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

ESS amt-1a

A loudspeakers translates electrical impulses into sound waves: Ideally,the loudspeakers/translator leaves nothing out and puts nothing extraneous in. It doesen't omit or color or mask. The perfect translator is perfectly simple. Simple and impossible until the Heil AirMotion Transformer revolutionized sound reproduction. The Heil midrange/high-frequency transformer is the perfect translator. There is only one compact system with a full-size Heil. The ESS amt-1a Bookshelf system. perfectly simple.

Your ears will appreciate the difference

Air-Motion Transformation: Midrange/High-Frequency

The Heil transformer, like most significant innovations, is much appreciated but a little mysterious. It is mandatory equipment for master reproduction techniques, yet the technological basis for its performance is often taken for granted. Actually, the Heil Principle of Air-Motion Transformation is as elegantly simple as it is effective.

The transformer's diaphragm resembles a lightweight pleated curtain mounted between powerful ceramic bar magnets. Conductive strips on the sides of each pleat cause the pleats to expand or contract in step with the signal. The air is squeezed out, and accelerated to five times the velocity of the diaphragm itself. In effect the Heil transformer uses air to move air, operating on the principle of pneumatic leverage.

Cone driving systems, on yhe other hand, are sluggish and inefficient by design. The cone's mass is huge, driving energy is largely devoted to overcoming its great inertia. The cone resonates and can "break up" at high frequencies. Acone driver only pushes air like a piston, in a one-to-one ratio.

The Heil driver's air-motion transformation ratio is five times better than that of any conventional speaker.

Other crucial design parameters are solved by the Heil Air-motion Transformer. The extremely light weight of its diaphragm eliminates resonance. Since the driving impulse is spread uniformly over the diaphragm surface, harmonic distortion from "cone breakup" is non-existent. These are inherent benefits of the Heilo design. For conventional speakers, they remain problematic goals.

REmarkable dispersion characteristics are another natural advantage of the amt's desugn. With a 120° pattern at 16 kHz, the amt maintains a solid expanse of stereo imagery to frequencies beyond audibility. Whatever the speaker/listener positioning, imaging is precise and penetrating.

The audible payoff is clarity, a perfect re-creation of the music 's fine and changing texture. Female vocal depth, the harmonic complexities of bow against string, and fleeting nuances of program ambience emerge with presence, immediacy, and power. It's all there.

Low Frequency performance

Deep, articulate low frequency response is provided by teh same 12" bass driver used in the top system of the ESS line, the amt-1a. Its 7 lb. 6,5 oz (3,36 kg) magnet assembly, rigid die-cast frame, and large-radius coil ensure state-of-the-art bass performance and dependability - response that feels substantial in the lower registers.


The amt-1a Bookshelf system is designed to convert high power loads into clean; full sound, without effort and without distortion. The air-motion transformer's Teflon diaphragm both resists and dissipates heat outstandingly. The bass driver's 2" coil and high-temperature cone composition are significant factors in the system's low-end strength. "At power" the amt-1a Bookshelf is clear and dependable after other compact systems have reached their limits.

Dividing Network

The sophisticated crossover network designed for the amt-1a Bookshelf operates at 850 Hz, providing excellent woofer/amt phasing and precise signal distribution. Air-cored inductors are used to avoid the high-amplitude distortion possible with metal cored units. Altough air-cored inductors are an unseen refinement, they significantly enhance the linearity of a dividing network.


Your listening environment's acoustic character may prompt some fine adjustment of teh speaker system. A continuosly variable attenuation or accentuation control affects 850 Hz to beyond hearing, without blunting or peaking the higher frequencies and upper harmonics. The control panel is situated at the rear of the cabinet for easy access.

The construction of the amt-1a Bookshelf speaker enclosure reflects the same concern for distortion-free reproduction shown in the system's hardware. The interior dimensions of the enclosure are meticulously coordinated to the bass driver's specific characteristics. precise mathematical tuning determines port design.

Walnut veneer is matched, fitted to the cabinet superstructure, and hand-finished from sanding to final rubdown. A strong weave of sonically-transparent polyester fiber is used in the grille treatment, completing the speaker's appearance of simple, Functional grace.

The Final Arbiter

A classic integrity, from cabinetry to driver mounting detail, pervades the manufacture of the amt-1a Bookshelf. Its superiority can be demonstrated in many ways, reflected at lenght in technical data. But to the final arbiter, your ear, There is only proof. The audible proof. A critical evaluation of the amt-1a Bookshelf speaker system will reveal how perfect translation can be.


Power Capacity: 75 watts continuous ; 350 watt peak Circuit breaker protected

Nominal Impedance: 4 ohms

Dispersion: 120 ° horizontal, 30° vertical

Crossover frequency: 850 Hz

Efficiency: 1 watt input produces 82 dB sound pressure at a distance of 15 feet (4 m)

Frequency Response: 50 - 20,000 Hz, ±3 dB

Heil Air-Motion Transformer

Total Radiating Area: 29 sq. in. (187,24 cm²)

Transformation Ratio: 5.0:1 velocity increase

Magnet Assembly Weight: 12 lbs. 15 oz. (5,87 kg)

Flux Density: 4,500 Gauss

Square Wave Rise Time: 15 microseconds at 5,000 Hz

Low Frequency Driver

Nominal Diameter: 12" (30,48 cm)

Voice Coil: 2" (5,08 cm)

Magnetic Assembly Weight: 7 lbs. 6,5 oz. (3,36 kg)

Flux Density: 10,500 Gauss


Midrange/High Frequency: Continuously variable attenuation oraccentuation from 1 kHz to beyond audibility


Finish: Oiled walnut veneer

Grille Color: Brown

Dimensions: 24" x 14" x 14" (60,96 x 35,56 x 35,56 cm)

Shopping Weight: 60 lbs (27,27 kg)

ESS amt-1b

Audible excellence is desired of every component in a high fidelity system. But the finest electronics can sound only as good as the loudspeakers they are played through. The newly refind and improved amt-1b Bookshelf owes its excellence largely to the Heil Air-motion transformer midrange-tweeter, the most revolutionary loudspeaker development of the past half-century. Unexcelled system coherency and balance is made possible by technically advanced crossover circuitry and newly improved low frequency system. Equal care in the construction of the handsome cabinet assures structural rigidity and acoustic superiority. The amt-1b Bookshelf is the finest bookshelf system ESS makes. Indeed, it is one of the finest in the world.

The Heil Air-motion transformer midrange-tweeter.

The remarkable Heil air-motion transformer is truly a monumental breakthrough in loudspeaker design, far superior to conventional cone drivers. The heil's light-weight Teflon diaphragm, equivalent in surface area to an eight inch midrange, is accordion-folded into a one inch pleated band. The diaphragm squeezes air between its pleats at five times its own speed, resulting in extremely swift air acceleration.

Each characteristic of the Heil contributes to an actual, audible superiority:

Its large driving area results in reduced distortion and increased dynamic range.

Folding this large area into a small point source results in superior dispersion and freedom from "boxiness".

The low mass of the lightweight diaphragm yields high efficiency and "instant acceleration".

High transformation, low diaphragm velocity and instant acceleration all lead to greater dynamic range and superb transients

The accordion-like pleats provide an evenly distributed drive. By preventing cone "break up", the pleats contribute to the Heil's great clarity and high definition.

The versatile amt-1b Bookshelf is the most compact system to incorporate the full-size Heil, the same one found in the incredible Transar/atd full-range Heil sound system by ESS. This newest version of the "Great" Heil offers a smoother, flatter response, owing to a new refinement in the folded "hinge" area of its diaphragm.

The superiority of the Heil air-motion trnsformer over conventional drivers is as dramatic as that of a jet aircraft over an old propeller plane. It is simply superior in too many ways and by too great a degree to be comparable.

The ESS Bextrene low frequency driver

Like the floor-standing 1b, the Bookshelf is equipped with an exceptionally rugged vacum-formed Bextrene low frequency driver newly improved and built entirely by ESS. Developed by BBC studio engineers for studio reference systems. Bextrene is a polystyrene compound with exceptional properties not found in pulp cones:

Low mass. High structural rigidity. Great internal molecular damping for superb quieting. Less susceptible to resonance and masking distortion. Greater clarity and accuracy.

Passive radiator

A rear-mounted 12" passive radiator operates in tandem with the Bextrene woofer to augment bass response. The passive radiator serves the same purpose as a port, but avoids the distortion added by a port or the loss of efficiency inherent in acoustic suspension systems.

Crossover circuitry and controls

Improved phase response, greater power handling capability and improved driver damping in the crossover region are all results of the 1b Bookshelf's completely new frequency dividing network. This sophisticated parallel type 1,000 Hz crossover assures proper matching of the woofer with the Heil by means of a steep 18 dB per octave slope.

The amt-1b Bookshelf now includes the same dual controls as the floor-standing system. They allow the listener to achieve precisely the midrange and high frequency performance desired.

Hand crafted cabinetry

The uncompromising performance of the amt-1b Bookshelf is also due in part to a cabinet design that is acoustically efficient as well as handsome. Each is made of select walnut veneers and is meticulously hand sanded, oiled and waxed to a silki sheen. An acoustically transparent rich brown grille provides the perfect finishing touch.

The amt-1b Bookshelf is, in every detail, the finest instrument ESS is capable of making in this convenient format. Keenly responsive faithfully accurate the 1b Bookshelf is the ultimate bookshelf system.


Full System

Power Capacity: 375 watts (clean music power)

Nominal Impedance: 6 ohms minimum

Dispersion: 120 ° horizontal, 30° vertical

Crossover frequency: 1,000 Hz

Efficiency: 1 watt input produces 90 dB sound pressure at a distance of 1 m

Frequency Response: 40 - 23,000 Hz, ±3 dB


Presence/Brilliance: Continuously variable attenuation from +3 dB to -∞ from 1,200 Hz to beyond audibility

Heil Air-Motion Transformer

Total Radiating Area: 21,5 sq. in. (139 cm²) equivalent to an 8" cone

Square Wave Rise Time: 15 microseconds at 5,000 Hz

Transformation Ratio: 5,3:1 velocity increase

Magnet Assembly Weight: 12 lbs. 15 oz. (5,87 kg)

Flux Density: 4,500 Gauss

Low Frequency Driver

Nominal Diameter: 12" (30,48 cm)

Cone Materials: Bextrene

Voice Coil: 2" (5,08 cm) Copper bonded with high temperature epoxy to an aluminum former

Magnetic Assembly Weight: 7 lbs. 6,5 oz. (3,36 kg)

Flux Density: 10,500 Gauss

Insulation: Single polythermaleze

Passive Radiator

Nominal Diameter: 12" (30,48 cm)

Diaphragm Material: .5 in rigid EPS styrene foam base material laminated to a damping skin of 250" open cell foam . Unitary free air resonance: 5 Hz


Finish: Oiled walnut veneer

Grille Color: Black/Brown

Dimensions (H x W x D0: 24" x 14" x 14" (60,96 x 35,56 x 35,56 cm)

Shopping Weight: 65 lbs (29,48 kg)

Heil Air-Motion Transformer by ESS

Figure 1

The heart of the Heil air-motion transformer is a featherweight pleated Teflon diaphragm bonded with conductive aluminum strips. The diaphragm is suspended within a massive magnet structure. Its steel conductor plates concentrate an intense magnetic field around the diaphragm.

When a signal passes through the diaphragm's foil strips, the bellows-like motion of the pleats squeezes air out at five fimes the speed of the vibrating diaphragm itself. This virtual "instant acceleration" distinguishes the Heil from all other loudspeakers.

Figure 2

Polar response curves at a wide range of frequencies reveal a broad horizontal dispersion pattern through-out the audible spectrum. The ability of the Heil air-motion transformer to disperse even the highest frequencies over a large area assures full stereo imaging anywhere in the listening environment.

Figure 3

The superior response of the Heil air-motion transformer is revealed in its relatively flat impedance. The entire system's frequency response curve shows a typically broad, linear bandwidth. This exceptional efficiency at all frequencies permits the amplifier to deliver necessary power at ultrasonic frequencies.

Figure 4

A pair of drawings illustrates the movements of the Heil's pleats and the corresponding musical sine wave signals. In Figure 4A, the front facing pleats contract as the sine wave rises, forcing the air out under pressure. Meanwhile, the pleats opening towards the rear draw air in. When the sine wave reverses, as shown in Figure 4B, the pleats contract in the opposite direction.

Figure 5

The "squeezing" action of the heil diaphragm's pleats viewed in detail from above. As the pleat walls (A) squeeze together, they force a large amount of air to accelerate under pressure through a narrow opening (B). The folds are 5.3 times as deep as they are wide, resulting in a 430 percent increase in air velocity.

Chario TS 1312

Modo unicamente italiano e la tendenza a farsi notare, a progettare qualcosa di vistoso ed originale, possibilmente non strettamente tecnologico. Come in questo caso, con le Chario TS 1312, dove le picolissime dimensioni ed il rivestimento in vera radica di noce con il piedistallo dedicato, ce ne è da non poter proprio passare inosservate. Con qualcosa come 8 litri di ingombro e contando solo sulla sospensione pneumatica il livello di prestazioni dipende in pratica solo dalla qualità dei componenti e dalla capacità di equalizzazione del filtro, queste ultime però duramente pagate in termini di efficienza.

Nelle TS 1312 si è preferito non indulgere in questo tipo di pratica, tollerando un certo alleggerimento relativo nella risposta sotto i 200 Hz in cambio di una efficienza in gamma media di ben 86 dB per 1 watt ad 1 metro, livello su cui è stato allineato anche il tweeter, con una personalità del complesso piuttosto aggressiva, e che fa sentire evidente la carenza all'estremo inferiore. Quanto a quest'ultima, se pure collocando il diffusore a muro o anche in angolo più sollevarne il rendimento verso il taglio inferiore, è pur vero che in gamma media, in particolare sopra i 500 Hz, non ci può essere alcun incremento, dal che resta invariato il sollevamento della banda sopra i 2500 Hz, riprodotta con linearità veramente esemplare dal tweeter delle TS 1312 e molto presente all'ascolto.

Nel complesso la filosofia di progetto delle Chario TS 1312 sembra essere diretta a consentire all'ascoltatore una ottima caratterizzazione dei timbri, senza alcun tentativo di mascherare o compensare le ridotte dimensioni del diffusore ed il relativo precoce taglio alle basse frequenze, al quale è lasciato come rimedio naturale la adozione di un sistema di subwoofer indipendente. A parte il leggero avvaliamento sul 2000 Hz, il filtro delle Ts 1312 sembra assai ben progettato,sia per scelta che per numero dei componenti, con uno standard costruttivo per tutta la realizzazione decisamente medio-alto, e, per fare un esempio, basta ricordare che sia woofer che il tweeter delle TS 1312 sono fissati al mobile con delle brugole avvitate su madreviti in ferro annegate nel legno.

Molto buona è la capacità dinamica e la tenuta in potenza, veramente insospettabile da un cosi piccolo trasduttore. Un plauso, infine alla stabilità ed alla precisione della scena acustica.


Tipo: Sospensione acustica


1 tweetwr a cupola;

1 mid-woofer da 130 mm

Impedenza: 6 ohm

Sensibilita: 86 dB 1W/1m

Dimensioni: 160 x 300 x 160 mm (L x H x P)

Peso: 5 kg

AVID Model 105 (1975)

The Avid Model 105 loudspeaker is the new reference standard for the critically acclaimed Avid "Series 100" line of loudspeakers. The result of extensive research, the Avid Model 105 is unquestionably the finest speaker we have maade.

Design Accomplishments

Uniform distribution of sound at all frequencies

Superior transient response characteristics

Exceptionally low distortion bass, even at high power levels

Broad, linear frequency response

"No compromise" reference monitor performance

Basic Design

All loudspeaker design involve trade offs between low frequency response efficiency and cabinet size Avid's engineers selected a floor standing, air suspension design to achieve the exceptionally low bass response, accurate reproduction and power handling capability expected in a "no compromise" reference standard monitor. The Model 105's large cabinet volume (2,3 cu. ft.) permits a flat response to 30 Hz while maintaining sufficient efficiency for use with 25 watt RMS to 200 watt RMS amplifiers.

The model 105 is a 3-way design employing five perfectly matched drivers carefully integrated by a sophisticated coil-capacitor dividing network. Several exceptional "state-of-the-art" design features are used in the Model 105 which deserve highlighting.

Long-Throw Woofer

The Model 105 employs a specially engineered 12' woofer with exceptional linearity and a long-throw (11/16"excursion) voice coil to achieve low distortion bass

"Basketless" Mid-Range

The Model 105's optimallysized 3" mid-range driver utilizes a new basketless construction which eliminates interior wave reflections that occur from the basket frame. such reflections cause irregularities in frequency response and degrade transient characteristics in conventional designs. Midrange frequencies in conventional design. Midrange frequencies are incredibly smooth and accurately reproduced with this advanced design.

High Frequency Driver Array

In addition to the superb 1" dome tweeter radiating forward, two auxiliary tweeters are employed to provide full 180 degree dispersion of high frequencies. The auxiliary tweeters are fired directly to the side rather than "angled off" to minimize interference effects with the front facing tweeter - a common problem that causes a peaky high end response on many multiple tweeter systems.

Zero Distortion Dividing Network

Drivers are perfectly integrated by an Avid-engineered dividing network utilizing only linear, zero distortion components such as air core coils.

The performance date below attest to the superb accuracy, smooth response and low distortion achieved by this system, but still fail to adequately portray the Model 105's incredibile openness and transparency which must be heard to be appreciated.

Frequency Response: is exceptionally flat, both on and off-axis, over the entire listening range from 30 Hz to beyond 18 kHz.

Low Frequency Distortion: we know of no other loudspeaker system with the Model 105's low distortion bass performance. There is less than 4% distortion at 40 Hz with an incredible 50 watts input.

Tone Bursts: are one of the best indicators of transient response: the ability of a speaker to accurately follow rapidly changing musical waveforms Note how well the Model 105 followes the 8-cycle input signal with minmum "hangover" and "blurring". These are exceptional toneburst responses, especially in the critical mid-range area.


Impedance: 8Ω nominal, 6Ω minimum

Power Handling Capacity: 200 watts RMS (program material with fuse overload protection)

Minimum Recommended Amplifier Power: 25 watts RMS

Frequency Range: 30 Hz to 18 kHz ±2.5 dB

Driver Complement:

Woofer: 12" high compliance w/butyl surround, 11/16" peak-to-peak excursion, 2½ lb. ceramic magnet; 2" 4-layer voice coil

Mid-Range: 3" air suspension cone with 1" high temperature voice coil, half-roll surround

Primary High-Frequency: 1" high velocity plastic dome with 1" low-mass voice coil

Auxiliary High-Frequency Drivers: Two side-firing , 1" wide dispersion cone tweeters

Crossover Network: coil/capacitor; 5 air core coils, 5 capacitors, 9 wire-wound resistors.

Low-Mid Crossover: 500 Hz

Mid_High Crossover: 4000 Hz

Auxiliary H-F Crossover: 9 kHz

Balance Controls: Two front-mounted, switch type constant impedance L-pad attenuators for mid- and high-frequencies, precalibrated flat, +2 dB, -2 dB.

Cabinet Size (W x H x D): 20" x 26¼" x 15"

Cabinet Finish: Hand rubbed walnut veneer over high density (45 lb) particle board

Grille Assembly: Acoustically integrated with system to minimize cavity resonances and diffraction effects: dark brown grille

System Weight: 75 lbs

QUAD 33 (1969)

The external design continues the Quad tradition of practical simplicity, which has won prizes and worldwide acclaim. The internal appearance is unmistakably Quad and reflects cocnern with quality of manufacture and ease of service.

The Quad 33 select and controls the radio tuners, gramophone pickup and tape recorder connected to it and feeds the loudspeakers via the power amplifier, providing for stereo or mono on either or both channels, from all inputs, plus monitoring and track selection facilites for tape.

Quad units may be used either free-standing or mounted in a cabinet, with plenty of scope for individual preference in layout design.

The standard Quad system of mounting is used, requiring only a rectangular cut-out for whiche a template is provided.


The controls are comprehensive but simple and are logically grouped to facilitate selection and control of the programme.


The filter is essential with modern good quality speakers and helpful at any time. It removes surface noise, tracing distortion and similar shortcomings in the upper frequency range of the recording or broadcast, and the two control filter system achieves this to a very fine degree without intruding unnecessarily into the harmonic range so essential for realistic reproduction.

Another fixed, built-in filter cuts out (without affecting the normal low frequency response of the equipment) unwanted signals at frequencies below 20 Hz, due to mechanical causes in motors and turntable mechanisms.

Bass and treble

Entirely separate from the filters are the bass and treble controls which provide independent adjustment of tonal balance when required. This operations is symmetrical and smooth without any unpleasant 'steps' in the response.

Every pickup correctly matched

To change the pickup matching merely remove the Disc Adaptor and plug it in again with another edge leading; four matching circuits on one board with provision to accomodate any future development in pickup design simply by changing the board. The input load is purely resistive over the entire audio bandwidth.


Any signal passing through the Quad 33 may be recorded without affecting normal reproduction on monitored off the tape (AB monitoring) as desired. The plug-in tape adaptor carries independent pre-set adjustments of signal level for both recording and replay on each channel, to suit the tape recorder in use. Again since this is a plug-in board, any future or special requirements can be met merely by replacing the board, thus adding further to the versatility of the Quad 33.

The Quad 33 control unit is designed to give maximum flexibility to the whole audio system combined with ease of operation. The unit features a simple and novel method of matching pick-up inputs, using a square printed circuit adapter board: each side of the board carries one circuit which can be plugged into the rear of the unit, so that the four sides offer four alternative circuits; tape recorder inputs are matched with a similar plug-in board. The controls are arranged in logical sequence suiting the importance of their function. While it is possible to adjust and correct for every eventuality required by the avid enthusiast, the design is such that once the minor controls are correctly set,

day by day operation becomes extremely simple. Two switched mains outlets at the rear of the unit supply the amplifier and radio tuner.


Distortion: All controls level, 0.5V rms output, with any input 0.2%; any control settings and any level within overload ratings <0.1%; both at 30 - 10 kHz

Residual Noise: 0 - 30 phon weighting 15.7 kHz bandwidth: <-90 dB controls level or cancel

Frequency Response: Any input, any output, RIAA or flat as appropriate: ±0.5 dB, 30 Hz - 20 kHz

Tone Controls: ±1 dB of curves shown opposite

Filters: To curves shown opposite at 5 kHz, 7 kHz and 10 kHz ±5%

Interchannel Balance: Within 1 dB with volume control varied from maximum to -45 dB

Balance Control Range: 9 dB either way

Crosstalk: Dependent on input sourec impedences. Replay/record typically better than 70 dB; interchannel typically better than 40 dB: both at 30 Hz - 10 kHz

Power input: 100 - 130 or 200 - 260 V, 50/60 Hz, 1.5 watts

Dimensions: Width 260 mm, Height 92 mmfree-standing, 83 mm panel only. Depth 165 mm free-standing, 140 mm behind cabinet panel when mounted.

Weight: 3 kg

QUAD 303 (1969)

The Quad 303 power amplifier is intended for normal domestic use with loudspeakers of moderate efficiency, but is also used by broadcasting and recording studios, groups and discotheques world wide, who appreciate its excellent performance and dependability.

The outstanding performance of the Quad 303 is largely due to the unique output circuit developed by Quad.

The Quad 303 is normally used with the Quad control unit, but can readily accommodate other signal sources. Since it has no controls it can be mounted out of sight in a well ventilated cabinet.

The amplifier won a Council of Industrial Design Award in 1969

The circuit employs symmetrical triples, greatly reducing distortion and rendering the quiescent current independent of output transistor temperature.

This development enables the designers to reduce distortion to any desired degree without sacrificing stability, and to maintain this excellence under all dynamic conditions.

To put this in perspective, the lowest theoretical distortion present on the very best tape and disc will still be some hundred times greater than that of the Quad 303.

Such a level is, of course, completaly inaudible no matter how refined the test.

The use of triples, permits simple and effective control of the output current and since the voltage is also controlled, the output transistors are completely protected and must always operate within their ratings with the obvious advantages of greatly improved reliability under all conditions, without the use of elaborate and expensive circuitry.

The amplifier cannot be upset even when overdriven by an asymmetrical signal or by shorting or disconnecting the loudspeakers.

The chassis and covers of the Quad equipment are in die cast aluminium and sheet steel finished in stove-enamelled

metallic beige and brown with off-white and marigold push buttons and control panels. The control unit, top left, and

the tuner, lower left, can be positioned together or separately. The amplifier, above, has no controls, and can

therefore be housed out of sight in a cabinet or cupboard, heat dissipation being greatly assisted by the aluminium

fins at the rear.


Power Output:

The amplifier is intended for use with loudspeakers of 4 - 16 Ω nominal impedance.

Poweroutput and distortion for various frequencies.

Continuos sine wave into 8Ω resistive load.

100 Hz any level up to 45 watts<0.03% Dtot

1 kHz any level up to 45 watts <0.03% Dtot

10 kHz any level up to 45 watts <0.1% Dtot

Output Internal Impedance: 0.3Ω in series with 2000μF and 6μF

Frequency Response: Ref. 1 kHz -1dB at 30 Hz and 35 kHz into 8Ω

Signal Input Level: 0.5V rms ±0.5 dB for 45 watts into 8Ω.

Amplifier loads the input by 22kΩ in parallel with 60 pF

Signal Input Overload: Instantaneous recovery up to +20 dB overload.

Crosstalk (input loaded by 1 kΩ): 30 Hz - 10 kHz > 60 dB

Hum and Noise (input loaded by 1 kΩ): "A" weighted -100 dB ref full power. Unweighted (15.7 kHz measurement bandwidth) -95 dB ref full power

Protection: This amplifier is suitable for use under the most arduous music conditions with speakers of impedances between 4 and 25Ω and for high level sine wave duty with loads of 8Ω or greater.

Stability: Unconditionally stable with any load

Power Input: 100-125 or 200-250 V, 50/60 Hz, 40-200 watts depending on signal level.

Dimensions: 120 x 159 x 324 mm (W x H x D)

Weight: 8,2 kg

ADCOM GCD-575 (1988)

Adcom GDC-575 CD player has been worth waiting for. Now there's a CD player with analog audio circuits as technically advanced as its digital stages. Since the human ear can only appreciate musical sounds in their analog format, Adcom began with the objective of producing the first affordable CD player whose direct-coupled audio output would deliver the long anticipated technical benefits of digital sound.

Designers and engineers usually use Class "A" audio circuits where price is no object. In its purest form, Class "A" offers a highly sophisticated level of audio amplification, often demanded by those who can distinguish outstanding sonic performance from the merely average. Adcom's GCD-575 employs a no-compromise, Class "A" analog audio amplifier section which provides superior resolution by more clearly defining low-level information. This higher resolution makes an audibly dramatic difference in the musicality of CD reproduction. To achieve this result, the analog audio circuits in the GCD-575 were based on the same proprietary high speed linear amplifiers used in Adcom's GFP-555 pre-amplifier, universally recognized for its outstanding musical integrity.

Importantly, Adcom's CD player is designed with a low output impedance (100 ohms) so that it can operate up to its maximum capability with a wide variety of associated equipment. It is not only compatible with virtually all input stages of amplifiers, preamplifiers, tuner/preamplifiers, etc. , but also permits the use of longer interconnecting audio cables, when required, with minimal signal deterioration.

Additionally the GCD-575 is supplied with a high quality, low-loss audio cable to prevent the sonic smear that conventional audio cables tend to cause. The use of this special cable and the 100 ohm output impedance permits the GCD-575 to be used with Adcom's SLC-505 passive straight line controller. If no other source equipment will be used, the variable output can be used directly into your power amplifier, bypassing the preamplifier circuits normally required by other CD players.

A muli-winding power transformer, connected to three separate tightly regulated power supplies for the audio, digital and display circuitry, insures isolation of the different functions and optimal operation of each without interference.

The four special heavy feet installed on the GCD-575 are reversible metal castings. On one side, the flat surface insures a wide contact area. The revers side is cast with buil-in "Iso-points" which, when used in a three-foot configuration, operates as a "tripod" support system.

A special polarity-inverting switch permits you to reverse the normal positive polarity to negative (inverted) polarity. This corrects playback of CDs in which the polarity was incorrectly recorded (inverted), or for use in systems in which one of the components causes a reversal of correct polarity


Frequency response: 5 - 20,000 Hz +0,1; -0,5 dB

Signal-to-noise ratio: 105 dB

Dynamic range: 98 dB

THD: 0,0025%

IMD (70 Hz difference): 0,00018% at 5 kHz

Channel separation (1kHz): 95 dB

Interchannel Phase Shift: less than 1,8 ° at 20 kHz

Output impedance:

Fixed: 100Ω

Variable: 100Ω

Digital: 75Ω

Output level:

Fixed: 2,5 V RMS

Variable: greater than 4,5 V RMS

Digital: 0,5 V peak-to-peak

Laser: GaAIAs semiconductor

Sampling rate: 176,4 kHz

Quantized bits: 16-bit linear

Power: 120 V AC, 60 Hz (available in 220/240, 50 Hz)

Dimensions (W x H x D): 430 x 87 x 285 mm (17" x 3-7/16" x 11-1/4")

Weight: 5,5 kg (12 lbs)

Mission DAD-7000 (1985)

''Mission DAD 7000 is an attractively small-dimensioned machine, being essentially the CD 104 with Mission's grey/black decor. It has adequate rather than exotic control features, but the advantages of the Philips oversampling technique and digital filters. Mission claim to have introduced new electronic features, described at length in a booklet and a copy of their Patent Application which they let me have. In essence, they have directed their energies at eliminating the spurious supersonic harmonic signals generated as part of the digital-to-analogue conversion process and the mandatory low-pass filters which follow it. The extent to which these by-product tones in CD reproduction affect the sounds we hear, perhaps through the generation of intermodulation components down into the audio band, has never been scientifically established.''

''So an additional low-pass filter and delay sequence has definitely been included, reducing HF components at the sampling frequency and its harmonics by a kind of combfilter cancellations effect. This is said to have been achieved "without adversely affecting the phase linearity of the audio band". However, a plan to incorporate full 16-bit D-A converters has been postponed, and so the machine is in fact 14-bit, though the Philips oversampling arraneement has already been proved to perform pretty well up to 16-bit standards.'' JOHN BORWICK.


Frequency response: 5 - 20,000 Hz ±0.3 dB

Total harmonic distortion: 0.005%

Signal-to-noise ratio: 90dB

Channel separation: 90dB

Output: 2V fixed

Dimensions (W x H x D): 320 x 87 x 298 mm

Weight: 7 kg

ADC CD-100X (1985)

The model CD-100X utilizes five servo circiuts:

Focal control servo

The astigmatic method is employed for the focus control which utilizes the fact that routing the reflected laser light through a semi-cylidrical lens changes the shape of the bean in accordance with the distance.

Tracking servo

Tracking servo is required to chase disc pit columns since CD systems do not have a guide to lead laser beam to the pit. The model CD-100X employs 3-beam tracking servo system.

Sled servo

The sled servo serves for dual purpose - to gradually move back and forth the entirely of the laser pickup in accordance with the procession of disc playing; and to move it quickly for searching tracks. The lens of the laser pickup is able to travel at a small distance to follow the pits when playing with the entire pickup stopped. As it approaches the limit of the travelable range, DC components come to be contained in the tracking servo signals. The sled servo acts to detect the DC components and maintains the lens to be in the middle of the moveable range, namely to maintain the DC component to be zero.

Auto Power Controller (APC) circuit

The APC circuit is provided to maintain the constant laser output level in spite of the variation in temperature etc. The monitor diode located in the close proximity of the lens feeds back the variation to keep the current flowing through the diode constant.

Constant Linear Velocity (CLV) servo circuit

Unlike analog records, the rotation of compact disc is 500 rpm in inner area and 200 rpm in outer area. The CLV servo acts to maintain the proper rotation of the motor. The reference to determine if the rotation is too fast or too slow depends upon the coincidence of the phase of the RF signal to U301 and the reference clock signal.

The laser pickup used for the model CD-100X comprises six photo diodes A to F, diodes A to D, consisting actually of one single diode which is divided vertically and horizontally into four parts, for signal detection and diodes E and F for tracking servo. Since the laser light scintillated onto the surface of compact disc is turbulently reflected by pit area and entirely reflected by no pit area, the digital signals in disc can be read out by detecting the reflected laser light.


Audio Section

Frequency response: 5 - 20 kHz ±0.5 dB

Total Harmonic Distortion: 0.004%

Dynamic range: 95 dB

Output level: 2 V rms

Signal-to-noise ratio: -90 dB V

Channel separation: 90 dB at 1 kHz

Output impedance: 600 Ω

Internal system

Optical pickup: 3-beam laser

D/A conversion: 16-bit linear

Filter: Seventh order passive filter

Error correction: CIRC dual error correction system


Music search: SKIP buttons

Fast forward/reverse: FF and REV buttons

Remaining time display: REMAINING key

program memory function: 16 selections, random

Repeat: of one progral, or all contents

Disc loading: Motor driven, horizontal loading


power requirements: 100 - 120 V, 220 - 240 V, 50/60 Hz

Power consumption: 12 W

Dimensions (W x H x D): 341 x 88 x 293 mm (13-7/16" x 3-7/16" - 11-9/16")

Weight: 3.3 kg (7 lbs. 5 oz)

Thorens TD 145 (1975-1976), Mk II (1976-1978)

For years turntable manufactures have been seeking the faultless tonearm system that would eliminate stylus damage and protect records. Thorens with its long tradition of advanced engineering and state-of-the-art technology, has achieved this breakthrough in the new TD-145. Its completely unique and innovative electronic sensing system automatically lifts the tonearm and shuts off power to prewent any mishaps.

Totally electronic, rather than machanical, as are most automatic lift-up/shouoff systems, nothing inhibits the tonearm or comes between it and the trip mechanism. As the tonearm approaches the final lead-out grooves of the record, a control signal activates a viscous damped elevating platform that lifts the tonearm and shuts off th epower. Further, the sensing system goes into action instantly should the power be inadvertently cutoff or if the tonearm accidentally slides across the record. It's virtually foolproof.

The new sophisticated Thorens TD-145 turntable comes complete with a wide range of advanced features which it has in common with Thorens' top of the line TD-125 Mark II series: magnetic anti-skate control with the highly acclaimed TP-16 gimbal suspension tonearm; a high torque, slow speed, belt-driven 16-pole synchronous motor; dynamically balanced, seven pound, 12-inch non-magnetic die cast platter; front panel precision cueing control; split-level suspension system that reduces rumbl, acoustic feedback and vibrations.

The TD-145 C is still another reason why Thorens is th efirst name in turntable and thelast word in precision performance. The TD-145 is the perfect choice for the audiophile seeking the precision of a manual turntable combined with semi-automatic features.


Drive system: 16-pole synchronous motor with belt drive

Record speeds: 33 and 45 rpm

Turntable platter: 12 -inch non-magnetic zinc alloy

Rumble : -48 dB (unweighted), -69dB (weighted)

Wow and flutter: 0,06%

Power requirements: 110 -130 volts AC, 220 - 240 volts AC, 15 watts 50/60 Hz

Dimensions (L x W x H): 505 x 360 x 165 mm

Net weight: 8,5 kg

TP-16 Tonearm

Lenght: 9,06" 9between stylus tip and vertical tonearm bearing)

Stylus overhang: 0,55' adjustable

lateral tracking error: less than 0,2% cm of radius

Bearing Friction: Less than 20 mg in vertical and horizontal planes


The 180-watt per channel R18 Receiver from SAE TWO.

It's like no other receiver you've ever seen. Or heard. It's a spectacular blend of all the state-of-the-art technology and innovative features that are SEA TWO. Aside from the digital read-out quartz lock, synthesized touch tuning, parametric equalization, and a lot more, the R18 offers a number of exceptional capabilites:

Five station memory allows you to pre-set your five favorite AM and five favorite FM stations.

Weather, sports, rock, whatever. Just press the memory button and they're yours. No hunting. No switching. No hassle.

A full time clock gives you the time whether the main power is on or off. It's continuos read-out, digital of couse.

But there's more. Much more. As a matter of fact, you couldn't find more in one receiver if you tried:

Digital Readout

Quartz Lock

Synthesized Touch Tuning

Parametric EQ

Bar Graph Display

External processor Input

Tape EQ

Digital Clock

Infrared Remote Control

Single Strata Voltage Amplifier

Fully Complementary Outputs

Relay Speaker Protection

Thermal protection

Moving Coil Input

Fluorescent Bar Graph Display

used for AM/FM tape, and power monitoring these low-voltage fluorescent displays react instantaneously to level changes without the ballistics problems common to conventional VU meters.

In the AM or FM mode, signal strength is displayed for both as well as multipath distortion for FM.

In the tape mode the level appearing at the tape record outputs is indicated referenced to 0 VU. You can actually improve your recordings by using the monitoring system as a guide. In the power mode, the fluorescents directly display the power level of the receiver from less than 1/10th of a watt to full output.

Digital Frequency Readout

Conventional receivers have continued to use the less accurate and informative "slide rule" style dial.

Instead, we looked at the most sophisticated instrumentation in science and industry and found the overwhelming preference for measurement display systems to be digital. Simply stated, with our new digital readout system, you never have to wonder what station you're listening to.

Quartz Lock Reference

In FM the IF bandpass filter is the heart of the tuner. It removes noise and distortion.It pretty much determines the fidelity of the system. For the IF to operate propery, the signal must be positioned and maintained precisely at the center of this bandpass. That's where the quartz lock comes in. It centers the signal more accurately than any other known system. Inn fact, it's the method the radio stations themselves usel. Regardless of signal, temperature or the age of the equipment, the quartz reference systems will always center tune the FM signal for lowest distortion, widest separation and greatest rejection of unwanted noise.

Synthesized Touch Tuning

We utilize the latest in Varactor front end and LSI (Large Scale Integrated) technology. The Veractor front end, not restricted by the mechanical constraints of conventional front end designs, is structured for optimum performance. All voltage circuitry for scanning and tuning is generated within the LSI chip itself. It tunes and centres the signal automaticaly, activating the quartz lock reference and monitoring the front end to obtain optimum signal reception. A simple touch of either of two tuning buttons instantly tunes and locks the desired station.

External Procesor

It provides a separate loop for signal processing and modification devices, like parametric equalizers and noise reduction systems, allowing you to take full advantage of the many such instruments and their varied benefits. You can equalize your tapes: the external processor loop can be placed between selected inputs (phono, tape aux) and tape outputs. Or modify any specific input, including tape.

Tape EQ

Here you are able to take full advantage of your built-in parametric equalizer capability by using it to equalize what you're taping. This is especially valuable if your're tailoring tapes for automobile systems, background music, etc.

Single Strata Voltage

As you may know the power amplifier is broken down into two components: the voltage gain stage and the power stage. In voltage gain, there are two critical criteria: gain and thermal stability. The individual devices must track thermally to maintain linear gain for low distortion and excellent stability under all conditions. Previously, this has been extremely difficult to accomplish as the active components could not be grouped together. Now our unique Single Strata Voltage Amplifier overcomes this by maintaining all active components of the voltage stage on a single strait. Complete current sourcing of input stages, and a fully complementary pre-drive stage with high Ft devices combine to from a voltage amplifier stage more sonically accurate than ever before thought possible.

Complementary Output Stage

We afforded the output stage the same careful attention with which we handled the voltage amplifier section. We use full complementary, Very High Speed Series outputs with 15 MHz Ft and a power handling capacity greater than eight times the rating of the unit. In order words, it's fast. It's strong. It can handle any speaker load.

Low Noise Phono IC's

A recent breakthrough in low noise IC technology makes this fully complementary operational amplifier the ideal phono stage. With complete supply isolation and individual current sources for each stage, noise modulation and distortion are virtually a thing of the past. Active devices are designed for wide gain-bandwidth to ensure low transient distortion and excellent overload recovery. Careful attention has also been paid to the RIAA equalization both inside and outside the audible band for completely stable phono cartridge loading.

Infrared Remote Control

Optional remote control offers you convenient turn on, balance, volume and tuning.

Specifications (IHF-202A, 1978 STD.)

Power (into 8 ohm from 20 - 20,000 Hz): 180 watts

Total Harmonic Distortion (from 250 mW to full rated power is less than): 0.05%

Intermodulation Distortion (SMPTE STD< 250 mW to rated output, lesss than): 0.05%

Power Bandwidth (1 kHz, 0.1% THD, 8 ohms): 10 Hz - 60 Hz

Damping Factor (1 kHz, 8 ohms): >40

Frequency Response:

Phono MC: ±0.5 dB

Phono MM: ±05 dB

Aux, Tape, Ext Pros: ±0.5 dB (20 Hz - 20 kHz); +0.5/-3 dB (5 Hz - 100 kHz)

Signal to Noise Ratio (IHF-A):

Phono MC: 80 dB

Phono MM: 84 dB (5 mV, IHF load); 94 dB (10 mV, shorted)

Aux, Tape, Tun: 80 dB (1 watt output); 100 dB (rated output)

Residual Noise (IHF-A): 10 mV

Input Sensitivity (1W/ Rated Output/Impedance):

Phono MC: 0.01 mV/0.25 mV/500 ohms

Phono MM: 0.11 mV/2.5mV/47 kohms

Aux,Tape, Ext. Pros. Tuner: 6.7 mV/150 mV/50 kohms

Output Level - Tape Out, Ext. Pros: 150 mV

Maximum Input Level:

Phono MC: 12 mV

Phono MM: 150 -300 mV

Aux, Tape, Ext. Pros., Tuner: 4 V

Parametric EQ


Level: ±16 dB

Frequency: 20 Hz - 1.2 kHz

Bandwidth: 0.3 - 3.6 oct.


Level: ±16 dB

Frequency: 1.2 kHz - 20 kHzz

Bandwidth: 0.3 - 3.6 oct.

Filter: 6 dB/octave at 30 Hz

Loudness Compensation (level -30 dB): =6 dB at 10 kHz, +8 dB at 100 Hz

Audio Muting: -20 dB

Volume Tracking Error (0 - 70 dB): ±1 dB

Dimensions (W x H x D): 559 x 165 x 457 mm (22 x 6½ x 18 inch)

Weight: 25 kg (55 lbs)