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

NAD 402 Tuner

The Model 402 embodies NAD's conviction that convenience, flexibility, and ease of use can be achieved with absolutely no compromise in sound quality. The 402 has AM and FM; preset distortion-free tuning for 60 radio stations

60 Presets 30 AM and 30  FM radio stations
NAD-Link Connectors allow control to and from other units
Blend facility to reduce noise at low signal strengths
75 Ω coax antenna connector
Lock facility to automatically tune precisely onto a station
Three separate modes of tuning with 25 kHz accuracy

Flexible Tuning
The 402 has three convenient tuning modes:
Search: Scans rapidly up or down in frequency, stopping automatically at the next strong station.
Preset: Up to 30 FM and 30 AM station frequencies can be stored in memory and instantly recalled. The "non-volatile" memory needs no battery or other power; frequencies are retained during power outages, even if you unplug the receiver for weeks at a time.
Tune: Dual-resolution tuning lets you scan rapidly through the broadcast band (with constant pressure on an up/down tuning button), or fine-tune in small 0,025 MHz steps by tapping on the buttons. This lets you optimise the reception of a weak station adjacent to a strong one.

Sensitive Digital Tuning
Precise digital frequency-synthesis circuits guarantee that each station is tuned with crystal-controlled accuracy. A dual-gate MOSFET FM circuit pulls in weak stations clearly but resists overloading on strong signals. A balanced quadrature detector provides consistently low distortion, even with over-modulated broadcasts. The composite stereo signal is phase-compensated to guarantee wide stereo separation at all frequencies, not just in the midrange.

Sharp selectivity, low noise
Linear-phase ceramic filters in the I.F. circuit provide an ideal combination of sharp selectivity and minimum distortion. Low-loss design gives the optimum signal level to the PLL MPX decoder, yielding a signal-to-noise ratio of nearly 75 dB with strong signals. So with local stations the ultimate stereo guieting is limited not by the receiver but the station itself.

FM Tuner Section
Input Sensitivity:
Mono (-30 dB T.H.D.+N) :  1,3 dBf (1,0 µV/75 Ω)
Mono (-50 dB SN) :  15 dBf (1,5 µV/75 Ω)
Stereo (50 dB SN) :  37 dBf (20 µV/75 Ω)
Stereo (60 dB SN) :  47 dBf (60 µV/75 Ω)
Capture Ratio:  less than 1,6 dB (45 to 65 dBf)
AM Rejection:  more than 60 dB (45 to 65 dBf)
Alternate Channel:  58 dB
Image Rejection:  70 dB
RF. Intermodulation:  60 dB
I.F. rejection:  90 dB
Subcarrier Suppression:  60 dB (19 and 38 kHz)
T.H.D. at 100% Modulation
Mono (1 kHz):  0,1%
Mono (100 Hz - 6 kHz) :  0,2%
Stereo (1 kHz) :  0,1%
Stereo (100 Hz -6 kHz) :  0,3%
Signal-to-Noise Ratio (at 65 dBf, IHF weighted)
Mono :  better than 80 dB
Stereo :  better than 74 dB
Frequency Response 30 Hz - 15 kHz:  ±0,5 dB
Stereo Separation:
1 kHz :  45 dB
30 Hz - 10 kHz :  35 dB
AM Tuner Section
Usable Sensitivity:  5 µV
Selectivity:  30 dB
Image Rejection:  45 dB
I.F. rejection:  35 dB
Signal-to-Noise Ratio (30% modulation, 50 mv Input):  45 dB
Total Harmonic Distortion:  0,5%
Physical Specifications
Power Ratting:   120,, 220 0r 240 V, 50/60 Hz
Power Consumption:  150 W
Dimensions (W x H x D):  420 x 91 x 273 mm
Weight [net/shipping}:  6 kg/7,1 kg

NAD 4020A Tuner

The NAD 4020A is a rationally designed and built, at moderate price,  AM/FM tuner, whose performance in most locations and with most broadcasts is audibly identical to that of many more expensive  and elaborate tuners. The 4020's quality of sound is limited only by the quality of the transmitted broadcast.
Recent dramatic advances in FM tuner circuitry, particularly in the development of inexpensive but high-performance "building block" circuit modules, have been incorporated in the 4020A to provide excellent sound at reasonable price.

Such crucial design parameters as sensitivity, low distortion and wide stereo separation have been given priority over the inclusion of costly superfluous features and esoteric circuitry whose benefits are totally inaudible except in rxtreme reception conditions. But no compromises whatsoever have been made in those performance areas which relate directly to the 4020's listening quality in normal and even somewhat difficult reception locations.
High Sensitivity
The "front end" tuning circuit, for example, employs a Junction FET amplifier, for an optimum combination of sensitivity to weak signals and resistance to cross - modulation from strong signals. The intermediate frequency (I.F.) amplifier, a high-gain IC, provides excellent limiting (static suppression), very good AM rejection (suppression of multipath interference), and smooth muting of interstation noise.
Low Distortion
While budget-price tuners commonly contain one or two ceramic I.F. filters, the NAD 4020A employs a total of three. Their sharp selectivity minimises interference from adjacent stations on the increasingly crowded FM dial, and their linear-phase respponse contributes to minimum distortion of stereo broadcasts. Multiplex stereo decoding is performed by the latest phase-locked loop (PLL) IC. In addition to low noise and wide stereo separation, the PLL decoder yields the lowest distortion in stereo reception - in particular, minimum inter-modulation between high audio frequencies and the 19 kHz stereo pilot tone.
Wide Stereo Separation
It is important to maintain wide stereo separation at low and high frequencies as well as the commonly specified 1 kHz midrange point. In the 4020A phase shift of the composite signal is minimised in order to preserve full low-frequency separation, and a special NAD phase-compensated crosstalk cancellation circuit increases high-frequency separation and minimises any residual distortion.
Instead of a costly and fragile moving-coil tuning meter the 4020A has a set of three LED indicator lights which form a remarkably simple and accurate meter. Either of two amber LEDs illuminates when the 4020A is mistuned to either side of a station frequency, and a green LED illuminates when the station is optimally tuned for minimum distortion 9within 0,025 MHz). The brightness of the green tuning LED indicates the signal strength, when it is dim the station is too weak for optimum reception.

For the music lover seeking uncompromised performance for a modest investment, the NAD 4020A is the logical choice. There are more costly tuners available, some of which have more impressive specifications,, but very few sound better in everyday use.
FM Tuner Section
Input Sensitivity
Mono -30db Total Harmonic Distortion+N :  10,9 dBf (1,9 µV/75 Ω)
Mono 50 dB S/N :  16 dBf (3,5 µV/75 Ω)
Stereo 50 dB S/N :  37 dBf (40 µV/75 Ω)
Capture ratio :  1,5 dB (45 - 65 dBf)
AM Rejection:  60 dB (45 - 65 dBf)
Selectivity:  65 dB
Image Rejection:  50 dB
IF Rejection:  75 dB
Harmonic Distortion:
Mono :  0,2%
Stereo :  0,3%
Signal-to-Noise Ratio:
Mono :  75 dB
Stereo :  70 dB
Frequency Response:  30 Hz - 15 kHz ±0,5 dB
Channel Separation:  42 dB (at 1 kHz)
AM Tuner Section
Usable Sensitivity:  250 µV
Selectivity:  30 dB
Image Rejection:  50 dB
IF Rejection:  40 dB
Power Rating:  220 V, 50 Hz   or 110 V, 60 Hz
Dimensions (W x H x D):  420 x 96 x 240 mm
Weight [Net/Shipping]:  4,2 kg / 5,6 kg

Boston Acoustic A70

In a stereo system, the loudspeakers are the key components. Because they are devices that you hear, the system can never be better than they are, if your speakers are less than excellent, accuracy will suffer, and so can your enjoyment.
The Boston Acoustic A70 is a highly accurate reproducer of music. In addition to faithfully recreating the full audible range of music, the A70 can image more accurately than most speakers offered at any price.

An accurate stereo image increases realism.
When you listen to a stereo system, close your eyes, and find out whether your mind's eye can "see" where each instrument is located.
Boston Acoustic speakers are well-known for their ability to recreate an accurate stereo image that increases realism and enjoyment. The slim profile of the A70 not only makes it easier for you to place the speaker unobtrusively in a room; more important from a music lover's point of view, the dimensions of the cabinet minimize unwanted sounds that would ordinarily muddy the stereo picture. The result is a crisp focused image.
Another characteristic that contributes to good imaging is a tweeter that's matched to the woofer in terms of its radiation pattern. A limitation of ordinary tweetere is that they radiate sound forward in a tight pattern, like a flash-light radiates light. In contrast, all woofers radiate over a broad area,like a table lamp. The tweeter incorporated in the A70 radiates in a very broad pattern, making the woofer and tweeter a well-matched team. Hence, the stereo image is clear and distinct.

The best combination of range and accuracy inn its price class.
The A70 maintaining the correct proportion while reaching farther into the bass than any other speaker in its price class. The quality of the drivers is largely responsible. The tweeter is the same one we use in most expensive nodel. The woofer is a helfty 8-inch driver designed to providethe best combinationof deep bass and efficiency. It reproduces the lowest notes in music - notes that most listeners never heat, except in live performances.

A room-size sound from as little as 15 watts
With very little  power, the sound of two A70 speakers will fill an average size room to overfloving. The A70 performs well with a receiver or amplifier as low as 15 watts per channel. Its efficiency means you can spend less money on your receiver or amplifier, and get excellent performance.

Frequency Response:  40 - 25,000 Hz ±3 dB
Impedance:  6 ohms nominal
Sensitivity:  1 watt produces 90 dB at 1 meter
Low-Frequency :  200 mm (8") long throw woofer with focused gap magnet assembly for low distortion
High-Frequency :  25 mm (1") soft dome tweeter with ferrofluid cooling
Crossover Frequency:   2000 Hz
Recommended Amplifier Power:  15 to 75 watts per channel
Power Rating:  75 watts nominal;  150 watts peak
Internal Volume:  28 liters
Cabinet Finish:  wood grain vinyl finish over non-resonant particle board
Dimensiond (W x H x D):  356 x  610 x 203 mm (14" x 24" x 8")
Weight:  11,8 kg (26 lbs)

Creek CD43

Creek compact disc player CD43 Features:
Infra-red remote control
High precision 24 bit, ΔΣ digital to analogue conversion
128 FS filter
3-beam optical laser pick up
16 program memory
LCD display - back lit green
Shuffle fnction ( random selection)
Repeat facility
Intro scan facility
Auto space facility

Frequency Response:  1 Hz - 20 kHz ±0,5 dB
Output Level :  2,2 V RMS at 1 kHz
Output Impedance :  600 Ω, min. Load 10 k Ω
Laser Type:  Semiconductor ALGaAs
Wavelenght:  790 nm ±25 nm
Light Output (cw):  0,18 mW typical
Signal-to-Noise Ratio:  better than 96 dB
Dynamic Range:  better than 100 dB
Number of Channels :  2
Total Harmonic Distortion:  less than 0,01% at 1 kHz
Power Requirements:  AC 220-240 V 50 Hz or AC 110-120 V 60 HZ
Power Fuse Rating:  T 250 mA or T 500 mA
Power Consumption:  15 Watts max

Dimensions (W x H x D):  420 x 70 x 289 mm