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





Sansui TA-2050

Separately Available Stereo Tonearm

This is the high quality precision-made TA-2050 stereo tonearm, virtually identical to the one that is standard equipment on the distinguished SR-2050C turntable, but now available as a separate item for those who desire the ultimate in sensitivity, tracking accuracy, tonal quality and service life. The only real difference between the TA-2050 and the tonearm of the SR-2050C is that the TA-2050's cuing control is integrated in its mounting base. Radiating functional beauty the TA-2050 is easily mounted on any quality turntable assembly, and will pay rich stereo dividends to its proun owners.


Light, sensitive instrument

The sensitive TA-2050 offers excellent resistance against bending and twisting, and expels proper resonance outside of the audible frequency range.

Very light, it allows the stylus to track the record groove fautfully ta an angle of 15 degrees to the record surface.

Aluminum Alloy Head Shell (1)

Designes to avert record-damaging "skips" - the headshell of the TA-2050 is made specially light punched aluminum alloy. Its edge is specially bent for increased rigidity and to help eliminate resonance, and the connecting plug, meeting the EIA standard, has special gold-plated, long-lasting terminals to assure safe connection.

Oil-Damped Arm Lifter (2)

The TA-2050 is complete with a silicon oil-damped arm lifter. A damp that gently lowers and raises the tonearm on the record, it permits even beginners to handle the tonearm without fear of damaging record or stylus.

Inside Force Canceler (3)

Designed from the standpoint of acoustics, dynamics and engineering to eliminate disruptive inside force, the TA-2050's inside force canceler or anti-skating device is free of the inertia of the tonearm and can be adjusted easily in proportion to the tracking force.

Main Weight (4)

The heliciod main weight can be rotated very easily to achieve horizontal balance and also to produce a stylus pressure of 0,5 to 3 grams in direct read-out 0,5 grams steps

Sub Weight (5)

To permit using the tonearm with a heavy 14 to 19 grams cartridge, the TA-2050 is equipped with a sub weight to aid in horizontal balancing.

Lateral Balancer (6)

The TA-2050 is complete with a lateral balancer to permit accurate adjustment of the lateral balance of the tonearm.

Friction-Free Bearings (7)

The TA-2050's bearing mechanism ensures friction-free vertical and horizontal rotary movements of the tonearm, enabling it to offer the same movenent in every direction in the record groove.

Adjustable Tonearm Height (8)

The TA-2050 can be secured at any desired height simply by moving it up or down and tightening the height adjustment screws.

Plug-in Output Plug (9)

The output cord for the tonearm has a 5 pin plug which only need be inserted into the output socket inside the tonearm base. No messy soldering is needed.

Specifications

Type: Static balanced

Overall Lenght: 302,4 mm

Effective Lenght: 220 mm

Adjustable Height Range: 67 - 115 mm

Overhang: 15 mm

Tracking Error: ±1,5°

Self Weight of Suitable Cartridge: 5 -14 gramms ( up to 19 grams by use of sub weight)

Self Weight of Head Shell: 9,1 grams

Tracking Force Adjustable Range: 0 - 3 grams (direct readout)

Head Connector: EIA Standard 4-pin connector

Accessory Devices: Inside force canceler, lateral balancer, silicon-damped arm lifter

Sansui XP-99

A turntable's dreaded enemy is vibration. Sansui's exquisite new XP-99 vanquishes this villain completelyy, and in unusual ways, as you'll see. Vibration robs music of its immediacy by making sound dull and lifeless. This happens beacuse vibration, when allowed to reach the tonearm, alters the actual geometry between the stylus tip and the record groove during play. The XP-99 activly and passively suppresses vibration. Actively suppressing vibration is our revolutionary Silent Synchrotor System. It is assisted by our "friction-free" linear coreless motor, D-O-B straight tonearm and solid, anti-vibration cabinet. Just one listen will convince you that the XP-99 sounds far superior to all other direct-drive turntables. It offers better definition, greater musical sonority and aharper transients.

Silent Synchrotor System

Despite the tremendous improvements that the direct-drive turntable has brought to hi-fi, many "golden eared" audiophiles have noted that they sound distant, fuzzy and unfocused. We have proven that there is a grain of truth to this complaint. In most direct-drive turntables, the motor is located near the center of the cabinet . When the motor rotates the platter clockwise, it applies a torque to the cabinet in the same direction. To compensate and restore balance, the cabinet attempts to create counterclockwise torque. This leads to a serious problem.

All direct-drive motors "cog" that is , they imperceptibly speed up and slow down in a jerky manner as the servo system tries to compensate for wow and flutter and other speed irregularities. These minute speed variations cause matching variations in motor torque, which in turn set up variations in countertorque generated in the cabinet. These variations are turned into actual physical vibrations that eventually find their way to the stylus. It is these vibrations that cause sound to be fuzzy and unfocused, because they change the delicate geometric relationship between the record groove and stylus.

The Sansui Silent Synchrotor System has felled this shortcoming of direct-drive turntables in a single blow. The second motor is mounted directly below the main drive motor and ahares the same axis. Controlled by the same servo system as the main motor, it rotates in the opposite direction, creating torque which exactly offsets the countertorque created in the cabinet.

Friction-free linear coreless motor

The motor we use in our Silent Synchrotor System is of an entirely new, high-precision design called the 'friction-free linear coreless motor'. It was expressly developed to overcome problems encountered by conventional coreless designs: Mechanical friction at the bearing due to strong magnetic attraction between rotor and stator; Drag on the rotor by the stator; Breaking effect on the rotor caused by eddy currents in the stator.

All these problems lead to ubeven rotation and undue mechanical wear.

Our new linear coreless motor has extremely low friction for the attraction between the rotor and stator is very low. Both drag and breaking effect applied to the rotor are reduced because the yoke rotor and rotor are mounted on the same spindle. Indeed, the motor of the XP-99 presents such low friction that, when spun by hand it keeps rotating on and on, almost like magic.

Straight D-O-B tonearm

The fulcrum of our D-O-B (Dynaoptium Balanced) tonearm is at the exact point of dynamic balance. As a result, there is no longer a mutual dynamic influence between the parts of the tonearm on either side of the fulcrum; vibrations picked up by the stylus never jeopardize the fulcrum's delicate balance, while outside vibrations never travel from the arm base to the stylus tip to alter the geometry between the stylus and the record. This is one more reason why the XP-99 delivers eminently superior sound.


Precision Double-Servo Quartz PLL System

A double-servo speed control system affords our linear coreless motor its highly accurate performance. As the platter starts up, the FG (Frequency Generator) servo applies a powerful accelerating torque to the motor, bringing the platter up to operating speed in 2 seconds. Then the Quartz PLL servo takes over, dynamically smoothing out the minutest fluctuations in speed. Our elaborate servo system and linear coreless motor provide amazingly low wow and flutter specs of a mere 0.012% (WRMS).

Computer-controlled fully automatic operation

A custom-made 4-bit microcomputer is at the heart of the XP-99, overseening every facet of turntable operation. It makes a number of automatic operations possible, including one-touch play, stop and repeat. It also fully protects the XP-99 from damage to turntable parts or the record on the platter . Manual operation, using the arm UP/DOWN button, is possible any time, of course.

Attractive solid cabinet

To prevent acoustic feedback and provide a solid base for the motor and tonearm, the cabinet is constructed of solid, high-density wood. Its exterior surface is finished to a deep piano-like luster. Controls, including tonearm UP/DOWN, are positioned outside the closed dust cover on a slanted front panel. The cabinet is exactly 430 mm wide, the same as other Sansui components.

A DC type head Shell

The tonearm comes with an ADC type head shell so you can easily change cartridges.

Moving-coil cartridge

The XP-99 comes complete with a moving-coil cartridge (AT-3100S) for crisp, transient sound. Unusual for an MC it features a user-replaceable sytlus.

Specifications

Type: direct-drive turntable

Speeds: 33 and 45 rpm

Platter: aluminium alloy diecast

diameter: 308 mm (12-1/8")

weight: 1,5 kg (3,3 lbs)

Motor: Coreless and Brushless DC with Quartz PLL servo

Wow and flutter: 0.012% (WRMS)

Signal-to-noise ratio: better than 78 dB (DIN-B), 62 dB (IEC-B)

Tonearm: statically-balanced type

Effective length: 230 mm (9-1/16")

Power voltage: 110-120V/220-240V 50/60 Hz

Power consumption: 15 W

Dimensions (W x H x D): 430 x 170 x 418 mm (16-15/16" x 6-11/16" x 16-15/32")

Weight net: 8.9 kg (19,6 lbs)

Specifications AT-3100S cartridge

Type: Moving-coil

Output voltage: 0,4 mV (1 kHz, 35,4 mm/sec)

Correct load impedance: 100 ohms

Frequency response: 20 - 23,000 Hz

Tracking forece: 1.7 ±0,3 g

Stylus: 0,5 mil diamond stylus

H. H. Scott 299 (1958 - 1966)

The H. H. Scott 299 is the ultimate in complete stereo amplifiers. Introduced just a year ago, it is now in use in more fine music systems than any other stereo amplifier in the world. it has won praise from many leading high fidelity experts. It eas "check-rated" and recommended by both leading consumer testing organizations. The 299 was selected for display at world expositions like the Moscow fair.

The proven 40 watt stereo amplifier will drive even the most inefficient speaker systems because its special subsonic filter directs all power into the audible music range and its output stage is of extremely conservative design. This fine amplifier gives you a unique combination of exclusive H. H. Scott features, advanced engineering and handsome apperance. If you are planning a truly fine music system the H. H. Scott model 299 complete amplifier is the ideal choice.

299-A (1958 -1960)

Stereo 40-watt Integrated Amplifier 17-wpc (RMS)

Scott's first "Stereomaster" Integrated Amp

"Christmas Tree" tri-function neon indicators, unique to 299-series

Bias control common to both channels

11 tubes:

(4) 12AX7

(2) 6BL8 (floating paraphase inverter w/AC balance pots)

(4) 7189

(1) 5AR4

299-B (1960-1961)

Stereo 50-watt Integrated Amplifier 21-wpc (RMS)

Larger transformers, changed phase splitters

Minor styling changes to knobs, indicators, logo/lettering, double-H, logo, replaced oval logo.

11 tubes:

(4) 12AX7

(2)6U8/6GH8 (floating paraphase inverter w/AC balance pots)

(4) 7189

(1) 5AR4

299-C (1961-1964)

Stereo 72-watt Integrated Amplifier 31-wpc (RMS) or 28-wpc (RMS) smaller transformer versions

Major upgrade for 299-series adapted from the older LK-72 (kit) 7591-design

Added Front-panel Headphone Jack,

More powerful final section center channel volume control some late "C" versions had 233 circuitry and smaller TRA-8-5-4 transformers

11 tubes:

(4) 12AX7

(2) 6U8 or 7199 (Split-load phase inverter)

(4) 7591

(1) 5AR4

299-D (1964-1966)

Stereo 80-watt Integrated Amplifier 34-wpc (RMS)

See 299C above See LK-72-B (kit)

S/N 249780 & up: used 233's output xformers: TRA-8-5-4

Updated, Extruded front panel styling

Minor service-related improvements

used wide "C" case/chassis

11 tubes:

(4) 12AX7

(2) 6U8 or 7199 (Split-load phase inverter)

(4) 7591

(1) 5AR4

Specifications

Frequency response: 20 - 30,000 Hz (with tone controls set flat)

Total Harmonic Distortion: 0,8% at full power output

IM Distortion: 0,3%

Noise and Hum:

Noise equivalent to 10 microvolts on low level input;

Hum better than 80 dB below full power output

Sensitivity Max.: 3 milivolts for rated output (will accomodate all low output pickups)

Outputs: Stereo Tape Recorder; 4, 8 and 16 ohm speaker output for each channel

Dimensions: 15½" x 5" x 12½" (W x H x D)

Audia Flight Pre

Audia Flight PRE MK3

The new reference quality Audia Flight PRE MK3 is designed for complete neutrality, allowing all the nuances and ambience in the music to shine through. Audia Flight PRE MK3 preamplifier is the perfect interface between source component and the power amplifier. Incorporating the excellent Audia Flight circuit design, highest quality volume control, and cabinet interior layout with isolation between key stages, the Audia Flight PRE MK3 exhibits complete transparency and lowest possible noise. The high current, Class A output stage, separate power supply for each channel and one for the logic control, the high quality input selector and constant impedance volume control, provides an extended frequency response, tonal accuracy and wide soundstage. Audia Flight PRE MK3 combines the merits of AUDIA FLIGHT circuit design based on the local feedback and the trans-conductance amplification, the use of a constant impedance attenuator with 0.5 dB steps and a chassis designed to get an a total separation among every stages, still keeping a single cabinet.

Cabinet

The cabinet plays a fundamental role in the realization of a preamplifier since its structure (and the corresponding placement of the boards) helps to fix the degree on immunity against external noises and of interaction among different internal stages.

In a preamplifier is also very important the shielding of audio boards with respect to transformers, since the stray flux could be “detected” and amplified by sensitive stages.

Audia Flight PRE MK3 is a single cabinet unit (the hypothesis of designing a “two chassis” unit has been left out for two main reasons: the problems connected with installation and encumbrance and the question of the alimentation cable that could have reached “worrying” length), however the internal volume is strategically divided to suppress interference, with the horizontal partition placed at half height. In the lower section are placed the three toroidal transformers into a secondary shield metal box and the main supply board, whereas in the upper section is placed the main audio board.

A massive sheet of damping material is stuck under the upper cover plate.

Since the Audia Flight PRE MK3 is microprocessor controlled, the control board is placed behind the front panel and it is closed in its proper volume in a metallic shell.

The cabinet is completely made of aluminium and has been made exclusively by means of Numerical Control (NC) units and laser machines; the front panel is realized starting from an aluminium ingot 25 mm – thick and worked out by means of NC micro millers.

Input selector

The input selector allows to choose four unbalanced inputs and two balanced ones by means of sealed relays in inert atmosphere and with golden terminations.

Only the selected input is connected to ground.

Supply stage

The main supply stage of Audia Flight PRE MK3 is placed in the lower part of the cabinet. Here, in fact, there are two toroidal 50VA transformers (one for each channel) and a third 15 VA one to feed the control logic.

All transformer are explicitly made for audio applications, that is designed to have the least stray flux but, at the same time, with a great driving ability. The 10.000 Gauss core plate is autoclave resin sealed and dried in oven. The coils are realized with automatic machine-tools assuring the appropriate wire tension.

The three toroidal transformers are close into a secondary shield metal box.

The high-current supply stages for the audio sections are realized exploiting, in each channel, four “Ultra Fast Recovery” diodes with bypass capacitance to eliminate possible commutation noises of the diodes. There are eight filtering capacitors by 3.300µF 63 V (52.800µF total) with high discharge velocity (low internal impedance) and discrete stages stabilizer , for a stabilized output tension of 50 + 50 V.

The third supply stage, the one for the control logic, uses EMI filters and an integrated stabilizer.

Moreover, on the amplification board are inserted four more dual discrete stages stabilized supply units per channel, that provide the alimentation of the various section of the amplification board, drastically reducing interference among different stages in the preamplifier.

In practice, Audia Flight PRE MK3 is endowed of a whole 18 stabilization circuits just for the audio stages supply, each designed as a discrete stage.

Attenuation control (volume)

Achilles’ heel of many preamplifiers is represented by the volume-control since usually this introduces a variable impedance element as a function of the attenuation value (that is of the position of the potentiometer).

The result is that the frequency response, the slew-rate and even the internal impedance couplings among different stages are not fixed but are function of the attenuation value (volume).

This is a problem which affects above all the potentiometers; using instead integrated attenuators (I.C. dedicated to volume control or the use of D/A converters) solves the problem of variable impedance, but not that of the frequency response and of the absolute velocity response.

For this reason, AUDIA FLIGHT developed a constant impedance attenuator, realized with discrete components (low-noise metallic film resistors), which provides a gain range as high as 127 dB, with constant steps of 0.5 dB.

The result obtained probably overcome the wall of standard performance, since Audia Flight PRE MK3 grants an extremely extended frequency response (3Hz / 1MHz –3 dB) and the high value of slew rate (> 250V/µs in all the gain range (-90 / +10 dB).

As the volume is micro controlled one, all interconnections between the analog stage and digital stage are insulated using hi-speed fotocoupler

Gain stage

The gain stage of the preamplifier is realized using AUDIA FLIGHT technique, that is using a current-feedback circuitry, entirely A – class biased and realized with discrete components.

As sketched in the section about “alimentation” is fed by four stabilized independent stages per each channel: one for the input buffer, one for the input stages for the signal amplification, one for the current mirror and the last for the output stage.

The high-current low-noise output stage, made of audio-use transistors, A-class biased, is not closed in the feedback ring.

Control logic

The hearth of this section is based on the use of an 8 bit micro-controller endowed with a 16 Kbyte ROM.

The control of peripherals is given to two PIO devices, to get the control of the 40 characters fluorescent alphanumeric display, of the infrared receiver, of the custom optical encoder, the buttons and the relays.

Remote control

The remote control too, as the front panel, is realized starting from an aluminum ingot later milled.

The surface is firstly completely brushed, then anodized.

Technical Data

Input: 2 balanced XLR / 4 unbalanced RCA

Gain range: -90 dB / +10 dB

Gain resolution: 0.5 dB

Frequency response (1W rms -3dB): 3 Hz ÷ 1 MHz

Slew-Rate (on 8 ohm): > 200 V/μS

THD: < 0,05 %

S/N Ratio: 95 dB

Input impedance: 680pF Unbalanced 51 Kohm

Balanced: 30 Kohm

Output impedance: Unbalanced 12 ohm

Balanced: 50 ohm

Main voltage AC (50/60Hz): 100, 110-115, 220-230,240 V

Power consumption: 60 W

Dimensions (W x H x D): 420 x 113 x 380 mm

Weigth: 12 Kg

Shipping dimensions and weigth 570x270x540mm (wxhxd) - 15 Kg

Audia Flight 100

Audia Flight 100 MK4 – A Class Power Amplifier

The uniquely designed circuitry of the Audia Flight 100 MK4 provides a powerful output with ultra-wide bandwidth and a high slew rate for a detailed, fast and smooth sound. The stable, high current capability increases bass response and gives the Audia Flight 100 MK4 control over even the most difficult loudspeaker loads. The Audia Flight 100 MK4 allows the listener to hear the recording in a powerful, accurate and musical way. The Class A, dual-mono design ensures high resolution and low noise. Two 700VA epoxy sealed toroidal transformers, sixteen transistors per channel enable the amplifier to deliver wide dynamic range with greater headroom extension.

Technical Data

Output power: 100/200/400 W rms 8/4/2 ohm

Gain: 26 dB

Input sensitivity: 1.41 Vrms

Frequency response: 0,3 Hz ÷ 1 MHz (1W rms -3dB)

Slew-Rate (on 8 ohm): > 200 V/μS

THD: < 0,05 %

S/N Ratio: 108 dB

Input impedance Unbalanced: 24, 28, 42, 57 Kohm

Balanced: 23 Kohm

Damping factor: 85 (on 8 ohm)

Main voltage AC (50/60Hz): 100, 110-115, 220-230, 240 V

Power consumption: 500 W, 1400 W MAX

Dimensions (W x H x D): 470 x 245 x 540 mm

Weigth: 52 Kg

Shipping dimensions and weigth: 540x400x620mm (wxhxd) - 60 Kg

Audia Flight 50

Audia Flight 50 MK4 – A Class Power amplifier

The new Audia Flight 50 MK4offers the same engineering and construction as the Audia Flight 100 MK4. The uniquely designed circuitry of the Audia Flight 50 MK4 provides a powerful output with ultra-wide bandwidth and a high slew rate for a detailed, fast and smooth sound. The stable, high current capability increases bass response and gives the Audia Flight 50 MK4 control over even the most difficult loudspeaker loads. The Audia Flight 50 MK4 allows the listener to hear the recording in a powerful, accurate and musical way. The Class A, dual-mono design ensures high resolution and low noise. Two 400VA epoxy sealed toroidal transformers, eight transistors per channel enable the amplifier to deliver wide dynamic range with greater headroom extension.

Technical Data

Output power: 50/100/200 W rms 8/4/2 ohm

Gain: 26 dB

Input sensitivity: 1 Vrms

Frequency response: 0,3 Hz ÷ 1 MHz (1W rms -3dB)

Slew-Rate (on 8 ohm): > 200 V/μS

THD: < 0,05 %

S/N Ratio: 110 dB

Input impedance Unbalanced: 24, 28, 42, 57 Kohm

Balanced: 23 Kohm

Damping factor: 80 (on 8 ohm)

Main voltage AC (50/60Hz): 100, 110-115, 220-230, 240 V

Power consumption: 250 W, 900 W MAX

Dimensions (W x H x D): 470 x 186 x 440 mm

Weigth: 30 Kg

Shipping dimensions and weigth: 540x350x550mm (wxhxd) - 37 Kg

Boston Acoustics A40 (1985)

In our continuing effort to lower cost of high performance stereo systems, we are pleased to announce the introduction of the Bosto Acoustics A40. Housed in a 343x210x197 mm deep wood-grained vinyl enclosure, the A40 uses a newly-designed 170 mm woofer manufactured by Boston Acoustics and a ferrofluid-damped 19 mm tweeter.

Tha A40 is ideal for moderate-sized rooms, dorms, dens, bedrooms, you name it - either as a primary or extension speaker. its imaging capability is unique in its price range, and its dispersion is exceptional. This remarkable performance makes the A40 a stiff competitor to anything at or near its price, and its compact size permits a wide range of placement options.

Specification

Drivers:

6½" (170 mm) long throw woofer,

¾" (19 mm) ferrofluid cooling tweeter

Frequency response: 68 - 20,000 Hz, ±3 dB

Sensitivity: 88,5 dB at 1 watt/1 m

Impedance: 8Ω (nominal)

Crossover frequency: 3500 Hz

Recommended power : 5 to40 watts

Dimension: 343 x 210 x 197 mm (13½" x 8¼" x 7¾")

Weight: 4,1 kg (9 lbs)

Cabinet finish: wood grain vinyl over non resonant particle board

B & W DM 320

DM 320; Floor-standing loudspeaker system

Model Dm320 follow in the successful tradition of B&W's 100 and 500 Series loudspeakers, incorporating features normally found in much more expensive systems to improve performance in terms of lower colouration, higher power handling and greater dynamics.

Product Summary

If greater efficiency and bass extension are called for then the DM320 with its larger

enclosure and the 3-way system comes into its own.

Equipped with two 8in bass units in a closed box configuration and the acclaimed magnetic

fluid-cooled, light-alloy domed tweeter offers an extended low frequency range with higher

sensitivity.

Technical highlights

The use of a aluminium domed tweeter immediately distinguishes the two models. The specially

created 26mm (1in) tweeter enables high power handling to cope with the heavier usage

imposed on modern hi-fi systems. Frequencies in excess of 20kHz are within its range.

Subtle changes to the cabinet such as the tweeter plate, and bevelled front edges of the cabinet,

help produce a dramatically more even frequency response. The B&W tradition of attention to

detail manifests itself other features, such as the reinforced low-frequency driven diaphragm, the

rigid die-cast chassis, and the provision for bi-wiring or bi-amplification.

Description:

3-way 3rd-order, closed box digital monitor system with bi-wiring/biamplification facility

Drive Units:

1 x 26mm high-frequency with metal dome

2 x 200mm bass/midrange with rigid die-cast chassis, reinforced polypropylene and 31mm high temperature voice coil on Kapton® former

Frequency range: -6 dB at 45 Hz and 30 kHz

Frequency Response: 60 Hz – 20 kHz ± 2dB

Reference Axis: horizontal 150 mmfrom top of cabinet

Sensitivity: 91 dB spl(2.83V 1m)

Nominal Impedance: 8 ohms

Crossover frequency: 400 Hz and 2,5 kHz

Power Handling: 25 W – 100 W into 8 ohms on unclipped programme

Internal volume: 33,4 litres

Dimensions (H x W x D): 656 x 262 x 280 mm (25,8 x 10,3 x 11 inches)

Weight: 12,3 kg (27 lbs)

Finish: Anthracite, black ash or walnut vinyl

Revox B 750 (1980)

Revox B750 Amplifier

This compact full amplifier transfers even extreme Crescendi from breath to Furioso in impressive purity. In order to be able to build the compact amplifier Revox B750, only musical high points had to be analyzed and over nostalgic tubes strengthened. The quality of an Revox B750 amplifier can be based not simply on its wattage, but to it, how distortion-free it shows the music. In addition, it is nearly unbelievable, which an amplifier must carry out. It processes even high-complex signal forms both with smaller as well as with largest volume in such a manner purely that remaining distortions can be only proven with most modern measuring methods.

In order to avoid distortions, with the tube amplifier the inverse feedback principle was already used. Simply expressed: A part of the output signal is attributed gegenphasig again to the entrance. The unevenness and distortions which are due to the reinforcement are waived by the revolution of the phase to a large extent.

In the transistor age one could increase this inverse feedback so strongly that rattle/clink became insignificant. But HiFi is now once a quality criterion, which one does not measure so much as feel can: The fine ears of fastidious Revox B750 discover physiological sound differences, to which with measuring instruments hardly is despite - or straight because of - this improvement to be gotten. They praise the warmer, rounder, fuller "tube sound" opposite the harder, cooler, more pointed Transsistorsound.

STUDER REVOX solved the problem of the TIM distortions (TIM or TID, transiently intermodulation Distortion) by complex measures: The output stage is full-complementary, symmetrical. Simply said: The positive and the negative side of the signal are symmetrically strengthened in separate transistors, from the entrance to the exit. The einzelstufen are approximately coupled in itself, so that only a small total inverse feedback is necessary. Also without this total inverse feedback (factor 1:20) the Revox B750 amplifier is "clean". All this sounds plentifully complicated; the more clearly however the in such a way intensified music sounds, and that is in the long run crucial. The first TIM free Revox power amplifier A740, a professional high speed output stage, excited large attention among experts and with the descriptor "in itself more cleanly, by impulse distortions of free amplifiers" was distinguished. The same concept was used also with the compact amplifier Revox B750. This trailblazing audio technology naeherbringt certainly the HiFi rendition of the musical truthfulness a large step.

Revox B750. The amplifier clean in itself The research found out: Transistor amplifiers have more trouble opposite high-quality tube amplifiers with "transient ones". Transiently is called volatilely, rapidly temporary - and transient ones occur in the music frequently: Shortest dynamic jumps, about a triangle clay/tone, a trill, a strong piano notice. They lead to short, but complex impulse distortions, which are too fast around a tiny little thing, when they could be corrected by the inverse feedback. Result: The Revox B750 amplifier is briefly overridden; the phase shift in the correction leads within the range of high frequencies to short, substantial distortions. While the "recovery period" the modulation which can be transferred is suppressed.

Specifications

Power Output: 60 watts into 4 ohms; 40 watts into 8 ohms

Total Harmonic Distortion: less than 0.2 % at any level up to rated output

Frequency response: 20 Hz - 20 kHz ±0.5 dB

Damping factor: better than 75 at 8 ohms

Inputs (sensitivity for 60 watts (4 ohms) / input im­pedance):

Tuner, Aux, Tape 1 +2: 200 mV/100 kohms

Phono 1: 1.5 - 7 mV/25, 50, 100 kohms (selectable)

Phono 2: 1.5 - 7 mV; nominal 5 mV/50 kohms

PWR AMPIN: 1 V/10 kohms

Overload levels:

Tuner, Aux, Tape 1+2: 9V

Phono 1, 2: 400 mV

Outputs:

Tape 2/Out (DIN): 6.5 mV/RL 10 kohms

Speakers A, B: 15.5 V/R min. 4 ohms;

Tape 1, 2 (phono sockets): 200 mV/RL min. 50 kohms

Tape 2 (Jack): 200 mV/RL min. 50 kohms

PRE AMP Out: 1 V/RL min. 10 kohms

Phones x 2: 15.5V/Ri 100 ohms

Signal to noise ratio, (with reference to 60 watts / 4 ohms):

Tuner, Aux, Tape 1, 2: better than 90 dB, (unweighted input termination 10 kohms)

Phono 1, 2: better than 70 dB, (unweighted input termination 2.2 kohms)

Channel separation (at 1000 Hz): better than 60 dB

Phono equalization (as per I EC 98 MOD 4 1976): 20 Hz - 20 kHz ± 0.5 dB

Tone controls:

Bass: ±8 dB in 2 dB steps at 120 Hz

Treble: ±8 dB in 2 dB steps at 8 kHz

Presence: ±8 dB in 2 dB steps at 3 kHz

Filter:

Low: 50 Hz, -3 dB (12 dB/octave)

High: 8 kHz, -3 dB (12 dB/octave)

Loudness: Volume -30 dB, 100 Hz; + 6dB, 10 kHz + 4dB

Semiconductors:

4 IC (voltage regulation), 107 transistors, 4 bridge rectifiers, 52 diodes

Current supply: 220/240 V, 50/60 Hz

Power consumption: 50 - 350 watts

Dimensions (W x H x D): 452 x 151 x 348 mm (17,8 x 6 x 13,7 inch)

Weight: 13 kg (28 lbs 10 ozs)

ElectroVoice EVR-200


12" low-frequency radiator
The EVR-200's low-frequecy radiator looks like a woofer but has no voice coil or magnet. yet, unlike the "ports" or "passive radiators" of many conventional bass reflex enclosures, the low-frequency radiator actually reproduces the lowest octave of system bass response. It is driven to full, low-distortion output by a relatively small motion of the woofer itself, interacting with the air inside the enclosure. A molded half-roll urethane foam surround provides stable, linear suspension of the moving system.
8" soft dome midrange-woofer
Because the low-frequency radiator produces the lowest bass, woofer diameter has been reduced for improved performance in the mid-bass and critical midrange. The high-frequency response of the 8-inch cone and soft fabric dust dome is precisely what is required to blend properly with the tweeter. only a single low-loss air-core inductor is needed for seemless crossover. The smail cone size provides wider midrange dispersion than the typical 10- or 12-inch woofer, distributing voices and other midrange sources throughout the listening area with unusually uniform quality. The light cone produces fast, tight reaction to the upper registers of bass instruments, for extraordinary clarity and definition.
Cone tweeter
The exceptional dispersion of the shallow, curved 2½-inch tweeter cone blends perfectly with the high performance midrange/woofer. Tweeter frequency response is essentially flat to 20 kHz, with uniformly excellent transient response. A first-order high-pass circuit protect the tweeter from undesired input below the 1500 Hz crossover frequency. A tweeter level control "tilts" response above crossover, matching to room acoustics or personal taste.
Specifications
Frequency response: 30 -20,000 Hz
Sound pressure level: 92 dB (1W/1m)
Nominal impedance: 8 ohms
Suggested amplifier ratings: 5 to 60 watts (RMS per channel at 8 ohms) max.200 watts
Midband power capacity: 200 watts short-term (10 ms); 20 watts long-term average
Crossover points: 76 Hz acoustic; 1500 Hz electrical
Dimensions: 16 x 27½ x 13½ inches
Weight: 35 lbs

ElectroVoice EVR-200


12" low-frequency radiator
The EVR-200's low-frequecy radiator looks like a woofer but has no voice coil or magnet. yet, unlike the "ports" or "passive radiators" of many conventional bass reflex enclosures, the low-frequency radiator actually reproduces the lowest octave of system bass response. It is driven to full, low-distortion output by a relatively small motion of the woofer itself, interacting with the air inside the enclosure. A molded half-roll urethane foam surround provides stable, linear suspension of the moving system.
8" soft dome midrange-woofer
Because the low-frequency radiator produces the lowest bass, woofer diameter has been reduced for improved performance in the mid-bass and critical midrange. The high-frequency response of the 8-inch cone and soft fabric dust dome is precisely what is required to blend properly with the tweeter. only a single low-loss air-core inductor is needed for seemless crossover. The smail cone size provides wider midrange dispersion than the typical 10- or 12-inch woofer, distributing voices and other midrange sources throughout the listening area with unusually uniform quality. The light cone produces fast, tight reaction to the upper registers of bass instruments, for extraordinary clarity and definition.
Cone tweeter
The exceptional dispersion of the shallow, curved 2½-inch tweeter cone blends perfectly with the high performance midrange/woofer. Tweeter frequency response is essentially flat to 20 kHz, with uniformly excellent transient response. A first-order high-pass circuit protect the tweeter from undesired input below the 1500 Hz crossover frequency. A tweeter level control "tilts" response above crossover, matching to room acoustics or personal taste.
Specifications
Frequency response: 30 -20,000 Hz
Sound pressure level: 92 dB (1W/1m)
Nominal impedance: 8 ohms
Suggested amplifier ratings: 5 to 60 watts (RMS per channel at 8 ohms) max.200 watts
Midband power capacity: 200 watts short-term (10 ms); 20 watts long-term average
Crossover points: 76 Hz acoustic; 1500 Hz electrical
Dimensions: 16 x 27½ x 13½ inches
Weight: 35 lbs