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





Elac PC-830 turntable

Getting back to basics

For all its seeming complexity, there are really only three basic requirements of any well designed turntable:

That the turntable platter rotate at a constant unvarying speed

The the tone arm enable the cartridge to trace the microscopic undulations in the record groove freely and accurately

That it be extremely reliable and trouble free.

The turntable proper

Let us examine the turntable mechanism first. In addition to rotating at an exact speed, a well designed turntable should be able to play a record with:

Minimum rumble - that is, it should not contribute any mechanical noise of its own to the music.

It should have undetectable wow and flutter. That means it must be free of slow and fast variations in pitch caused by momentary variations in speed.

Belt drive plus.

The primary cause of turntable rumble is the transmission of vibrations from the drive motor to the tone arm as it tracks the record.

Over the years, various methods have been devised to reduce rumble. Perhaps the simplest, most affective and reliable is the use of a belt drive system. By connecting an elastic belt from the drive shaft of the motor to the rim of the turntable platter, while the belt acts as a very effective mechanical filter damping out motor vibrations.

However, there is one drawback to this otherwise admirable system. It lacks sufficient torque or start up power to actuate the arm lifting and cycling functions quickly and efficiently.

To remedy this problem, Elac has designed an ingenious drive system with an idler assist called Belt Drive Plus, which is incorporated in the new Elac PC 830.

An idle wheel driven directly by the motor brings the platter up to speed quickly and indexes the arm over the lead-in groove of the record. As soon as the tone arm descends and the stylus touches the record, the idler is disengaged end the turntable operates in the belt drive mode only.

To reduce wow and flutter, the Elac PC 830 couples the motor to a heavy (4:4 pounds), dynamically balanced turntable platter. The mass of the platter in rotation creates a flywheel effect and very effectively smoothes out any momentary speed variations.

It's worth noting that the flat, precision ground rubber drive belt used in the Elac PC 830 is resistant to heat and humidity. Moreover, long term dimensional stability is insured through the use of an automatic belt release that reduces tension on the drive belt when the turntable is not in use.

Precise and continous speed monitoring is provided for via an illuminated strobe and a pitch control that is adjustable over a range of ±3% of nominal speed.

In addition, the Elac PC 830 satisfies another vital, but often overlooked, requirement of a well designed turntable. It incorporates a dual element, tuned suspension system that provides maximum isolation from external vibrations, thus rendering it virtually immune to acoustic feedback as well  as other sound bluring sources.


 The well behaved tone arm

Just as a well designed turntable should do nothing more than rotate silently at a precise, unvarying speed, so should the tone arm assume a completely bening role. Its only function, to present the cartridge to the record without let or hindrance.

But this is more easily said than done. For today's better cartridges play at such very low tracking forces, often 1 gram or less, that many tone arms are hard pressed to cope with them. As a result performance can be seriously degraded.

To operate properly at these very low tracking forces, a tone arm must be very light and rigid. In addition, it should have a very low moment of inertia, so as not to impede the movement of the stylus in the groove. But that's only the begining, a well designed tone arm should also have:

Very low mass, especially at the head where it counts most.

Very low tracking error. That is, its design geometry should permit it to remain as nearly tangent to the groove as possible, at any point on the record.

Skating or side thrust compensation to keep the stylus centered in the groove.

The ability to function properly with a wide veriety of cartridges

A cueing control for simple and precise manual operation

To successfully meet all these requirements. Elac has designed a superb new tone arm for the PC 830.

Special alloy, tubular construction makes it very light and rigid while significantly reducing mass. Freedom of movement has been optimized through the use of microprecision ball bearing races in both the vertical and horizontal pivos enabling the tone arm to perform faultlessly with most lightweight, high compliance cartridges.

To provide greater stability and further improve tracking, the tone arm is dynamically balanced which has the added advantage of making turntable leveling non-critical. The offset angle (geometry) of the head minimizes tracking error and a positive contact, slide-in cartridge mount permits precise adjustment of stylus overhang to further reduce distortion.

To insure perfect centering of the stylus, in the groove at any point on the record, a highly effective antiskating adjustment is provide for conical elliptical and CD-4 styli. Thus uneven groove wear and distortion are materially reduced. A viscous damped cueing  control sets the tone arm down gently anywhere on the record. And the same gentle lowering  action also comes into play during automatic operation.

The finishing touch

In the final analysis, however, any first rank turntable is more than a collection of features. It is a study in human engineering. It should respond instantly and effortlessly. It should enable you to play a single record or a batch of records whit a minimum of fuss and bother. In short, it should never get between you and the music .

 


Specifications

Drive System:  Precision ground belt plus idler assist

Operational Mode:  Single and multiple play

Speeds:  33-⅓ and 45 rpm

Speed Adjustment:  ±3%

Wow and Flutter (DIN) ±0,6%

Rumble DIN

Unweighted ;  better than 44 dB

Weighted :  64 dB

Tone arm: 205 mm tubular alloy

Tracking Error:  less than ±1,4 degrees

Tracking Force Adjustment:  0,5 - 4 grams

Platter:  285 mm diameter zink diecast

Platter Weigth:  4,4 pounds

Power Requirements:

Power Consumption:  15 watts

Dimensions (W x H x D):  435 x 175 x 350 mm

MBL 7006 amplifier

 

The MBL 7006 integrated amplifier is an excellent choice for music enthusiasts seeking a compact integrated amplifier.. Its exquisite visual appeal is matched by sophisticated engineering that puts it in the genuine high-end market. The clarity and precision of sound will blow your mind - but not your speakers. The MBL 7006 lends your music a power and a natural quality that are unparalleled in this class.

 


Specifications:

Inputs:  XLR, 2 CD, 2 High Level, processor bypass

Outputs:  Fixed out

Frequency Range:  DC -400 kHz

Signal-to-Noise Ratio:  103/107 dB

Input Impedance:  10 k Ω (CD)

Rated Power: 

120 W at 8 Ω

185 W at 4 Ω

Damping Factor:  300 (4 Ω)

Dimensions (W x H x D):  450 x 100 x 410 mm (18" x 4" x 16")

Weight:  15 kg (33 lbs)

Denon PMA-700V amplifier

Dual Super Non-NFB Power Amplification

The PMA-700V are high power amplifier equipped with a Dual Super Non-NFB power amplifier for crystal clear reproduction of digital sources. Added to his extremely pure non-feedback amplification system, the use of DC circuitry without a single coupling capacitor in the signal path from the MC input to the speaker output terminals and a new current mirror circuit in the voltage amplification stage, using high speed transistors with excellent high frequency response, all work to obtain a high slew rate of ±350 V/µsec.

Furthermore, a Pc 80W , Frequency Response 20 kHz multi-emmiter structured large chip power transistor is used for the output transistor. This outstanding output transistor and the mighty power source which greatly increases current supply capacity provide truly high power.

 

Pure Current Supply - decreases ynamic Intermodulation DIstortion Distrotion by 60 dB

The large size heat sink and toroidal transformer, as well as audio capacitors for large scale capacity (33,000 µF) increase momentary current supply capacity to the same level as high-output top-of-the-line separate power amps. The use of this Pure Current Supply circuit with Denon's original bridged block capacitor system suppresses dynamic Intermodulation DIstortion , and together with the high capacity power transformer provides high dynamic power.

Electronic Switches and Ideal Chassis Construction Eliminate External Noise

In order to eliminate the influence of magnetic and electrical noise, the chassis construction divides the power supply section and main signal circuitry at the heat sink, thus markedly reducing mutual interferences. In addition, electronic switches are used for the input se;ectors, reducing wiring and resulting in an ideal layout to make signal paths simple.

 

Two sets of Video Inputs

VCR or Laser Disc Video input selection is performed with a newly developed complimentary push-pull circuit which provides low distortion and wide range response (DC - 10 MHz ±1 dB) for excellent image transmission performance. One set of inputs is located on the back panel, and the other one is on the front panel for convenient use.

 


Specifications

Power Amplifier Section

Output Power Rated Both Channel Drives (Tuner - SP Out)

100 watts minimum rMS per channel, 8  load with less than 0,02% T.H.D. from 20 - 20,000 Hz

150 W + 150 W at 4  load, 1 kHz, DIN, T.H.D. 1%

120 W + 120 W at 6  load, 1 kHz, IEC, Subject to change by temperature test

Total Harmonic Distortion : 

0,004% (20 Hz - 20 kHz at -3 dB rated output 8  load)

0,0025% (1 kHz at rated output, 8  load)

Input Sensitivity/Impedance:  150 mV/30 k

Equalizer Amplifier Section

Equalizer Amplifier Output (Rec Out Terminal):  150 mV rated output

Input Sensitivity/Impedance:

Phono MM :  2,5 mV/ 47 k

Phono MC :  200 µV/100

Tuner, Aux, Tape, CD :  150 mV/30 k

Video 1, 2 :  150 mV/30 k

RIAA Deviation

Phono MM :  within ±0,2 dB (20 Hz - 20 kHz)

Phono MC :  within ±0,3 dB (20 Hz - 100 kHz)

Maximum Input Voltage

Phono MM :  160 mV/ 1 kHz

Phono MC :  12 mV/1 kHz

Signal-to-Noise Ratio (IHF A Network)

Phono MM :  94 dB (input terminals short-circuited for 5 mV input)

Phono MC :  75 dB (input terminals for 500 µV input)

Tuner, Aux, Tape, CD :  107 dB (input terminals short-circuited)

Video 1, 2 :  107 dB (input terminals short-circuited)

Tone Controls

Bass :  ±10 dB at 100 Hz

Treble :  ±10 dB at 10 kHz

Loudness Contour

Low Frequency :  +7 dB at 100 Hz

High Frequency :  +6 dB at 10 kHz

Subsonic Filter:  16 Hz , 12 dB/oct

Power Supply:  110/ 120/ 220/ 240 V 50/60 Hz

Power Consumption: 220 W 3,8 A (120 V)

Dimensions (W x H x D):  434 x 157 x 397 mm (17-5/64" x 8-3/16" x 15-5/8")

Weight:  10,5 kg (23 lb 2 oz)

Akai AA-1030 receiver

 

The Akai model AA-1030 , is another machine that's packed with power.

Minimum 30 watts per channel RMS at 8  from 20 to 20,000 Hz with no more than 0,3% T.H.D. And frankly we're probably being over modest. It's certainly worth emphasising here that the power rating is a minimum. Typical samples, when measured with both channels driven at 1 kHz into 8 , should demonstrate quite clearly the importance of comparing specification in power output.

There's a delicately balanced flywheel for picking your spot on the waveband. And with AFC (Automatic Frequency Control) you get perfect FM centre tuning with completely drift-free reception. A low noise FET and 3-gang frequency rectilinear variable capacitor in the front end eliminate intermodualtion distortion for clear broadcast reception. Ceramic filters in the FM IF section give better reception of weak signals. IHF sensitivity is 2,0 µV. The Phase-Lock-Loop circuit produces complete stability with separation better than 40 dB

As with the AA-1020, the AA-1030 also has variable FM muting to let you select not only the strongest stations and the weakest stations the tuner can pick up, but any point in between as well. There's also a level adjuster to allow you to cut out local atation interference. There are separate bass and treble tone controls; loudness switch; high and low filters; the same comprehensive tape dubbing facilities as the AA-1020 (you can connect two tape decks for simultaneous recording from a single source and Tape monitor 1 has parallel DIN and phone connections), two sets of phono jacks; aux jacks; connections for two speaker systems; FM and AM antenna terminals and a distance/local switch.

 


Specifications

Amplifier Section

Continuous Power Output: 

30 watts per channel , min. RMS, at 8 ohms from 20 Hz to 20 kHz, with no more than 0,3% T.H.D.

2 x 40 watts into 8  at 1 kHz, with no more than 0,3% T.H.D. both channel driven

2 x 50 watts  into 4  at 1 kHz, with no more than 0,3% T.H.D. both channel driven

Power Bandwidth (IHF) :  10 Hz to 60,000 Hz / 8  (Distortion within 0,3%)

Input Sensitivity/Impedance

Phono 1, 2 :  3 mV/50 k

Tape 1, 2 :  150 mV/80 k

Aux :  150 mV/80 k

Signal-to-Noise Ratio (IHF)

Phono :  better than 80 dB

Aux :  better than 90 dB

Channel Separation (IHF):

Phono :  better than 55 dB (at 1 kHz)

Equalizer Phono :  RIAA ±1 dB

Tone Controls

Bass :  ±10 dB at 100 Hz

Trebble :  ±10 dB at 10 kHz

Loudness Contour: +10 dB at 100 Hz; +6 dB at 10 kHz (Volume control set at -30 dB position)

Filter:

High :  -8 dB at 10 kHz

Low :  -8 dB at 50 Hz

FM Tuner Section

Frequency Range:  88 MHz - 108 MHz

Sensitivity (IHF):  1,9 µV

Capture Ratio (IHF):  1,5 dB

Selectivity (IHF):  better than 70 dB at 98 MHz

Signal-to-Noise Ratio :  better than 70 dB

Image Rejection:  better than 65 dB at 98 MHz

IF Rejection:  better than 90 dB at 98 MHz

Spurious Rejection:  better than 70 dB at 98 MHz

Harmonic Distortion

Mono :  less than 0,2%

Stereo :  less than 0,4%

FM Stereo Separation:  better than 40 dB ( at 1 kHz)

FM Muting:  Variable (2 µV to 100 µV) On-Off

Antenna Input:  300   (balanced), 75   (unbalanced)

AM Tuner Section

Frequency Range:  535 kHz to 1605 kHz

Sensitivity (IHF):  200 µV/m (Bar antenna); 5 µV (ext. Antenna)

Image Rejection:  better than 55 dB at 1 kHz

IF Rejection:  better than 45 dB at 1 kHz

Selectivity (IHF):  better than 30 dB at 1 kHz

AM Distortion:  less than 0,6%

Signal-to-Noise Ratio:  better than 50 dB

General Section

Semiconductors:  1 FET, 33 Transitors; 15 Diodes; 3 ICs

Power Requirements:  120 V, 220 V, 240 V 50/60 Hz

Dimensions (W x H x D):  440 x 140 x 350 mm (17,3" x 5,5" x 13,8")

Weight:  13 kg (28,6 lbs)