Originally printed in the July 1994 issue of Gramophone.
If Arcam can be said to have an image in the cosmetic sense, then that image is one of deliberate avoidance of image. They have made a style out of functionality, with controls, legends and layout as anonymous as possible, with the result, of course, that you can spot an Arcam a mile off.
This refusal to put anything on their products which has no practical value makes the concept of a 'no-frills' Arcani a curious one, but nonetheless that, in a sense, is what the Alpha 5 is. The family resemblance to Arcam's Delta range goes without saying, and it looks for all the world like a Delta 290 stripped down to its basics.
The Alpha 5 is a straightforward no-nonsense amplifier in the best Arcam tradition, providing in its simplest configuration a classic straight-wire-with-gain topology. It has four identical line-level inputs, labelled for convenience Aux, CD, Tuner and Video, and unlike its big brother comes with a Phono preamplifier (albeit a more basic one than that offered as an option on the Delta 290) built in as standard. A conventional Tape monitor circuit completes the input facilities, and unusually there are two tape record outputs, the second labelled Aux/Video and having no corresponding monitor selector. The signal presented to the recording terminals is the same as that being listened to—there is no separate Record selector switch.
The front panel is dominated by the large Volume control, which is logical since in most situations it will be the only operative knob on the unit. In common with other Arcam amplifiers, the Alpha 5 features a Direct switch which bypasses the tone and balance controls completely, minimising the active signal path and thereby offering a slight improvement in sound quality.
Those tempted to tinker with the tone controls should not expect startling results—these are the most subtle bass and treble circuits you are ever likely to encounter, quoted as giving only 3dB of boost and cut at 100Hz and 10kHz. This is fine for very gentle tweaking, but no more; those with problem sources or an enthusiasm for frequency responses other than flat should look elsewhere.
A switch marked SP2 does not, as might be assumed, divert the amplifier's output to an alternative set of loudspeakers. It merely switches on an additional pair of outputs, the main pair being hardwired and permanently 'on' on the basis that any switch in the signal path is a potential source of trouble. For the same reason, the headphones socket does not disconnect the loudspeakers when a plug is inserted; if frequent headphone-only listening is required then the second, switched, loudspeaker outputs must be used. At least headphones users are catered for.
The loudspeaker connections are Arcam's usual excellent 4mm binding post/sockets. The shrouds around these terminals guide the wires neatly into place and minimize the chance of stray strands protruding and causing trouble. The result is a safe, tidy connection whose contact area must be far greater than that offered by any 4mm plug's grub screw or solder bucket. The rest of the rear panel is taken up by phono connectors for the various line level ins and outs and a standard three-pin IEC mains inlet.
So what's missing? Compared with the Delta 290, the answer is nothing essential and only some of the luxuries. As already mentioned, the record selector switch has been dispensed with, as has any form of remote control. It should be pointed out here that there is yet another related model, the Alpha 6; this not only features remote control but allows the Phono input to be operated as a further auxiliary input by means of a rear-panel switch if a turntable is not to be used. The other main difference between the Alphas and the Delta 290 is the power output, down from 75W to a modest but respectable 40W per channel (SOW for the Alpha 6), although it must be remembered that since this is still more than half the rated power of the bigger amplifier it is less than a 3dB difference.
The performance is all one has come to expect from Arcam equipment. On the bench it measures at least as well as the manufacturer's specs, the only surprise being that the Direct switch increases the gain by 1dB right across the band. It has little discernible effect other than this, indicating that the tone and balance circuitry is properly set up and that the relevant knobs Specification have their centre detents accurately calibrated. The treble control turns out to have a wider range than specified, giving up to 45dB of boost at 10kHz if required—still subtle but useful.
When it comes to the perceived performance, I have to say that this is my kind of amplifier, delivering the music transparently and effortlessly to the loudspeakers without any nonsense on the way. Neutrality and accuracy right across the frequency spectrum should be the aim, and the Alpha 5 appears to provide that at all available volume levels, whatever the source material. Subtlety and excitement, ambience and raw power all come across as intended, and although its floor-shaking capabilities may not quite match those of its bigger stablemate, it can produce more than realistic listening levels in an average-to-large room without any sign of strain whatsoever.
I have no hesitation in warmly recommending the Alpha 5; it delivers the goods in a neat, simple package, and it is hard to see what more one could ask for at the price.
Output power: (20Hz-20kHz at 0.5% THD) 40W, both channels into 8 ohms.
Total harmonic distortion: (30W into 8 ohms at 1kHz) 0.01% typical.
Tone controls (typical variation) ±3dB at 100Hz and 10kHz.
Crosstalk: -70dB at 1kHz.
Input sensitivity: line-level 135mV; phono 22mV.
Noise (CCIR, ref rated power) line-level 93dB typical; phono 75dB.
Input impedance: line-level 20k ohms; phono 47k ohms.
Overload margin: line-level 30dB; phono 33dB.
Output impedance: tape/auxiliary 8k ohms; headphones 330 ohms.
Headphones maximum output level: 1OV into 600 ohms.
Power consumption: 320VA max.
Dimensions (WxHxD) 430 x 248 x 74mm.
Manufacturer A&R Cambridge Limited, Pembroke Avenue, Denny Industrial Estate, Waterbeach, Cambridge CBS 9P8. Telephone 0223 440964 UK retail price £229,90