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Product Review
 

Audio Note M3 Stereo Tube Preamplifier

October, 2003

Jason Victor Serinus

 

Specifications:

 

Tube compliment: Philips 5687 Philips 6072
Input impedance: 100KOhms line input and 47KOhms phono input
Gain: 8.2 Line in (18dB) and 1900, Phono in (65dB), both at 1KHz
Output noise: Less than 0.08mV RMS, unweighted line input. Typically 12mV RMS, unweighted, phono input.
Maximum output: 4.4 volt RMS
Output impedance: Less than 10 Ohms

Power Consumption: 81W with 1A anti-surge fuses

Dimensions: 141(H) ¥ 445(W) x 410(D)(mm)
Weight: 16kg

MSRP: $7,500 with Phono preamp, $6,000 Line Stage only

 

Audio Note

www.audionote.co.uk
 

Introduction

My introduction to some of the original Audio Note products is discussed at length in my August 2003 review of the Audio Note CD2.1x CD Player. Please refer to: http://www.hometheaterhifi.com/volume_10_3/audio-note-cd21-cd-player-8-2003.html for complete information.

When I attended HE 2003 in San Francisco, Audio Note’s U.S. distributor Ray Lombardi asked me if I wished to review the $6000 line stage version of Audio Note UK’s M3 preamplifier. This is Audio Note’s Level 3 preamp, the most costly preamp listed on their website.

Given that I had never before heard such a costly, premium preamp in my system, I leaped at the offer. My sincere thanks to reviewer Constantine Soo for bringing the M3 over from his home and recently retrieving it on short notice when Ray needed to get it to the opening of a new Audio Note dealership in Sacramento, California.

Technical Discussion

Since the preamp arrived chez Serinus devoid of packaging and manual, I have relied on technical descriptions I have been able to piece together from the Audio Note website and other reviews. Though I regret being reduced to the status of a parrot, I note that it is a most beautiful bird.

Audio Note states that the M3 preamp uses a complementary dual mono power supply incorporating valve rectification and double choke smoothing. The unit is completely hand-wired throughout. Its audio circuit, hand made and hand wired, uses the company’s own Tantalum film resistors, high quality Cerafine capacitors, pure copper foil signal capacitors and Black Gate de-coupling capacitors. Output transformers are copper wired IE-core with M4 laminations. The dual mono power supplies use independent 6X5WGT double choke rectifiers for each channel.

The M3’s line stage output is configured as a small "power amplifier" with one 5687WB double triode per channel. An output transformer couples the output of the vacuum tube to the input of the power amp. This allows the M3 to utilize not only two sets of single ended RCA outputs but also a 600 Ohm fully balanced output with a Lemo type connector.

The M3 linestage offers six inputs. Each uses a 5687WB series zero-feedback plate follower driving an output transformer. Eight transformers are employed in the M3. The faceplate’s four Noble pots control Inputs, Tape Monitor, Balance and Volume. All jacks are thickly silver-plated over solid copper.

Initial Impressions

When I first received this quite weighty, solid feeling, large-sized preamp, I could not resist giving it a listen. At the risk of sounding like an easily excitable adolescent, my initial reaction was “Wow!”

Compared to my much lighter and slimmer reference Bruce Moore Companion III linestage preamp, whose fully upgraded version costs $2000 less than the $6000 Audio Note linestage M3, the Audio Note produced a far larger, more dynamic soundstage. Everything seemed big, fatter, rounder – more saliva inducing. The M3’s far more impactful bass also suggested that it had a larger power supply than the Companion III.

Starry-eyed lovers, however, do not necessarily write reliable reviews. It was therefore necessary for me to remove myself a bit from my initial state of infatuation and ground my statements in objective comparison. To accomplish this, I spent some months listening to and reviewing other components and auditioning a variety of other preamps. Only then did I return to the Audio Note.

Listening Deeper

As my listening proceeded, I began to notice several things. One was that the tone of the preamp seemed rather sweet. It was a delicious sweetness, one more likely to please than to induce hypoglycemia, but it was a sweetness nonetheless. I also sensed that while the M3’s sound was unquestionably liquid and musical, it produced somewhat round edges, softening the image. Even though the Bruce Moore could in no way produce the size, weight, and seductiveness of the Audio Note’s image, it did seem to provide more inner detail.

Before I had any technical information on the preamp, I brought it over to technical whiz David Tonelli. David taught at the College of Recording Arts for 19 years, has built radio stations from scratch, and regularly repairs vacuum tube and studio equipment. He’s known by audio engineers throughout the Bay Area.

When I began to describe what I heard from the Audio Note, David opened it up and took a look. “Sure enough,” he said. “Just what I suspected. It’s a tube-based linestage that uses output transformers.”

“How do output transformers affect a preamp’s sound,” I asked?

David explained that output transformers can be used for a number of reasons. They provide a very low impedance output, enabling a preamp to easily drive a larger number of different components. They can also drive a very long line without losses, and provide a balanced output. By creating isolation between components, output transformers can break up ground loops and minimize the effects of cables.

David also noted some potential disadvantages of output transformers. Output transformers can very slightly color the sound of signals passing through them. The better the transformer, the less the coloration, and the greater likelihood that the coloration is primarily of a euphonic quality. To quote David, “The coloration can make everything sound warm and fuzzy, but you can lose some transient detail.”

David suggested that euphonic qualities can makes sonic images seem bigger. Because output transformers can deliver current like a small power amplifier, they can drive an amplifier harder, especially at low frequencies. This can result in fatter bass response. While fatter is not necessarily tighter, fatness does not decrease tightness. Tightness relates to speed of the bass transients, while fatness refers to sustain in the bass.

Finally he observed that the M3’s power supply is unusually large for a preamp. This results in more current being available for the current hungry 5687 tube and its associated output transformer. The power supply is very well filtered by using two filter chokes and a large amount of capacitor reservoir, which translates into more current.

David considers the M3’s build quality unusually high. “It’s like a piece of pro (broadcast) gear,” he proclaimed. “It’s built like a tank.”

I’ll second that one.

Detailed Listening

Of the four preamps here for review, the Revelation Audio OM-1 Quantum solid state linestage, when played without its optional battery pack power supply, lists for almost the same price as the Audio Note M3. I therefore conducted a series of detailed comparisons between the units, focusing on six recordings. My selections and experiences are detailed below:

1. Arleen Auger: Love Songs (Delos). This exceptional recital features the exquisite soprano Arleen Auger at the height of her maturity. The M3 definitely produced a bigger and more liquid image than the OM-1 Quantum. With the attack of the piano, however, the experience of hammers hitting strings to produce a series of tones and overtones, was clearer with the OM-1. Its sound seemed more neutral and relaxed, while the Audio Note seemed warmer, more delicious, but a bit hyped up.

2. Hilary Hahn: Brahms Violin Concerto (Sony). I seemed to hear more glint from Hilary’s violin with the OM-1 Quantum, and more detail in the string section. Hahn’s violin also seemed to emerge more from a quieter background, with more lower midrange and bass from the orchestra. On the other hand, the M3 seemed more liquid, its highs soaring like water shooting from a fountain. This made for a delicious violin listening experience.

3. Karina Gauvin: Songs of the Auvergne (CBC Records). Another  exquisite performance, this time from a soprano most associated with early music, accompanied by a masterful chamber orchestra playing a chamber reduction of Canteloube's colorful score. I enjoyed the music through both preamps. The quality that stood out most about the OM-1 Quantum was that its reproduction of the orchestra’s bass seemed tighter, with pitches more clearly defined. Images were also a bit easier to pinpoint in space.

4. George Faber: Blues (BAT Records). At HE 2003, I asked several reviewers about new non-classical releases suitable for reviewing components. Without hesitation, Wayne Garcia recommended this initial release from BAT Records. Thanks to Geoff Poor of Balanced Audio Technology for giving me an autographed copy.

Again, I would have wished more tightness from the M3's bass. I also missed a very clear edge around the voice, and the manner in which the OM-1 Quantum caused the voice to stand out from a silent background during moments when instrumental accompaniment briefly ceased.

5. Terry Evans: Puttin it Down (JVC-XRCD). Listening to my favorite “Blues No More” track, a track I turn to over and over again, Ry Cooder’s guitar seemed a little rounder and fatter on the Audio Note. Bass notes, however, were not as tight. There was a beautiful transparency, but the M3’s cymbals did not achieve ultimate delicacy – they seemed more like splashes of sound than the product of sharp attacks. I also felt that the quieter background of the OM-1 Quantum produced a greater sense of air around the trombone.

6. Rachmaninoff: Symphonic Dances (Reference Recordings). Early in this recording, within the first two minutes, there is an audible cough that can be heard from an orchestra member situated on stage left (audience right). I certainly heard the cough with both preamplifiers, but it was clearer and fuller on the OM-1 Quantum. Some listeners of course may question both the desirability of hearing such a level of detail, let alone the possibility of ever hearing it in a live situation. I will therefore never claim that greater detail = greater truth or musicality. The choice, ultimately, is one of aesthetics.

Conclusions

The Audio Note M3 preamp certainly deserves its top-of-the-line status. It is a solidly built unit capable of producing a most seductive, liquid, and eminently musical sound. Other preamps in this price range may more offer more detail, tighter bass, less coloration, or a blacker black, but these are not necessarily the qualities that many listeners value most highly. The Audio Note M3, for example, would prove an excellent complement for a CD source or amp - especially a solid state amp - that tended to
produce bright, edgy, or overly etched sound.

When all is said and done, the Audio Note UK M3’s large, mouth watering presentation and non-fatiguing reproduction of digital sources will prove the perfect cup of tea for many audiophiles.


- Jason Victor Serinus -

Associated Equipment:

Digital Front End:
Alex Peychev heavily modified Sony 707ES transport
Theta Gen. 5A single-ended DAC (to be replaced with the Gen.VIII); Benchmark DAC-1
Perpetual Technologies P-1A with Modwright modified Monolithic Power Supply and Revelation Audio umbilical power cable
Audio Alchemy DDS-Pro transport

Amplification:
Bruce Moore 100W dual mono tube power amp with Electro-Harmonix KT-88s and Siemens Cca tubes

Preamp:
Bruce Moore Companion III tube preamp with Electro-Harmonix gold pin 6922s and Jan Philips 12AU7 equivalents; Reflection Audio Om-1 Quantum battery-powered preamp in non-battery mode

Loudspeakers:
Talon Khorus X speakers (with final modifications)

Cabling:
Digital: Nordost Valhalla interconnects and digital interconnects
Nordost Valhalla bi-wired speaker cable
Powercables: Elrod EPS-1, 2, and 3 and EPS Signature-2.
Nordost, AudioPrism Super Natural S2 (on the cheap DVD player).

Accessories:
PS Audio P600 Power Plant power synthesizer with MultiWave II
PS Audio Ultimate Outlet; PS Audio Power Ports
Michael Green Deluxe Ultrarack, Basic Racks, room treatment, and Audiopoints
Black Diamond Racing Cones
Inner tube, maple cutting boards, bags of sand
Shakti stones on Amp and Monolithic/P-1a
Bedini Quadra Beam Ultraclarifier
Audioprism Stoplight and Blacklight, Marigo Disc
Gryphon Exorcist
Sheffield/XLO degmagnetiser and break-in disc and Ayre demagnetizing disc

 

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