Arcam Alpha 2 amplifier

The improvements that have been taking place in turntables, CD players, and loudspeakers demand a new level of performance from the amplifier - the heart of every hi-fi system. The discerning buyer expects that today's amplifier should combine a natural yet dynamic and powerful sound quality with good looks and ease of operation. above all, the amplifier's standard of manufacture and quality control should promise years of consistent, trouble free performance.

Until now, only a handful of designs were able to meet all of these stringent criteria. Unfortunately the prices of amplifiers in this select group often made them incceassible to those on a limited budget. Arcam, recognising this unfulfilled demand, has now designed and produced  a modern, top quality amplifier that is truly affordable - the Arcam Alpha 2.

Offering many of the sonic benefits of more expensive models, the Arcam Alpha 2 would be regarded as a fine amplifier at any price. However, when its outstanding performance, facilities and construction are compared with other amplifiers at its price level, it is clear that the Alpha 2 is destined to become a classic, setting the new standards by which all others will be judged.

Philosophy

The Arcam Alpha 2 is a product of Arcam's many years of experience in amplifier design and manufacture. Detailed theoretical analysis and extensive listening have produced a design that is technically outstanding. This design has been realised in practice using high quality components selected for optimum electrical and sonic performance. The result is an amplifier that maintains the full dynamics of a musical performance while reproducing the subtleties and emotion both accurately and naturally.

Power

Not only does the Alpha 2 produce a generous 30 watts continuous output per channel into 8 ohms,  but its special high peak current output stage will drive loudspeakers whose impedance dips as low as 2 ohms. Unlike many other amplifiers the Alpha 2 can be run continuously at high levels because its coolrunning aluminium chassis will not overheat.

Versatility

As well as working properly with all commonly available loudspeakers, the Arcam Aplha 2 is fully compatible with a wide variety of programme sources. Five inputs are available; four are selected by a rotaty switch and the fifth by the nearby tape monitor button. all the inputs use a high quality and robust design of phono socket.

The Alpha 2's cartridge input is specialy optimised for use with any moving magnet cartridge or high output moving coil cartridge. The highest quality low output moving coil cartridges can also be accommodated using our optional plug in MCA pre-pre-amplifier board.

There is a dedicated input for a CD player, further inputs for a Tuner and Video playback and finally a set of line level input and output sockets suitable for use with a tape recorder.

Fexibility

A quality domestic hi-fi amplifier can and should possess those genuinely useful facilities which can improve the performance of the complete system. Typical of Arcam's attention to detail is the Alpha 2' volume control which has been psychoacoustically designed to allow ease of adjustment at the low volume levels often used in the home. limited range bass and treble controls of advanced design are also provided. These allow precise adjustment of the frequency extremes without coloration of the critical midfrequency band. Used sensibly they can help correct for imperfections elsewhere in the system, particularly those associated with cartridges and loudspeakers. The constant power law balance control also helps in this respect. The tone and balance controls all have a centre click stop to provide a reference response in the centre position.

The Alpha 2 has a front pabel socket which will suit a wide variety of stereo headphones. The headphones and loudspeakers will normally work together as the main loudspeaker sockets are wired directly to the amplifier's output to obtainthe best possible sound quality. However  a second pair of loudspeaker socket is also fitted enabling the loudspeakers to be muted automatically whenever headphones are plugged in.

Electronic Design

The disc pre-amplifier uses a low noise professional IC and employs audiophile grade 1% metal film resistors and polypropylene capacitors in the critical RIAA equalisation network. This ensures a clean, accurate sound.

Uniguely the Alpha2 is also configurated to accept out plug in moving coil cartridge pre-pre-amplifier board, the MCA. The MCA and Alpha 2 combination has a much lower noise level and correspondingly greater fidelity than other similarly priced amplifiers. This allows the Alpha 2 to be used successfully with some of the world's finest MC cartridges.

All other inputs are fed directly to the Alpha 2's volume control to ensure a virtually infinite overload margin. The preamplifier stages which follow the volume control again employ low noise professional quality ICs and make minimal use of coupling capacitors to avoid degradation of the sudio signal. All preamplifier circuits are powered by two lownoise, low-impedance regulated power supplies.

The Arcam Alpha 2's power amplifier is an advanced bipolar, high slew-rate design with direct coupled fully complementary class AB output stages. Constant bias circuitry for the driver transistors maintains a clean, dynamic output throughout the entire operating range. The amplifier has a very high transient current capability, made possible by use of 100 watt power transistors combined with high value low ESR reservoir capacitors and a generously rated toroidal mains transformer. Together these permit instantaneous peak output levels of some 250 watts from a single channel into a 2 ohm load. Nevertheless the amplifier is effectively protected against overload. readily accessible fast-blow output fuses are also fitted for loudspeaker protection. They are connected within the main  feedback loop to prevent degradation of the signal. In addition the layout of the PCB has been optimised for such factors as maximum transient power capability and minimum on-board interaction.

Finally, the loudspeaker outputs use ultra high quality PCB mounted 4 mm sockets. These employ silver loaded contacts amd are soldered directly to the PCB to ensure integrity of the signal path. High quality matching plugs are supplied as standard.

Specifications

Output Power: 

30 W  - both channels into 8 ohm (20 Hz - 20 kHz at 0,5%THD)

40 W  - single channel at 1 khz into 8 ohm

60 W  - single channel at 1 khzinto 8 ohm

Total Harmonic Distortion:  0,02% (at 25 W into 8 Ω at 1 kHz)

Overload Margins: 

Disc Inputs :  32 dB at 1 kHz

Other Inputs :  50 dB

Frequency Response:

Disc Input :  60 HZ - 20 kHz , ±0,5 dB, -3 dB at 20 Hz

Other Inputs :  30 Hz - 20 kHz ±0,5 dB, -1 dB at 20 Hz

Tone Controls:

Bass :  +-8 dB at 50 Hz

Treble :  +-8 dB at 15 kHz

crosstalk:  -65 dB at 1 kHz

Disc Inputs:

Suitable for MM and high-output MC cartridges

Sensitivity :  2,5 mV

Noise :  -72 dB

impedance :  47 k Ω  in parallel with 100 pF

With MCA board fitted, for low output MC cartridges

Sensitivity   250 µV

Noise :  -70 dB

Impedance :  330 Ω

Tuner, TApe, Video :

Sensitivity :  200 mV

Noise :  -95 dB

Impedance :  25 k Ω

CD

Sensitivity :  450 mV

Noise :  -95 dB

Impedance :  10 k Ω

Outputs Nominal Level/Impedance

Tape :  220 mV/2 k Ω

Headphones :  suitable for 8 Ω  - 2 k Ω  impedance

Loudspeaker:  30 W into 8 Ω  at 1 kHz

low frequency daming Factor :  200

Suitable for speaker of 4 Ω  or higher nominal impedance

General

Power Supply:  240 V , 110 V ; 50/60 kHz

Power Consumption :  120 VA

Spares Provided

Two loudspeaker fuses;

Two red and two black 4 mm plugs

Dimensions (W x H x D):  430 x 230 x 84 mm (16,9" x 9,1" x 3,3")

Weight:  4 kg (8,8 lbs)

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