) Inudness Control (Vol30 dR) 100 Hz/10 kHz Filers Schoome (III Hz) High (8 kHz) |
0.6 mV
(31 white per micro- second 150 mV 1005 ± 10 dB 1 10 dB + 6 dB/ + 8 dB - 12 dR/oct 6 dB/oct. |
|
Damping Latter (Tail), Bapmal
Residual Hum & Noiseal Speaker Outputs Translent Response (Sale role) Phano Muzemani Input Capuely (1 kHz) Tope Controls Bass (100 Hz) Truble (10 Hz) Truble (10 Hz) Linutress Control (Vol -30 dR) 100 Hz/10 HHz Lifete Schoome (III Hz) High (Biolz) Output Voltage |
0.6 mV
68 white per micro- second 150 mV 1605 ± 10 dB ± 10 dB + 6 d8/+8 d8 12 dR/set 6 dB/oct. |
FM TUNER SECTION
| Energuency Range | 85-105 MHz |
|---|---|
| Usable Sensitivity | |
| Mone | 10.8 dH (1.9 µV) |
| 50 dFi Quieting Sensitivity | |
| Mono | 13.7 dB((2.7 PV) |
| Starco | 37 dbf (39.4V) |
| Nummum Signal-In-Noise Patio | |
| Mana | 75 dB |
| Stereo | 70 dB |
| Total Hamone Delerion | |
| Monin 100 Hz | 0.2% |
| 1 8147 | 0.2% |
| BAHL | 0.35% |
| Steven 100 Hz | 0.055% |
| 1.8212 | 0.3% |
| G kHz | 0.4% |
| Energoency/Temportoe | 2011z - 15,00011z |
| + 1, -2 dB | |
| Alternate Channel Selectivity | |
| at ± 400 kHz | 75 dB |
| Daphure Datio | 1.2.60 |
| AM Suppression Batio | 55.dB |
| 1 ki tr | 45 dB |
|---|---|
| 10 kHz | 35 dB |
| Spanous Pasparse Repoten (38 MHz) | 80 dB |
| image Rejection Ratio | 70 dB |
| (P Rejection Ratio (98 MHz) | 90 dB |
| Muting threshold | 5 #V |
| AM TUNER SECTION | |
| Frequency Bange | 525-1620 ki Iz |
| Usable Sensitivity (Fenite | |
| Esternal Antenna) | 300 yV/m-30 yV |
| Signal-on-Noise Patio (at 5 m)//m)- | 45.8N |
| Selectivity | 35 JB |
| Image Rejection Flatio (1000 ki tr) | 50 dti |
| (F Rejection Ratio (1000 kHz) | 45-08 |
| GENERAL | |
| Dimensions (W x H x D) | 18%" x 5%" x 11%" |
| E REI BATE | Natiral Wood with |
| Textured Steel Top |
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