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





Toshiba SB-620

L'SB-620 fa parte, assieme al modello SB-820 di una nuovissima linea di apparecchiature della Toshiba. Ciò Che colpisce subito nell'osservare questo amplificatore di media potenza è la cura che è stata posta nella progettazione del panello frontale, con l'estetica molto riuscita. Il frontale dell'ampli , realizzato con alluminio anodizzato e spazzolato, è suddiviso in tre sezioni da alcune piacevoli scanalature; nella prima di queste sezioni, sulla sinistra, troviamo l'interuttore di accensione, con luce incorporata, e l'uscita per una cuffia; nella sezione centrale sono situati i controlli di tono , a scatti, con comando unico per i due canali ed i selettori che permettono di scegliere diverse frequenze di intervento (400 e 200 Hz per i bassi , 2,5 e 5 kHz per gli alti). Sempre al centro troviamo l'interruttore del controllo fisiologico, il filtro bassi (15 e 30 Hz), quello alti (8 e 20 kHz), il selettore mono/stereo, il bilanciamento ed infine il commutatore che permette l'ascolto di due sistemi di altoparlanti in tutte le possibili combinazioni.

Nella sezione di destra è situata la grossa manopola del volume (funzionamento a scatti) provvista di scala tarata in dB; completano questo settore il muting (-10 e -20 dB), il selettore degli ingressi, il tape monitor per due registratori, l'interuttore di coppia e due jack che permettono il collegamento rapido di un registratore. Le manopole, tutte di alluminio pieno escluse quelle di diametro minore, sono leggermente zigrinate sul dorso per facilitare l'utilizzo e gli interuttori sono del tipo a levetta; originale e ben riuscita la linea delle manopole del selettore degli ingressi e del tape monitor.

La costruzzione meccanica, tesa ad una utilizzazione razionale degli spazi, è senz'altro robusta. Il gruppo delle aletta di raffredamento dei finali è ben dimensionato come anche il trasformatore di alimentazione; anche i transistor piloti sono provvisti di aletta di raffreddamento. Il cablaggio non è dei più ordinati ma mostra un serraggio manuale delle trecce di cavi.Il montaggio è quasi totalmente a schede disinseribili.

All'interno sono situati due fusibili posti in serie ai secondari del trasformatore; i transistor finali, Toshiba 2SB555 e 2SD425, sono fissati all'aletta di raffreddamento non direttamente tramite viti ma utilizzando un telaietto, stretto a sua volta da viti, che permette un miglior contatto termico fra transistor ed aletta. I due condensatori di stabilizzazione sono da ben 10,000μF l'uno.

Le prese di ingresso del segnale poste sul retro , sono di tipo PIN, quella per il secondo registratore è duplicata DIN; utile la separazione tra le sezioni pre-finale; le morsettiere a molla che permettono il collegamento di due coppie di diffusori risultano pratiche. Sempre sul panello posteriore sono situate due prese di terra, il cambia -tensioni (220V e 240V) ed il fusibile di rete.

Specifications

Sezione Finale

Potenza continua: 65 + 65 W at 8Ω, 75 + 75 W at 4Ω

DIstorsione armonica: 0,2%, (0,05% at 1W)

Distorsione di intermodulazione: 0,2%, (0,05% at 1 W)

Risposta in frequenza: 10 Hz to 80 kHz (+0, -1 dB)

Sensibilità: 1 V (50 kΩ)

Fattore di smorzamento: >30

Impedenza degli altoparlanti: 4 - 16 Ω, (8 - 16 Ω only A+B)

Sezione Pre

Sensibilità degli ingressi:

Phono 1: 2,0 mV (50 kohms)

Phono 2: 2,0 mV (50 kohms)

Tuner: 150 mV (50 kohms)

Aux 1, 2: 150 mV (50 kohms)

Uscita registratore: Tape Rec: 150 mV, DIN: 30 mV

Uscita Pre: 1 V

Risposta in frequenza: 10 Hz - 50 kHz (+0, -1 dB)

Distorsione armonica : 0,05% (all levels)

Controlli di tono:

Bassi: ±10 dB at 100 Hz

Alti: ±10 dB at 10 kHz

Filtri:

Bassi: 15 Hz, 30 Hz (6 dB/oct)

Alti: 8 kHz, 20 kHz (6 dB/oct)

Muting: -10, -20 dB

Controllo fisiologico: 9 dB (100 Hz), 3,5 dB (10 Hz)

Equalizzazione RIAA: 30 - 15,000 Hz ±0,2 Hz

Accettazione Phono Input: 1 kHz, 400 mV

Rapporto S/N:

Phono: 73 dB (IHF, pesato A)

Aux: 90 dB (IHF pesato A)

Potenza assorbita: 400 W

Dimensioni: 450 x 148 x 375 mm

Peso: 14 kg

Toshiba SB-820

Toshiba SB-820 appartiene alla nuovissima linea di apparecchi della Toshiba. L'SB-820 è un modello superiore di potenza rispetto all'SB-620, ma l'impronta estetica risulta molto simile, il frontale è suddiviso in tre sezioni da eleganti scanalature con le medesime manopole e interruttori.

Il pannello anteriore è in alluminio anodizzato satinato (5 mm ) e lescritte serigrafate in nero. Nel primo settore sulla sinistra sono posti l'interruttore di accensione ed una presa per cuffia. Nel settore centrale troviamo tutti i comandi relativi alla manipolazione del segnale; i bassi, gli alti e gli interruttori che permettono di far intervenire i controlli di tono a diverse frequenze (200 Hz e 400 Hz per i bassi; 2,5 kHz e 5 kHz per gli alti); questo tipo di controllo è molto utile quando ci si trova nella necesità di intervenire solo sulla gamma dei bassi profondi senza per questo alterare la gamma medio bassa. Troviamo poi il comando di bilanciamento, il selettore di copia tra tre registratori, quello di "mode" 9stereo, reverse, L+R, L, R), il filtro bassi (30 Hz e 10 Hz), quello alti (8 kHz e 20 kHz) ed infine il selettore per i diffusori . Nella sezione destra ci si trova grossa manopola del volume provvista di una comoda scala tarata in dB, per completare c'è anche il comando muting (-10 e -20 dB), il selettore degli ingressi, il tape monitor di tre registratori e due ingressi tipo jack per collegare comodamente un registratore sul frontale.

Sul panello posteriore, a fianco degli ingressi Phono , troviamo un deviatore a slitta che offre la possibilità di sceliere due valori di impedenza di carico dell'ingresso Phono2: 47 kohm per le testine standard e 100 kohm per quelle quadrofoniche. Troviamo anche una presa DIN che duplica le connessioni per il secondo registratore; sull'SB-820 la separazione pre-finale è stata realizzata con un comodo deviatore a slitta. Sono presente due prese di terra ed una serie di morsettiere del tipo a molla, per consentire il collegamento di due coppie di diffusori. Sulla destra del panello posteriore sono posti il cambia-tensione e fusibile di rete.

La costruzione del modello SB-820 risulta estremamente robusta e seria. Il trasformatore di alimentazione è posizionato sulla sinistra del telaio, completamente racchiuso in una scatola metallica. Sulla destra sono situati i circuiti finali inseriti verticalmente tramite schede su uno dei circuiti madre posti orizzontalmente. I circuiti di equalizzazione sono posti direttamente a ridosso degli ingressi e la commutazione di questi ultimi viene effetuata tramite una lunga asta che dal panello anteriore giunge fino a quello posteriore; una soluzione che permette di eliminare i cablaggi e di migliorare i rapporti segnale/rumore. L'amplificatore è dotato di potenziometro del volume Alps di tipo a film spesso di grande precisione. I transistor finali sono dei Toshiba 2SB554 e 2SD474. Lo stadio di uscita è quindi a simmetria totalmente complementare. I due condensatori di stabilizazione hanno una capacità di 15,000μF ciascuno. Le alette di raffreddamento dei finali, sono state realizzate per offrire una grande superficie di dissipazione del calore , pur senza essere imponenti.

Specifications

Sezione Finale

Potenza continua (1 kHz): 90 + 90 W at 8Ω, 110 + 110 W at 4Ω

DIstorsione armonica: 0,1%, (0,05% at 1W)

Distorsione di intermodulazione: 0,1%, (0,05% at 1 W)

Risposta in frequenza: 10 Hz to 80 kHz (+0, -1 dB)

Sensibilità: 1 V (50 kΩ)

Fattore di smorzamento: 40

Impedenza degli altoparlanti: 4 - 16 Ω, (8 - 16 Ω only A+B)

Sezione Pre

Sensibilità degli ingressi:

Phono 1: 2,0 mV (50 kohms)

Phono 2: 2,0 mV (50 kohms)

Tuner: 150 mV (50 kohms)

Aux 1, 2: 150 mV (50 kohms)

Uscita registratore: Tape Rec: 150 mV, DIN: 30 mV

Uscita Pre: 1 V

Risposta in frequenza: 10 Hz - 50 kHz (+0, -1 dB)

Distorsione armonica : 0,02% (all levels)

Controlli di tono:

Bassi: ±10 dB at 20 Hz

Alti: ±10 dB at 50 kHz

Filtri:

Bassi: 10 Hz, 30 Hz (12 dB/oct)

Alti: 10 kHz, 50 kHz (12 dB/oct)

Muting: -10, -20 dB

Controllo fisiologico: 9 dB (100 Hz), 3,5 dB (10 Hz)

Equalizzazione RIAA: 30 - 15,000 Hz ±0,2 Hz

Accettazione Phono Input: 1 kHz, 600 mV

Rapporto S/N:

Phono: 73 dB (IHF, pesato A)

Aux: 90 dB (IHF pesato A)

Potenza assorbita: 500 W

Dimensioni: 450 x 148 x 375 mm

Peso: 16 kg

AVID Parte II "La soluzione"

Avid risolve finalmente i problemi della diffrazione acustica.

Pur costantemente impegnati al raggiunimento della più alta fedeltà, molti altoparlanti anche trai piùcostosi, sono generalmente affetti da un difetto comune; suonano come altoparlanti, o - più esattamente - si sente sempre e comunque che il suono proviene da un box (cassa, scatola etc.)

Il Vostro cervelldo "sente" la scatola

Anche chi è completamente privo di nozioni di psico-acustica, sa che gli altoparlanti hanno ormai talmente condizionato il nostro cervello che questo all'ascolto subito "riconosce" i suoni come provenienti da una scatola, con ben determinate caratteristiche di forma, misura etc.

Cosa contribuisce a creare questo spiacevole ed innaturale effetto di limitatezza?

Principalmente le onde sonore riflesse o ri-radiate quele cioè che rimbalzano sugli spigoli della cassa e del panello frontale , è a causa loro che nostro cervello "inscatola" la musica.

Niente diffrazione, niente scatola

Il problema è illustrato graficamente qui sopra. Eliminando gli spigoli del mobile e del panello frontale si riduccono gli effetti di diffrazione vale a dire si elimina l'effetto scatola. E questo è ciò che abbiamo fatto con gli altoparlanti della nuova serie Avid i Minimum Diffraction Loudspeakers™

Per aprire la scatola, abbiamo chiuso il coperchio.

trovare la soluzione è stato incredibilmente semplice. Abbiamo ideato un insieme di componenti, cassa e pannello frontale che vengono a formare un sistema acustico totalmente integrato, che elimina le diffrazioni causate dal mobile e quindi l'effetto scatola a tutte le ... scatole parlanti. I nostri nuovi tweeter e midrange vengono installati con speciali flange che ne aumentano la dispersione e che riducono al minimo la difrazzione (le abiamo chiamate Optimum Dispersion Couplers™). I pannelli frontali sono stati raelizzati in modo da completare ed enfatizzare la dispersione uniforme delle onde sonore senza alcuna diffrazione. Anzi per renderle ancor più libere da ostacoli e ridurre perciò quel dannoato "effetto scatola". Queste semplici, ma significative innovazioni, unite alle oramai famose linearità ed accuratezze dei prodotti Avid Vi permetterano di scoprire una dimensione totalmente nuova d'ascolto dandoVi un senso di spazialità e realtà prima d'ora mai raggiunti.

AVID Model 330

The pursuit of perfection in listening is not a new venture at Avid. For more than 20 years, we have pioneered in the development and manufacture of quality audio components for educational, commercial and industrial application. And for the past five years we've been vigorously involved in teh hi-fi loudspeaker business.

From the first, Avid's philosophy has been simple and straight-forward... to provide, at a reasonable cost, products that deliver the ultimate in listening performance and overall reliability. This total commitment to quality has shaped the standards of design zealously adhered to by the company.

Since their introduction in 1974, Avid loudspeakers have consistently garnered enthusiastic critical accalim. For the past two years all of us at Avid have been working behind the scenes to make good even better. The result is the new line of acoustically integrated, minimum diffraction loudspeakers described on the pages that follow. We sincerely believe that these totally integrated systems represent a signigicant advancement and provide more listening enjoyment for the dollar than has ever before been possible.

A Philosophy

The purpose of a high fidelity component system is to reproduce the original source as faithfully as possible. At Avid, we're strongly dedicated to the beliefe that the loudspeaker, like all other parts of teh system, should restate its input signal as accurately as possible. Believe it or not, there are companies that manufacture loudspeakers taht purposely enhance sound. They add bass, color mid-range, even peak highs for a more "saleable" sound. That is not, and never will be Avid's way.

Introducing Minimum Diffraction Loudspeakers ™ by Avid

There are five models in Avid's new minimum diffraction loudspeaker line.

The Model 80a and 102a are improved versions of the most popular bookshelf models from our critically acclaimed Series 100 line. The 110, 230 and 330 speaker systems are totally new designs incorporating newly developed Avid drivers and crossover networks. Each model is a totally integrated acoustical system in the truest sense of teh word. A natural result of this careful engineering commitment to accuracy is the striking similarity in the tonal balance and performance between each model. Each has the same kind of sound, clarity, low distortion bass, and overall accuracy that has earned Avid great praise in the industry. This, coupled with the new sense of spaciousness and realism made possible by our totally integrated minimum diffraction system desing, makes Avid a must consideration for most serious listeners.

We sincerely believe that the degree of accuracy and openness achieved by each model is unsurpassed in its price range; and, in fact, often is comparable to competitive systems costing considerably more.

Reliability

Since their introduction in 1974, Avid loudspeakers have proven to be exceptionally reliable. In an industry where it is not uncommon to find failure rates in excess of 5%, Avid warranty repairs rate has been less than 1/2 of 1%. Not only are Avid minimum diffraction loudspeakers build to last, but they will continue to perform at the same high level for years.

Our efficient drivers have excetionally high power handling capability. Where appropriate, extra protection is provided against accidental overload. Models 102 and 230 are fuse protected. The Model 330 contains a unique Avid engineered Auto-Reset Protective Circuit that continually monitors input to each driver and automatically shuts the system down if an overload occurs.

Guaranteed Performance

Avid's unique, Q-Span™ testing program ensures that the speaker you purchase meets or exceeds published specifications and is a perfectly matched system. It is the most comprehensive testing program we know of in the industry. "Frequency response charts are run on every loudspeaker manufactured"

Sansui SP-2000

In Sansui's continuing search for the "absolute" in audio reproduction, this handsome 4-way ,6-speaker system represents nothing less than a major triumph. It combines a powerful 70 watt handling ability with the finest in components and internal engineering for a totally new dimension in high fidelity purity and realism. Each of the SP-2000's six speakers is unique, yet all are designed and positioned in close relationship to the characteristics of Sansui's exclusive pipe-duct enclosure, 12dB/oct crossover network and 3-position level controls. The result is uncompromised lifelike stereo reproduction throughout a wide 30 to 20,000 Hz frequency response range. Every bit indicative of the SP-2000's rich performance and internal engineering is its specially selected walnut cabinetry. This wood has been precision-mitered, hand-crafted and finished in oil to blend in with the finest furniture.

The SP-2000 is the most brilliant 4-way speaker system we've made to date. Intended for audio perfectionists only, it incorporates a 12-inch woofer, 6-1/2 and 5-inch mid-ranges, two 2-inch horn tweeters and a 1-3/8-inch horn super tweeter.

Woofer

The massive magnet assembly, precision-made voice coil, specially selected cone materials and unique cloth-edge suspension assures the best possible linearity at the deepest bass levels. Built into Sansui's pipe-ducted bass reflex enclosure, this woofer deliveres full, solid bas at all amplitudes.

Mid-ranges

It is often said that the sound quality of mid-range speakers determines the value of a speaker system. Most speaker systems tend to neglect the mid-frequency range, giving too much care to both high and low ranges. The SP-2000 houses two rear-sealed mid-ranges with aluminum radiators for the faithful reproduction of sound, from that of strongly attacked percussion instruments to that of soft vocal music.

Tweeters

The two horn tweeters and one super tweeter give smooth, peak-free response beyond the upper limit of audibility, without coloration.

Speaker Designed for Natural sound

Speaker performance may be mechanically measured by laboratory instruments, but "live" sound must be proved by human ears and actual listening tests. Sansui speaker systems are designed on the basis of a wide variety of data obtained from repeated actual listening tests, as well as from laboratory tests. These tests are made in rooms of different dimensions, decors and construction materials. That's why Sansui speaker systems reproduce natural sound wherever they are installed.

Pipe-ducted Bass Reflex

The secret to the SP-2000's powerful bass reproduction can be traced to Sansui's exclusive pipe-duct. Generally, a bass reflex enclosure is said to generate "boomy" bass. But the SP-2000 assures outstanding low-frequency characteristics because the pip-duct system has been designed in close relation to the performance of the cloth-edge suspension woofer.

12 dB/oct Crossover Network

Sansui's exclusive 12 dB/oct crossover network with a large ferrite core transformer divides the woofer, mid-range, tweeter and super tweeter response perfectly and prevents interaction between the speakers at the crossover points.

3-position level Controls for Mid and High Ranges

These 3-position level controls enable you to tailor the response to the acoustics of your room without affecting the damping characteristics of the speakers.

Enclosure

One of the design guidas followed in building the SP-2000 was the assumption that the performance of a speaker system depends more on the enclosure than on the speakers themselves. Accordingly, the SP-2000 enclosure has been carefully constructed of hard chipboard for distortion-free reproduction at the highest power levels.

Acoustic Material

The SP-2000 is baffled, enclosed and damped with 1-inch thick corrugated fibre glass to prevent the harmful standing wave from occuring in the enclosure. Mutual interference between speakers is completely eliminated for clear sound reproduction.

Grille

The fine furniture quality of the SP-2000's hand-craved fretwork grille will enhance the beauty of your listening room. The enclosure is finished on all four sides for horizontal or vertical placement.

Specifications

Speakers: 12" woofer, 6½" mid-rangr, 5" midrange, a pair of 2" horn tweeter and 1" horn super tweeter.

Max. Input: 70 watts

Impedence: 8 Ω

Crossovers: 1,500 Hz, 5,000 Hz, 10,000 Hz

Frequency Response: 30 - 20,000 Hz

Network: 12 dB/oct

Dimensions: 15" x 25¾" x 12¾"

Weight: 45 lbs

Pioneer F-26

The F-26 tuner, like the other components in the Series 20 line, received carefully design engineering to push the technological envelope on tuner design. In true audiophile fashion, it featured FM only. It was a higher performance, lower profile design compared to the F28 tuner. Pioneer employed newfeatures and circuitry having: Quartz-Locked Touch Sensor Tuning, an elaborate "Clean Pilot" system for cleaner high-frequency, and a Parallel Balanced Linear Detector( PBLD) for vastly improved signal-to-noise ratio and detection efficiency. This tuner also featured automatic wide/narrow IF bandwidth slection. The F-26 was design with a large power supply and two 6000 microfarad power supply capacitors, a muting level control on the rear panel, adjustable stereo/mono signal switchover, adjustable muting control, and gold plated terminals.

Specifications

Circuit system:

Quartz sampling locked, IF band auto switching, P.B.L. A detector, the pilot signal auto cancellar built-in PLL MPX

S/N (sensitivity 50 dB):

mono: 3.5 microvolts (new IHF and 16.1 dBf),

stereo: 40 microvolts (new IHF and 37.2 dBf)

Practical speed: mono: 1.8 microvolts, new IHF 10.3 dBf

S/N ratio:

mono: 86 dB,

stereo: 83 dB

THD:

Wide: 0.05% (20 Hz)

Mono:

0.03% (1 kHz),

0.03% (10 kHz),

0.04% (15 kHz)

Stereo:

0.06% (20 Hz),

0.05% (1 kHz),

0.1% (10 kHz),

0.25% (15 kHz)

THD Narrow:

mono: 0.15% (1 kHz),

stereo: 0.3% (1 kHz)

Capture ratio Narrow: 2.0 dB

Effective selectivity Narrow: 75 dB (300 kHz)

Stereo separation:

Wide:

55 dB (1 kHz),

50 dB (50 Hz - 10 kHz),

40 dB (20 Hz - 15 kHz)

Narrow: 50 dB (1 kHz)

Image stonewalling ratio: 120 dB

IF stonewalling ratio: 120 dB

Spurious stonewalling ratio: 120 dB

AM supression ratio: 65 dB

Subcarrier ratio: 75 dB

Muting operation level: 5.5 microvolts (20 dBf) - a 55-microvolt (40 dBf) variable

Auto mono-switching level: 17 microvolts (30 dBf) - a 170-microvolt (50 dBf) variable

Antenna: 300 Ω balance type, 75 Ω unbalance type

Level/Output load impedance (100% modulation):

Fixed: 650 mV / 2.2 kohm

Variable: 50 mV - 1.3V/3 kohm (Max)

I multipath output:

Vertical: 100 mV / 5 kohm (AM, 1 kHz, 30% modulation)

Horizontal: 500 mV / 4.1 kohm (FM, 1 kHz, 100% modulation)

The semiconductor used:

FET: 10 pieces,

Transistor: 66 pieces,

IC: 16 pieces,

Diode, others : 54 pieces

Power supply 100 - 240 V, 50/60 Hz

Power consumption: 14 W

Dimensions (W x H x D): 420 x 81 x 355 mm

Weight: 7,5 kg

KEF KM-1

KEF KM-1
The Ultimate listening Experience
KEF's KM1 is a remarkable loudspeakers. Indeed, KM1 could fairly lay claim to being the Ultimate Loudspeakers.
To see KM1 for the first time is midly awe-inspiring. To hart it is to be immediatelly struck by a sense of sureness, ease and authority in the reproduction of music, and indeed by how quiet they sound, despite the system's enormous loudness capability. For Km1 is an exercise in low distortion and headroom KM1 can 'cruise' when playing at very high volume levels, with power to spare, and yet achieve a degree of dynamic resolution unknow to virtually any other conventional loudspeaker system.
Dynamic Resolution
itis not sufficient a loudspeaker to be capable of handling the full dynamic range between loud and soft, it must be able also to resolve fine, low level musical detail whilst simultaneously reproducing complex loud pasages of music. It can only achieve this if the system has extremely low levels of colouration. This was a crucial element in the Km1 design rief.
Originally developed for the British Broadcasting Corporation as a high-level pop studio monitoring loudspeaker, they have been in use at the BBC's Maida Vale music studios in London since the spring of 1982 with extremely satisfactory results.
In the development of professional monitoring loudspeakers the demand for higher and higher sond pressure levels has tended to obscure the pursuit of sound quality.
There are many loudspeakers available which produce accurate smooth sound but which are too fragile to be used at the very high continuos levels required in recording studios. On the other hand there are numerous loudspeakers capable of going very loud, but which have irregular frequency response, poor transient behaviour, considerable colouration and severe non-linear distortion.
KM1 is therefore ideally suited to satisfy the professional recording engineer or the disceming audiophile with a large musicroom, in search of a system without compromise. KM1 will satisfy the professional musican, perhaps with recording facilities in his home, who wishes to combine the finest possible domestic sound reproduction with his creative activities. KM1 also makes an ideal auditorium loudspeaker for small to medium-sized halls and theatres.

Immutable physical laws - elegant enginering solutions.
KEF engineers have merely accepted the basic limitations of dynamic loudspeaker engineering - and then applied a variety of ingenious engineering techniques to push them harder thananyone has managed hitherto. The target for KM1 was 123 dB spl, which compares with the 112 dB maximum of Model104/2 and 108 dB max for Model 105.2. Considering that 6 dB represents a doubling of sound pressure and quadrupling of sound power, and that 10 dB involes ten times the sound power, and task was by no means easy. To achieve these design parameters, it was decided to use active driv, whereby each drive unit is powered by its own amplifier.
Multiple bass units can be used without prejudicing stereo performance, so four 300 mm units, similar to those used in Model105.2 are each driven by a 100W amplifier, each operating into its own separate enclosure. The midrange presents unique and conflicting problems. These arise from the needto achieve high output lewels with low coloeuation, whilst at the same time maintaining good dispersion which necessitates the use of a small drive unit.
The Km1 solution is to use two units a vertical array to create good stereo imaging, and then to drive each unit with a 350 watt amplifier to achieve the required levels.
B110 units with specially modified polipropylene diaphragms cope easily with the high g-forces involved. Fluid cooling conducts heat from the coils to the magnet structures and thence via 64 mm diameter metal bars to a massive heatsink covering the entire rear face of the mid and high-frequency enclosure.
A single tweeter is necessary to obtain the best stereo performance so a very special version of the T52 was developed. Efficiency is quadrupled by a massive 21,000 gauss magnet system.

Cooling of any high output system should be both efficient and quiet. Cooling by fan can be distracting, switching in as it often does, in a quiet passage following a period of high-level running. KM1's amplifiers and midrange heat sinks are cooled quietly and efficiently by air covenction in a centrally situated 'chimney' arrangement. The emphasis on cooling arrangements in KM1's mid-and high-frequenc section is essential. It ensures that the three units voice coils run cool, preventing compression of high level signals.

In KM1 the use of ferrofluids, coupled with the elaborate heat dissipation arrangements, mean that thermal compression effects are reduced to an insignficant level - less than 0,5 dB over the whole frequency range, even at very high continuous levels of playback.
KM1 is fitted with a comprehensive but entirely practical protection system. This system gets much closer to the heart of this problem area than any hitherto devised. Real time information on the voice coil and heat sink temperatures is provided by onboard analogue computers whilst the system is playing. Whwn these temperatures approach predeterminated thresholds the playback levels is reduced until conditions return to normal.

The construction of the system is modular. A metal frame centre section carries MF/HF enclosure together with the amplifier and power supply. The two bass 'wings' bolt onto the sides of the frame thus forming the central chimney. The MF/HF and amplifier sections are mounted in two filing cabine style slides which may be pulled forward for easy servicing

KM1's elegant design and immaculata finish allow it to blend equally well into a high-tech studio environment or a home music room. The swept back frontal aspect permits stereo imaging of astonishing accuracy.

Specifications

Frequency Response: 38 Hz - 23 kHz ± 2dB (-6dB at 34Hz and 25kHz)
Directional Characteristics: Within 1.5 dB of reference axis response for ±7.5º vertically, to 20 kHz and for ±15º horizontally, to 8 kHz
Maximum Output: At least 120 dB each third octave from 60 Hz - 20 kHz free field from one system at 1metre, or 2 systems at 2 metres.
Thermal Volume Compression: Typically less than 0.5 dB at any frequency and at any level up to maximum output under normal programme conditions.
Distortion: Second and third harmonic less than 3.2% @ 110dB, less than 1% @ 90dB from 60Hz to 20kHz measured at 1m in anechoic conditions.
Input Impedance: 22k ohms - floating
Input sensitivity: Full output for nominal 0 dBm input (0.774V) adjustable in 3dB steps from - 21dBm to + 12dBm.
Signal/Noise Ratio: >105dB
Driver complement:
LF 4 x 30mm Bextrene direct radiator,
MF 2 x 110mm polypropylene direct radiator,
HF 1 x 50mm Mylar dome radiator.
Weight: 140kg (308lb)
Dimensions: 87mm (37/16 in.)
Overall Dimensions (H x W x D): 763 x 1315 x 665 mm; (30 x 51¾ x 26 1/8 in.)

Pioneer M-25

Pioneer M 25 is amplifier in Class AB technology, plays in Class A up to 30 +30 watts and automatically adapts to AB-Circuitery at higher levels. Maximum output power is 120 +120 Watts RMS at 8 Ohms. Minimal distortion is guaranteed. Excellent dynamic, fresh and clear sound with high resolution soundfield.

Carefully Selected High-quality Parts

Each and every part which makes up the M-25 has been singled out for its quality so that only the best is finally chosen. Among the parts employed are gold-plated input and speaker terminals, printed circuit boards of paper epoxy resin with a high insulation resistance, and printed circuit boards using 70u thick copper foil, low-resistance pure copper plates for parallel connections and for the grounding wire, and non-inductive cement resistors.

Esthetically Satisfying and Full-bodied Design

The visual appeal of the power transistors and heat sinks mounted on a broad-based silver-toned aluminium die-cast chassis is what you would expect from a top-quality power amplifier. Just one look at the M-25 is enough to convince you of its tremendous power and stability.

The first stage of the M-25 adopts a dual transistor differential amplifier with a current mirror as the load for a superb stability and gain right from the lowest low frequencies to the highest high frequencies. The pre-driver stage consists of a voltage amplifier with a constant current circuit as the load, and this makes for a significant improvement in the degree of use of the power voltage, and also for a satisfying gain and linearity. The power stage features a Class AB pure complementary parallel push-pull circuit with a three-stage Darlington connection. A newly developed power transistor called a Ring Emitter Transistor (RET) has been introduced into the new Class AB circuitry. This feature guarantees an ultra wide frequency range which turns the attributes of the RET to maximum advantage, and also a superior low-distortion response whatever the power rating - across an ultra-low to full power spectrum. The M-25 delivers continuous power output of 120 watts per channel, min at 8 ohms from 5 Hertz to 30,000 Hertz with no more than 0.01% total harmonic distortion.

In particular, the Class AB SEPP circuit functions as a Class-A circuit which is highly rated on account of its hi-fidelity sound reproduction capabilities with low power outputs (up to 3W/8-ohms). This means that you can enjoy the final sound as you would from a Class-A amplifier. Finally, the pre-driver section contains an over-drive limiter and a power limiter for protecting the power transistors. This helps to greatly improve the reliability.

Twin Transformer Power Supply for Excellent Separation

The Pioneer M-25 is symmetrically designed with completely separate heavyweight class power supplies for each channel. Each employs large-capacity capacitors (two 22,000uF for each channel) which not only feature excellent regulation but also have plenty of reserve. Along with the wide-band frequency response, they ensure a superior channel separation and a reproduction of sound which is both clear and full of latent energy. There is also a surge-killer circuit to keep the inrush current from the power transformers as well as the high current which charges the electrolytic capacitors to the bare minimum, and this feature reduces the load on all of the related parts.

Highly Dependable Protective Circuitry

The M-25 employs a relay type of protective circuit which is equipped with a current detector and an over-current detector. This circuit is designed to protect the speakers from unforeseen accidents caused by the generation of current in the output, or from short-circuiting of the speaker terminals owing to faulty contacts, as well as the power transistors by releasing the output circuitry momentarily. Moreover, the output circuit relay is for 4-circuit high current uses and all the circuits are connected in parallel for enhanced reliability. This circuitry can also be counted on to perform muting when the power switch is flipped between On and Off.

Specifications

Circuit system:

3 steps of first rank differential current mirror load-intensities Darlington
Parallel push pull pure complimentary OCL circuitry (AB class operation, DC amplifier stream composition)

Effective output (both channel drive):

8 ohm: 120 W+120 W (5 Hz – 30 kHz, THD 0.01%), 120 W+120 W (5 Hz – 80 kHz, THD 0.05%)

4 ohm: 120 W+120 W (5 Hz – 20 kHz, THD 0.02%)

THD (5 Hz – 30 kHz, 8 ohm):

At the time of an effective output: 0.01%
At the time of 60 W output: 0.01%
At the time of 1 W output: 0.007%

Cross modulation distortion (50 Hz : 7 kHz = 4:1 or 8 ohm):

At the time of an effective output: 0.006%
At the time of 60 W output: 0.005%
At the time of 1W output: 0.005%

Output bandwidth (IHF, both channel drive):

5 Hz – 45 kHz (0.01% of distortion)
5 Hz – 100 kHz (0.05% of distortion)

Frequency response: 5 Hz-200 kHz +0-1 dB (at the time of 1 W output)

Input terminal: Input: 1V/50kohm

Output-terminal: Speaker: 4 ohm – 16 ohm

Dumping factor: 100 (20H z – 20 kHz, 8 ohm)

SN ratio (IHF, A network) Short circuit: 120 dB

Channel separation: 1 kHz:105 dB; 100 kHz:70 dB

The semiconductor used: Transistor: 55 pieces, Diode, other:53 piece

Supply voltage: 100V - 240V, 50Hz/60Hz

Power consumption: 280W (Electrical Appliance and Material Control Law)

Maximum electric power consumption: 800W

Dimensions (W x H x D): 420 x 153 x 370 mm; 16-9/16 x 6-1/32 x 14-9/16 inch

Weight: 23,5 kg; 51 lb 11 oz (without package)

B&W Matrix 802 S3

B&W MATRIX™802 Series 3

Floor-standing loudspeaker system

Product Summary

The Matrix 802 has a highly linear, high efficiency motor system which delivers the long throw and symmetrical field required to produce an outstanding low frequency response. The Matrix 802 shares many of the key attributes of the Matrix 801. Its only real difference is size. Although only slightly taller than the Matrix 801, it occupies less than half the floor space. The Matrix 802 is therefore the natural choice where floorspace is limited, but the demand is still for a superb studio quality 3-way monitor.

Technical highlights

Kevlar®: B&W developed and patented the method of using Kevlar® for loudspeaker cones to reduce unwanted standing waves. DuPont originally created Kevlar® for use in bulletproof vests.

Tweeter on top: B&W's Tweeter on top technology ensures that the sound remains focused and time-sensitive and that the stereo-image is presented with unparalleled three dimensional accuracy.

Matrix: The basic construction of nearly all loudspeakers is exactly the same - panels of wood-based materials, bonded to form a rectangular box. B&W studied and evaluated how each aspect of cabinet behaviour and the efficiency of various materials and construction methods affects sound.

Description: 3 way vented-box system

Drive Units:

1 x 25 mm metal dome - high frequency

1 x 126 mm Kevlar® - midrange

2 x 180 mm Cobex® - bass

Frequency Response: 42 Hz – 20 kHz ± 3dB on reference axis

Sensitivity: 90 dB spl (2.83V 1m)

Nominal Impedance: 8 ohms (minimum 3.4 ohms)

Power Handling: 50W – 250W into 8 ohms on unclipped programme

Dimensions (H x W x D): 1040 x 300 x 370 mm

Finish: Black Ash, Walnut, Rosewood

Grille: Black Cloth

B&W 802 FS

B&W 802 FS

Floor-standing loudspeaker system

Product Summary

Sheer size dictates that not many homes can accommodate a professional monitor system. But many a music aspires to enjoy, at home, the new era of enhanced listening pleasure such a system opens up. The 802 FS has conceived as a domestic monitor directly related to the 801 FS professional system, but with significant differences tailored to the home listener’s needs.

Technical highlights

The midrange head assembly incorporates Fibrecrete (glass reinforced concrete) a B&W innovation. The secret is that the outer casing of this component is moulded from rigid polystyrene while the inner lining is Fibrecrete. The Environmental controls located on the back of the midrange head assembly are specially developed by B&W. These controls enable the user to make the subtlest of adjustments, compensating for such factors as peculiarities of listening room conditions and the unusual balance that sometimes occur in digital recording. The superb high frequency driver has a motor diaphragm assembly which operates as a diminishing-size sound source as frequency increases. This advanced technique results in vastly superior high-frequency dispersion, high power handling capacity and a new order of transient behaviour in the 8Hz to 20kHz region.

SPECIFICATIONS

Drive Units:

1 x 26 mm multi-filament polyester weave dome; 26 mm dia. High temperature voice coil

1 x 100 mm Midrange frequency drive unit; 25 mm voice coil

2 x 165 mm low frequency drive units; 38 mm voice coil

Frequency Response: 55 Hz to 20 kHz ±2 dB

Sensitivity: 85 dB spl (2.83V 1m)

Nominal Impedance: 8 ohms

Power Handling: Minimum amplifier 100 watts into 8 ohms No upper limit due to automatic

protection device.

Dimensions (H x W x D): 1040 x 300 x 370 mm

Finish: Walnut, teak, black ash, light oak or rosewood

Pioneer CT-F 1000

Pioneer Model CT-F 1000,

a stereo Dolby cassette deck with monitoring (separate recording and playback) head configuration, in metal case.

It is a beautiful machine. Not only does it glitter with Pioneer's traditional care in front-panel detailing, but without going beyond that panel the user can see the two-in-one head, and feel the elegance of the click-stopped level knobs and of the solenoid-controlled drive system via the transport buttons.

The drive speed is unaffected by line-voltage changes and has extremely low wow and flutter in the lab's measurements. Not only that, but its playback speed is adjustable, from +13,4% to -10,6% of normal , or approxmately a whole tone in either direction – to tune the recording to a live performance or to correct tapes made on off-speed machines. The adjustment system does not affect recording speed and has a very positive detent in the control at the normal playback speed, which, while 1,3% fast in absolute terms, matches the recording speed exactly.

The metering system strikes us as very good, admirers of peak metering though we are. The meters themselves are of the averaging type with good ballistics and wide calibration range (from -40 to +5). In addition, there is a peak LED that triggers at the +5 level.

Playback response from the standard test tape is unusually fine. The chrome-tape record/play response is extremaly flat, with extended, smooth bass and a high end that remains very flat up to the beginning of rolloff, which occurs at a higher than average point. Ferrichrome response is a little less flat across the band but is flatter than most ferrichrome curves and extends very high at the top end.

Specifications

Speed accuracy: record and detented playback position 1,3% fast no measurable difference at 105, 120 and 127 VAC

Wow and flutter: playback 0,05%, record/play 0,08%

Rewind and Fast-forward time (C-60): 58 sec

S/N ratio (re 0VU, Dolby off,CBS weighting):

playback: L ch 54 dB, R ch 54,5 dB

record/play: L ch 50,5 dB, R ch 51 dB

Erasure (333 Hz at normal level): 70 dB

Crosstalk (at 333 Hz):

record left, play right: 43 dB

record right, play left: 43 dB

Sensitivity (re DIN 0 VU):

line input: L ch 64 mV, R ch 67 mV,

mike input: L ch 0,33 mV, R ch o,33 mV

Meter action (re DIN 0 VU):

L ch: 6 dB high, R ch: 7 dB high

Maximum output (re DIN 0 VU):

L ch: 0,95 V, R ch: 1,0 V

Dimensions: 16-1/2 x 7 inches (front), 13 inches deep

Pioneer PL-530

Pioneer PL-530

Features

High Torque DC Servo Motor Uses Hall Elements

The DC brushless Hall motor combines Hall elements with a high torque motor and a semi-conductor circuit. Hall elements, production-engineered by Pioneer, are used to switch the polarity in the motor. Since purely electronic commutation is used for switching the motor drive circuit, harmful noise is not generated, and smooth, even rotation can be obtained with high durability. By combining precision engineering with high fidelity circuit technology, excellent characteristics of 70 dB (DIN-B) or more S/N, and 0,03% (WRMS) wow and flutter have been achieved.

Two-Motor Fully Automatic Turntable Uses Precision Geared Motors

A specialized precision geared motor is used for the lead-in and return functions of the tonearm. Since the return function employs the velocity detector principle, stable operation is consistently maintained.

Newly Developed High-Sensitivity S-Shaped Tonearm

High sensitivity angular contact bearings are used for both vertical and horizontal axis movement of the tonearm, so that there is minimum play and friction. High sensitivity and durability are obtained. Both an anti-skating mechanism and a lateral balance adjustment are built in, therefore, even when a low tracking force, high compliance cartridge is used, the unit turns in an excellent tracking performance. An independent tonearm lift device is incorporated in the fully-automatic mechanism, so the stylus can be raised easily even during playing without damage to the stylus or record.

Panel layout Facilitates Easy Operation

This layout places the speed adjusters, function buttons, record size selector, and arm lift lever all at the front of the unit, concentrating controls for eay operation. A headshell stand is built-in for a spare cartridge. The dust cover uses free-stop fastener hinges.

Cabinet Designed for Sound Quality

The power source transformer and operating mechanism are all mounted in the hard particle board cabinet, while the platter and tonearm are kept floating above the cabinet by the floating suspension, contributing to the improvement of the tone quality. External vibrations are doubly damped by the insulators to obtain a very high resistance against acoustic feedback (howling).

Specifications

Motor and Turntable

Motor: Brushless DC servo Hall motor

Turntable Platter: 330 mm diam. Aluminum alloy die-cast

Moment of Inertia: 260 kg/cm (including platter mat)

Speeds: 33-1/3 and 45 rpm

Speed Control Range: ±2% (individual control for all speeds)

Wow and Flutter: Less than 0,03% (WRMS)

Signal-to-Noise Ratio: More than 70 dB (DIN-B)

Tonearm

Type: Static-balance type, S-shaped pipe arm

Effective Arm Length: 221 mm

Overhang: 15,5 mm

Usable Cartridge Weight: 4 g (min.) to 4,5 g (max.)

General

Power Requirements: AC 120 V, 60 Hz

Power Consumption: 7 W

Dimensions (W x H x D): 480 x 170 x 390 mm, (18-29/32 x 6-11/16 x 15-11/32 in)

Weight: 10 kg, (22 lbs)