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 SX-424

 The SX-424 is a medium-powered, budget-priced AM/FM solid state stereo receiver with special features for sensitive FM tuning and wide frequency response.
Pioneer SX-424 is proof positive taht stereo on a limited budget doesn't have to mean limited stereo sound. In a handsome package of quality circuitry and reasonable price, the SX-424 offers up to 50 watts of music power at 4 ohms, very sensitive FM reception a wide linear type dial scale for fine FM tuning, and highly respectable  specifications both for the FM tuner section and the audio section. It's versatile unit, too because you can use it with almost all music sources available today, including records, tape, FM and microphone. Best of all it's Pioneer made, which means that, for its price, there is probably nothing available today that can compare with its quality.

Amplifier Section
Music Power Output (IHF):  50 W at 4 Ω;  37 W at 8 Ω
Continuous Power Output (1 kHz each channel driven):
18 W / 18 W at 4 Ω
14 W / 14 W at 8 Ω
Continuous Power Output (1 kHz both channel driven):
13 W + 13 W at 4 Ω
12 W + 12 W at 8 Ω
Total Harmonic Distortion:  less than 1% (continuous power output)
Intermodulation Distortion:  less than 1% (continuous power output)
Power Bandwith (IHF):  20 Hz to 45 kHz (8 Ω, T.H.D. less than 1%)
Frequency Response:  20 Hz to 70 kHz ±3 dB
Speakers output Impedance:  4 to 16 Ω
Damping Factor:  40 (8 Ω, 1 kHz)
Input Sensitivity/Impedance:
Phono Mag :  3 mV/50 k Ω
Mic :  6,5 mV/50 k Ω
Aux :  180 mV/100 k Ω
Tape Monitor :  180 mV/100 k Ω
Tape Monitor (DIN) :  180 mV/100 k Ω
Recording Output:
Tape Rec (Pin Jack) :  180 mV
Tape Rec (DIN connector) :  36 mV
Bass Control :  -9 dB, +9 dB / 100 Hz
Treble Control :  -9 dB, +6 dB / 10 kHz
Equalization Curve (Phono):  RIAA standard
Loudness Contour:  +9,5 dB/100 Hz; +5,5 dB/10 kHz (with volume control set at -40 dB position)
Hum and Noise (IHF): 
Phono :  more than 75 dB
Aux :  more than 85 dB
FM Tuner Section
Requency range:  88 MHz to 108 MHz [87,5 MHz to 108 MHz, FTZ approved]
Usable Sensitivity (IHF):  2,3 µV
Capture Ratio (IHF):  3,5 dB
Image Rejection:  more than 50 dB (98 MHz)
IF Rejection:  more than 80 dB (90 MHz)
Spurious Rejection:  more than 70 dB (90 MHz)
AM Suppression:  45 dB
Signal-to-Noise Ratio:  65 dB
Harmonic Distortion:
Mono :  less than 0,6% (100% mod.)
Stereo :  less tahn 0,8% (100% mod.)
Tuning Indicator:  Signal strength type
Stereo Separation:  more than 40 dB (1 kHz)
Sub Carrier Suppression:  more than 35 dB
Noise Filter:  Switchable to On-Off
Antenna Input:  300 Ω balanced; 75 Ω unbalanced
De-emphasis Selector:  50 µS (FW model only)
AM Tuner Section
Frequency Range:  525 kHz to 1605 kHz
Usable Sensitivity (IHF):  15 µV
Image Rejection:  more than 45 dB (1,000 kHz)
IF Rejection:  more than 35 dB
Signal-to-Noise Ratio:  more than 50 dB
Antenna: Built-in ferrite loopstick antenna
Semiconductors:  Transistors 30, Diodes 24; FETs 1
Requirements :  120 V 50 Hz; 220 V 50/60 Hz, or 110, 120, 130 220, 240 V (switchable) 50/60 Hz
Consumption:  90 W max
AC Outlets:  1 Unswitched, 1 switched
Dimensions (W x H x D):  431 x 146 x 347 mm (16-31/32" x 5-3/4" x 13-21/32")
Weight (net): 
120 voltage model :  7,5 kg (16 lb 8 oz)
220 voltage model:  7,9 kg (17 lb 6 oz)

Yamaha NS-200M

Check our references
First trust your ears, thentrust the experts. That's  a reliable way to judge speaker systems. Especially reference monitors.
Yamaha make this point because of the response our studio monitor speakers have received from recording engineers at top studios like A&M, A&R, Hummingbird, Universal and Westlake. As well as Yamaha's own music research and development facility and professional studio in Glendale, California.
And thet response has been extraordinary. Here's why: accurate reproduction. Which brings us to the new NS-200M and NS-500M.

The Yamaha NS-200M is compact without compromise. It can easily handle the wider dynamic range and frequancy response of today's sources. Its 10-inch pure spruce woofer cone is made of the same material that goes into the soundboards of our fine pianos. Its titanium carbide dome midrange and tweeter produce crisp, clear highs. And its low-loss cross over makes sure signals get to the drivers unscathed.

Type:  3-way, 3-speaker acoustic suspension
Low Frequency :  250 mm (10") woofer carbon fiber/spruce cone
Mid Frequency :  60 (2-1/2") mm midrange titanium-carbide dome
High Frequency :  30 (1-1/4")mm tweeter titanium-carbide dome
Controls: Midrange and tweeter level controls
Power handling:  200 W
Sensitivity:  90 dB 1W/1m
Frequency Response:  40 Hz - 20 khz
Impedance:  6 ohms
Dimensions (W x H x D):  320 x 554 x 322 mm
Weight:  16,5 kg

Yamaha NS-5000

Yamaha finally  introduces the new top of loudspeakers NS-5000.  3-way bookshelf speaker system that illustrates the future direction of Yamaha's speaker technology grown out of years of cutting-edge research on all aspects of designing Hi-Fi speakers, including components and materials. The NS-5000, built upon the tradition of natural sound for which all Yamaha speakers have been known  and sets a new standard in sound excellence expected of Yamaha's top-of-the-line speaker. With non-colouration of sound, wide frequency response, consistent sound characteristics across the frequency range, and extremely low distortion set as self-imposed requirements for a new-generation speaker, we scientifically probed each of these characteristics to be incorporated into a flagship capable of bringing out the best of high-resolution audio sources. The result is the superb NS-5000, with sound and performance that sets a standard for all Hi-Fi speakers to come.


Newly Developed Diaphragms Boast Acoustic Velocity Comparable to That of Beryllium
 Newly developed R.S. (Resonance Suppression) Chambers Suppress Unwanted Resonance in the Mid and High Ranges
 12-inch, 3-way Bookshelf Design Draws on the Tradition of the Legendary NS-1000M
 Newly Developed Acoustic Absorber Eliminates Sound-absorbing Material to Revive the Original Presence of the Music
 Glossy Black Piano Finish Provides Improved Signal-to-noise Performance—and Adds to the Luxurious Joy of Ownership
 Carefully Crafted Laminated Plywood Enclosure Made of Japanese White Birch from the Island of Hokkaido

Type:  3-way Bookshelf Bass-reflex Type
Woofers:  300 mm (12") cone type
MidRange Driver:  80 mm (3-1/4") dome type
Tweeter:  30 mm (1-1/4") dome type
Frequency Response:  26 Hz - 40,000 Hz (-10dB);  -100 kHz (-30dB)
Nominal Input Power:  200 W
Maximum Input Power:  600 W
Sensitivity:  88 dB / 2.83 V/1 m
Crossover Frequencies:  750 Hz / 4500 Hz
Impedance:  6 Ω  (minimum 3.5 Ω )
Dimensions (W x H x D):  395 x 690 x 381 mm; (15-1/2” x 27-1/8” x 15”) (with speaker terminals)
Weight:  35.0 kg (77.2 lbs). / unit

Marantz 2385

Power Amplifier Section
High-Power Full Complementary Symmetry Output
The mammoth power of these Marantz receiver is generated by the most sophisticated full complementary output stages in use. Transistor array is  triple-paralleled in this 2385 - designs occasionally used separate components, but never before in receivers. They help provide long life, high power operation and exceptionally low Total Harmonic Distortion. As low, in fact, as that of the Marantz 510M professional power amplifier.
Also like the 510M, the Marantz 2385 are engineered to produce an extremely wide safe operating area - that range where voltage, current and temperature conditions permit reliable output stage operation. The amplifier sections are so stable, they will drive a load at virtually any frequency or level without breaking down.
In addition, the output stages of both receivers are biased for Class AB operation, a measure that prevents crossover distortion and ensures uncompromised performance to well below 1/1000 of full rated power.
Output device and speakers are guarded by a professional-calibre enrgy-sensing circuit that doesn't limit the low energy, high amplitude short term transients essential to accurate music reproduction. As a result, output signals are free of the distortions and instabilities caused by conventional volt/amp limiting circuitry used in most receivers.

Direct Coupled Power Output
Provides wide power bandwidth, excellent low frequency transient response and improved damping factors. A number of high-power transistorized amplifiers still use capacitor - or transformer-coupled output stages to ensure reliability. However essential this design was in the past, it tended to limit low frequency power response or cause degrading phase shift.
The Marant 2385 achieve their high degree of stability without the need for coupling transformers and capacitors and the sound inaccuracies they can cause. The benefits are extremely high damping factors at low frequencies and excellent low frequency response.

Toroidal Dual Power Supply
A specially designed toroidal-core power transformer wwith dual secondaries gives you two independent power supply sections. Each channel can perform at its best, at all frequencies and levels, without affecting the other channel. In fact, even when one channel is driven by a high level dynamic signal demanding considerable power output, the other can still maintain exceptionally low distortion.
Complementing the transformer are high-capacity dual section electrolytic capacitors. This combination provides high power reserves, reliability and low distortion while keeping heat and weight to a minimum.
Peak Indicators
Both receivers use the same type of sophisticated peak LED display featured in the Marantz Model 510M power amplifier. Rather than simply sense the amp's output voltage as in most LED displays, the unique Marantz circuit tracks variations in the power supply. You get an accurate indication of maximum amplifier output regardless of low or high AC line conditions. Peak indicators, unlike VU meters, react instantaneously to audio transients or excessively high input signals that cause clipping.

Tuner Section
Steep Quieting Slope
The quieting slope specification measures a tuner's ability to provide good Signal-to-Noise performance 
Under actual operating conditions. It's a far more reliable indication of quality than the IHF sensitivity figure often quoted as the prime specification to consider when evaluating an FM tuner.

Highly Sensitive Dual-Gate MOSFET FM Front End
The superior quieting sensitivity of Models 2385 is largely due to the use of a dual-gate MOSFET RF amplifier and mixer stage. Moreover, MOSFET devices deliver extremely linear operation, providing low RF intermodulation distortion and excellent rejection of spurious signals.
An outstanding selectivity specification is ensured by a five-gang tuning capacitor, while a dual-tuned RF interstage provides improved image and spurious signal rejection.

Phase Locked Loop FM Stereo Demodulator
The phase locked loop (PLL) design was developed by the space industry to provide a state-of-the-art. Communication system. Today the same technology is used in all Marantz receivers and tuners to assure low distortion, supoerior noise rejection and excellent stereo separation.
PLL circuitry locks to the stereo pilot signal broadcast by an FM station. This positive "phase lock" enables the multiplex demodulator to separate the stereo channel information from the FM multiplex signal with more accuracy and less distortion than demodulators using other designs.
PLL is dependent on pilot phase and not on pilot aamplitude, making it less susceptible to false triggering from various types of noise interference.

Multi-Stage IF Section
Built into both receivers is a comprehensive six-stage IF amplifier section incorporating five dual-element ceramic filters. The characteristics of these filters produce a 200 kHz passband which is linear in phase, consequently eliminating a major source of high frequency distortion and loss of stereo separation. Sharp cut-off slopes improve tuner selectivity, assuring superior reception even when stations are closely spaced.   A multi-stage limiter comprised of two integrated circuits provides superb AM rejection and an excellent capture ratio - specified at 1 dB. Distortion (at 1 kHz) is kept at a minimal 0,1% in mono, and 0,2% in stereo.

Plug-in Dolby FM Capability
On the back panel of Model 2385 is a convenient receptacle that accepts the optional plug-in Marantz DLB-1 Dolby FM Decoder. Inside the receivers is a 25-microsecond Dolby FM equalization circuit. In tandem, they can cut the noise from a Dolbyized FM broadcast by as much as 12 dB.. That's the equivalent of reducing the noise power of a received FM signal sixteen times below normal.

Additional  Features
The Model 2385 receiver have a multiplex noise filter that reduces the background noise of weak FM stereo signals, while maintaining full frequency response. And they feature adjustable FM muting, a pivoting  AM antenna and an "F" connector for simple connection of coaxial FM antenna cable.

Preamplifier Section
Flexible Tone Controls
The more flexible the the tone controls, the more accurately yoy can adjust for non-linearities caused by speakers, speaker placement, room acoustics or the program material itself.
The tone control system in Marantz Model 2500; 2385 features a sophisticated five-position tone turnover/mode switch for versatile bass, midrange and treble control. This eliminates a major shortcoming of conventional tone controls - their tendency to affect too wide a band of frequencies. Optional frequency turnover points limit the bass and treble controls to just the desired range.
The advantages can be illustrated by a practical example: boosting the low bass (under 100 Hz) to compensate for a deficiency in room acoustics. Most conventional tone controls, even if capable of supplying the boost, will also increase the output in the 300 Hz to 1,000 Hz region.
With the turnover point set at 100 Hz on a Marantz receiver, the bass control can provide the desired bass boost up to the frequency point of 100 Hz and leave the frequency range above the point essentially flat and unaffected.
This flexible, easy-to-set system permits a virtually unlimited number of repeatable settings, enabling you to adjust for the desired tonal balance in any listening environment.

Precision Four-Gang Volume Control
Model 2385 feature a precision-calibrated, stepped volume control. Its superb tracking accuracy of ±0,5 dB between left and right channels enables you to repeat volume settings with total accuracy.
The four-gang design helps produce exceptional Signal-to-Noise performance - typically greater than 10 dB over conventional volume control designs.

Superior Filter Design
The Model 2385 feature an 18 dB per octave Bessel-derived high filter - the most advanced filter design in audio. It reduces high frequency noise - and produces a more natural less colored sound because it eliminates the overshoot and "ringing" common to other filters. Results are linear phase response and greatly reduced phase and transient distortion. An 18 dB/octave 15 Hz subsonic Butterworth low filter cuts turntable rumble and subsonic transients that prevent accurate reproduction of low frequency signals.
Never before has such advanced filter technology been applied to any audio components, separates or receivers. 18 dB/octave filters provide positive filtering action with little coloration of sound by concentrating their effect only at the specified frequencies. Filters with slower roll-off characteristics, on the other hand, must start acting toward the midpoint of the frequency range in order to perform adquately at the extreme high or low end of the audio spectrum.

Flexible Tape Copy Functions
In addition to the standard phono and auxiliary inputs, two sets of tape inputs and outputs are provided to facilitate dubbing between a pair of tape decks. A built-in tape copy facility can function independently of program selector and tape monitor circuitry, enabling you to dub from one deck to another while listening to a different program sourece.
Also featured are front-panel dubbing jacks that allow you to add a third tape deck without disturbing any rear panel connections.
Reat panel facilities include conections for two sets of speaker systems, main in/pre out jack's a Quadradial output jack and two convenience AC outlets.

Amplifier Section
Minimum Continuous Power per Channel (from 20 Hz to 20 kHz, both channels driven): 
Into 8 ohms :  185 W
Into 4 ohms :  240 W
Total Harmonic Distortion
At 8 Ω :  0,05%
At 4 Ω :  0,1%
IM Distortion (IHF method, 60 Hz : 7 kHz = 4:1 at rated power output):
 at 8 Ω :  0,05%
At 4 Ω :  0,1%
Damping Factor (at 20 Hz):  60
Preamplifier Section
Input Overload at 1 kHz :  200 mV
Equivalent Input Noise "A" weighted:  0,48 µV
Dynamic Range:  113 dB
Input Sensitivity at 1 kHz :  1,8 mV / 47 k Ω
Signal-to-Noise Ratio "A" weighted (at rated output & 7,75 mV Input):  83 dB
Frequency response (RIAA, 20 Hz to 20 kHz):  ±0,25 dB
Input Capacitance:  100 pF
High Level Inputs (Aux  & Tape):
Input Sensitivity/Impedance :  180 mV /47 k Ω
Signal-to-Noise  (A weighted):  98 dB
Output Impedance
Tape Out :  500 Ω
Pre out:  50 Ω
AM/FM Tuner Section
IHF Usable [mono]:  8,75 dBf (1,5 µV)
IHF -50 dB Quieting
Mono :  12,1 dBf (2,2 µV)
Stereo :  33,2 dBf (25 µV)
Quieting Slope (mono)
RF input for 30 dB Quieting:  6,8 dBf (1,2 v)
Quieting at:
20 dBf (5,5 µV) :  58 dB
25 dBf (10 µV) :  66 dB
40 dBf (55 µV):  78 db
65 dBf (1,000 µV):  80 dB
Quieting Slope (stereo)
Quieting at:
30 dBf (17 µV) :  49 dB
45 dBf (55 µV) :  62 dB
50 dBf (173 µV):  70 db
65 dBf (1,000 µV):  75 dB
Distortion, Mono and [stereo] at 65 dBf:
At 100 Hz :  0,15% [0,35%]
At 1,000 Hz :  0,1% [0,2%]
At 6,000 Hz :  0,15% [0,3%]
Hum and Noises (at 65 dBf) Mono :  -80 dB
Frequency Response (30 Hz to 15 kHz)
Mono and Stereo :  +0,2 dB -1,0 dB
Capture Raatio:  1 dB
Alternate Channel Selectivity:  85 dB
Spurious Response Rejection:  120 dB
Image response Rejection:  120 dB
IF Rejection(balanced):  120 dB
AM Suppression:  60 dB
Stereo Separation
At 100 Hz :  45 dB
At 1,000 Hz :  50 dB
At 10,000 Hz :  42 dB
Subcarrier rejection:  75 dB
AM Usable Sensitivity (IHF):  10 µV
AM Distortion  at 30% Modulation:  0,4%
AM Signal-to-Noise Ratio:  55 dB
Dimensions (W x H x D):  491 x 178 x 435 mm (19-1/4" x 7" x 17-1/8")
Weight:  27 kg (59,4 lbs)