Cambridge Audio • Edge M Monoblock Power Amplifier
Although it had already been in business in one form or other for a couple of decades at the time, Britain’s Cambridge Audio first appeared on my audiophile radar in 1985 when they launched the world’s first two-box CD player, the CD1. Back in those days I was still in the digital audio camp so I lusted after one, even though the £1,500 price tag was far beyond my meagre means. (I should mention that is was only a few years later that I also lusted after the Goldmund Reference turntable, but at more than £10,000 it was even further from my grasp!)
Cambridge Audio has changed owners since then, and now manufactures a variety of audio electronics at various price points. A few years ago we favourably reviewed the Azur 640P, an affordable phono stage with remarkable sound quality considering its price. For this review, we’re considering the upper echelons of Cambridge Audio’s offerings, their Edge series of electronics, specifically the Edge M monoblock power amplifier.
Technical Description
The Edge M is a solid state monoblock power amplifer, offering up to 200W RMS into 8 Ohms (350W RMS into 4 Ohms), and is fully balanced from input to output.
The back panel contains the IEC mains inlet plug, a voltage selector switch (which should be set to the correct voltage at the factory), a pair of gold-plated XLR and RCA sockets (one of each for balanced and single-ended input respectively, and another one of each for output, allowing one to daisy-chain two amplifiers together, for example to facilitate bi-amping), and a pair of gold-plated 5-way speaker binding posts. Additionally, a pair of 3mm sockets provide remote triggering capability, and finally a small switch enables the user to select between the single-ended and balanced inputs, and another disables the automatic power down.
The front panel, which is made from a thick sheet of metal, contains just the power switch and its LED power-on indicator. The sides are made up of a pair of massive heatsinks; this is a good thing because the Edge M uses Class XA amplification, which tends to run hotter than a traditional Class AB amplifier. Class XA is Cambridge Audio’s proprietary implementation of a Class AB circuit that adds a bias voltage for lower crossover distortion. A good circuit topology is only as good as the components used in its implementation. To this end, the Edge M employs many hand-picked components.
Not content with using just one transfomer in the Edge M’s power supply, Cambridge Audio use a pair of 325 VA, precisely orientated, toroidal transformers for the output stage. This arrangement allows for the EM fields from the transformers (as low as they are) to cancel each other out, greatly reducing hum and increasing musical detail. An additional, 42 VA, transformer supplies the input stage. Finally, eight custom made, 10,000 μF capacitors provide an impressive 80,000 μF of energy storage.
The output stage is comprised of four pairs of output transistors, enabling the Edge M’s generous power output. Another pair of transistors is used to implement the Class XA circuit.
The Edge M has excellent fit and finish, and evokes a sense of high quality when handled. Also of a very high standard is the packaging in which the Edge M is shipped. The amplifier itself is in a soft cloth bag, and a silicone band is used to protect the top cover and top of the heat sinks. The bag is cocooned in protective foam, which is double-boxed in sturdy cardboard. Underneath the amplifier is a small cardboard box, containing the power cable, a link cable, and the user guide.
Setup and Listening
Setting up the Edge M monoblocks was trivial: I set them on my amplifier stands, verfied that the single-ended inputs were selected, connected the cables and was off to the races! To make sure I was listening to the Edge Ms at their best, I used them for about 100 hours to ensure that they were fully burned in before I started my formal listening evaluation.
As long-time readers will no doubt recall, Mike Oldfield’s Tubular Bells [Virgin Records V2001] is one of my all-time favourite records. I think that it—especially Part 1—is a masterpiece, and has suprisingly good sound quality, especially considering its relatively humble genesis. So it is somewhat fitting that my evaluation of the Edge M started with Tubular Bells, a record with which I am intimately familiar after numerous listens over more than four decades.
The first thing I noticed when listening to Tubular Bells was the delicateness of the piano and warmth of the bass. Another pleasantly surprising find was the prescence of overtones in the piano part in the finale that I haven't heard before!
One observation that comes to mind when listening to Tubular Bells is a slight hardening in the mids: the electric guitar just before the nasal chorus was, to my ears, a bit strident.
Next on my turntable was the Tron Legacy soundtrack by Daft Punk [Walt Disney Records D001356101]. This album has prodigious amounts of deep, cavernous bass which the Edge M handled with aplomb, its thunderous bass shaking my room at times: great fun! The Edge M isn't just a one trick pony: delicate details, like the faint cymbals near the beginning of Armoury, are also nicely reproduced.
Switching genres, the next record I listened to was the exquisite Scheherazade by Rimsky-Korsakov [Classic Records/RCA Victor LSC-244], as interpreted by Fritz Reiner conducting the Chicago Symphony Orchestra. The opening brass blast has great heft, blat, and weight which makes for an interesting counterpoint to the sweet tones of the solo violin and harp that follows. The ambience from the hall is particularly noticable when the solo violin is playing. Similarly with the woodwinds, which can be heard reverberating off of the rear wall.
Staying with classical music, next on my Forsell turntable’s platter was one of my favourite orchestral pieces: Prokofiev’s Lieutenant Kije [Classic Records/RCA Victor LSC-2150]. This record has a very wide dynamic range—from the ppp of the opening, off-stage trumpet, to the thunderous fff of the orchestra playing full tilt—which the Edge M handled with self-assured ease. The Edge M amps certainly have plenty of power on tap!
One minor critique that I must report is the slight hardening in the opening cymbal crash of the third movement, Kije’s Wedding. It's not very serious, but was enough to draw itself to my attention.
To end my description of Lt. Kije on a positive note (no pun intended!), the tintinnabulation from the bells in Troika is impressive. Something else that was impressive is the deep and wide soundstage, which spread beyond the edge of my speakers, and sitting firmly behind them. Portraying a realistically deep and wide soundstage is, for me, a crucial part of the home listening experience. In this respect, the Edge M does not disappoint!
Next up was You Look Good To Me from The Oscar Peterson Trio’s LP, We Get Requests [Analogue Productions V/V6-8606]. The opening bell and sawing of the double bass really stands out (in a positive way), and I could hear Ray Brown grasping his bass just before starting to play it (a detail I don’t recall having heard before). And judging by his quiet humming along while playing, I could tell that he was really enjoying himself.
To see how the Edge M fared when reproducing voices, I listened to Bill Henderson’s take on Send in the Clowns [Jazz Planet JP 0779-12]. I noticed a slight stridency of the louder spoken passages, but this could be the mic preamplifier overloading, or the tape being over saturated. This minor quibble notwithstanding, the intimacy of this recording is laid bare, and the subtle restaurant noises in the background add to this. Henderson’s trio were righ there in my music room! The same can be said for Dusty Springfield singing The Look of Love, from the Casino Royale soundtrack [Classic Records/Colgems COSO 5005-45]. The air around the saxaphone is impressively palpable.
Another old favourite of mine is Jean-Michel Jarre’s Revolutions [Disques Dreyfus 837 098-1]. On the right system, listening to this record is a treat, and the Edge M didn't disappoint: when called upon to do so, the Edge M is more than capable of delivering stygian bass. Take, for just one example, the synthesized behemoth “steam engine” at the beginning of Industrial Revolution Part 1. When playing this album with the lights out (which is my preferred modus operandi during serious listening sessions), I was taken back to that cold October 1988 night in London’s Docklands, where I was in the audience for the first of two Destination Docklands shows. Of course the fireworks and searchlights weren’t in my room, but the thunderous bass sure was!
All the deep bass in the world is of limited appeal if it can’t carry a tune. The tablas and synthesized bass on Arena from Colourbox’s eponymous debut LP [4AD CAD508] are warm, deep, and tuneful. The Edge M certainly does not commit the cardinal sin of one-note bass!
The last track I listened to using the Edge M with my Audio Research LS27 line stage was Ride of the Valkeries [Sheffield Lab 7]. Fine details abound in this classic direct to disc recording for which Sheffield Lab were so famous. Even when the orchestra is going full blast in the finale, the bite from the brass, the tintinnabulation from the bells, the snare of the drum, and the rasping of the strings are clearly deliniated. Great stuff!
For the remainder of my evaluation, I used the Edge M’s companion component, the Edge NQ preamplifier with streaming network player, instead of my LS27. I didn’t evaluate the streaming functionality of the Edge NQ, just its preamp section.
The first track I listened to with the Edge NQ performing line stage duties was Kate Bush’s Wuthering Heights from her debut album, The Kick Inside [EMI EMC 3223]. Considering its genre and vintage, this album has remarkable sound quality through the Edge NQ and Edge M combo. Instruments are clear, and Bush’s angelic voice floats over them. The bass is deep and tuneful, but there’s a slight hardening of the mids draws attention to some of the notes plated on the celeste.
The last record I listened to was Zubin Mehta conducting the Los Angeles Philharmonic Orchestra play Gustov Holst’s The Planets [ORG/London Records ORG 122]. What a revelation it was! The soundstage size of this recording when played through the Edge combo is nothing short of astonishing, extending well beyond the edge of my speakers and the front wall.
Verdict
For the most part, the Edge M is an impressive sounding power amp. With the exception of the slight hardening in the mids I observed, the Edge M has many virtuous qualities: the bass is deep, tuneful, and warm; the highs are delicate and sweet; and the soundstage is cavernous.
Build quality and fit ’n’ finish are excellent, as are the packaging and documentation. If you’re in the market for a new power amplifier, an audition of the Edge M is a must.
Specifications
Description Solid state monoblock power amplifier.
Continuous output power 200 W RMS into 8 Ohms, 350 W RMS into 4 Ohms (< 1% THD+N).
Frequency response < 3 Hz to > 80,000 Hz ±0.3 dB.
Gain 28 dB (RCA); 22 dB (XLR).
Distortion < 0.002% THD 1 kHz at rated power (8 Ohms),< 0.02% THD 20 Hz to 20,000 Hz at rated power (8 Ohms).
Input impedance 100K Ohms (XLR), 47K Ohms (RCA).
Input sensitivity 1.7 V RMS (RCA), 3.4 V RMS (XLR).
Signal to noise ratio > 93 dB (Ref 1 W into 8 Ohms), > 115 dB (Ref max power).
Max power consumption 1000 W.
Standby power consumption < 0.5 W.
Dimensions (hwd) 150 mm x 460 mm x 405 mm.
Weight 23.6 kg.
Finish Grey anodised aluminum.
Serial number of units reviewed HT C11215 7061 0029 and HT C11215 7061 0057 (Edge M), HT C10973 7255 0034 (Edge NQ).
Price CAD $6,599.99 each (Edge M), CAD $7,999.99 (Edge NQ).
Warranty Two years transferable.
Manufacturer
Cambridge Audio
Gallery Court
Hankey Place, London SE1 4BB
United Kingdom
+44 (0)20 7940 2200
www.cambridgeaudio.com
Canadian Distributor
The Watershed Group
10 Abbott Court, Unit 402A
Brantford, ON N3S 0E7
(888) 253-1207
thewatershedgroup.ca
Associated Equipment
Analogue source Forsell Air Reference Mk 2 turntable and arm.
Phono cartridge Lyra Atlas.
Phono stage Audio Research PH8.
Line stage Audio Research LS27 and Cambridge Audio Edge NQ.
Power amplifiers Cambridge Audio Edge M and PrimaLuna ProLogue Sevens.
Speakers MartinLogan Spire.
Cables Phono: Nordost Frey. Interconnects: Nordost Frey. Speaker: Nordost Frey. AC: stock.
AC power Dedicated subpanel supplying five 20A circuits using identical lengths of 10 gauge wire; Leviton hospital grade receptacles.
Accessories Target and SolidSteel equipment stands; Mission Isoplat; Audio Physic cartridge demagnetiser; Acoustech carbon fibre brush; Lyra SPT stylus cleaner; Audio Additives digital stylus force gauge; Spin Clean Record Washer Mk II.