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 QX-4000

 A new four-channel stereo receiver capable of decoding all kind of matrixed program sources into a living presence sound field.
A tremendous 4-channel receiver value, the QX-4000 features a liner type FM dial scale, an extra-large signal meters for precise FM tuning, and is equipped with Pioneer's Matrix Decoding circuitry for capability of decoding any kind of matrix 4-channel program sources, including the QS sources. Output power of up to 108 watts is more than enough to fill a conventional sized listening room with full-bodied distortio-free sound. The unit can also be used asa conventional 2-channel receiver, in addition to discrete 4-channel reproduction.
 You thought the excitementof four-channel sound was beyond your budget? Think again. With the new QX-4000, Pioneer is happy to introduce economically-priced 4-channel to the merketplace. But it's not the kind of 4-channel receiver that performs of looks inexpensive. To the contrary, the QX-4000 offers all the important performance features of Pionner's larger, more expensive receivers. Things like sensitive AM/FM reception. Two kinds of matrix decoders for reproduction of all the important matrix encoded sound sources available today, including popular SQ sound. A linear type FM dial scale and extra-large signal strength meter for precise tuning. And power, too, up to 10 watts x 4 at 8 ohms with all four channels driven simultaneously. So if you don't think you can afford 4-channel today. Pioneer asks you to stop and consider the QX-4000, authentic four-channel sound on a two channel budget.
FM Usable Sensitivity(IHF):  2,2 µV
FM Selectivity (IHF):  more than 40 dB
Music Power (IHF):  108 watts at 4 Ω; 80 watts at 8 Ω
Continuous Power at 4-CH Driven:  10 watts x 4 at 8 Ω
Harmonic Distortion:  less than 1%
Power Bandwidth (IHF):  15 to 20,000 Hz (8 Ω, 4-Ch driven, less than 1% THD)
Dimensions (W x H x D):  17-3/4" x 5-11/16" x 13-3/4"

Weight:  22 lb, 4 oz

Kenwood KA-3344

 The rich, treasure-laden sound of 4-channel stereo is a listening treat you should not miss. Kenwood's KA-3344 multi-purpose amplifier makes 4-channel reproduction all yours in an easy-to-operate instrument. That's beacuse the KA-3344 is especially-designed to reproduce all 4-channel sources-discrete type,matrix type and quasi-4-channel program sources. Rear channel speaker systems are driven by the stereo main-amplifier. Still another receiver or pre-main amplifier controls front channel speaker systems. Built-in encoder circuitry helps to reprint matrix 4-channel tape from discrete 4-channel tape. Booming, ultra-sensitive 4-channel effects are then reproduced through Kenwood-sophisticated decoder circuitry. Throughout, the ultimate in all-purpose amplifier uses.
 Special Features
4-Channel Reproduction
The KA-3344 includes the newly developed Kenwood method 4-channel matrix circuitry and stereo main amplifier. By adding KA-3344 and a pair of speaker system for rear channel to the ordinary stereo system, the surround sonic 4-channel reproduction is perfectly enjoyable from all kinds of program sources - the encorded 2-channel sources, the ordinary 2-channel sources and of course discrete type 4-channel sources.

2-Channel Tape from 4-Channel Tape
The built-in encorder circuitry enables to reprint matrix 4-channel (usable as an ordinary 2-channel too) tape from discrete type 4-channel tape. It can be reproduced with satisfactory 4-channel effect through KA-3344's decorder circuitry.

Sound Illumination
By the exclusive Color Sound System, the sound performance can be monitored and enjoyed through the illuminating color varieties. The whole frequency range is electronically divided into 3 parts and is lighted colorfully. The suitable operating point can be settled by the Level Control attached, and can be cancelled when it is unnecessary.
Dynamic Power Output (IHF):
30 W at 4 ohms
26 W at 8 ohms
Continuous Power Output (each channel driven):
11 W - 11 W at 4 ohms
10 W - 10 W at 8 ohms
Harmonic Distortion:
At rated output :   less than 0,8%
At -3 dB rated output :  less than 0,2%
Intermodulation Distortion:  less than 0,8% at rated output
Frequency Response:
(IDS) : fo - 30 kHz ±2 dB
4 CH :  25 - 30 kHz ±2 dB
Power Bandwidth:  40 - 20 kHz ±2 dB
Input Sensitivity (for rated output):  100 mV
Low Output (IDS):  80 mV
Recording Output:  100 mV
Hum and Noise:  less than 1 mV
Damping Factor:  50 at 8 Ω
Speaker Impedance:  4 to 16 Ω
Bass Control:  +_8 dB at 100 Hz
Treble Control:  ±8 dB at 10 kHz
Loudness Control (at -30 dB):  8 dB ±3 dB at 100 Hz
Crossover Frequency:  400; 800; 5,000 Hz
Power requirement:  110/117 V, 220/240 V, 50/60 Hz
Power Consumption:  80 W (at full power)
Dimensions (W x H x D):  16 ¼" x 4 ¾" 12"

Weight:  16,5 lbs

Teac CD-3

 Center-Mounted Mechanism
The CD drive mechanism is mounted in the front center of the unit, providing ideal chassis balance and stability. In the CD-3, the large power supply transformer is positioned in the rear center, and the digital and analog blocks are on opposite sides, preventing any interference from degrading sonic purity.

High-Precision 1-Bit Bitstream D/A Conversion
Bitstream Conversion is the latest advance in 1-bit D/A conversion technology. It converts the original 16-bit music data to a high-speed 1-bit data stream, which is then converted into analog signals by the high-performance 1-bit DAC. This 1-bit processing eliminates the main source of non-linearity and distortion, resulting in exceptionally transparent music reproduction, especially of delicate, low-level signals.
The CD-3 also employ a 20-bit 8-times oversampling digital filter. This  sophisticated filter stage eliminates left and right channel interference and even-order high harmonics while maximizing signal-to-noise ratio for incredibly clear sound reproduction.
 CN Servo
Servo feedback is a possible cause of signal noise, which is why these players are designed to require a minimum of servo correction. To protect against any residual interference, they are equipped with Teac's exclusive CN (clean Noise) servo system. It uses a low-pass filter to eliminate potentially de-stabilizing elements from the servo signal, and also helps minimize vibrations in the optical assembly.

Track Focus Holding System (T.F.H.S.)
Teac's unique T.F.H.S. prevents tracking slips and increases stability. Even if the disc surface is scratched or dirty, T.F.H.S. will read tracking and focus error signals accurately while the pickup holds those signals directly in front of the dirty or defective area. As soon as it is passed, the laser continues reading the same track. The result is fewer errors for more accurate music reproduction.
 Other Important CD-3 Features
Multi-function reomte control unit.
High-speed search keys.
20-selection random and delete programming.
4-way repeat function (One/All/Program/A-B Block)
Index search.
Auto space.
Program pause.
Numerical display (Total/Playing/Program/Index).
Time display (Each/Total Remaining/Each Remaining)
RCA Coaxial Digital and  analog outputs
Channels:  two
D/A Conventer [Type/Number]:  Bitstream Conversion / 4
Digital Filter [Type/Oversampling]:  20-bit / 8x
Analog Filter [Type/Order]:  Butterworth / 3rd
Frequency Response:  1 Hz - 20 kHz (±0,5 dB)
Signal-to-Noise Ratio:  104 dB (1 kHz)
Dynamic Range:  97 dB (1 kHz)
Harmonic Distortion:  0,0022% (1 kHz)
Wow and Flutter:  Unmeasurable (Quartz accuracy)
Channel Separation:  102 dB (1 kHz)
Analog Output:  1,7 Vrms
Digital Output:  0,5 Vp-p / 75 ohms
Dimensions (W x H x D):  447 x 124 x 276 mm

Weight:  3,8 kg net

Rogers Export Monitor

 The Rogers Export Monitor meets the demands of thousands of enthusiasts that have pleaded for an LS3/6 loudspeaker with increased power handling. Based on design expertise acquired from five years of manufacture of the Rogers BBC LS3/6 Studio Monitor, this three unit system offers a standard of performance which makes it a class leader and power handling more than adequate for domestic use. The BBC LS3/6 has enjoyed an enviable reputation both home and abroad and has come to be regarded as a standard by which others are judged. The need for higher power handling, especially for the export markets has been researched exhaustively with a refusal to accept deterioration in sound quality. The Export Monitor has been received with enthusiasm worldwide and shows a remarkable lack of colouration, with very low harmonic and intermodulation distortion.

The Rogers Monitor pioneer units in Bextrene Cone Technology, are the result of many years research by the British broadcasting Corporation into loudspeaker cone behaviour.

Available in Teak or walnut veneer finish as standard with black grillecloth. De-luxe castor trolleys are available which provide correct positioning relative to the floor, whilst allowing easily manoevorability for cleaning or listener position change.
Originally intended for monitoring purposes in the smaller studio, this loudspeaker will give superlative reproduction in domestic high fidelity installations, where the associated equipment is of a sufficiently high standard.
The superb bass response is not dependent on corner location and the speaker is best set away from wall and corners, so avoiding too much excitation of room resonances. Due to the efficient and exxtended treble response of the speaker a slight amount of filtering may prove beneficial an all but the very best programme material. For this reason an amplifier with a good low pass filter should be used.
The nominal power handling capacity of the loudspeker is 35 watts speech and music. This power level is entirely adequate for all normal domestic applications and is also satisfactory for the small studio.
The main drive unit used in the system is specially constructed and the performance carefully evaluated for each loudspeaker. The special plastic cone and surround material employed ensures a uniform response, any slight residual colouration being minimised by individual doping of the cone, a process carried out by hand by a skilled craftsman.
The tweeter units are specially selected and all must meet a rigid pass specification. Matching of bass unit and tweeter unit efficiencies is controlled by a low loss autotransformer with 1 dB tappings.
A sophisticated crossover uses close-tolerance inductors and stable low-loss capacitors for lifelong stability of operation. The enclosure is made from selected woods, which in conjunction with special internal damping materials,  avoids resonance and colouration.
The standard finish is teak or walnut veneer.

All Rogers Export Monitor Loudspekaers are individually measured on Bruel and Kiser automatic curve tracking equipment, installed in our own anechoic building at Catford. Each speaker is carefully adjusted to meet a rigid specification and an individual response curve graph taken.
After frequency response tests have been carried out the final performance of each individual speaker is  compared to a Reference Standard BBC LS3/6 Loudspeaker on pink noise and master tapes of the highest quality.
Enclosure Type:  3-way, bass reflex
Overall Frequency Response:  40 - 25,000 Hz;  40 - 14,000 Hz ±3 dB
Power handling capacity:  35 watts, speech and music
Impedance:  suitable for 8 - 16 Ω matching amplifiers
Drive Units:  3
Dimensions (W x D x H):  305 x 305 x 635 mm (12" x 12" x 25")
Weight:  15,5 kg (34 lbs) net

Finish:  Teak or Walnut veneer with black grillecloth

Hitachi HA-3500 (1979)

 Hitachi HA-3500 Stereo Integrated Amplifier (1979)
Low-distortion power amplifier
Power level meters for output power readout
Connection facilities for two pairs of speakers
New ICs in the Equalizer and pre-amplifier
Subsonic filter that cuts out rumble and wow in the ultra-low frequencies without impairing the sound quality
LED program source indicators
Power Output:
30 watts per channel, (min. RMS, at 8 Ω from 20-20,000 Hz, with no more than 0,05% THD)
33 + 33 W/channel (both channels driven into 8 Ω, 20-20,000 Hz, 0,05% THD)
36 + 36 W/channel (8 Ω, 1 kHz, 0,05% THD)
38 + 38 W/channel (4 Ω, 1 kHz, 0,15% THD)
Power Bandwidth:  10 Hz - 50 kHz
Frequency Characteristics:
Tuner, Tape 1, 2:  10 Hz - 40 kHz (+0,5 -1,5 dB)
Phono :  RIAA ±0,3 dB
Total Harmonic Distortion:
Less than 0,05% at rated output
Less than 0,03% at ½ rated output
Intermodulation Distortion:  less than 0,03% (at ½ rated output)
Input Sensitivity/Impedance:
Phono :  2,5 mv / 47 k Ω
Tuner :  150 mv / 33 k Ω
Tape 1, 2 :  150 mV / 33 k Ω
Output level:
Tape Out :  150 mV
Phono Overload Level (at 1 kHz, 0,05% THD):  200 mV
Signal-to-Noise Ratio (IHF a network):
Phono :  75 dB
Tuner, Tape 1,2 :  90 dB
Damping Factor:  30 (1 kHz , 8 Ω)
Bass Control:  ±10 dB at 100 Hz
Treble Control:  ±10 dB at 10 kHz
Loudness Control:  +9 dB at 100 Hz; +4 dB at 10 kHz
Subsonic Filter:  20 Hz (-12 dB/oct)
Semiconductors:  4 ICs, 24 transistors, 18 diodes (2 LEDs)
Power Supply:  AC 120 V 60 Hz; 220 V 50/60 Hz; 240 V 50/60 Hz; 120/220/240 V 50/60 Hz
Power Consumption:  160 W (at rated output) 240 W (at rated output)
Dimensions (W x H x D):  435 x 110 x 275 mm

Weight:  6 kg

Hitachi FT-3500 (1981)

 Hitachi FT-3500 AM/FM Stereo Tuner (1981)
Circuitry:  AM/FM 2-band Stereo Tuner
Semiconductors:  3 ICs; 12 transistors (1 FET); 10 diodes (2LEDs)
FM Section
Frequency Range:  88 - 108 MHz
Usable Sensitivity:  10,8 dBf (IHF), 1,0 µV (75 Ω DIN)
Image Interference Ratio:  50 dB (98 MHz; IHF and DIN)
IF Interference Ratio:  80 dB (98 MHz, IHF and DIN)
Total Harmonic Distortion:
Mono :  0,1% (1 kHz)
Stereo :  0,25% (1khz)
Signal-to-Noise Ratio:
Mono :  77 dB (IHF) 70 dB (DIN)
Stereo :  70 dB (IHF) 64 dB (DIN)
Frequency Response:  30 Hz - 12 kHz (75 µs ±2,0 dB)
Selectivity:  50 dB  (±400 kHz, IHF), (±300 kHz, DIN)
Stereo Separation:  45 dB (1 kHz IHF and DIN)
Capture Ratio:  1,0 dB (IHF and DIN B.P.F. 1 kHz)
AM Suppression Ratio:  50 dB (IHF and DIN)
Output Voltage:  550 mV (400 Hz, 75 Hz deviation)
Antenna Terminal:  300 Ω balanced and 75 Ω unbalanced
AM Section
Frequancy Range:  530 - 1605 kHz
Sensitivity:  15 µV (IHF), 40 µV (DIN); 400 µV/m (IHF loop antenna)
Image Interference Ratio:  50 dB (IHF and DIN)
IF Interference Ratio:  40 dB (IHF and DIN)
Selectivity:  34 dB (±10 kHz, IHF); 30 dB (±9 kHz, DIN)
Signal-to-Noise Ratio:  53 dB (IHF and DIN)
Output Voltage:  165 mV 9400 Hz, 30% modulation)
Power requirements:  AC 110-120 V, 220-240 V 50/60 Hz
Power Consumption:  6 watts
Dimensions (W x H x D):  435 x 83 x 253 mm (17-1/8" x 3-1/4' x 9-61/64")

Weight:  3,4 kg (7,5 lbs)

Lowther PM6

 PM6 Drive Unit for use with Acousta Enclosures
The PM6 is an 8 inch twin cone unit of similar design to the PM3, plastic foam suspension, aluminum voice coil and a modified form of Stabilizer being used in the construction.
 The magnetic structure, lathough not as large as on the PM3, nevertheless produces a gap flux of 17,500 gauss - well above comparable units. All the benefits attendant with such a large magnetic field are derived - minimum transient distortion - greater efficiency - improved high frequency response. The PM6 has been designed for use in enclosures which provide direct high and mid-frequency rediation and produce the necessary rear loading in the bass range. Mounted in such an enclosure the full capabilities of this drive unit will be realized, ensuring smooth extended bass reproduction free of "boom" and " one not bass", while in the upper range, reproduction will be well balanced and crisp-yet not tiring.
The performance of the Acousta  - or any similar enclosure - will be greatly enhanced when used with the PM6 drive unit,

Due to the high order of efficiency of the PM6, fusing is recommended in order to prevent damage resulting from overloading of the unit.
Frequency Range:  20 - 18,000 Hz
Gap Flux:  17,500 gauss
Power rating:  25 Watts (Integrated program material)
Impedance:  16 Ω
Dimensions:  8½" (High) x  8" (Wide) x 5" (Deep)
Weight:  6,5 lbs

Lowther Acousta (1960)

 This extremely well designed enclosure is engineered to complement the Lowther PM6 Drive Unit, providing a performance throughout the audible range that is quite outstanding.
The Acousta employs a folded horn, or exponential labyrinth, which operates from the rear of the drive unit. This structure produces the necessary diaphragm loading at the resonant point of the loudspeaker and provides a reinforcement of the frequencies in the bass range, resulting in a smoother and extended bass response with negligible distortion. The high and mid-range frequencies are obtained by direct radiation from the front of the loudspeaker.
 The Acousta enclosure, moderate in size and price, is ideally suited for contemporary living - without in any way sacrificing performance. Two of these enclosures for stereo reproduction provide a realism in sound that must be heard to be believed. They are offered in both a De Luxe and Standard form.  Standard finishes available are walnut and mahogany. Workmanship throughout is executed by skilled craftsmen, thus ensuring that both performance and appearance are of the highest order. The Acousta is also offered in kit form, allowing the builder to enjoy all the superior performance of this enclosure at a great saving in cost.

Acousta Standard
Dimensions (W x H x D):  18-5/8"x 34" x 16-1/2"
Weight:  50 lbs net
Acousta De Luxe
Dimensions (W x H x D):  21" x 34" x 17-1/2"

Weight:  50 lbs net

Yamaha A-550

 The Latest Technology for the Best In Sound and Convenience
The Yamaha A-550 is a top-performance integrated amplifier offering the very latest in sound reproduction technology. The preamp section is constructrd with the lowest noise components and design for the cleanest possible reproduction with an absolute minimum of distortion. Whether your input is phono, tuner or tape, every delicate musical detail is brought to you with stunning accuracy.
The power amplifier is a pure complementary SEPP (Single Ended Push-Pull) design with current mirror circuitry and a bipolar power supply for exceptionally stable, accurate reproduction under even the most demanding conditions.
Direct coupled circuitry and an OCL (Output Capacitor Less) output stage assure that the signal sent to your speakers is as close as possible to a perfect image of the original input signal.
The A-550 specifications alone cannot give you an accurate idea of its superb sound quality, but your ears will certainly hear the difference. For convenience, the A-550 front panel is arranged so you can start up your system to monitor any input source by pressing just two buttons: power and the Input Select button of your choice. The Power and Input Select buttons are easy-handling illuminated types that show you the amp's operating mode at a glance.
The A-550 also offers fully independent recording and listening: a feature that lets you listen to any input source while recording from any other. There's even a convenient tape monitor/copy function that makes recording and dubbing continuously variable loudness control ensures that you get proper perspective tonal balance at any listening level.

For top-quality sound and convenience the A-550 is hard to beat. And its surprising affordability makes it a best buy.
 Ultra-Low-Distortion Design
In any sound system, distortion is the most detrimental element to accurate reproduction. The more distortion is present, the more the shape of the original music waveform will be altered, resulting in only a vague representation of the actual sound. And, of course, any distortion that appears at your speakers is the sum of all the distortion levels throughout your system. One weak link in the chain can make your expensive system sound like a bargain basement special.

The A-550, however, offers exceptionally low distortion throughout every stage - phono equalizer, preamp, tone control, and power amp - from input to output. Total harmonic distortion is no more than 0,02% at full power, from 20 Hz to 20 kHz. So no matter how hard you drive it, the A-550 delivers super clean, accurate sound.
 To maintain the A-550's superb 0,02% distortion figure even at full 40 watts per channel output, the power amp section is an advanced direct coupled OCL design with pure complementary SEPP, current mirror and bipolar power supply circuitry. There are no capacitors in the signal path to cause phase shift and distortion of the music waveform. And transient response is exceptionally fast so the sound is always crisp.

Since the cartridge output signal is so small, any noise present in this critical stage will be amplified many times before reaching your speakers. The A-500 phono equalizer provides the outstanding signal-to-noise ratio of 98 dB (IHF A Network). And since only the highest quality components are used in the RIAA equalization network, frequency response is ruler flat. This kind of superior equalizer performance lets you take full advantage of the high signal-to-noise ratio and extended frequency response of the latest direct-cut and PCM recorded discs.

Independent Recording and Listening
With most preamps and integrated amplifiers, when you record a source, or dub from deck to deck, you're stuck with the source you're recording or dubbing, i.e. you can't listen to anything else. Not so with the A-550. yamaha's original Rec Out selector lets you send any source to your tape deck while you listen to any other selected by the Input Select buttons. You can tape a friend's record while listening to your favorite FM program, dub tapes from deck to deck while listening to a record, or any other convenient combination.
 Built-in Subsonic Filter
High-level low frequencies generated by warped records or other sources can cause damge to your speaker system and sap vital power from the power amplifier. To eliminate this potential proble, the A-550 features a built-in subsonic filter that sharply cuts out these damaging frequencies without affecting overall sound quality.

Power Protection / Muting Circuitry
Since the A-550 power amplifier section can accurately handle signals virtually down to DC, a special power protection circuit has been incorporated which shuts down the output stage and speakers if any potentially damaging DC leakage is sensed at the output. This circuit also functions to prevent damage to speakers and the output stage due to the power shock surge that occurs when the unit is switched on.
Minimum Output Power (Continuous RMS Power per Channel):
40 W at 8 Ω, 20 - 20,000 Hz (IHF)
45 W at 4 Ω, 20 - 20,000 Hz (IHF)
53 W at 8 Ω, 1 kHz (DIN)
Total Harmonic Distortion:
Phono to Rec Out (3 V, 20 - 20,000 Hz) :  less than 0,005%
Tuner to Sp Out (20 W, 20 - 20,000 Hz) :  less than 0,01%
Intermodulation Distortion:
Tuner to Sp Out (8 Ω, 20 W, 60 Hz : 7 kHz = 4:1):  less than 0,005%
Power Bandwidth (8 Ω, 20 W, 0,05% THD):  10 Hz to 70 kHz
Damping Factor:  over 50 (8 Ω, 1 kHz)
Frequency Response:
Tuner, Aux, Tape 1 & 2 to Sp Out:  4 Hz to 70 kHz (+0 -2 dB)
RIAA Deviation:  40 Hz to 20 kHz (±0,2 dB)
Input Sensitivity/Impedance:
Phono :  2,5 mV/47 k Ω (220 pF)
Tuner, Aux, Tape 1 & 2 :  150 mV/47 k Ω
Maximum Input level:
Phono (1 kHz, 0,005% THD) :  over 200 mV
Tone Control Characteristics:
Bass (500 Hz) :  ±10 dB at 20 Hz
Treble (3 kHz) :  ±10 dB at 20 kHz
Output Sensitivity/Impedance:
Rec Out :  150 mV/600 Ω
Signal-to-Noise Ratio (IHF A network/New IHF):
Phono :  better than 98 dB (10 mV)/69 dB
Tuner, Aux, Tape 1 & 2 :  better than 104 dB / 83 dB
Residual Noise (volume minimum):  120 µV
Channel Separation (1 kHz):
Tuner to Sp Out (Input 5,1 k Ω) :  better than 65 dB
NDCR, phono to Sp Out:
IHF-A network, 0,1% distortion, vol at -20 dB:  12 mW to 40 W
Headphone Output:  50 mW (8 Ω, rated output)
Power Supplies:  models available for all supply voltages and frequencies
Power Consumption:
U.S.A. and Canada :  240 W, 310 VA
Australia and Britain :  290 W
Germany :  260 W
Other Areas :  240 W
Dimensions (W x H x D):  435 x 112 x 338 mm (17-1/8" x 4-1/2" x 13-1/4")

Weight:  7,8 kg (17 lb 2 oz)

Yamaha K-550

 Natural Sound Stereo Cassette Deck
Yamaha Low-Impedance Pure Sendust Rec/Play Head
Unique, High-Performance Two-Motor Transport
Metal Tape Compatibility
Direct Tape-Loading with Flip-Up Mechanism Cover
Direct Mode-to-Mode Switching and Full Auto Shutoff
Several specialized technologies in which Yamaha offers the highest degree of expertise, in combination with absolute mechanical precision attainable only through painstaking research and design.
Naturally, the K-550 also offers plently of convenience and control features to  make high-fidelity cassette recording and listening easy and enjoyable - you can even add an optional remote control unit for easy-chair transport control comfort.
With the Yamaha K-550 you're assured of unparalleled sound reproduction quality, unfaltering reliability and extended durability based on uncompromising engineering precision plus a total dedication to providing only the most natural, accurate music reproduction.

Advanced Head Design
Pure Sendust - Pure Sound
Yamaha's extensive research into the effects of various head materials on record/playback characteristics has revealed that the properities of Sendust, widely accepted as one of the most ideal materials for tape reproduction heads, improve markedly as its purity increases. Armed with this information, Yamaha engineers then went on to develop a special process for producing extremely pure Sendust.
The resulting high-vacuum centrifugal casting technique permits production of Sendust ingots that are more than 99,999999% pure, and which, after being machined into tape head cores, provide the following advantages.
 Higher permeability for increased sensitivity, improved recording and playback efficiency.
High maximum flux density for excellent linearity even with large signal current.
Reduced magnetic distortion and noise for maximum signal-to-noise ratio.
High Curle temperature for improved stability over extended periods under a wide range of temperatures.
Exceptional wear resistance and freedom from dust accumulation for minimized dropouts and modulation noise.

Unique Low-Impedance Design
The number of coil windings used in the K-550 reproduction head has been reduced to half that of conventional designs. The results of this seemingly simple design feature include dramatically reduced ringing on sharp wavefronts for improved transient response, improved linearity for reduced high-frequency distortion, wider dynamic range for more natural reproduction and improved channel separation for more precise stereo imaging - all vital factors for true high-fidelity sound.

Full Metal Tape Compatibility
High-performance metal cassette tape formulations have become widely accepted as providing sound performance rivalling that of open reel tape, and even discs.
Unless the cassette deck's heads and electronics are designed to provide precise matching with the tape's characteristics, however, the superb reproduction capabilities of metal tape will not be fully realized. The K-550's low-impedance pure Sendust head, high-current double-gap ferrite erase head and reproduction electronics are all critically balanced for ideal performance with metal, CrO₂ and normal tape formulations. Whichever tape you use, you're guaranteed to get the highest reproduction performance it can provide.
 One-Touch Recording
Unlike conventional cassette decks, the K-550 has no pause control. The pause mode is entered automatically when you push the record button. Then, pushing the Forward button initiates transport motion. You can return to the pause mode again at any time by pushing Record. This makes for simpler, miss-free transport operation.

Dolby Noise Reduction
This renowned noise reduction system from Dolby Laboratories can considerably improve the signal-to-noise ratio of your recordings. High-frequency hiss is reduced by more than 9 dB on signals 5 kHz and higher, for low noise even in low-level passages. An MPX filter is automatically switched on when the Dolby circuit is activated, to prevent interference by the 19 kHz pilot signal when making FM recordings.

Peak-Level Meters
These fast-acting meters make accurate setting of record levels easy, for perfect results every time you record. A green LED lights to show peaks =3 dB and above, while a red LED shows peaks =8 dB and above.

Full Logic Transport Control with Remote Control Option
All transport functions are fully logic controlled, ensuring sure, error-free transport operation. You can switch directly from one transport mode to another without fear of damaging the tape or transport, and response to commands is exceptionally fast, making critical record timing easy.

Other Features
Record mute function facilitates compilation of a professional-quality music library.
Hall-element auto shutoff mechanism stops the transport safely at tape end.
Independent tape selectors offer one-touch selection of normal, CrO₂ or metal tape bias/EQ.
Timer recording function permits timer activated recording.
Universal headphone output jack permits use of virtually any impedance headphones with no loss in sound quality.
Track Configuration:  4-track, 2-channel stereo
Motor:  DC servo motor (capstan); flat torque DC motor (reel)
Low impedance pure Sendust rec/playback head;
Double-gap ferrite erase head.
Tape Speed:  4,75 cm/sec ±1%
Rapid Transport (F.Fwd/Rew):  75 sec. (C-60)
Wow and Flutter:
WRMS :  0,04%
DIN 45500 :  0,15%
Signal-to-Noise Ratio (Dolby Off):
CrO₂ Tape :  better than 60 dB
Frequency Response (-20 VU):
LH Tape :  40 - 16,000 Hz  ±3db
CrO₂ Tape :  40 - 18,000 Hz ±3 dB
Metal Tape :  40 - 20,000 Hz ±3 dB
Overal Distortion:
LH Tape :  less than 1,0%
CrO₂ Tape :  less than 1,5%
Metal tape :  less than 1,0%
Input Sensitivity/Impedance:
Mic :  0,3 mV/5 k Ω
Line :  60 mV/80 k Ω
Output Level:
Line :  340 mV/ 1 kohm
Phones :  0,6 mV/8 Ω; 3 mW/150 Ω
Power Supply:  120 V AC, 60 Hz
Power Consumption:  23 W
Dimensions (W x H x D):  451 x 129 x 294 mm (17-3/4" x 5" x 11-1/2")

Weight:  5,7 kg (12 lb 9 oz)

Marantz Model 250

 Marantz Model 250 Professional Stereo Power Amplifier
250 Watts of contiuous power may be more than enough for you own homemade jam session. Because the Model 250 offers the kind of brute strength you need for vibrant, professional stereo sound in a variety of  uses, such as studio monitoring, sound reinforcement and custom stereo applications. Although it's rated at 250 Watts RMS (125/channel), under typical use this Marantz amplifier delivers up to 300 Watts of power into 8 ohms, from 20 Hz to 20 kHz, with less than .05% THD and IM distortion. An added feature for the pro is the illuminated output level meters with Power Range Switching. These meters work as visual indicators, showing actual power output to speakers. With them, speaker overload and/or overdriving amp inputs can be checked and, consequently, avoided. Power, features, price. And the nicest thing about the 250 is that you don't have to compromise one for another.
Power Output (Contiuous Power at 8 Ω, at or below rated distortion 20 Hz to 20 kHz. Both channels driven at rated distortion):  250 Watts (125 Watts/channel)
IM Distortion (At or below rated power, any combination of two frequencies between 20 Hz to 20 kHz, both channel driven):  0,1%
Total Harmonic Distortion (At or below rated power, any frequency from 20hz to 20 kHz, both channels driven):  0,1%
Frequency Response:   20 Hz to 20 kHz (±0,1 dB)
Power Bandwidth (IHF, both channel driven):  7 Hz to 60 kHz
Input Sensitivity/Impedance (Nominal):  1,5 V / 100 k Ω
Damping Factor:  100
Total Noise (into 8 Ω):  better than 106 dB below rated output
Power requirements:  120 V AC, 500 W, 50/60 Hz
Dimensions (W x H x D):  15-3/8" x 6-1/8" x 9-1/2"

Weight [unit/shipping]:  28 pounds / 34 pounds

Marantz Model 240

 Marantz Model 240 Basic Stereo Amplifier
Not just another pretty face, the Model 240 offers the same reliable power, the same craftsmanship and endurance as the Marantz 250. what it doesn't offer is the two front panel meters. With this model you get all the same high-performance features - but you don't get the meters to tell you about them. You get the Variable Overlap Drive, which automatically compensates for natural aging of components, giving continual "like new" performance. And the Model 240 offers complete stability regardless of load, massive heat sinks and more. 250 Watts continuous power into 8 ohms speakers, (typically 300) from 20 Hz to 20 kHz with total harmonic and intermodulation distortion under 0,1%. So, far the identical Marantz quality you're saving yourself some money. When you're thinking about buying a stereo power amplifier, think of the Model 240 as the one that's made to listen to - not look at.
Power Output (Contiuous Power at 8 Ω, at or below rated distortion 20 Hz to 20 kHz. Both channels driven at rated distortion):  250 Watts (125 Watts/channel)
IM Distortion (At or below rated power, any combination of two frequencies between 20 Hz to 20 kHz, both channel driven):  0,1%
Total Harmonic Distortion (At or below rated power, any frequency from 20hz to 20 kHz, both channels driven):  0,1%
Frequency Response:   20 Hz to 20 kHz (±0,1 dB)
Power Bandwidth (IHF, both channel driven):  7 Hz to 60 kHz
Input Sensitivity/Impedance (Nominal):  1,5 V / 100 k Ω
Damping Factor:  100
Total Noise (into 8 Ω):  better than 106 dB below rated output
Power requirements:  120 V AC, 480 W, 50/60 Hz
Dimensions (W x H x D):  15-3/8" x 6-1/8" x 9-1/2"

Weight [unit/shipping]:  26 pounds / 32 pounds

Mordaunt-Short Pageant Series 2

 The Mordaunt-Short PAGEANT SERIES 2 offers musical reproduction of the highest quality, a response of the utmost smoothness over the entire audible spectrum and a clarity of detail previously associated only with professional equipment.
 Incorporating the DSB208 bass- and mid-frequency transducer, a carefully matched synthetic dome tweeter of exceptional dispersion characteristics and independent controls for adjustment of the acoustics balance in adverse listening conditions, the PAGEANT SERIES 2 is thus a full frequency high performance system to be used to advantage with compatible equipment of virtually any power rating.
Specification and Performance Data.
Nominal Frequency Range:  25 - 25,000 Hz
Specific Frequency Response:  65 - 20,000 Hz 3 dB)
Acoustic Balance Controls:  Independent toggle switches affording four choices of frequency response:
Mid-frequency :  level or -2 dB, 1,000 - 3,500 Hz.
High frequency :  level or -2 dB, 3,500 - 25,000 Hz.
Impedance:  8 Ω nominal. For use with amplifiers of 4-8 Ω output impedance.
Sensitivity:  6.5 V r.m.s (5.3 watts) to produce 96 dB at 1 metre in anechoic conditions using pink noise.
Maximum Sound Pressure Level:  110 dB in typical listening-room.
Continuous Programme Rating:  20 V r.m.s (50 watts) contoured random noise, including transients up to 56 V peak to peak.
Amplifier Power Compatibility:  15 - 100 watts per channel. Amplifiers of higher power may be used with care.
Distortion:  Substantally less than 1% THD within frequency range of 150 - 25,000 Hz at 6.5V r.m.s input (nominal 96 dB sound pressure level).
Fundamental System Resonance:  65 Hz.
Dividing Frequency:  3,500 Hz.
Filter Characteristics:
Low pass :  12 dB/octave.
High pass :  18 dB/octave.
 System Design:
Resistively loaded reflex enclosure with mid and upper frequency controls for compensation of acoustic balance in adverse listening conditions. For use horizontally or vertically not less than 300mm from floor.
15mm high-density board construction with internal bracing, sides wood veneered with internal balancing veneers; rear spray finished neutral fleck.
Acoustically transparent, deep brown woven fabric on 9mm board frame with nylon stud fastenings.
Cabinet Finish:
Selected teak or walnut veneer.
Bass/mid-frequency:  DSB208.
High-frequency:  25 mm wide dispersion synthetic dome.
Dividing network:
High grade, ferrite core inductors and low-loss, close tolerance capacitors on printed circuit board.
Electrical Connections:
Terminal moulding, incorporating both standard DIN socket and spring-loaded push-button connectors for stripped wire ends. Plugs and leads supplied.
Dimensions (H x W x D):  533 x 330 x 230 mm (21" x 13" x 9")
Single Speaker, (unpacked):  9.6 kg (21 lb 1 oz)

Per Pair, (packed):  22.25 kg (49 lb)