SANYO SQL (SAMPLING QUARTZ LOCKED) TUNING SYSTEM
Theory of Operation
The Sanyo SQL system 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
Sanvo SOL Tuning System
"locked" at the exact point of minimum distortion and interference — with an accuracy measured in parts per million.
To understand how SQL works, first note that all FM stations broadcast on frequencies that are exact multiples of 100kHz (or 0.1MHz). As a result, the correct local oscillator frequency, 10.7MHz higher, must also be a multiple of 100kHz.
SQL takes advantage of this fact by generating a quartz crystal-controlled 100kHz 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 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.
Fluid Convection Radiator heat sink.
Rather than adopt the usual approach to heat sinking and use several pounds of black aluminum, Sanyo fitted the PLUS 200 with a totally new heat dissipator — the exclusive Fluid Convection Radiator. In this
system, a sealed metal loop partially filled with liquid Freon connects the output transistor mounting blocks to an array of thin, closely spaced fins. When heat builds up in the output devices, it quickly causes the Freon to boil. The gaseous Freon travels to the upper end of the loop, where it gives up its heat to the metal fins and changes back into its liquid state. Gravity then causes the liquid to run back to the lower half of the loop, where the process is continuously repeated. The result is extremely efficient heat removal — with approximately 80% less weight than conventional heat sinks, and without the annoyance of noisy cooling fans.
12-section LED power indicators.
The PLUS 200 uses a pair of highresolution LED peak power displays, with twelve LEDs per channel for unusually precise indication. The LEDs respond instantly to peak outputs, and unlike many
systems, read both positive and negative peaks. A display range selector increases the sensitivity of the system by a factor of ten or one hundred, allowing power outputs as low as 5 milliwatts to be accurately read.
Two-piece "docking" design
Realizing that not everyone would have available a shelf capable of accommodating the PLUS 200's considerable size and weight, Sanyo designed it as two separate chassis, capable of being separated via an optional connecting "umbilical" cord. The front tuner/preamp section, containing all controls, is less than 8" deep and light in weight, allowing it to be placed virtually anywhere. The larger power amp section may be placed out of sight in a cabinet (with adequate ventilation), or may even be located across the room, near the speakers. Hence speaker leads may be kept very short, assuring maximum damping factor.
Its phono section was painstakingly designed and refined, stage by stage, until it could stand comparison with costly separate preamplifiers. To achieve the PLUS 200's outstanding 70dB S/N ratio with moving coil cartridges, new ultra-low noise input transistors were necessary resulting in a truly staggering 97dB S/N ratio with moving magnet cartridges!
The phono section's first stage consists of a bipolar differential amplifier with current mirror load, for high gain with low distortion. The differential configuration effectively isolates the equalization network from the input, preventing frequency response errors due to interaction with the phono cartridge impedance. A singleended class A gain stage follows, using an active current source load and driving the class A complementary output stage. Feedback to the input differential stage is through a precision RIAA equalization network, and includes a switch-selected shunt to establish the correct gain for the selected cartridge type while maintaining the best possible noise and distortion figures. The use of class A circuitry throughout assures distortion which is in some cases virtually unmeasurable, and the high voltage power supply provides more than adequate overload margin for any recorded signals, including direct-todisc and digitally mastered recordings
Variable Cartridge Loading
Since it is now well known that the electrical load connected to a moving magnet phono cartridge can have a significant effect on its response, the PLUS 200 provides a choice of three different resistances and three different capacitances, which may be paired in any desired combination for optimum response flatness.
Three band discrete tone equalizer with defeat.
The PLUS 200 goes far beyond conventional receivers in its flexibility of tonal compensation. Both the bass and treble controls offer a selection of three turnover
points, spaced an octave apart (see curves). The 400Hz and 2.5kHz frequencies provide control action similar to conventional fixed-turnover bass and treble controls. The 100Hz and 10kHz positions affect only the extremes of the audio spectrum, and are ideal for "touching up" the sagging low frequency response of many speakers, the slightly overbright sound of some phono cartridges, and other common
| 2 |
|---|
| X |
| n x |
| 100 |
| 15k2 |
| 4 DITE |
| ++ |
| 21 |
| N |
audio problems. The 200Hz and 5kHz positions provide an intermediate response which is useful for some situations.
The PLUS 200 also includes a separate midrange control, with a moderate ±6dB range at 1kHz which permits adjustment of musical "presence" from a bold, "up front" sound to a subdued, distant effect ideal for background music.
The tone control uses fully discrete, class A design to prevent any significant signal degradation. In addition, a defeat switch is provided to completely bypass the tone control section for instant flat response.
Subsonic and high filters, loudness compensation.
The PLUS 200 is provided with an 8kHz high filter useful for removing hiss and scratches from noisy program, plus a 12dB/octave subsonic filter that sharply attenuates record warp and arm resonance signals, preventing power waste amplifying inaudible interference, without loss of audible bass. The loudness control provides
$SANYO
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 200 allows recording and monitoring with two tape decks, as well as dubbing from one to the other at the push of a button.
External Processor Loop.
Consisting of a pair of input and output jacks and a front panel switch, this feature eliminates the need to sacrifice a set of tape monitor jacks whenever an auxiliary signal processor is connected. Typical accessories include graphic equalizers, noise reduction adaptors, special speaker equalizers, dynamic range expanders, time delay units, etc.
When the external processor loop switch is engaged, any signal being monitored, whether from the selected source or one of the two tape deck inputs, will be processed by the external device before passing to the volume and tone controls.
Audio muting switch.
This switch reduces the listening level 20dB, and is useful for interrupting the program for phone calls, etc. It may also be used as a range expander for the 41-detent volume control, to provide finer adjustment capability at very low levels.
Preamp out/power amp in jacks.
These rear-panel jacks (normally strapped together) allow separating the tuner/preamp and power amplifier sections of the PLUS 200. Thus, the insertion of additional signal processing devices (active speaker equalizers, electronic crossovers for biamplification, graphic equalizers, etc.) into the audio path is possible.
POWER AMP SECTION High Speed DC Amplifier
Except for the DC blocking input capacitor, the PLUS 200 power amplifier is totally direct coupled from first stage to speaker terminals. Frequencies from 5 to over 100,000Hz are reproduced with vir-
tually no phase distortion, and the extraordinary 170 volt per microsecond slew rate rules out any possibility of transient or slewinduced distortion. Musical signals are reproduced exactly as recorded, for the ultimate in realism.
All-differential drive circuitry.
The power amplifier's first stage consists of an integrated pair of matched FET's with an integrated, matched bipolar transistor pair connected in cascode configuration. The FET input provides extremely high input impedance and essentially perfect isolation of feedback and feed-forward signals, while the cascode devices greatly increase the response speed of the input stage.
Two more fully differential stages follow, the last with current-mirror loading and temperature-compensated biasing for the double-Darlington parallel output stage. The fully complementary output stage uses the latest Ring Emitter Transistors to achieve its excellent linearity and ultra-high slew rate.
PLUS 200 Stereo Receiver
□ High-speed DC amplifier: 200 watts RMS per channel into 4 or 8 ohms, 20-20.000Hz, with no more than 0.009% total harmonic distortion.
□ "Docking" design with separate tuner/preamp and power amp sections.
SQL guartz-locked tuning with "Digital Plus" analog and digital frequency display.
Although the last few years have seen a spate of high power receiver introductions, too often these huge, heavy maxicomponents have seemed designed more to capture headlines in the audio "horsepower race" than to satisfy the real needs of extremely high quality audio reproduction.
The new Sanyo PLUS 200 was conceived and developed to avoid this pitfall. Starting with the assumption that the PLUS 200 would be used only with the finest of today's speakers, phono cartridges, turntables, tape decks, and auxiliary equipment, it became vital that each and every section, subsystem, and component in the receiver be strictly "state of the art" in design.
After many months of intensive development and critical listening, the PLUS 200 was born — perhaps the best-performing, most thoroughly engineered receiver ever introduced. Yes, its power output is exceptionally high — but this is far from the most important fact about the PLUS 200. For even if it were only half as powerful, it would still be one of the most uniquely pleasurable sound reproduction components ever offered to the audiophile community.
TUNER SECTION 5-Gang FM Front End
Despite a trend toward cheaper and simpler front end designs in most new stereo receivers, the PLUS 200 maintains its "no compromise" philosophy by incorporating 5-gang tuning and three RF amplification stages. All three stages utilize high performance dual-gate MOSFET transistors, and each stage is AGC-controlled to prevent overload and cross-modulation distortion. Even when there is an extremely strong local station crowding a much weaker station you are trying to tune, the PLUS 200 delivers dependably superior reception.
Selectable IF Bandwidth
Like a few very expensive component tuners, the PLUS 200 permits tailoring response of the IF section to the specific reception conditions. When interference by neighboring stations is a problem, select the Narrow mode and enjoy the astounding 80dB selectivity provided by the combination of two tuned LC filters and four ceramic filters. If interference isn't a problem, select the Wide mode, in which two of the ceramic filters are replaced by a buffered LC section, and harmonic distortion drops to an insignificant 0.09% (at 1kHz). Even in Narrow mode, special, flat-group delay ceramic filters keep distortion extremely low.
Pilot-Canceling MPX Decoder
The PLUS 200 uses a Phase Locked Loop integrated circuit to lock onto the 19kHz pilot tone transmitted by FM stereo stations, which enables decoding of the stereo information.
Unlike most tuners, the PLUS 200 utilizes this same PLL circuit to generate an out-of-phase replica of the stereo pilot tone, which is then added to the demodulated signal to exactly cancel the original tone. Virtually all other receivers attempt to remove the MPX tone (which may be audible, and can interfere with the Dolby circuits in tape decks) with simple low-pass filtering. Since no filter has a perfectly sharp cutoff, however, there is always some loss of frequencies below 19kHz well into the audible range. The beatcanceling circuitry eliminates this possibility of audible high frequency loss, and works so effectively that the PLUS 200's 19kHz filter may be switched out without significant blot tone takage.
The FM stereo circuity, excels in other respects: storeo separation reaches an amazing 50dB, and signal-to-noise ratio in stereo reaches 28dB — better than virtually any program source available.
| FM | ||
|---|---|---|
|
DE-EMPHASIS
75µ3 |
IF BAND
normal |
SIGNAL |
| - |
LED Signal/Multipath/Deviation Indicator
Conventional tuning meters are replaced in the PLUS 200 by a linear array of seven light emitting diodes. Three front panel pushbuttons select the various display modes:
Signal strength, which shows the relative RF signal level received at the antenna input terminals.
Multipath, which indicates the presence and degree of multipath interference (slightly delayed reflections of the desired signal, bounced off hills, buildings, etc.) The multipath display makes it easy to rotate the receiving antenna to minimize multipath distortion.
Deviation, which shows the amount of frequency modulation (deviation) the FM station is applying to its carrier wave, and serves as a check on overall signal quality
SQL Quartz-Locked Tuner Circuitry.
The PLUS 200 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 (see inset for an explanation of SQL operation).
"Digital Plus" Tuning.
Unquestionably, the most striking feature on the PLUS 200'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.
FM Hi-Blend Switch
When receiving extremely weak stereo FM signals, a bothersome level of high frequency hiss may be present. Rather than switch to mono and give up all stereo effect, this switch can be used to reduce stereo separation only at high frequencies, thereby canceling the out-of-phase hiss while preserving enjoyable stereo at mid and low frequencies.
Dolby* FM Deemphasis Switch
Conveniently located on the PLUS 200 front panel, this switch changes the FM deemphasis characteristic from the standard 75µs to 25µs, for proper decoding of Dolbyized FM broadcasts with an external Dolby adaptor or tape deck.
PREAMPLIFIER SECTION Advanced phono preamplifier with moving coil cartridge capability.
It had been said that a receiver is only as good as its phono preamplifier, and in fact, the unsophisticated phono circuits found in many receivers are a major reason for their vaguely irritating sound. Not the PLUS 200.
Trademark Dolby Laboratories
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 "human-engineered" 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 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 spec sheets 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 "air."
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.
PLUS 200
POWER AMPLIFIER SECTION
|
Continuous RMS Sine Wave Power per
Channel, Both Channels Oriven from 20 H to 20.000 Hz at no more than stated Total Harmonic Distortion |
2 | |
|---|---|---|
| into 8 ohms |
200 W at
0.009% THD 200 W at 0.009% THD |
|
|
Frequency Response (1 W output,
8 ohms) |
7 Hz-100 kHz; +0,
-1 d8 |
|
| Signal-to-Noise Ratio (IHF-A weighted) | 110 dB | |
| Damping Factor (1 kHz, 8 ohms) | 60 | |
| Transient Response (Slew rate) | 170 volts per micro- | |
PREAMPLIFIER SECTION
| Reference in the second | time along the state of the set o | |
|---|---|---|
| Input Sensi | Svity/Impedance | |
|
Phono (MM)
Phono (MC) Aux, Tape 1, 2 |
2.5 mV/47 k-ohms | |
|
250 µV/100 chms
150 mV/47 k-chms |
||
| Frequency | Response | |
| Phono (RIAA standard curve) | ±0.2 d8 | |
| Aux, Tape | ±0.3 dB | |
| (20 Hz - 20 kHz) | ||
| Signal-to-N | (cise Ratio (IHF-A weighted) | |
| Phono N | (Mr (at 10 mV) | 97 48 |
| 1 | IC (at 250 UV) | 70.08 |
| Aux, Tape | 95 48 | |
| Phone May | kmum Input Capacity | |
| (1 kHz) | N3M | 250 mV RMS |
| MC | 25 mV RMS | |
| Tone Cont | ola | |
| Bass (10 | 00 Hz) | ± 10 dB |
| Midrange (1 kHz) | 1 6 4 8 | |
| Treble ( | 10.0 kHz) | ± 10 3B |
| Bass Turno | over Frequencies | 100/200/400 Hz |
| Treble Turr | nover Frequencies | 2.5/5.0/10.0 kHz |
| Loudness | Control (Vol30 dB) | |
| 100 Hz/10 kHz | *8dB/*3dB | |
| Filters | ||
| Subsonic (30 Hz) | -12 dB/oct. | |
| High (8 kHz) | -6 dB/oct | |
FM TUNER SECTION
| Frequency Range | 88-108 MHz |
|---|---|
| Usable Sensitivity | |
| Mona | 10.3 dBf (1.8 µV) |
| 50 dB Quieting Sensitivity | |
| Mono | 13.5 d8! (2.6 µV) |
| Stereo | 36.3 dB! (36 "V) |
| Total Harmonic Distortion (Narrow/Wie | :0) |
| Mono 100 Hz | 0.15%/0.1% |
| 1 XHz | 0.15%/0.09% |
| 6 kHz | 0.3%/0.15% |
| Stereo 100 Hz | 0 3%/0 15% |
| 1 kHz | 0.2%/0.1% |
| 6 kHz | 0.3%/0.2% |
| Signal-to-Noise Ratio (1 mV anterna | |
| input) | |
| Mono | 83 dB |
| Stereo | 78 cB |
| Frequency Response |
20 Hz - 15,000 Hz
+ 0.5, -1 dB |
| Alternate Channel Selectivity | and the second se |
| at ±400 kHz (Narrow/Wide) | 80 dB/55 dB |
| Capture Ratio (Natrow/Wide) | 1.8 08/1.2 08 |
| AM Suppression Ratio | 60 dB |
| Stereo Separation (Narrow/Wide) | |
| 45 (39/50 (48 | |
| 1 kHz |
AM TUNER SECTION
| Frequency Range | 525-1620 kHz | - ( |
|---|---|---|
|
Usable Sensitivity (Ferrite —
External Antenna) |
280 #V/m-30 #V | |
| Signal-to-Noise Ratio (at 5 mV/m) | 45 08 |
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