The SCA 2 preamplifier was initially conceived to fulfil a specific need - to create a no-compromise amplifier to partner the range of ATC active loudspeaker systems. However, as development progressed it became abundantly clear that the SCA 2 preamplifier was capable of enhancing the performance of any audiophile separates system.
In fact, the outstanding ability of the SCA 2 left many who auditioned the final pre-production prototype in no doubt that they were listening to possibly the finest example of preamplifier design - ever.
A key feature of the SCA 2 is the total elimination of audio integrated circuits in the main signal path which is made possible through the introduction of no fewer than ten high performance discrete circuitry gain blocks. Furthermore, all amplifiers in the monitor chain are of similar type and built from discrete bipolar transistors and FETs. The input stage is a fully complimentary dual long tail pair arrangement which uses low-noise bipolar transistors with constant collector voltages provided by cascoded junction FETs. Output of the current mirrors is buffered by a pair of complimentary Sziklai Darlington transistors. To further minimise signal degradation, input circuitry including all sockets, selection relays and tape buffer is mounted directly onto a single PCB.
In essence, the gain block within the SCA 2 is a high output, low distortion amplifier with a very wide bandwidth which is easy to use in conventional feedback configuration because it has only one stage of gain (in other words, there is only one possible source of roll-off and phase shift at high frequency.)
The result is remarkable audiophile product which, in both laboratory and subjective listening tests, clearly redefines the state of the art.
Clean stable power supplies result from local active decoupling of supply rails adjacent to each gain stage, with each channel separated to minimise crosstalk of supply artifacts.
Auditioning reveals an open, neutral, transparency the amplifier creating a solid soundstage which is both wide and deep. Voices are reproduced with uncanny realism being portrayed with natural warmth and articulation. Bass takes on a rich, superbly controlled solidity. Strings are reproduced with a fine degree of detail and texture, while brass is conveyed with attack and clarity. Percussion is handled with great speed and definition. As you'd expect from a design as highly specified as the SCA 2, dynamic range is outstanding.
The distinctive case of the SCA 2 is constructed from aerospace grade peened stainless steel. The 440mm (17%) wide front panel is edged with bead-blasted machined aluminium the fascia being finished in polished acrylic. Optional alternative colours and surface treatments are available to special order.
'Volume', 'Monitor' and 'Record' selection can be operated manually at the front panel using rotary controls (Volume, via a precision motorised potentiometer, Monitor, and Record, via processor-controlled switchs). Three push buttons activate Standby/Reset, Mute, and Gain, the latter providing 12db attenuation for convenient low-level listening. Alternatively, all functions may be accessed remotely from the system's optional SCA R handset. Output is automatically muted during any input selection function.
The SCA 2 offers eight audio inputs - all of which are electronically buffered and selected by precision gas-filled gold-plated relays: two are balanced (CD Bal and Aux 1 - each individually trimmed for optimum CMRR), while CD, TA/AV, Tuner, Aux 2, Tape 1 and Tape 2 are unbalanced. Buffers for both tape circuits use a monolithic operational amplifier as used extensively in recording studio equipment and provides monitor and 'howlround' protection.
For the ultimate in vinyl replay, ATC's own SPH 2 optional in-board phono stage can be specified to special order. This definitive design is capable of extracting the very most from today's state-of-the-art moving coil and magnetic cartridges. Being a totally discrete design with no integrated circuits, the SPH 2 uses ATC proprietary capacitors, features split passive/active equalisation, and provides for both resistive and capacitive cartridge matching. On board power supply regulation is separate for each channel.
The SCA 2 preamplifier offers both balanced and unbalanced main outputs. Balanced output is via XLR connections and offer high output drive capability (15V from 10 Ohms). Consequently, the SCA 2's ability to drive long cable runs of up to 50 metres without any signal loss makes it an ideal partner for active loudspeaker systems. Unbalanced output is provided by RCA phono connections assuring full compatibility with power amplifiers which do not offer balanced operation.
For those whose enjoyment of recorded music is paramount, auditioning the SCA 2 will prove both a revelation and a source of enjoyment for years to come. For those who appreciate not only fine audio performance, but also innovative design and outstanding build quality, the SCA 2 will continue to impress long after the novelty of lesser products has waned.
The SCA 2 by ATC. A landmark in audiophile preamplifier design.