Stereo Amplifier

Review: Technics SU-A900 mk2 Stereo Amplifier

Like car design, audio equipment styling lends to follow trends - today silver, tomorrow black; today stark and angular, tomorrow curved and soft. Also like cars, the basic functionality dictates certain aspects of appearance, and as ergonomics become more refined so the distinctions marking out one manufacturer from another tend to become less pronounced. Thus the influence of the wind tunnel has led to cars which are subtle variations on the aerodynamic ideal, with manufacturers' identifying hallmarks restricted to small cosmetic details. So too with audio. Having established what the consumer wants from a system, there are only so many ways the required switches and knobs can be fitted to a box which can blend discreetly into the average living room. Despite this, the manufacturers strive constantly for a corporate identity (some with more subtlety than others!), and manage time and again to achieve it.

Technics, I am sure, would never pretend to be minimalists when it conies to equipment design, although first sight of the SU-A900 might suggest that it is a simple, no frills amplifier. The obligatory enormous central volume control dominates, and a few small push-buttons with associated LEDs deal with inputs and loudspeaker outputs. A further button for selecting or defeating the apparently absent tone controls gives away (in case you hadn't noticed it already) the hinged flap behind which lurk the remaining facilities. Opening the flap reveals the SU-A900 to have as many bells and whistles as one is likely to want or get from a serious amplifier, and provides one or two surprises.

This amplifier is generously provided with inputs, including two tape monitor loops and a phono circuit switchable between moving-coil and moving-magnet operation. Unusually, the MC/MM switch is easily accessible on the front (albeit behind the flap), which seems both unnecessarily cluttering and slightly risky - this is not a function which one would like to find unexpectedly set wrong. The tape inputs are labelled Tape 1 and Tape 2/DCC, underlining Technics' commitment to the DCC format as evidenced in their excellent recorder, f trust no one would be misled by this into deducing that the design precluded the connection of any other recording format.

As usual, the line-level inputs (everything apart from phono, including Tuner, CD and Aux) are electrically identical, and the SU-A900 provides no less than three methods of switching between them. One, obviously, is the remote control handset, of which more anon, but the amplifier itself has two sets of selector switches. On the main panel, a pair or nudge buttons steps back and forth through the possible inputs, which is effective if a little clumsy, while behind the flap is a set of straightforward direct access buttons. What the motivation behind this duplication can be I cannot imagine, beyond the simple one of giving the user as many controls as possible to play with - an attraction to some but an irrelevance to many. Note that the tape monitor circuits - for checking a recording while it is taking place with a suitably - equipped recorder - are only available from the hidden controls, which step through a choice of Tape 1, Tape 2 and Source.

The flap also conceals selector switches for the two loudspeaker outputs; these may look rather small for the task, but operating them produces the reassuring clunk of big relays somewhere in the back of the cabinet. There is no direct unswitched loudspeaker feed. Next to the switches is the headphones socket, which in the interests of reliability and quality does not break the signal to the loudspeakers - these must be switched off in the normal way. The aforementioned tone controls are also on this sub-panel, offering 10dB of boost and cut at the unusually extreme frequencies of 20Hz and 20kHz. While these can be switched out of circuit, the adjacent balance control cannot, making it important to check that it is sitting at its centre detent at all times. Fortunately this position gives accurate channel balance to within 0.25dB. All these three controls are small and fiddly, made the more so by being recessed behind the flap, but for most of us this will not be a problem as they will rarely be required.

The rear panel carries phono sockets (not gold-plated) for all the line-level inputs and outputs, together with two pairs of loudspeaker terminals in the form of shrouded 4mm socket/binding posts. There is a socket for Technics' global remote control interconnection, and a mains connector - a surprisingly small two-pin socket of the type fitted to portable cassettes and shavers. To be fair, this is more than capable of delivering the required amount of mains power to the amplifier, but it looks decidedly lightweight compared with, say, the 10A IEC 'kettle lead' connector more often used for this purpose.

By contrast, the rear panel also carries a cooIing fan which will cut in when required; this must be for emergencies only, as lengthy listening at high levels Tailed to make it spring into life, as a consequence of which I am unable to comment as to whether or not it makes an unwarranted noise.

The remote control deals with most of what will be required - adjustment of the motorized volume control and input selection - and although it will not select the tape monitor loops, it has banks of controls for other related equipment; CD players, recorders, tuners and even the Technics DCC machine.


Measurements showed the justification for the lone control defeat switch; while the calibration was reasonably accurate, the HF was over 1dB down at 20kHz with the controls switched in - not a major audible problem but worth avoiding if the controls are not required. With them out of circuit the response is flat well beyond audibility, being 3dB down at 120kHz and unchanged down to 15Hz. As mentioned, the chosen frequencies for the tone controls are at the very ends of the spectrum, making them subtle in operation despite their ±10dB range.

Listening tests showed the Technics SU-A900 to be a very able performer. It is a comparatively high-powered amplifier, and deals effortlessly with all kinds of musical material right up 10 unnecessarily high volumes. The high end has an attractive glossy sheen to it which flatters most of what it touches; the treble in fact seems to go on and on, and leaves little chance of missing anything of importance in the upper frequencies. The bass tends to be heard rather than felt, but is nonetheless not noticeably lacking - in fact, as with the treble, it comes across as very extended, revealing rumbles which other amplifiers might conceal. There is perhaps a lack of continuity between the low bass and the low midrange on some material - not a frequency response deficiency but a feeling that the elements of the music are somehow slightly disconnected - but this is very subtle and subjective and reflects little on the overall excellent and comfortable sound. Transients and dynamic range are well presented, while spatial depth, stereo image and rendition of ambient information are all impressive. Immediacy and presence are readily available when required, but never at the expense of subtlety. Several times I had to force myself to listen specifically to the amplifier as I found myself enjoying the music too much - which of course is just as it should be.

The overriding impression of the SU-A900 is that of a rugged workhorse amplifier which promises years of high-performance service with as many facilities as one chooses to use. Some may find many of its features superfluous, but then this is probably not aimed at them. For the rest, the Technics SU-A900's marriage or sound quality and control is a happy one which merits close inspection.