Cambridge Audio • Azur 640P Phono Stage
One of the things that puts off newcomers to vinyl is the need for a phono stage. Not only must one spend at least several hundred dollars on a turntable (I discount those sub-$200 turntables, which, in my (admittedly limited) experience should be ignored if one wants a taste of what vinyl can really deliver), but a similar sum must also be spent on a phono stage. In days of old, this wasn’t an issue because all integrated amps and preamps came with built-in phono stages. But that isn’t so any more, and the phono stages that do come with most more affordable integrated amps, preamps, and even receivers, shouldn’t be regarded as anything more than a “get you going” facility so as to fill a check box.
Make no mistake: once you get into vinyl, sooner or later you’re going to want a separate phono stage. Not only will a separate phono stage help you get the most out of your records, it will also enable more flexibility in your choice of preamp or integrated amp because you will no longer be limited to those with built-in phono stages. Although a really good phono stage can set you back more than $1,000 (sometimes much more!), there are more affordable options. One such option is the Azur 640P, from Britain’s Cambridge Audio.
Although they were formed in 1968, Cambridge Audio first appeared on my audio radar in 1986 or so when they launched the world’s first two-box CD player, the CD1, for the then-princely sum of £1,500. Before I got out of CD, the CD1 was a player I lusted after—although not as much as I lusted after a Goldmund Reference turntable! (Yes, for a year or two way back then, a Marantz CD 73 CD player was my primary music source. I hasten to add that I sold it and most of my CDs to pay the deposit for my first high-end turntable, a story I may relate in these pages one day...)
Since those days, Cambridge Audio has changed hands and now manufactures a variety of audio electronics at several price points. Two of those products are the Azur 540P and 640P phono stages; it is the latter that is the subject of this review.
Technical Description
The Azur 640P is a compact solid state phono stage. It features two pairs of gold-plated RCA input sockets (one for MM cartridges, the other for MC cartridges), and a pair of gold-plated output RCA sockets. There’s also a subsonic rumble filter (which may turned on or off very easily).
In addition to the input and output sockets, the back panel houses the rumble filter and input selection switches, a grounding post, and a socket for the 12 VAC power supply. The transformer for the latter is, unfortunately, one of those wall warts, but on the positive side it does help keep the 640P’s cost down. The 640P is intended to be permanently powered, so there is no main power switch.
The front panel, which is made from a 3 mm thick sheet of aluminum, is available in either a silver or black anodised finish. It houses the blue LED power indicator.
The 640P’s smaller brother, the 540P, comes in a package the same size as its bigger brother but omits the MC set of input sockets, the rumble filter, and the input selector switch. The 640P also uses “more exotic amplification circuitry” for better sound quality.
It’s Pretty on the Inside Too
Inside the 640P’s case is a neatly laid out circuit board. On the right side of the circuit board is the power supply, which contains the rectification and first stage of regulation. The power supply is shielded from the rest of the components by an L shaped piece of metal which also doubles as the voltage regulators’ heat sink.
On the left side of the board, as far away from the potentially noisy power supply as possible, are the MC and MM gain stages. Impressively, each is independently implemented, and the input stages are individually shielded.
Each stage of the amplifier has its own local power supply regulation capacitors, and a relay mutes the output for about 15 seconds after power up to help prevent heart-attack inducing thumps from the speakers.
All in all, pretty impressive. In fact the only criticism I feel justified in making (considering the 640P’s very reasonable price) is that the RCA sockets are a bit too close to each other, making it hard to use upmarket cables with larger RCA plugs (the WBT plugs on my Nordost Frey interconnects barely fit). Of course, such expensive interconnects are unlikely to be used with the 640P in real life, but this is something of which potential purchasers should be aware.
Setup and Listening
For best performance, Cambridge Audio recommend leaving the 640P powered on at all times (unless one is going away for an extended period). I followed this advice, so the 640P was powered for nearly the entire review period. After dozens of hours of informal listening, I started my formal evaluation. At all times I used the MC input, with the rumble filter turned off.
Given the 640P’s reasonable price, I had my reservations about its potential sound quality. I’m very pleased to report that my fears were unfounded; “remarkably good!” say my listening notes. Yes, the frequency extremes are a bit soft, and details are obscured by a haze, but the essence of the music is there. When listening to a record like Mike Oldfield’s Tubular Bells [Virgin Records V2001], you can tell that there are more details waiting to be dug out of the groove—and are sometimes offered a tantalising glimpse of them—but ultimately they are lost in the mire.
Moving on to specifics, the bass is warm without being overly so. An example of this is the bass line in Tubular Bells’ finale. With only a little muddiness, it is easy to follow. It’s not quite as clear as it could be, but comes very close. No, the 640P’s bass won’t give your woofers (or subwoofers) a workout (especially in the bottom octave or two), but within its limitations, it is quite good. The extension limitation I mentioned just now shouldn’t be judged too harshly; in the context of most front ends the 640P is likely to be used with, they’re not serious at all.
Moving up the frequency spectrum to the midrange, voices (perhaps one of the most important instruments) are well reproduced. Male voices, like those of South African a cappella group, Ladysmith Black Mambazo, aren’t tinged with any chestiness (here I’m specifically thinking of the track Rain, Rain, Beautiful Rain from Shaka Zulu [WEA 925 582-1]). Just as important, of course, are female voices. Dusty Springfield singing The Look of Love on the Casino Royale soundtrack [Colgems COSO 5005-45] is just wonderful.
The frequencies most affected by the veiling were the higher ones, for example, the tinkling bells near the beginning of Tubular Bells, or the celeste in the second movement of Lt. Kije [Classic Records/RCA Victor LSC-2150]. When everything is right, the sound made by the hammer when it hits the metal plates is clearly audible. With the 640P, not so much, and the bloom surrounding the instrument is diminished.
Sound staging and imaging are fine: very respectable considering the price point. When listening to the Nasal Choir on Tubular Bells, I could hear several individual noses, rather than one great big one. Similarly with the arc of singers on Shaka Zulu. In both cases, the individual sound sources were identifiable if I listened intently enough. Yes, on a more accomplished phono stage the individual positions would be more readily apparent, but that fact that they’re audible at all impresses me. The sound stage itself was smaller than it should be, especially in the stage depth department, but it’s doubtful whether the sort of front end the 640P would likely be paired with would throw a huge sound stage anyway!
In addition to a correct tonal balance, one of the things that helps me suspend disbelief when I’m listening to music at home is appropriately wide dynamic contrasts. If the timbres and positioning of the instruments are accurate but the dynamics aren’t realistic, much of the illusion is (for me) lost, and I am reminded that I am “just” listening to a home stereo, rather than being at a live event. In this respect, the 640P does a passable (but not stellar) job. The foot stomps in Who Were You Talking To (from Shaka Zulu) don’t have the heft they ought to, nor is the room’s reverberation. Similarly, the drum thwacks in Lt. Kije’s third movement aren’t as startling as they should be.
Verdict
The 640P is a good sounding, versatile phono stage. It has more than acceptable build quality, and features that would not be out of place on more exotic phono stages. The fact that it is compatible with MC cartridges (unusual for phono stages at this price point) is a big bonus, although in all fairness I should point out that the 640P’s MC gain is only just sufficient for very low output MCs like my Lyra Parnassus; higher output MCs that are more likely to be paired with the 640P will be fine.
Before I heard the 640P I was under the impression that all phono stages in this price range were hopelessly flawed, but I’m pleased to be proven wrong. The 640P not only surpassed my expectations, it did so by a wide margin. If you’re in the market for a budget-conscious phono stage, the Azur 640P should be on your “must audition” list. Very highly recommended, if we gave awards for exceptional products, the 640P would be a strong contender. Perhaps we should start doing so...
Specifications
Description Solid state phono stage.
Frequency response 20 Hz to 50,000 Hz ±0.3 dB.
Crosstalk > 69 dB @ 20,000 Hz (MC); > 83 dB (MM).
Gain 55 dB (MC); 39 dB (MM).
Distortion < 0.002% THD (20 Hz to 20,000 Hz MC), < 0.005% (MM).
Input impedance 100 Ohms (MC), 47K Ohms (MM).
Input capacitance 180 pF (MC), 200 pF (MM).
Phono equalisation RIAA.
Sensitivity 0.5 mV (MC), 3.35 mV (MM).
Signal to noise ratio > 72 dB (MC), > 86 dB (MM).
Dimensions (hwd) 46 mm x 215 mm x 133 mm.
Weight 900 g (excluding PSU).
Finish Silver and black anodised aluminum.
Serial number of unit reviewed YN C2195 0912 0010.
Price $220.
Warranty Three years non-transferable.
Manufacturer
Cambridge Audio
313 Marion Road
Le Gardeur, QC J5Z 4W8
Canada
(866) 271-5689
www.plurison.com
Associated Equipment
Analogue source Forsell Air Reference Mk 2 turntable and arm.
Phono cartridge Lyra Parnassus.
Phono stage Allnic Audio Labs H-1200.
Preamps Audio Research SP9 Mk 2.
Power amplifiers PrimaLuna ProLogue Sevens.
Speakers MartinLogan Spire.
Cables Phono: Nordost Frey. Interconnects: Nordost Frey. Speaker: Nordost Frey. AC: stock.
Accessories Target and SolidSteel equipment stands; Mission Isoplat; Furman Elite 15-PFi power conditioner; Audio Physic cartridge demagnetiser; Acoustech carbon fibre brush; Last record and stylus cleaning products; The Cartridge Man tracking force gauge; Spin Clean Record Washer Mk II.