Cambridge Audio promises nothing less than pure British sound with the Edge A stereo amplifier. In other words, nothing is added to the playback and nothing is left out.
Cambridge Audio believes that at the word, after all, the manufacturer is one of the main pillars in the hi-fi segment that has coined this term for decades. From its founding in 1968, the humble beginnings of a group of enthusiastic graduates in engineering to the hi-fi blacksmith that is now based in London, Cambridge Audio can look back on a long success story. It all started with the legendary first amplifier, the Cambridge Audio P40. This is considered the first commercially available full stereo amplifier using a toroidal transformer.
One of the founders of Cambridge Audio involved in the development of the P40 at the time was Professor Gordon Edge, whose surname is now synonymous with the manufacturer’s premium series. The objective when developing the new edge models was accordingly: The dream system of the developers at Cambridge Audio should be implemented regardless of costs and effort. It is therefore not surprising that the fine tuning was largely carried out by ear, so the choice of components was made via a hearing test and not based on the price list or the specifications. Nevertheless, the data read impressively: The crosstalk is given as less than –100 decibels (dB) measured at 1 kilohertz (kHz). The frequency response ranges from under 3 Hz to over 80 kHz with a tolerance range of just ± 1 dB. It is also gratifying that the USB connection of the Edge A supports high-resolution PCM files with up to 32 bit resolution and 384 kHz sampling rate and even DSD 256. Speaking of connections: Cambridge Audio provides the Edge A with numerous digital inputs, an HDMI ARC connection and balanced XLR inputs and outputs.
With the Edge A, the development dream manifests itself as a beefy and at the same time futuristic stereo full amplifier with a purist, analog signal path and a wealth of analog and digital connection options. Even a TV-HDMI connection (audio return channel) is available, which makes the luxury amplifier also interesting for the living room. First of all we want to dedicate ourselves to the construction and this is one thing above all: massive! With its 24.4 kilograms, the Edge A is a real chunk. The design makes a lot of things, with the thick cooling fins, which cover the entire flanks of the amplifier and express it unequivocally: “This is power!” Together with the solid, gray finish of the aluminum housing and minimalist controls on the device, this results in an absolutely successful Appearance that exudes both strength and a good dose of British understatement. Speaking of the controls, they only consist of a concentric rotary control, the rear ring (corrugated surface) allowing input selection and the front ring (smooth surface) controlling the playback level. The currently active input is displayed via an LED ring. You won’t find a display, but we didn’t miss it. The Edge A looks pretty chic and timeless, although the amplifier was not always practical to use. First, the LEDs are not titled with common AV abbreviations for the respective input, but with A1 to A3 for the analogue and with D1 to D5 for the digital inputs. Once memorized, this is not a problem. Rather, the legibility of the lettering at a distance of a few meters is no longer guaranteed. If you prefer control via the remote control, you should memorize the LED positions including the associated inputs. And where we are already complaining: The solid metal surface of the remote control leaves such a successful impression that the plastic underside seems like a missed opportunity.
The XXL remote control scores with an ergonomic button arrangement and the operation is a pleasure overall. This is of course also due to the fact that the range of functions is also minimalistic due to the puristic concept of the signal path. Tone control, loudness switching or even digital room corrections have been consistently dispensed with here. Caution should be exercised when raising the volume using the remote control, because the powerful start of the Edge A means that only a few keystrokes are enough to increase the volume to the disco level. The volume can be adjusted more elegantly and sensitively using the massive rotary control on the device itself, which has a very special surprise. The volume control is motorized, moves to different positions for “self-calibration” after switching on and is also not an ordinary potentiometer. Cambridge Audio uses semiconductor technology to implement the level control, which is supposed to solve the most common problem with stereo potentiometers: the often audible tolerances between the channels. Even in the case of higher-priced devices, one notices in the lower control range in particular that the stereo balance is distorted on one side or the other by level differences between the channels. This is by no means laziness of the manufacturers, but due to the problem that tightly tolerated stereopotis can only be produced with enormous effort. In any case, the semiconductor solution of the Edge A works very well. The stereo channels remain perfectly balanced over the entire control range and the feel is also a dream. Headphone users will also be pleased to note that when the headphone cable is pulled out, the amplifier does not overwhelm the connected speakers, but automatically mutes and adjusts the volume.
Circuit and specification
However, the solid-state level control is not the only technical trick that is hidden in the Cambridge Audio Edge A. The Cambridge Audio power amplifier is implemented as a class XA circuit. This should combine the tonal advantages of a class A circuit with the power and efficiency of a class AB amplifier stage. For this purpose, a class AB design is provided with a preload selected in this way, so that takeover distortions are virtually eliminated. The manufacturer does not reveal exactly how Cambridge achieves this goal, we guess that the area in which the power amplifier works as a class A is very large. This is also indicated by the measured 160 watts that the Edge A draws in idle mode (switched on without sound output). As already announced, something special awaits us with the transformers of the Edge A as well. Cambridge Audio works with oppositely symmetrical double toroidal transformers. Similar to a symmetrical cable connection, these are supposed to efficiently suppress interference voltages and at the same time ensure stable performance regardless of the playback level. Of course, an integrated amplifier can only sound as good as the rest of the chain allows, which is why we used a suitable UHD-BD player from Cambridge as a source and used contour speakers from Dynaudio to request the amplifier. In the absence of a measuring system and EQ options, the listening room should be acoustically optimized according to the qualities of the hi-fi components and the speakers should not only be set up by eye.
Sound and practice
What does a futuristic and at the same time puristic looking power pack with exquisite audio components sound like? Instead of a spontaneous “wow effect” and typical sound descriptions such as light, dark or center-weighted, the Edge A initially conveys one thing above all: tremendous calm and control. That’s why you should listen to your favorite album in one go to gradually discover the qualities of the amplifier. Listening for hours is highly recommended, because the playback does not tend to exert or fatigue and cheap tricks like a sound that is too soft or too hard were foreign to the integrated amplifier at every volume setting. The character of the Edge A can best be summed up in one word: clean. And that is largely independent of the playback level. Even if the Edge A is extended as far as the ears and neighbors allow, there are no audible distortions on the part of the amplifier, which often creep in warningly on other models. Edge A also stands out positively at the other end of the level range. The sound balance does not break down even with whisper-quiet playback and even the stereo image remains stable. Speaking of the stereo image: It’s razor-sharp. Even in dense arrangements, all elements in the mix can be seen without effort. And if the recording shows that, you can easily follow the microdynamics of each instrument.
The speech intelligibility is also impressive, not only when listening to music, but also via the ARC-compatible HDMI connection. Movies are shown with an excellent balance of effects, music and crystal-clear speech and all without separate channel controls and adaptive special algorithms. Multi-channel audio soundtracks should be downmixed to high quality stereo-quality players. Our only criticism of the sound of the Edge A is that the depth grading did not match the qualities of the other sound parameters, at least in our set-up. That doesn’t mean it’s bad per se, but the sound seemed to stay a little more on the line between the speakers than the otherwise fine-grained, precise amplifier sound did. We want to end our test with an audio sample of an artist who has contributed his own part to the “British sound”. Peter Gabriel’s song “Sledgehammer” from the album “So” is an excellent production that knows how to uncover the weaknesses in the playback chain. The good news: there is no need for any form of criticism, because the Edge A copes with all the passages in an exemplary manner. With Tony Levin’s legendary fretless bass, edited with the Octaver, you can even hear the swinging of the string exactly. The instrument sound is sonorous and growling with a fantastic, precise wire click at the ready. The drums are big and gaudy with wonderfully drawn transients. The brass section sounds powerful and present and Mr. Gabriel’s voice is also clearly emphasized. It’s nice how you can hear all the duplications and the like in the latter. To put it simply: Songs like this really make you happy with the Edge A!
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