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I remember, around the time I started at Stereophile, telling Art Dudley that I wanted to review “a lot of power amplifiers” because amplifiers are the “blood-pumping heart machines” that “reanimate the artistry” of musicians: Horowitz, Björk, Bill Monroe. Whereupon he looked over his glasses and spied me with bare eyes like a stern parent and said, “Just be sure to not review any amplifiers that weigh more than 65 pounds.”
I warned Art that this could be a problem because I only like class-A amplifiers, “and they all weigh more than that.” Art rolled his eyes, turned his head toward the next room, and scolded his barking dog, Chatter.
As usual, everything I mock I become: Since confessing my allegiance to class-A, I have reviewed class-D and class-AB integrated amplifiers almost exclusively. Until now, the 51lb Pass Labs’ INT-25 is the only pure class-A integrated to roll through my door.
My first review for Stereophile was of the Rogue Audio Sphinx, a traditionally handsome, $1595 hybrid integrated amplifier that weighs only 25lb and is rated to deliver 100Wpc into 8 ohms; the Sphinx uses a tube input, which drives a class-D output stage. Previous to the Sphinx, my only experience with hybrid amplifiers of any kind was a 30lb, 150Wpc New York Audio Labs Moscode 300 power amplifier, which was loaned to me by audio wizard extraordinaire, the late Harvey Rosenberg. It featured a tube input and a MOSFET output and looked like a hot-rodded Hafler. It drove my 1984 Rogers LS3/5as and my Quad ESL electrostatic speakers in a manner that seemed atmospherically richer, fuller, and more enticing than the Marantz 8B it replaced.
Ever since my Moscode and Sphinx experiences, I’ve always been on the lookout for hybrid amplifiers. I’ve noticed a few in the under-$1k zone, but in the higher audiophile ranks, this type of amplifier is not common. Besides the Rogue, the only other hybrid in Stereophile‘s Recommended Components is the $93k/pair Ypsilon Hyperion Monoblock.
My scouts reported: NuPrime, Absolare, Aesthetix, BAT, and Audio by Van Alstine also make hybrid amplifiers.
My scouts somehow missed the stylish, hybrid, pure class-A Riviera Levante integrated amplifier ($16,500), which is made in Italy. I discovered it during a conversation with Riviera’s importer, Jonathan Halpern (Tone Imports). “Herb, this one’s pure class-A; I’ll introduce you to Riviera’s principals, Luca and Silvio,” Jonathan said.
In my introduce-myself email, I asked Riviera’s head of public relations and sales, Silvio Delfino: Does the name “Levante” refer to a late summer easterly wind on the Mediterranean? Or a coastal region in the Middle East?
“The name of our company Riviera came naturally, since both I and Luca (Riviera’s engineer-designer Luca Chiomenti) were born and live on the Italian Riviera,” Silvio told me. “Riviera is also an Italian word that is easily understood in many languages. It evokes a nice, peaceful place in front of the sea. In Italy, there are numerous touristic areas named Riviera. Our integrated amplifier was designed on the Riviera di Levante in front of Portofino Bay. Of course, it is also a well-known wind, so to us, [the name] sounded very nice.”
Philosophy and design
Before they agreed on the cool name, Luca and Silvio spent years discussing what kind of amplifiers they’d make if they started an amplifier company. They agreed on a few things right away. It would be a vacuum tube/solid state hybrid. It would operate in pure class-A, with no global feedback.
What’s more, my email conversations with Luca indicated that Riviera amplifiers are engineered to measure in a precise, premeditated, yet unorthodox manner. In a three-page answer to my pesky Herb questions, Luca explained that he had spent three decades researching and studying “the relationship between subjective audio listening and laboratory measurements.” These studies led him to conclude that “an audio amplifier must reproduce a signal with the highest fidelity—for the human ear, not for instruments. Which means we must define the characteristics of the reproduced signal as they are best received by the human ear and processed by the human brain, not for electronic measuring systems.” “On its own, the human ear adds as much as 10% harmonic distortion to incoming sounds. Some of this distortion is later canceled during the brain’s processing,” Luca said, echoing theories proposed by Jean Hiraga (footnote 1). “The shape of the ear’s harmonic distribution is very important. There is a high predominance of lower order harmonics with a decreasing spectrum of higher order harmonics. THD does not need to be extremely low, but it must absolutely mimic the ear’s distortion shape” so that it, too, may be canceled by the brain. “We use zero global feedback and minimum levels of local feedback to minimize the negative effects those techniques have on sound quality.”
“We believe that an amplifier does not have to generate distortion. But when it happens, if the distortion spectrum generated is similar to that of the human ear, it will result in an amplifier that makes extremely clean sound, a type of sound our brain perceives as pure and musical.”
Description
The Levante is the only integrated amplifier in the Riviera Labs lineup, which otherwise includes two headphone amplifiers, three line preamplifiers, and three mono power amplifiers.
Luca described the Levante’s circuit topology as “an ECC81/12AT7 twin-triode voltage amplifier configured as a totem pole. No feedback at all. This input stage is polarized not to be a perfect push-pull but to have the distortion shape of the ear, like a single SE triode that if well-tuned is probably the configuration with a distortion spectrum most similar to the ear’s. There is a MOS [metal-oxide semiconductor] buffer after the tube. A great part of the distortion and ‘character’ of the (Levante’s) sound is due to this first stage circuit, which changes simply by changing the tube.” Pay special note to Luca’s last sentence. I will discuss this in practical/empirical terms in the listening section.
“The power stage uses 6+6 MOSFETs”—six each of Vishay’s IRFP240 and IRFP9240 power transistors—”driven by BJT [bipolar junction transistors]. There is local feedback on the power stage, the minimum I can apply. No protections, just a fuse on the rails.”
A knob switch on the Levante’s front panel allows users to choose 30W in class-A or, when more power is required, 120W (into 8 ohms) in “high-bias” class-AB. According to the Riviera website, “in AB Class, the first 6 Watts are in Class A.”
The Levante’s back panel was interesting for what I didn’t see: no digital inputs, no fixed or variable line-level (pre-out or tape-out) outputs, no HDMI or trigger ports. The Levante is 100% analog, 100% integrated. What I did see was one pair of balanced (XLR) inputs and four pairs of single-ended RCA inputs. One RCA pair is labeled LINE 4/PH, indicating where you would connect a record player if you chose the phono-stage option. Lower, I found the tightest-fitting, toughest-built speaker-cable binding posts I’ve encountered.
Before I knew all this technical stuff, I was taken by the aesthetics of the Levante’s front panel. I preferred the “Metallic Sand” faceplate. Mine had silver knobs; gold is standard with the Sand faceplate. The big knob is of course the volume, and it was a pleasure to use. The smaller knob to its right is the output-class selector knob. The same-sized knob on the far right is the input selector knob. Directly below that knob is the Power button. To its left is the Night button, which dims the red indicator LEDs. To its left is the button I loved most—spoiler alert—which mutes the speakers and turns on what might be the best headphone amplifier I’ve encountered in a regular-issue integrated amplifier. To its left is the Levante’s single ¼” (6.3mm) headphone output jack.
During my listening, I took the opportunity to swap 12AT7 input tubes. When I removed the Levante’s aluminum top plate and inspected the insides, it soon became clear that no amplifier I’ve encountered—not even at $250,000—equals the Riviera Levante in fit’n’finish.
The Levante’s chassis measures 17.3″ wide × 5.1″ high × 19.3″ deep. It weighs 66lb—1lb more than stern Art admonished.
Listening
When the time came to install the Riviera Levante, I had been powering my Falcon Gold Badge LS3/5as with RAAL-requisite’s 11.7lb, 10Wpc (into 8 ohms), HSA-1b headphone/speaker amplifier. The little RAAL amp is unique in that it was engineered to put 7A into a capacitive 0.4 ohm load. Powering my more resistive/inductive 15 ohm Falcons, it was almost scary how much strong blues mojo, rhythmic drive, and vibrant physical presence the RAAL amp threw into the reproduction of R.L. Burnside performing “Poor Black Mattie T2 (Electric)” on Rollin’ & Tumblin’ (16/44.1 FLAC, Wolf Records/Tidal).
With full awareness of the RAAL’s positive (and negative) traits, I put in the warmed-up and broken-in Riviera Levante and played “Poor Black Mattie” again.
This “sequence is everything” moment was unusually revealing. I did not hear what I expected to hear, and it threw me off my game. I did not pre-imagine how switching from one low-power solid state amp to another only slightly more powerful one could do that much to change the sound.
My first take was: The Levante’s sound was too lush. Too big. Too densely atmospheric.
RAAL-requisite’s HSA-1b played Rollin’ & Tumblin’ in a clean, solid, keep-the-beat manner. Very third-harmonic, front’n’center. I would describe the RAAL’s version of transparency as an unmitigated clarity that, while remarkable and enjoyable, exhibited a rather narrow depth of field that limited my ability to peer deeply into recordings (this latter characteristic, I suppose, is best described as a deviation from transparency). The Levante’s version of Rollin’ & Tumblin’ included much more reverberance, enhancing the Riviera’s inner vision, making it more textured, shimmering, and microscopic, with more harmonic nuance. The Levante-Falcon combo brought out previously unnoticed details from the spaces beside and behind Burnside. This detail was either not there or less noticeable with the RAAL.
If I were to speculate, I would wager that the RAAL develops a third-harmonic–dominant distortion spectrum while the Levante reverses that equation. I say this because high third harmonic and low second harmonic produces a sense of clarity and beat-keeping, whereas the reverse emphasizes space and atmosphere.
Thinking about this reminded me of what Luca Chiomenti wrote in his email. “A great part of the distortion and ‘character’ of the (Levante’s) sound is due to this first stage circuit, which changes simply by changing the tube.” Because there is no feedback or degeneration on the 12AT7 totem pole, every tube change can, and likely will, make a noticeable, possibly measurable difference in the Levante’s sound character. (JA take note!)
Curiosity revved, I decided to swap tubes.
Footnote 1: See Keith Howard’s 2006 discussion of Jean Hiraga’s hypothesis here.—John Atkinson
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COMPANY INFO
Riviera Audio Laboratories s.r.l.
Italy
US distributor: Tone Imports
(646) 425-7800
toneimports.com
ARTICLE CONTENTS
Page 1
Page 2
Specifications
Associated Equipment
Measurements
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