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"Quote: This input stage is polarized not to be a perfect push-pull but to have the distortion shape of the ear"
I'd love to see how that distortion shape of the ear was measured?
Cheers George
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 fidelityfor 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 mostspoiler alertwhich 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 encounterednot even at $250,000equals the Riviera Levante in fit'n'finish.
The Levante's chassis measures 17.3" wide × 5.1" high × 19.3" deep. It weighs 66lb1lb 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-harmonicdominant 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.
"Quote: This input stage is polarized not to be a perfect push-pull but to have the distortion shape of the ear"
I'd love to see how that distortion shape of the ear was measured?
Cheers George
Hi
Me too. I'm very interested to know how our ears are measured.
IMO, it is either the amp maker's trade SECRET or simply trumpet-blowing
sales pitch !
For $16,500, only JJ or Russian Mullard triodes are provided. Profiteering here goes ! Give us consumers a break, please.
Even my humble home-brew phono-preamp, I purposely used Mullard ECC82 made in U.K. for the linestage. U.K. Mullards sound better than another other makes, IMO.
Jack L
Students,
You are all familiar with the skull and crossbones graphic used to denote poisons on product labels.
Your assignment, should you decide to accept it, is to design a graphic suitable for use in the reviews of audio products that indicates that the highly-experienced John Atkinson has determined that an amplifier has a "distinctive sonic character" or a loudspeaker has a "'tailored' frequency response in the treble".
Should you choose not to participate in this challenge, which your faculty acknowledges involves unusual subtlety, it will have no effect on your grade.
it is imported by Tone Imports. Luscious sound and gorgeous design. Italian audio equipment is always interesting to look at and to listen to. Romantic and euphonic. Sometimes the design is excessive and a little "Gucci" but other times just beautiful like a handmade instrument.
On this non-inexpensive ($16.5k) integrated amplifier, I don't much like the seemingly low budget amateurish design aesthetics. The front panel design is an inconsistent hodgepodge of text fonts, sizes, directions of orientation and marking methods on a panel with a disorganized haphazard layout of the control switchgear. The industrial design aesthetics matter, and since they obviously lack enough talent in that, they should hire or rent a skilled professional industrial design consultant. There is certainly no shortage of that talent in Italy.
Also, integrated amplifiers are a bundle of compromises. While integration does reduce manufacturing costs and simplifies consumer's system design and space claim, it comes at the expense of a major reduction in system design flexibility, reduced optimization to the requirements of a specific application, and with greatly reduced long term reliability.
Expanding on the point of reduced system reliability, consider that once this device is out of production, out of warranty, and suffering obsolescence in the internal monolithic integrated electronic components (especially in the control subsystem), when an important functionality eventually fails the entire unit becomes trash, dumpster fodder. With separates, a failed subsystem component can be replaced or upgraded when and if it fails and cannot be repaired, and only that small fraction of the whole system becomes dumpster fodder.
In comparison to this integrated amplifier, some very good separate components can be had within similar $16.5k budget.
For example, look at the US made Schiit Freya plus for $949, which includes relay switched resistor network stepped attenuation. In addition to the balanced inputs, the unit also converts single ended inputs to a differential throughput and balanced output. It includes quiet low distortion solid state gain stages and a bypassable/defeatable pair of circlotron tube stages using 6AS7 dual triodes. That allows for a choice of either clean gain or bypassable added tube based euphonic distortion effects, as desired for different various program material.
Maybe add a pair of US made Benchmark AHB2 amplifiers configured as bridged monoblocks at $3k each for high purity gain and balanced inputs.
You could also add a Schiit Modi 3E external DAC for $129, and a short pair of well made inexpensive nonesoteric low capacitance single ended interconnects (eg. under $40 for the pair of 18 inch interconnects from Blue Jeans Cable).
Also add a couple of balanced audio cables consisting of some non-esoteric and moderately priced well made low capacitance shielded twisted pair or StarQuad terminated with XLR connectors. Maybe take advantage of the low noise balanced interconnection by locatimg the amplifiers adjacent to the loudspeakers, allowing use of short loudspeaker cables. With balanced interconnection, there is no need to locate the front end near the amplifiers.
Sum total is well under half of the $16.5k budget with less noise, lower distortion (when not using tube based stages), and with use of separates providing flexibility of system modularity and with that improved reliability via the possibility of future replacement or upgrade of the separate components.
The balance of the budget could buy better loudspeakers and/or better subwoofers and/or a couple of PSI Audio AVA C20 active bass traps and/or passive room acoustics treatments. ...things that matter significantly in playback system performance.
tells you how to build a watch. thank you for the filibuster reply to a simple comment about a well reviewed product (by a reviewer who's ears I trust.) I'm happy that you love Benchmark audio products. Personally I think they look like power supplies for welding or medical equipment. I'm sure they give you a lot for your money and give you musical pleasure. Thanks for telling me how we all should think and feel about reproduced music.
"Stop liking what I don't like."
The measurement mafia is sharpening their knives ;)
Not surprisingly Michael Lavorgna gushed over this amp as well. Look forward to hearing one.
It sure is pretty.
It could sit nearby the LazyBoy, warming the heart, with it's Chrome & Gold.
but so could a pair of gorgeous Woo Fireflys which probably look better. ( to my vintage taste )
I'd like to see some assurances that the Silk-Screening on the Front panel will survive usage considering todays environmental limitations banning old school enamels in favour of water based inks. A safe route would have the panel laser etched instead of printed .
I'd like to discover and learn what System the Manufacturer intended for revealing this device's full potential ! ( not that I'd purchase , hmm )
Tony in Florida
...is available in black, white, and various other colors, exhibits good permanency, and is well suited to applications such as silk screened printing on the front face of control panels, in filling milled or deeply engraved markings, and in ink stamping reference designations and item identifications on other surfaces.
This stuff is pricy compared to standard Nazdar Solvent based Inks. ( x4 )
It still is Solvent based and they do promise good adhesion.
It looks like the front panel is Silk Screened which has me thinking that epoxy setup/curing would ruin the screen so batch printing involves shooting a new screen.
We have laser etchers now-a-days, at the price of this device I'd think they'd etch instead of print.
I've had the letters fall/wear off touch panels. ( funny tape labels end up on the fronts )
We could call the Manufacturer in Italy, presume English is spoken but I'd bet their Chassis provider doesn't know what ink is used or how well it's applied.
Tony in Florida
Herb wrote: "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." The Lamm Industries M1.2 Monoblocks, PS Audio BHK Signature 300 Monoblocks and PS Audio Stellar M1200 Monobocks are also on the Recommended Components list.
for the big 'catch' . . .
Now I must call Paul and Vladimir and beg forgiveness.
all hail the hybrid !
h
Probably Bascom too, though Paul I'm sure can pass it along.
I miss those amps and pre's... sigh.
Herb - Great review as always. I own and love one of these. The option to fine-tune through a couple of relatively cheap tubes is a fun feature. Seems like new-production Russian Mullards were used in the review - I'd love to try some NOS British ones.
Might be fun to read a follow-up by one of the folks who have reviewed Lamm. The Lamm gear is (even) more expensive, but it's interesting that the brains and ears behind Lamm and Riviera have seemingly similar listening/measurement theories.
w.
Novel design and well implemented.
After this and JVS' newest darTZeel reviews, I remain convinced they are the best delivery methods.
I really like hybrid amps and I owned a Counterpoint SA220 back around 1994 and used it to power Apogee Centaur Major speakers. I have a hybrid Audio By Van Alstine 600R power amp that uses 2 12AT7 tubes and it has a MOSFET output stage that provides 300 w/Ch. I didn't like the stock JJ tubes in this amp so I replaced them with NOS Mullard 4024 tubes. This amp is a great value at $3500. Stereophile should review Audio By Van Alstine products. TAS reviews AVA products and the 600R and the FET Valve CF preamp are on their recommended list. Since Stereophile reviews other direct from manufacturer products such as Tekton speakers, they should start reviewing AVA products. I'm not affiliated with AVA in any way. Maybe I'm unaware of the history of AVA and Stereophile. Steve Guttenberg reviewed one of their least expensive 60 w/Ch amps recently and raved about it.
Several products ago, I reviewed a 176 lb. stereo amplifier. Now a friend and I just tried to install a 90 lb. component, only to discover that it's 1/2" too wide for my rack. Art Dudley, please shine a bit of your light on this poor acolyte. As you do, please remember how much you are missed.
jason