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





Marantz PM-7001 KI amplifier


PM7001 KI - Signature Integrated Amplifier
The KI Signature series is for many years synonym of finest electronics with best sound quality. Every aspect of the design and construction of the PM7001 KI stereo amplifier has received Ken Ishiwata's personal attention to attain uncompromised quality. The copper-plated chassis and rear panel reduce signal-degrading electromagnetic interference, while its rigid dual layer chassis and solid aluminum front panel virtually eliminate mechanical vibration. Delivering 2 x 70 watts into 8 ohms (120 watts, 4 ohm), this 2-stage constructed Current Feedback amplifier features symmetrical circuits for perfect image balancing, and uses audiophile Customized Components and the new HDAMs to preserve the music's dynamic structure, tonal quality and stereo image. Power handling characteristics have been reshaped and the large toroidal transformer is designed for this renewed circuitry. Its low impedance, wide-bandwidth power supply ensures a massive reserve of energy, to drive even difficult speakers with ease. Enjoy the exclusivity of the Ken Ishiwata Signature integrated amplifier.

Sufficient real power capability to fill the room with musical enjoyment
Ultra low vibration and leakage flux keeps the signal sharp and minimizes internal electro magnetic distortion
Excellent frequency response and superb sonic performance for the highest standard such as SACD
Achieving a unprecedented dynamic, accurate and detailed sound reproduction
Two times identically lay out symmetric audio circuit boards secure precise stereo imaging
Bypasses the tone control circuitry to ensure the purest sound quality
Allows tonal adjustment to personal taste
For bi-wired connection of loudspeakers, or for multiroom applications
Flexible system integration and total control via one system remote

A touch of Ken Ishiwata
The PM7001 KI is a clear example of benchmark engineering and craftsmanship of Ken Ishiwata and features a number of Marantz sound enhancements. The PM7001 KI integrated amplifier is built on a rigid dual layer enforced chassis. All of the analogue signal and control circuits are separated and shielded to prevent cross-talk and other unwanted interference. A high grade power supply centered around a special selected toroidal transformer secures maximum separation, clarity and dynamics. This design configuration is capable of a clear and powerful reproduction of the most demanding musical performances. The strength of each KI Signature design can be found in the attention to detail and the synergy of the different elements


Specifications:
Power Output (20 Hz - 20 kHz, simultaneous drive of both channels)
2 x 70 W at 8  load
2 x 100 W at 4  load
Total Harmonic Distortion (20 Hz - 20 kHz, simultaneous drive of both channels, 8 ):  0,02%
Power Bandwidth (8  load, 0,05% T.H.D.):  5 Hz - 60 kHz
Frequency Response:  5 Hz - 100 kHz ±3 dB
Damping Factor:  100 (8  load, 20 Hz - 20 kHz)
Input Sensitivity/Impedance
Phono  MM :  2,5 mV/47 k
Cd, Line, Tuner, Aux :  200 mV/20 k
Main In :  1,6 V/20 kohm
Output Load/Impedance
Pre Out :  16 V/560
Max. Allowed Phono Input :  130 mV
RIAA Deviation (20 Hz - 20 kHz):  ±0,5 dB
Signal-to-Noise Ratio (IHF-A, 1 W, 8  load)
Phono MM :  85 dB (5 mV input)
Cd, Line, Tuner, Aux :  88 dB (500 mV input)
Main IN :  107 dB
Tone Control
Bass :  ±10 dB at 50 Hz
Treble :  ±10 dB at 20 kHz
Power Requirement:  AC 230 V 50/60 Hz
Power Consumption:  470 W (2 x 100 W output, 4 )
Dimensions (W x H x D):  440 x 128 x 364 mm
Weight:  10,5 kg

Audio Analogue Puccini amplifier

 Stereo Integrated Amplifier
Specifications:
Power Output (both channels driven, 8 Ω):  2 x 40 W
Input Sensitivity/Impedance (RMS):
Phono MM :  10 mV /47 k Ω
Phono MC :  1 mV / 100 Ω
Line :  1 V / 50 k Ω
Signal-to-Noise Ratio
Unweighted
Phono MM :  better than 70 dB
Phono MC :  better than 60 dB
Line :  better than 80 dB
A-weighted
Phono MM :  better than 80 dB
Phono MC :  better than 70 dB
Line :  better than 90 dB
Tape Output Level/Impedance (RMS):  1 V / 600 Ω
Total Harmonic Distortion:  less than 0,196 % (at 40 W, 8 Ω, 1 kHz)
Damping Factor:  better than 100 (at 1 kHz, 8 Ω, 1 W)
Slew Rate:  better than 10/µsec
Bandwidth:  20 Hz - 20 kHz (±0,1 dB);  5 Hz - 20 kHz (+3 dB)
Channel Separation (at 1 kHz, unused input shorted):  better than 80 dB
Inputs:  Phono MM/MC, Tuner, CD, Video, Aux, Tape
Nominal Voltage Supply:  115 V AC, 230 V AC; 50/60 Hz
Max. Power Consumption:  170 VA
Dimensions (W x H x D):  445 x 85 x 365 mm (17,52" x 3,35" x 14,4")
Weight:  7 kg (15,5 lbs)


Harman/Kardon HK 725 pre-amplifier

Harman Kardon introduces low negatiwe feedback design for inaudible TIM distortion
For the last few years,, audio manufacturers have been rushing to bring you newer,lower T.H.D. levels in their amplifier sections. And every year, they've accomplished this the simplest way they could. By adding negative feedback, a form of electronic compensation. Unfortunately, this "cure" for T.H.D. - typically 60 - 80 dB of negative feedback - creates another form of distortion. Transient Intermodulation Distortion, or TIM, which does far more to degrade the music than T.H.D. at Harman Kardon, we lowered T.H.D. the right way. With unique circuit design (US Patent #4.176.323) that lets us use just a fracrtion of the negative feedback typically used. The result is our new HK 700 series High Technology Separates. Built around our low negative feedback amp/preamp combination that delivers a crystal clear, totally transparent 65 watts per channel. You can also choose from a full-featured digital tuner, a phase locked analog tuner, and the most advanced cassette deck on the market.

The HK 725 High Technology pre-amplifier
Many of the critics from the most widely recognized audiophile publications consider the HK 725 one of the best preamplifiers on the market
As with all our components, the KH 725 was designed with careful attention to even the finest details. Instead of the typical 4-stage phono section, we used 8 stages. And we used FET front ends on both our low and high level stages. These provide higher Signal-to-Noise ratio than other designs. Instead of conventional rotary tone controls, we used fixed resistor push-buttons because they provide lower distortion. The HK 725 also allows you to defeat the tone controls altogether, giving you the clearest, cleanest sound possible.
Even our volume controls is unique. With twelve wipers instead of the usual four. This extra bit of engineering not only provides a smoother acting, longer lasting control, but also helps lower distortion as well. And we didn't forget convenience. You get facilities for two tape decks, with 2 way tape copy that allows you to monitor any source you like while copying from one deck to another. Plus loudness, subsonic and high cut filters to help you contour your system to your listening environment.
The Harman kardon HK 725 stereo preamplifier is housed in a relatively small metal cabinet that matches its associated model HK 770 power amplifier. Individually, or in conjunction with the power amplifier, the sound quality is best described as "exceptionally clean" particularly with respect to the deep bass. An unusual feature is switch-selected bass and treble equalization, rather than rotary controls. The bass and treble have eight switches each, four providing boost in steps of 2 dB at 50 Hz and 10 kHz; four providing attenuation in 2 dB steps at the same frequencies. An illuminated switch in the center of each row of buttons provides a tone control defeat. Subsonic and high cut filters round out the equalization. Switching is provided for automatic tape duplication from, or to, either of two recorders. A panel-mounted headphone jack allows the signal to be monitored without going through the associated power amplifier. One unswitched and two switched AC convenience outlets are provided.
Specifications
Frequency Response : less than 1 Hz to beyond 150 kHz   +0 -1 dB
Total Harmonic Distortion: 
Phono :  0,009%
High Level :  0,005%
Intermodulation Distortion:  0,009% at 2 volts output
RIAA Equalization:  ±2 dB (20 -20,000 Hz)
Signal-to-Noise Ratio:
Phono :  90 dB IHF-A
High Level :  106 dB IHF-A
Phono Overload:  250 mV at 1 kHz
Input Sensitivity/Impedance:
Phono :  2,3 mV/47 k Ω
High Level :  145 mV/23 k Ω
Slew Rate:  Greater than 200 volts/µsec to output with IHF standard
Tone Control Range
Low :  ±8 dB at 50 Hz
High :  ±8 dB at 10 kHz
Dimensions (W x H x D):  385 x 72 x 320 mm (15,2 x 2,9 x 12,6 inches)
Weight:  4,2 kg (9,25 pounds)

Harman/Kardon HK 770 power-amplifier

The HK 770 is certainly one of the most sophisticated stereo power amps you can buy. With 65 watts per channel, and plenty of extra headroom, the  HK 770 can easily handle the most demanding of transients.
Unlike most conventional amplifiers, negative feedback levels in the HK 770 are kept below 20 dB, reducing TIM distortion to inaudible levels. Also unlike conventional power amps, the brawn behind the Kh 770 comes from a pair of independent power supplies. We use two discrete rectifier circuits. Two sets of electrolytic capacitors. And two massive toroidal transformers, which eliminate the stray magnetic fields that cause hum.
Our twin power supply design provides you with two distinct benefits.
First, it eliminates the possibility of channel-to-channel interference. It also prevents one channel from draining the power available to the other. Each power supply is further divided into high and low level stages. This ensures that the power requirements of the high level stages do not drain current at the expense of the low level stages
Unlike most power amps, the HK 770 gives you, accommodations for two pairs of speakers with independent speaker switching. Plus a power display that allows you to monitor performance. And for more accuraate power readings at low listening levels, display aensitivity can be increased by a factor of 10. The HK 770 packs a lot of power and lot of technology into a surprisingly compact amplifier.
The Harman Kardon HK770 Stereo Power Amplifier is FTC rated for 8 ohms at 65 watts RMS per channel, 20 Hz to 20 kHz, at less than 0,03% Total Harmonic Distortion. Test results were considerably better than even the low claimed distortion, resulting in some of the lowest distortion figures ever attained from a power amplifier. The sound quality reflects the low distortion, being exceptionally clean, particularly in the deep bass. Special construction techniques result in an unusually small cabinet for an amplifier of this power rating. The front panel has left and right LED dual range output power indicators calibrated 0,05-100 watts and 0,005-10 watts into 8 ohms.
The LED power output indications were essentially precise, with a virtually flat 20 Hz to 20 kHz Frequency Response. An output power hold-off prevents power supply turn-on transients from being fed to the speakers. One unswitched AC convenience outlet is provided.
Specifications
Power Output:  65 watts (RMS per channel into 8 Ω, both channels driven simultaneously from 20 Hz to 20 kHz with less than 0,03% T.H.D.)
Power Bandwidth:  less than 8 Hz to 100 kHz at 32,5 watts per channel with less than 0,03% T.H.D.
Total Harmonic Distortion:  0,006% at rated output
Intermodulation Distortion:  less than 0,01% at rated output, both channels driven at different operating frequencies
Frequency Response:  below 1 Hz to 250 kHz +0, -3 dB
Damping Factor:  greater than 50
Slew Rate:  150 V/µsec into 8 Ω at rated power output, both channels driven
Square Wave Rise Time (20 kHz):  1,5 µsec into 8 Ω at rated power output, both channels driven
Square Wave Tilt:  less than 2% at 20 Hz
Total TIM Distortion:  less than 0,007% at rated output
Total Interface I.M. Distortion:  less than 0,007%
Power Supply Crosstalk:  greater than 100 dB (20 Hz to 20 kHz) unused channel sherted input
Amplifier Configuration:  Twin toroidal transformers with positive and negative supplies plus high and low voltage supplies for output and driver stages
Signal-to-Noise Ratio:  123 dB (IHF-A)
Input Impedance:  35 k Ω
Sensitivity:  1,2 V for rated output
Dimensions (W x H x D):  385 x 72 x 320 mm (15,2" x 2,9" x 12,6")
Weight:  10,1 kg (22,2 lbs)