Introduction

When a relative is in the market for a new amplifier, it's nice to be regarded as the one who knows. It's also a nice opportunity to survey the scene and select a likely candidate for serious evaluation.

And so it was the other week. A relative asked for my help in selecting an integrated two-channel amplifier for his system. A newspaper review of several amplifiers revealed the Cambridge A5, available from nearby Colchester, was at the top of the pile, so a trip to Richer Sounds secured the attractive silver version. We got the distinct impression that the unit could be returned with no cost penalty if we decided it wasn't for us.

The illustrations in this article are of the amp ensconced in its new home, so clearly no return was necessary. The price from Richer Sounds was attractive and the performance is good. Here, then, are the details of the amplifier and tests.

General

The outer casing of the packaging had a convenient carry-home handle, and inside the packaging were the usual polystyrene cheeks and a lovely blue Cambridge Audio bag. Inside the bag was the amplifier.

A period of 36 hours is recommended as the running-in time for the amplifier, so that's what it got. Happily, the time available for review overlapped with the loan period of the Tannoy Sensys DC2s that I'd just finished evaluating. Having decided those were smooth, transparent, and revealing, it can be no surprise that I pressed them into service as my reference for the tests of the A5.

This amplifier is available in silver (illustrated) and black. Just lifting the box gives a clue to the care that has been taken over the power-supply implementation. Yes, most of that weight is due to the mains transformer, ensuring there is plenty in reserve for the best moments in your favorite Wagner or Leppard.

Terminals are labeled upside-down to ease connections when looking over the top of the amp.

Features

There are inputs for Tape/Minidisk, Aux/Phono, AV/DVD, CD, and Tuner, along with low-level outputs for recording and for feeding to another power amplifier.

The output terminals for speakers are provided via binding-posts which have solid cores. I would have preferred these to be bored out with 4mm centers to allow easy plug-in. That combination would have catered for those who insist on bare-wires only connecting to the amp, and those, like me, who do not hear a difference when good quality 4mm plugs are used. However, sufficient sets of terminals are provided for single and bi-wiring. This could have been assumed to be flim-flam on the part of Cambridge, imitating product from a much higher league. I would not say this is the case; the amplifier is a serious piece of Hi-Fi and deserves the connectivity you'd expect for such a category.

The control knob that dominates the front view is the volume control (gain control). It has a smooth feel with no roughness and just the right amount of drag to let you know it will stay where it's left. There is no detectable back-lash. It follows from all this that it's not one of the stepped variety of controls. In many cases, these only mimic a stud-fader and have no electrical benefit. I do not feel the amplifier would be one jot better if the controls were stepped, and could indeed be worse.

The tone controls, on the other hand, have a central detent to indicate 'flat'. The benefit of these is two-fold. When requiring boost or cut in one register while leaving the other alone, it's useful to have a reference point for the one set to flat. The other benefit is for a reviewer! Setting both tone controls to their central detent position provides the ideal opportunity to listen for any difference in tonal coloration when selecting between tone-control and bypass, using the push-button provided. I performed that test with each of my music selections and didn't detect a difference. It's a useful feature, though, to ensure the shortest possible electrical path through the amp.

The phono input is not fitted with a magnetic-cartridge equalization stage. On the one hand this allows for use of an outboard equalization/gain stage of the highest quality which can be optimized for the turntable pickup cartridge in use. It also saves some money at initial purchase for anyone with no intention of using a vinyl source with the amp. On the other hand, and for greatest neatness and convenience, anyone intending to use a turntable would be well-advised to buy the optional internal phono stage within a few months of purchase in case there is any danger of continuing availability in coming years as models in the range come and go.

Performance

With no music playing, with the gain control set to maximum, and with an ear pressed to each speaker in turn, the noise level was extremely low - barely audible. But just above the 'noise-floor', in the right-hand side only, there was a slight 100 Hz hum. The amp itself gave a similar buzz acoustically. Even in the dead of night, with the quietest of music playing at a high gain setting, none of these can be heard from a normal listening distance, or anywhere above about one foot away, for that matter.

The input selector appears to be a physical, rotary switch rather than an electronic switching matrix, though there is no way of knowing from the outside whether the switching actually is performed electronically. Either way, I felt it worth checking for breakthrough between sources, since insufficient attention to design and implementation can compromise isolation for both circuit configurations. Several combinations of used-input and selected input were tried and none had any breakthrough whatsoever.

All my regular CDs were tried, and then some. Abbey Road had a certain warmth which I was not expecting. I'd become used to a clinical, perhaps even cold delivery from the Quad-Tannoy reference system. Whether this effect from the Cambridge was due to some frequency-response imbalance, I am not in a position to discover. The frequency-response specification is, unfortunately, meaningless. Quoting 3 dB points tells us nothing about how flat the response is across the audible band. No doubt we are meant to assume the response is flat between the "3 dB points" and only falls gracefully with a single-pole characteristic to meet the 3 dB points at the quoted frequencies. The response figures quoted could equally be met by an amplifier whose response varies from -3 dB to +3 dB anywhere in the band. My listening proves the amp does not behave in this way, but the spec-writers should tighten up what they are claiming to give a better indication to those of us who'd like potential problems in this area taken out of the equation. Maybe there's a 1dB lift in the response in the mid-range somewhere? Not huge but such a lift could be audible on some material.

A nice pairing of previous speaker tests and amp performance is given by the Sarah McLaughlan tune "I Love You" from Surfacing. Any lack of control in that massive bass will stand out like a sore thumb, but there were no problems whatsoever from the A5. The damping-factor in the output stage is clearly good enough to handle this challenge, so all credit goes to this design and, indeed, the design of the power supply that underpins it.

On a related topic, interference from typical offending sources such as the refrigerator thermostat is completely ignored by the amp. In other words, noise immunity is a strength of the unit through correct attention to the power supply, grounding, and shielding arrangements. Not all devices can say this, and the listener pays the price during some quiet section of a favorite piece when 'click-ker-click' shakes you back into listening to the equipment rather than the music. Cambridge Audio spare us from all this.

The realism you get from the A5 makes this an attractive amp at its price point and probably well beyond it. Anyone interested in an audition should take along a copy of Bridge Over Troubled Water. My own experience was to feel that I had rarely heard a more realistic-sounding piano on this recording. It's an odd but interesting facet of equipment evaluation that each unit brings fresh understanding of familiar material, and this was one such case.

Conclusions

The Cambridge Audio A5 is a good performer, and many manufacturers would happily charge a great deal more for similar performance. The features will meet the needs of most enthusiasts. I can't help feeling that the amp brings 'enthusiast' performance at 'general public' prices.

- Graham Vine -

Associated Equipment:
Sources: Philips CD, DVDR70
Speakers: Tannoy Sensys DC2

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