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

Pioneer SPEC-4

Pioneer SPEC-4
Stereo Power Amplifier in “DC” Configuration with Independent Left/Right Dual Power Supplies and Circuitry.

Think of the Pioneer SPEC-4 Power Amplifier as two independent mono amps in one chassis. Our stayahead reputation in hi-fi technology is upped another big step here by achieving real independence for the essential circuits in both the left and right channels. Physically separated signal paths and dual power transformers, four big capacitors (two per channel) to prevent power dry-up, separate left-right relays – everything to prevent crosstalk and distortion that erode stereo clarity and tonal quality. Because the SPEC-4 is of Pioneer's new generation of “DC” configuration power amps, its performance is never compromised by capacitors in the negative feedback loop. The results; a continous power output of 150 watts per channel, min. RMS, at 8 ohms from 20 to 20,000 Hz with no more than 0,1% total harmonic distortion.  
Why go for a separate component for power amplification? Pioneer's SPEC-4 clears up that question, and your music, with indisputable proof that separate power amplification is really worth it. Massive power reserve is available throughout the spectrum, including the super-low and ultra-high ends. Pulsive signals – i.e. musical signals – are reproduced with transparency and clarity at all levels, at all times. This high quality is achieved with Pioneer's  stay-ahead technology, as explained below.

the Pioneer SPEC-4 uses the latest ciruitry for power amplification, as follows. The input is formed by a dual PNP transistor differential amplifier , loaded by a current mirror circuit. This is followed by a constant-current-loaded predriver and a 3-stage Darlington connected driver. The final output is in the parallel SEPP (Single Ended Push Pull) configuration. Here are the advantages one by one:
(1)        Dual PNP Differential – Zero DC voltage is constantly maintained at the input.
(2)        Current-Mirror Loading – Reduces the load to the dufferential input to achieve a high gain which, in turn, permits the application of sufficient negative feedback for the effective reduction of distortion. DC stability is also improved.
(3)        3-Stage Driver – Against loads are reduced so that the transistorsin the circuit are called on to operate only at their most linear operating curve. Distortion is reduced and gain is high.

(4)         Parallel SEPP – This output configuration reduces by half the amount of current flowing through the output (power) transistors, again allowing the utilization of only the most linear parts of their operational curves, reducing distortion without sacrificing output.
Better 2-channel performance all around. That's the result of physically separating the left-channel and right-channel power supplies and signal paths. Paired power transformers are employed, one for each channel. The advantages show up in steady-state as well as  dynamic conditions. We've even separated the power relays for the two channels. No matter how complex the signal handled by one channel , the other is always ready to perform independently for more musicl clarity. Think of the SPEC-4 as two independent mono amplifiers housed in one stereo unit, both as perfect as we can make them.

Power dry-up? It takes an acute ear to detect it from most amps when tey are playing ordinary music. But it shows up easily during dynamic stareo passages in rock, classic and other music unless definite measures are taken to prevent it. The Pioneer SPEC-4 takes those measures. Because it operates on a “DC” basis, with no capacitors whatsoever in the negative feedback loop, and because it features a truly dependable power supply formed of two huge power transformers and four 22,000uF filter capacitors, power dry-up is entirely avoided. Your music is reproduced with vivid, full-power lows and natural transients for high resolution.

Impedance plays a vry important role in amplifier design and behavior. High impedance in the grounding and hot lines can result in significant losses of power and increases in distortion. The SPEC-4 avoids this in the following ways:
(1) Pure Copper Grounding -  Low impedance prevents the generation of distortion and safeguards power loss. We've achieved it with the use of pure copper plates, 20 mm wide by 2 mm thick, in the ground path of the dielectric capacitors.
(2)        14-Gauge Cables – Again, low-impedance performance is assured with the use of very thick (2,03 mm or 14 gauge) stranded cables in connecting the power output assembly to the output terminals and throughout significant large current circuits. Reproduction never suffers, even with large current flows are suddenly introduced. These “coat-hanger” cables also permit the dielectric capacitors to charge quickly and efficiently.

(3)        Copper-Foil Circuit Boards -  Conventional printed circuit boards use thin layers of copper foil. Ours use layers twice as thick – 70 u – to further reduce circuit impedance even when large current flows are required.
The logarthmically compressed scales of the twin power-output meters on the front panel of the Pioneer SPEC-4 make it easy to read peak power output in both channels accurately. No sensitivity changing is necessary when large or small output levels are chosen. The large, outer-magnet type meters indicate the full output peaks within 70 milliseconds, aided by an advanced detection circuit for instant-by-instant accuracy. Their direct-readout scales indicate from 0,01 watt to 300 watts.


Also on the froont panel are independent level controls for each channel's input. Optimum input level sensitivity is thus easy to achieve regardless of the output of the connected preamplifier. Each control is an attenuator with 22 stops, calibrated precisely in 1 dB increments from 0 to -20 dB. Gang error and indication error are minimum so that you may adjust inputs delicately and accurately.
The SPEC-4 circuit for speaker and power transistor protection is formed  of a quick-response power relay and a dependable electronic detection stage. Detection of DC components and overload currents is instant, triggering the relay and electrically disconnecting the amplifier from your speakers and its own output stage. The protection circuit also serves as a muting circuit which eliminates click noise otherwise heard when you switch the power on or off we've taken extra steps to protect stereo separation with the use of two independeny relays, one for each channel, with twin contacts in parallel. Surge current, introduced as you switch the power on, never reaches the large power transformer/capacitor block thanks to this extra protection.

Rear Panel Trminal Protection -  Rear terminals are protected from damages with a terminal protector.

Rack-Mounting Ready -  All dimensions/specifications suitable for use in standard EIA equipment racks.
Circuitry:  Current mirror loaded differential amplifier, 3-stage Darlington parallel push-pull, direct-coupled OCL, (DC amplifier construction)
Power Output:  Continuous power output of 150 watts per channel min, at 8 Ω from 20 Hz to 20,000 Hz with no more than 0.01% total harmonic distortion of 180 watts per channel at 4 Ω from 20 Hz to 20,000 Hz with no more than 0.03% total harmonic distortion.
Total Harmonic Distortion (20 to 20,000 Hz, 8 Ω) :
 No more than 0.01% (continuous rated power output)
No more than 0.01 % (75 watts per channel power output)
No more than 0.01 % (1 watt per channel power output)
Intermodulation Distortion (50 Hz : 7,000 Hz = 4:1, 8 Ω )
No more than 0.01 % (continuous rated power output)
No more than 0.005% (75 watts per channel power output)
No more than 0.005% (1 watt per channel power output)
Frequency Response:  5 to 100,000 Hz, +0 dB, -1 dB
Input Sensitivity/Impedance:  1 V/50 K Ω
Output Speaker:  4 to 16 Ω
Damping Factor:  100 (20 to 20,000Hz, 8 Ω )
Hum and Noise:  115 dB (IHF, short-circuited A network)
ICs:  2
Transistors:  61
Diodes:  62
Power Requirements:  110/120/220/240 Volt 50/60 Hz (switchable)
Power Consumption:  760 watts/950 VA
Dimensions (W x H x D):  19” x 17 ¾” x 7”

Weight :  54 lbs unpacked 

Denon DE-70

 Dynamic Sound processor Stereo Graphic Equalizer

Newly developed dnamic sound equalization circuitry with years of experience in the design and production of professional equipment.
Idependent twelve bands control for each channel.
A full array of functions ready for the era of taping.
Highly refined design sophistication.
Built-in an expander function for wide dynamic range.
Frequency Response:  10 Hz - 200 kHz +0, -2,5 dB
Maximum Output Voltage:  8 V
Rated Output Voltage:  1 V
Total Harmonic Distprtion:  0,003%
Input Sensitivity:  1 V
Dynamic Range:  113 dB (1 kHz)
Input Impedance:  40 k Ω
Output Impedance:  800 Ω
Gain:  0 dB ±0,2 dB
Variable Range:  ±12 dB (max)
Center Frequency:  16; 31,5; 63; 125; 250; 500 Hz - 1; 2; 4; 8; 16; 32 kHz
Expander Function:  With On/Off functon, level control and peak indicator
Dynamic Function:  With On/Off function, level control and peak indicator
Power Source:  110, 120, 220, 240 V 50/60 Hz
Power Consumption:  20 W
Dimensions (W x H x D):  432 x 132 x 300 mm
Weight:  6 kg

Product Year:  1983

Denon PMA-710

 Super Equalizer Non-Switching Class-A Integrated Amplifier
Non-switching class-A circuit eliminates switching distortion for improved sound characteristics.
Ultra-wide frequency response from the Super Equalizer: 20 Hz -100 kHz performance with an RIAA deviation of only ±0,5 dB, maximizing the performance of today's cartridges.
Quick response LED's indicator output power from 0 to 40 W.
Clean and functional front panel design.
Rated Output:  40 W + 40 W at 8 Ω
Total Harmonic Distortion:  0,03% (20 Hz - 20 kHz)
Frequency Response:  5 Hz -150 kHz +0, -3 dB
RIAA Devition:  20 Hz - 100 kHz ±0,5 dB
Power Source:  110, 120, 220, 240 V 50/60 Hz
Dimensions (W x H x D):  434 x 97 x 292 mm
Weight:  6,5 kg

Akai AA-1050

 The AA-1050 the top-of-the-line stereo receiver. Part of Akai's new 1000 series of Stereo and Quad components. We believe it's the finest line of receivers, for the money, in the business.
Like all our receivers, the AA-1050 was built with the same commitment to quality that made Akai tape equipment internationally famous.
We feel you won't find another receiver that comes on for the price with better sound or performance. Or better styling. Clean. Brushed aluminum. Beautiful. The strength of Akai. It's in our AA-1050. it's in our 1000 Series. With power output from 14 watts to 80 watts per channel, there's an Akai receiver for you. So you can make your own strong statement.
Amplifier Section
Continuous Power Output:
50 watts per channel, mon.RMS, at 8 Ω from 20 - 20,000 Hz , with no more than 0,15% THD
2 x 60 watts into 8 Ω at 1 kHz with no more than 0,15% THD (both channel driven)
2 x 60 watts into 4 Ω at 1 kHz with no more than 0,15% THD (both channel driven)
Power Bandwidth (IHF):  7 Hz to 70,000 Hz  / 8 Ω (distortion within 0,15%)
Input Sensitivity:
Phono 1 & 2 :  3 mV/ 47 k Ω
Aux :  150 mV/100 k Ω
Tape 1 & 2 :  150 mV/100 k Ω
Signal-to-Noise Ratio (IHF);
Phono :  better than 80 dB
Aux :  better than 90 dB
Channel Separation (IHF): 
Phono :  better than 60 dB (at 1,000 Hz)
Equalizer:  RIAA ±1 dB (Phono)
Tone Control:
Bass :  ±10 dB at 100 Hz
Treble :  ±10 at 10 kHz
Loudness Control:  +10 dB at 100 Hz, +6 dB at 10 kHz (Volume control set at -30 dB position)
High :  -10 dB at 10 kHz
Low :  -8 dB at 50 Hz
FM Tuner Section
Frequency Range:  88 MHz to 108 MHz
Sensitivity (IHF):  1,8 µV
Capture Ratio (IHF):  1,0 dB
Selectivity (IHF):  better than 100 dB at 98 MHz
Signal-to-Noise Ratio:  better than 75 dB
Image Rejection:  better than 95 dB at 98 MHz
IF Rejection:  better than 100 dB at 98 MHz
Spurious Rejection:  better than 90 dB at 98 MHz
Harmonic Distortion:
Monaural :  less than 0,15%
Stereo :  less tha 0,3%
FM Stereo Separation:  better than 40 dB (1,000 Hz)
FM Muting:  Variable (3 µV to 300 µV) / On-Off
Antenna Input:  300 Ω balanced; 75 Ω unbalanced
AM Tuner Section
Frequency Range:  535 kHz to 1605 kHz
Sensitivity (IHF):  180 µV/m (Bar antenna); 8 µV (external antenna)
Image Rejection:  better than 55 dB at 1,000 kHz
IF Rejection:  better than 45 dB at 1,000 kHz
Selectivity (IHF):  better than 30 dB at 1,000 kHz
AM Distortion:  less than 0,6%
Signal-to-Noise Ratio:  better than 50 dB
Semiconductors:  1 FET; 49 Transistors; 25 Diods; 3 Ics
Power Requirement:   120 V at 60 Hz or 220 V at 50 Hz
Dimensions (W x H x D):  480 x 155 x 390 mm (18,9" x 6,1" x 14,4")
Weight :  13,0 kg (28,6 lbs)

Rotel RP-500

 Stereo Semi-Automatic Belt Drive Turntable
This is everything a belt drive turntable should be with a newly developed 4-pole Hystersis synchronous motor, bringing you precise, stable rotation speed and negligible wow and flutter. Whit a highly sensitive straight pipe tonearm and featherlight headshell, the RP-500 offers real value and top performance.
Motor:  4-pole Hystersis Synchronous Motor
Drive:  Belt - Drive system
Speds:  33-1/3 and 45 rpm
Wow and Flutter;  0,05% (JIS WRMS)
Signal-to-Noise ratio:  Better than 55 dB (IEC-B); 65 dB (DIN-B)
Platter:  Aluminum diecast
Diameter:  310 mm
Tone -arm
Type:  Static-balanced straight pipe arm with plug-in headshell, oil damped cueing device, direct-readout stylus gauge counter weight, anti-skating device.
Overhang:  15 mm
Tracking Error:  +2,5 deg. to -1,5 deg.
Suitable Cartridge Weight:  2,5 g to 9 g
Suitable Stylus Pressure:  0,7 g to 3 g
Cartridge 2RC-5 (optional)
Type:  VM (Varible  Magnetic)
Frequency Response:  20 to 25,000 Hz
Channel Separation:  28 dB at 1 kHz
Load Impedance:  47 kohms
Compliance:  6,3 x 10¯⁶ cm/dyne
Stylus Pressure Range:  1,5 to 2,5 g
Suitable Stylus Force:  2,0 g
Stylus Tip:  0,6 mm
Cartridge Weight:  5,5 g
Replacement Stylus Type:  RN-5
Power Requirement:  220/240 V, 50 Hz

Power Consumption:  8 watts

Stax UA-7cf

 Models UA-7 Features:
Type: Multi-use integrated arm with replaceable arm tube
Pickup cartridge acceptable: Magnetic or condenser types
Bearing:  Special dual suspension type (Ultra sensitive jewel bearing and stabilizer utilizing outer race of ball bearing)
Balancing:  Static balancing
Headshell;  U-shaped non-resonant structure compatible with all pickup cartridge design
Arm-lifter:  Oil dumped
Output Cable:  Noiseless low capacitance type of 120 cm long
Height adjustment: 45 - 78 mm between player board and cartridge  mounting surface of head shell.

Rotational Friction:  5 mg or less
Tracking Error:  0,10°/cm or less
Stylus Pressure Adjustment:  3 g/l revolution 0,1g step
Bias Compensation:  1 g - 3 g variable
Weight of Pickup Cartridge:  2 g - 16 g
Overhang:  13 mm
Distance Between Bearing and Turntable centers:  227 mm
Effective Length:  240 mm

Overall length:  340 mm

Pioneer TX-6800

 Pioneer TX-6800
Stereo FM/AM High Fidelity Tuner
Improved Performance-to-Cost Ratio Gives You Lower Tuning Error for Lower Price in This new Pioneer Model.
Clean Audio Output: Flat 20 Hz to 15 kHz +0,5 dB, -1,0 dB.
Extra-Long Tuning Dial with LEDs
Straight-Rule Twin Tuning Meters
Pioneer-Exclusive ICs with Automatic Pilot Canceller.
A Very Clean Audio Output
When designing the TX-6800 stereo FM/AM tuner, Pioneer put sound quality first on the list of objectives. We made sure the audio output is as clean as possible – free of distortion and noise. Our goal was achieved the frequency response reaches from the almost inaudible low of 20 Hz to the upper reaches of your hearing at 15,000 Hz. Plus 0,5 dB, minus 1,0 dB or better. Special ICs developed exclusively for Pioneer are used throughout, wherever it was possible to eliminate bulky discrete parts without harming performance quality. In fact, these special ICs anable us to reduce cost and improve performance quality, not only in this model but in our most expensive tuners and receivers as well.
FM Front-End Section FET Assures High Sensitivity.
Radio-frequency signas entering the tuner via the antenna are passed throughthe front end. It is here that the broadcast signal to which you have tuned on the 3-gang variable capacitor (via the tuning system) is sorted out fromall the others. Pioneer has employeed an FET in this section to see that the signal selected is stripped of noise and distortion, this permits us to step up the sensitivity of the sectionto achieve more “reach”. The usable sensitivity in FM mono, for instance, is a respectable 10,8 dBf (1,9 uV). At the same time, the spurious response ratio is improved to 70 dB.
The FM IF Section The First Pioneer Exclusive IC
A one-stage buffer amplifier and the Pioneer developed IC No. PA-3001A team up here to amplify the IF or Intermediate Frequency. The special advantage of the IC here is low-noise performance; the signal-to-noise ratio obtained is an excellent 80 dB (mono) or 74 dB (stereo).
Phase-Linear Ceramic Filters
Also, in the IF section, a pair of phase linear ceramic filters are put on line amomg the IC and IF amplifier. Without them, the high frequencies in the final audio output would be far less clean and clear. A further advantage is that the ceramic filters offer excellent interference rejection characteristics.
Our New Quadrature Discriminator.
We call this new circuit a One-Pack Phase Shifter because it packs the conventional micro inductor and the discriminator with new bobbin material in one shielded case. The benefits include the following:
Positive protectionagainst distortion
Improvement of input vs. distortion characteristics
reduction of noise for a better S/N
Increased stability against temperature/humidity changes.
 FM Stereo Section
in the multiplex section of the TX-6800, we use a microelectronic integarted circuit (the Pioneer exclusive IC No. PA-1001A) which contains a throughly reliable PLL or Phase-Locked Loop circuit. Unlike the old-fashioned “demodulators” which were subject towide errors in performance depending on outside influences like temperature and humidity, our PLL is entirely error free. Always-stable, very wide stereo separation in FM is the result.
A Built-In Pilot Canceller Circuit.
The multiplex switching signal mentioned erlier is a 19 kHz signal which is broadcast along with the two stereo channels. Its only function is to “trigger” the multiplex section to separate the left and right channels; once that function is done, it must be removed entirely lest it interferes with the audio signals processed in the following sections of the tuner. Old-fashioned tuners used a low-pass filter for removing that “switching signal”, now called the “Pilot”. But such filters tend to “chop off” desired audio frequencies, too. We ve avoided this with the use of a built-in Automatic Pilot Signal Canceller, quite different in concept and operation from the “active filter” type another advantage is an improvement of carrier leakage by 20 dB over conventional types. Also, it should be pointed out that this Automatic Pilot Signal Canceller is incorporated within the PA1001A itself and thus enjoys the same high reliability and protection from outside influences.
 AM Fidelity Is Improved
Better Frequency Response - A high-density IC (HA-1138) is used in the AM section of the Pioneer TX-6800 to contribute greatly to improved frequency response, permitting a flatter, more faithful reproduction over a wider range.
AM Distortion Reduced - The IC likewise serves to reduce the sound- spoiling distortion in AM reproduction especially in the very low frequencies around 100 Hz.
Variable Capacitor - Our use of a 2-gang system in the variable capacitor for AM permits liner tuning and higherlinearity. AM sound you might once have thought to be “lo-fi” is received and reproduced with more pleasant results.

Still More Advantages
Extra Long Tuning Dial - It's unusual to find a tuner in this price range with such a good tuning “feel”. The major contribution to more convenient and accurate station selection in the Tx-6800 is its long (300 mm) tuning dial for AM/FM. The FM band, by the way, is “frequency linear” - divided into equidistant sections.
Srtaight-Rule Meters The Twin Tuning Meters on this model reflect Pioneer's policy of providing maximum readability and impeccable accuracy. The staraight-rule scales of the Signal meter (for AM/FM signal strength) and the Tuning meter (for FM center-of-channel) are calibrated for easy reading and finished in Pioneer blue for eye appeal.
FM Muting Switch - This front-panel feature permits you to cut out inter-station tuning noise while tuning FM stations. in the Off/Mono position the muting circuit is taken off line to permit tuning of distant/weak stations; reception mode is then switched to monophonic.
LED Indicators - These long-life Light Emitting Diodes let you know tuner status for AM, FM and Stereo FM at a glance.
Function Switch - Select FM or Am ; a special back-up circuit prevents pop noise as the switch is used. 
FM Section
Usable Sensitivity:  10,8 dBf (1,9 µV) [Mono]
50 dB Quieting Sensitivity:
Mono :  15 dBf (3,1 µV) / Stereo :  38 dBf (44 µV)
Signal-to-Noise Ratio:
Mono :  80 dB / Stereo :  74 dB
At 100 Hz :  0,1% (mono) / 0,2% (stereo)
At 1 kHz :  0,1% (mono) / 0,2% (stereo)
At 6 kHz :  0,15% (mono) / 0,25% (stereo)
Frequency Response:  20 – 15,000 Hz +0,5 dB, -1,0 dB
Capture Ratio:  1,0 dB
Alternate Channel  Selectivity:  60 dB
Spurious Response Ratio:  70 dB
Image Response Ratio:  60 dB
IF Response Ratio:  80 dB
AM Suppression Ratio:  55 dB
Muting Threshold:  17,2 dBf (4,0 µV)
Stereo Separation:  40 dB (1 kHz) / 35 dB (30 – 15,000 Hz)
Subcarrier Ratio:  50 dB
SCA Rejection Ratio:  50 dB
Antenna Input:  300 Ω  balanced,  75 ohm  unbalanced
AM Section
Sensitivity:  300 µV/m (IHF, ferrite antenna) / 15 µV (IHF, external antenna)
Selectivity:  35 dB
Signal-to-Noise Ratio:  50 dB
Image Response Ratio:  40 dB
IF Response Ratio:  70 dB
Antenna:  Buil-in ferrite loopstic antenna
Semiconductors:  1 FET;  3 ICs;  8 Transistors;  15 Diodes
Power Requirement:  120 -240 V,  50/60 Hz
Power Consumption:  14 watts
Dimensions (W x H x D):  451 x 151 x 284 mm (17-3/4” x 5-15/16” x 11-3/16”)
Weight:  5,3 kg (11 lb 11 oz) net

Pioneer TX-7800

 Pioneer TX-7800 Stereo FM/AM Tuner with Servo-Lock / Touch-Sensor Tuning.
Significant Improvements in Accuracy Fidelity and Convenience
Servo-Lock / Touch-Sensor Tuning – Drift-free performance and ease of use with unique FM station selection system.
Servo Re-Lock Included – Selkected stations is re-locked when you re-the tuner.
Pioneer “Clean Design” - High S/N ratio and low distortion in FM stereo.
Selectable AM IF Bandwidth – You choose Wide or Narrow for better AM sound in any reception situation.
High Sensitivity / Stability – Enjoy true high fidelity performance every time. Sensitivity is a high 9,3 dBf (1,6 uV).

Pioneer's Servo-Lock Tuning for FM
Three  important criteria were included in the design concept drafted by Pioneer for this attractively -priced stereo FM/AM tuner. First was high tuning accuracy – station-pulling capability in any reception circumstances is the least we can offer customers who look to us for state-of-the-art performance. Superior high fideelity tonal quality and improved tuning convenience were also on the list. Our engineers developed the unique Stereo-Lock/Touch Sensor system featured here so that all three demands are fully met. Here's how it works
Touch to Tune, Let Go to Lock
When you tune an FM station, simply follow these easy steps:
Step 1 – Grip the special Touch Sensor tuning knob as you would any other tuning control. The difference here is that the built-in  Servo-Lock circuitry in the Pioneer TX-7800 is turned Off the instant your fingers make contact. As they do, the Locked indicator goes Out.
Step 2 – Tune in the FM station you desire, observing the Twin Tuning Meters and the dial pointer.
Step 3 – Now, remove your fingers from the knob. The Servo-Lock is immediately put back in the On mode and your station is accurately, stably locked in until you intentionally de-tune it for another selection.
To confirm this, observe the green LED in the dial panel. When you are on-station, it lights to indicate Locked status.
By the way, if the station you have tuned in stereo, the Stereo indicator lights in red. It, too, is an LED which can never burn out. And on the rear panel of the TX-7800 is a selector for High or Low sensitivity for the Touch-Sensor itself to accommodate the tuning knob to your particular touch.

How Pioneer's Servo-Lock Ends Drift.
Absolutely no changes of temperature, humidity or other environmental factors can cause the drift or de-tuning of an FM station once you,ve locked it in. this “miracle” of technology is not so difficult to understand when our tuning circuitry is examined in depth, as follows:
first, the signal enters the FM antenna and is passed on to the mixer stage where it meets the output of the local oscillator.. if the station ypu have selected is, say, 100MHz, the local oscillation frequency is 110,7 MHz to meet the 10,7 MHz IF frequency in the next stage. Now lets say the local oscillator frequency drifts +100kHz. The IF frequency will then vary to 10,8 kHz and the results will show up in the output of the discriminator transformer in an “S” mcurve. That difference is rectified into DC voltage, and detected and fedback to the local oscillator through a varicap. Immediatel, the local oscillation frequency is shifted down to resume the correct 10,7 MHz for accurate reception of the selected station , Locked reception.
 The beauty of the system is that it is oolproof. Like the high-precision servo-systems used in computers, it uses error to correcterror – all so fast your ears can detect no error at all.

Automatic Re-Lock System, Too
The accuracy of the Servo-Locksystem in the TX-7800 is unfailing, even when you power-off the tuner. When power is restored, the previously selected station is instantly Re-Locked. Tape buffs will note that this is a definite plus when using the tuner with a pre-set timer clock for unassisted off-the-air recording.

Improvrd Tuning Aids
You'll appreciate the new design of the scales used for the Twin Tuning Meters. We've used s strsight-line format for easier reading, and long-throw needles for more indication margin. The scales are in brilliant blue to match the quick-response fluorescent peak/Average meters on the latest Pioneer tape decks and SA integrated amps. The meter on the left is for Signal strength for FM and AM broadcasts; on the right is the Tuning meter for center-of-channel tuning for FM.

Beautiful Tonal Quality is Assured
Superior high fidelity tonal quality was on our list of design criteria along with tuning accuracy and tuning convenience. We've  found answers to the challenges of providing a high S/N ratio, lower distortion and high stereo separation in the TX-7800 in order to deliver that tonal quality without compromise. Along with these hi-fi musts, our advanced circuitry also provides the high sensitivity, high spurious response ratio, high image response ratio and other specifications requiredfor the elimination of all forms of interference. Tonal quality is optimized under any reception conditions – from too-weak and too-strong stations alike. Audiophiles will be interested in the details, and here they are.

Sophisticated FM Front End with MOS FET
A low-noise, dual-gate type MOS FET is employed in the FM front end of the TX-7800. It has superior cross modulation characteristics that is responsible for the high sensitivity and high interferenc rejection capability in FM reception. Proof is in the specs -9,3 dbF usable sensitivity, 100 dB IF response ratio, 85 dB image response ratio and 95 dB spurious response ratio.
The MOS FET work with an elaborate frequency-linear 4-gang variable capacitor and the above mentioned Servo-Locksystem to assure stable tuning accuracy at all times.

Three Phase-Linear Ceramic Filters in FM IF
Integrated circuitry empoloying the latest microelectronic techniques is very popular among Pioneer engineers for a number of very good reasons. They offer, for instance, higher accuracy and higher dependability than discrete parts in most situations. Not incidentally, lower production costs and a much lower incidence of costly repair are also on the list of advantages offered by ICs.
In the FM IF section of the TX-7800, two high-gain iCs are employed as differential type IF amps. They are deployed with no fewer than three phase-linear ceramic filters to further improve interference rejection characteristics. FM alternate channel selectivity, for example, is an excellent 75 dB.

New Quadrature Discriminator
A Pioneer-developed IC, the PA-3001A which is found only in our best tuners and receivers, takes part in FM detection and IF amplification. But the highlight of the circuitry here is the new Quadrature discriminator transformer with which the PA-3001A works. We call it a “one-pack phase shifter” because it packs the conventional micro inductor an dthe discriminator with new bobbin material in one shielded case.
Benefits include the following:
Positive protection against distortion.
Improvement of input vs. distortion  characteristics.
Reduction of nopise for a better S/N
Increased stability against temperature/humidity changes
 Still Other Pioneer ICs in FM Section
Audiophiles know that Pioneer was among the first to perfect an MPX or stereo FM multiplex demodulator that resists all externbal influences to provide clean, wide stereo separation. This means the stereo images in the reproduced sound field never waver or blur, never leave you in doubt if the station you are hearing is stereo or mono. In specific terms, the stereo separation in the TX-7800 is a full 50 dB at 1 khz. Frequency response is in no way compromised to achieve wide separation, by the way. It remains 20 to 15,000 Hz +0,2 dB, -0,5 dB at all times.
The Pioneer-exclusive IC no. PA-1001A encapsulates our PLL MPX together with a built-in Automatic Pilot Signal Canceller system to ensure that the stereo FM switching signal does its intended job with no problems. Also included is a new independent left/right-channel MPX Lowpass Filter; since the filter sections are independent for each channel, mutual interference is remarkably reduced. The Pioneer PA-1002A, still another exclusive IC, is found in the audio amp and FM muting section. Higher accuracy and better musicality are again the benefits.

A new AM broadcastsing channel plan has been put into effect worlwide. It reduces the conventional interval between AM stations from 10 kHz to 9 kHz, a fact we expect to increase AM noise and interference still more. We took this into consideration when we built the TX-7800 and included a selectable Wide/Narrow IF bandwidth for the AM section.
A wide band LC filter is put on line when you switch to Wide band AM. This reduces distortion to suit the higher sensitivity of the tuner when receiving AM signals of normal strength; this, in turn, means a wider effective frequency range and cleaner reproduction. When the station you want is weak or distant, switch to Narrow. Here a precision ceramic filter is added to the circuit to cut out all sorts of interference. You can easily hear the differences .
A tip: the movement of the signal meter is related to the characteristics of the Wide/Narrow selectivity of AM. When you tune in strong-signal stations we recommend that you use the Narrow mode for pinpoint selection, then switch to Wide to enjoy better sound quality.

AM Circuitry Aims at Hi-Fi Quality.
No one can rigtly claim that AM is truly hi-fi in the conventional sense of the term. But Pioneer engineers have tackled distortion, noise and frequency esponse factors to make AM as “hi-fi like” as possible. An IC with superior characteristics in lowering low-frequency distortion is used in the RF amp and AM detection stage. After detection, the signal is sent to two Pioneer exclusive ICs for amplification.  With the Wide/Narrow facility described above, this elaborate circuitry does make AM listening more enjoyable by eliminating booms, whines and whistles for a cleaner sound.

Still More Advantages.
Output Level Control – Front panel control to adjust output level.
Twin Outputs – Two sets of stereo output terminals are provided. One has a fixed output, use it for connection with your amplifier. The other has variable output ( with output control), use it for direct connection to tape deck, etc.
MPX Noise Filter – Front panel switch to cancel stray noise from FM carrier when taping.
FM Muting /Mode – In the Off position the Servo-LockFM Tuning system is out of ciruit.
LED Indicators/Index Markers – Further aids to fast and accurate tuning. The lights for Stereo and Locked (red and green) can never burn out. The index markers slide to your favorite stations for convenient re-tuning.
FM De-Emphasis – Rear panel switch for selectable de-emphasis.
FM Multipath Outputs – Horizontal and vertical
Click Noise Canceller – All function switches backed by clik-noise canceller circuit for silent operation.
Versatile Styling -  Straightforward looks and diamond cut dial scale finish increase appeal. Styling is coordinated with other new products from Pioneer.
FM Section
Usable Sensitivity:  9,3 dBf (1,6 µV) [Mono]
50 dB Quieting Sensitivity:
Mono :  15,5 dBf (3,3 µV) / Stereo :  37,1 dBf (39,2 µV)
Signal-to-Noise Ratio (at 85 dBf):
Mono :  83 dB / Stereo :  79 dB
Distortion (at 85 dBf):
At 100 Hz :  0,08% (mono) / 0,1% (stereo)
At 1 kHz :  0,05% (mono) / 0,08% (stereo)
At 10 kHz :  0,06% (mono) / 0,3% (stereo)
Frequency Response:  20 – 15,000 Hz +0,2 dB, -0,5 dB
Capture ratio:  1,0 dB
Alternate hannel Selectivity:  75 dB
Spurious Response Ratio:  95 dB
Image Response Ratio:  85 dB
IF Response Ratio:  100 dB
AM Suppression Ratio:  65 dB
Muting Threshold:  19,2 dBf (5,0 µV)
Stereo Separation:  50 dB (1 kHz) / 35 dB (20 – 10,000 Hz)
Subcarrier Ratio:  70 dB
Multipath Jacks:  Vertical and Horizontal
De-Emphasis Switch :  25 µS - 75 µS (switchable)
Antenna Input:  300 Ω  balanced, 75 Ω  unbalanced
AM Section
Sensitivity:  300 µV/m (IHF, ferrite antenna) / 15 µV(IHF, external antenna)
Selectivity [Wide/Narrow]:  15 dB / 50 dB
Signal-to-Noise Ratio:  50 dB
Image Response Ratio:  45 dB
IF Response Ratio:  50 dB
Antenna:  Buil-in ferrite loopstic antenna
Audio Section
Output Level/Impedance:
Fixed :  650 mV (FM), 200 mV (AM) / 4,2 k Ω
Variable :  0 mV to 1,3 V (FM), 0 mV to 400 mV (AM) / 3,6 k Ω
FM (100% Mod)
AM (30% Mod)
Semiconductors: 2 FET; 7 ICs; 11 Transistors; 30 Diodes
Power Requirement:   110 -240 V 50/60 Hz
Power Consumption:  23 watts
Dimensions (W x H x D):  420 x 150 x 390 mm (16-9/16” x 5-7/8” x 15-3/8”)
Weight:  7,5 kg (16 lb  9 oz) net

Pioneer CS-R500

With the new R-series, Pioneer introduces a new concept in speaker system design: the individualistic speaker. Even at the first glance, these speakers look different, with their two-part front grilles and powerful-looking, massive enclosures. But connect a pair of Pioneer R-series speakers to a good stereo amplifier, play a pro$am of rock, jazz or folk music, and you'll realize that these speakers are different. We've designed them with the emphasis on impact and richness rather than on laboratory data.
That's what makes Pioneer R-series speakers so ideally suited for modern music while also lending a new feel to the classical repertoire.

Compared with conventional designs, Pioneer R-series speakers sound somewhat brighter and at the same time richer. This effect was achieved by a carefully selected and tested combination of numerous factors: selection of special material for the woofer cone, balancing of the different speaker units, selection of crossover network constants, adoption of the bass reflex principle in the enclosure - without, however, causing that notorious "boominess" of bass reflex constructions.
In a bass reflex system (in which the sound waves from the rear side of the woofer are reflected, reversed in phase and radiated to the front through a special port), careful selection and balancing of the speaker units and of numerous other design parameters is extraordinarily important. In the Pioneer R-series, a partition of sound absorbing material is provided in the enclosure, preventing mutual interference of the speaker units and avoiding "standing waves." This and the careful dimensioning of the port lends these speaker systems their crisp bass response. What seemed to be impossible has been realized: speaker sound that is momentous without being boomy, modern without being untrue to the original.

The CS-R500 is equipped with continuous level controls for the MID and HIGH sound ranges. To adjust these, first set the tone controls on the amplifier to their center ("flat") positions and turn high and low noise filters off. Then play a familiar tape or record and adjust the two level controls on the speakers so that you obtain the most pleasing sound. Rotation toward MIN decreases response in the particular sound range, rotation toward MAX increases it.

25 cm Cone-type Woofer
Use of newly developed FB cone paper improves frequency response and gives the woofer its excellent transient characteristics. The cone surface is especially coated over to avoid partial vibrations, thereby resulting in vastly improving transient characteristics and tonal qualify.
The woofer edge is made of soft polyurethane foam which prevents distortions due to edge resonances and improves stability under various temperature and humidity conditions.
To permit high power input and to avoid distortions caused by transient bass impulses, a long-throw voice coil and an aluminu m sheet bobbin are used.
A large 12cm ferrite magnet with a pure copper cap on its center pole suppresses harmonic distortions, however little, in the middle range.

12 cm Cone-type Mid-range Speaker
The mid-range speaker, too, employs a cone made of special FB paper with its extra strong magnet, its newly adopted center cap combined with rigid duralumin and damper, and its hermetically sealed back chamber. Therefore, this speaker lends itself to superb reproduction of the all-important mid sound range with excellent response and freedom from distortions.

Horn Tweeter
The diaphragm is made of a special polyester-type synthetic resin with excellent stability against changes in temperature and humidity, and is vapor-coated with aluminum. Together with the aluminum diecast horn, this construction explains the very flat frequency response up to an ultra-high range and the wide sound dispersion angle. The high and very high sound range has impact and presence from any listening position.

Design provides for optimum speaker system frequency response. Stringent component selection and use of a compensating circuit designed to limit woofer and mid range impedances guarantee ideal transmission characteristics around the crossover point, as well as good transient characteristics.
Enclosure:  Bass-reflex type
System:  3-way, 3-speaker system
Woofer :  250 mm (10-inch) cone type
Midrange :  120mm (5-inch) cone type
Tweeter :  Horn type
Frequency Range:  35 to 20,000 Hz
Input Impedance:  8 Ω
Sensitivity:  91 dB/W at 1 m
Max.Input Power:  60 W
Crossover Frequencies:
Lows - Midrange :  650 Hz
Midrange - Highs :  6,000 Hz
Dimensions (W x H x D):  350 x 610 x 306 mm (13-25/32" x 24" x 12-1/32")
Weight:  18,5 kg (40 lb 13 oz)