February 2003Opera Audio Consonance Reference 1.1 Preamplifier
by John Potis
Recently I had the opportunity to review two pairs of SET amplifiers from Chinese audio manufacturer Opera: the Reference 9.9A and 9.9C. Even though the amplifiers incorporated two different output tubes, I found both pairs of monoblocks a sonic treat, offering slightly different -- albeit very high -- levels of sophistication and musical enjoyment. It was with an equally high level of anticipation that I turned my attention to Operas Consonance Reference 1.1 preamplifier, which was supplied for review along with the amps. Would it provide the same overachieving level of satisfaction as its siblings? I could hardly wait to find out.
Outside and inside
Sharing many of the same cosmetic cues of the Opera Consonance Reference 9.9 amplifiers, the $2995 USD Reference 1.1 preamplifier is both beautiful to look at and substantially built. Utilizing the same nicely finished cherry-planked top, a similar 1/3"-thick brushed-aluminum faceplate, and adding highly reflective rounded control knobs, this is one good-looking piece. One knob serves as the power on/off switch, another the source selector, another the stepped volume control, and the last as gain selector allowing 0dB and -10dB settings for use with high-efficiency systems. Taking a look around back doesnt disappoint either. Five pairs of high-quality gold plated RCAs (three stereo inputs and two pairs of outputs) and a fused IEC power connection round out the bells and whistles. The Reference 1.1 measures 17" wide by 4 1/2" tall by 14 1/2" deep. The manual puts the Reference 1.1 at 18 kg -- about 40 pounds -- but I put the actual weight at around 23 pounds. Underneath the Reference 1.1 are three rounded yet hard footers of unspecified composition. These shouldnt scratch shelves, but they will allow the Reference 1.1 to slide easily. Just a little caution is advised.
Inside, the Reference 1.1 is a phase-inverted tube line stage incorporating what Opera says is a specially made power supply using an "improved SRPP circuit with no negative voltage feedback." Opera says that AC voltage is applied to the input and routed to the EZ80 rectifier tube and choke and then to the plate load of a single ECC82 and dual ECC82s that provide voltage gain, so the Reference 1.1 uses a total of four tubes. Opera continues explaining that the SRPP circuit is a special design in which a lower tube (for gain) and upper tube (which serves as the plate load for the lower tube) are used. Opera claims that the upper tube also acts as both a cathode follower and as a constant current source for the lower tube. The claimed advantage is that, if properly designed, the circuit can offer improved performance over an ordinary resistor-loaded tube stage.
The Reference 1.1 preamplifier (with Virtual Dynamics Power 2 power cord) spent an inordinate amount of time in my system and was teamed with a wide array of gear. Along with Operas own Reference 9.9A and 9.9C amplifiers, the 1.1 also spent a lot of time with my own Herron M150 amplifiers. Speakers used were primarily the Silverline Sonata II, but Zu Cables Druid, Merlin's VSM Millennium, and JMlab Mini Utopia loudspeakers also saw action, as did Magnepan MG1.6/QRs and MG3.6/Rs. CDs were by way of a Pioneer DV-525 DVD player used as a transport to feed a Bel Canto DAC1.1, and SACD was via the Sony SCD-CE775. Interconnects and speaker connections were JPS Labs Ultra Conductor, and the digital cable was the DH Labs D-75. Power cords on the amplifiers were the Virtual Dynamic Power 3. All analog pieces were plugged into an Audio Magic Stealth power purifier, and Vibrapods were used extensively.
The Reference 1.1 arrived to me not directly from the factory and with a slightly different tube complement than that which comes with a stock unit. I used the Reference 1.1 for some weeks before Opera was able to provide me with the standard tubes. By that time, the preamp was broken in and my only concern was to put some hours on the tubes before starting my assessment. I make mention of these facts because Im unable to speak to a brand-new out-of-the-box Reference 1.1 and cant comment on issues of break-in. Observations relative to this review were made after many hours of operation.
Finally the sound
The Reference 1.1 has a slightly tilted-up and forward tonal balance that gives favor to the upper midrange. While not bright by any means, as compared to my own reference, the 1.1 is just a degree or two north of absolute neutrality. Often this lent the Reference 1.1 an engaging presence, particularly on well-recorded classical music. Brass and strings were given a slightly elevated prominence that was still within acceptable limits of neutrality and provided an engaging and lively perspective on the music. As combined with the preamp's essentially neutral, if slightly sweet treble, this aspect of the preamplifiers tonal balance made it equally engaging on rock and pop music. Its up-close-and-personal-yet-not-in-your-face perspective will suit many types of music in a variety of systems.
Midrange clarity is also a strength. Details emerged from the system with the Reference 1.1 at the helm just about as well as with any preamplifier Ive used, and the Reference 1.1 provided a fresh canvas for the music no matter what ancillaries were in the system. Transparency was very high, and I was allowed as much insight into the recorded venue and music as Im likely to ever desire. Imaging was good. Outlines were generally delineated well and image focus was also commendable, which also lent to the air of overall transparency.
While some may confuse the difference between imaging and soundstaging, the Reference 1.1 competently demonstrates that the two are not the same. In fact, it was the Reference 1.1s lack of soundstaging prowess that is its most limiting performance aspect. Though details within the soundstage were fairly well detailed and focused, the 1.1 curtailed the dimensions of that soundstage to a degree that I found disconcerting for a piece of equipment in the $3000 price class. With no combination of equipment was I able to alleviate the Reference 1.1's somewhat two-dimensionality. Soundstage depth didnt approach what my reference preamp regularly achieves, and while image height seemed good enough, this only lent something of a discontinuity to the overall sound. "Raised Up Family" from James Taylors October Road [Columbia CK 63584] evidenced some nicely portrayed midrange with solid and natural-sounding vocals and guitar, but the images were somewhat constricted at the plane of the speakers.
Bass presentation was a weaker aspect of the Reference 1.1s performance. It was powerful enough, and tonality was very good as there was no egregious slurring of bass notes or anything of the sort. Bass drums had easily differentiated tonality, and there was no problem tracking an acoustic bass through its scales. But the Reference 1.1 was lacking in the kind of inner detailing that separates the often -- though not always -- indistinct purr of an electric bass guitar from the physically tactile growl of an acoustic one.
Take, for instance, the opening two bass notes on "Jump Up Behind Me" on James Taylors Hourglass SACD [Columbia CK 67912], which has very much become a bass reference for me. Ordinarily both notes have so much snarling detail that I can almost count the bass cycles. Ditto the bass line throughout "Up Er Mei." But with the Reference 1.1, that texture-rich growl was smoothed over in favor of a purr. Tracks such as "Yellow Rose" are not recorded as closely and suffered no additional blurring by the Reference 1.1 -- they sounded quite good, as a matter of fact. "Carry Me On My Way" from October Road features some concussive low frequencies that came across as nice and fast, if still lacking the last iota of musicality and tonal color. At the other end of the spectrum, I noted a slight lack of air and shimmer on cymbals, though not to a bothersome degree. Between the frequency extremes the music sounded very good. Taylors voice had an engaging warmth about it (for Taylor, that is), and acoustic guitar came through with almost crystalline clarity, including crisp transients and good body.
One other aspect of the Reference 1.1s performance can neither be judged as a weakness nor a strength, but it will require some careful system matching. The Reference 1.1 is not a preamplifier that provides a highly fleshed-out perspective on the music. Its presentation is not what I would call meaty, or as I sometimes like to say, a presentation that borders on the visual. Without a doubt I think that people will disagree on the desirability of this aspect of the Reference 1.1s performance as different rooms, systems and speakers, in particular, will combine in conflicting or synergistic ways. For instance, the JMlab Mini Utopias can often present with a picture on the music that is too concrete -- particularly with multi-track recordings. Its too vivid and too colorful for some listeners (myself included) to accept as natural. The Reference 1.1 will allow a Mini Utopia-based system to take a step toward credibility. On the other hand, with the more ethereal Silverline Sonata II, tonal colors were too washed out to be engaging on some material.
During my evaluation of the Opera 9.9A amplifiers, one of the CDs that just brought magic to my room was Sonys Rostropvich Return to Russia [Sony SK 45836]. A deep and wide soundstage showcased image outlines that were just superbly focused. Lots of air and three-dimensionality combine with richly detailed double-bass lines on Tchaikovskys Symphony No.6 in B minor, op.74 "Pathétique" for a supremely believable experience. Through the Reference 1.1, though the music was more than listenable, much of that magic was gone, no matter which amplifiers I used. Missing was the focus, the tonal color, and the richness that contributed to the you-are-there-ness I experienced previously.
As for matters of partnered amplification as it relates to the above, I found that the Reference 1.1 actually worked better sonically with my solid-state Herron M150s than it did with Operas own tube amps. In my review of the Opera amps, I warned that they did little if anything to flesh out the body of instrumental tones. I found that the lite presentation of the Reference 1.1 in combination with the 9.9s distinct non-euphony produced a sound too lacking in tonal color and density. The Herron M150, with its greater bass and lower midrange warmth and higher degree of visibility and palpability, made a more synergistic match with the Reference 1.1.
Comparison to my 25% more expensive Herron VTSP-1A made life very difficult for the Reference 1.1. The Herron has compared favorably to preamps three times its price, and though the Reference 1.1 was in the running in some key areas, where it fell short it did so in some convincing ways. The Reference 1.1s midrange transparency and detail, though not the Herrons equal, was close enough given the price differential. Where the two preamps were closest to being equal was in the treble. Both pieces have smooth and detailed highs, and in the case of the Reference 1.1, the treble never became an issue. In direct comparison to the Herron, it was easy to hear the differing tonal balance -- the Herron being slightly darker, but its superior bass detail was also as evident. It was in the area of soundstaging where the Opera preamp lost the race. It just couldnt match the open, airy and dimensional presentation of the Herron.
Recently the McCormack MAP-1 multichannel preamp spent some time in my two-channel rig for evaluation purposes. Though solid state, less expensive, and seemingly designed with a differing set of priorities, the Opera and McCormack preamps were more comparable sonically. In the areas of midrange detail and transparency (the Opera preamps strengths), the Reference 1.1 had a slight yet important advantage. Treble performance between the two pieces was a wash, which is to say that both are good in this regard. Bass performance was much closer too, with the McCormack having a slight edge in the area of detail. But again, in the area of soundstaging, the Reference 1.1 just couldnt measure up. The McCormack cast a more convincing sense of dimensionality than the Reference 1.1 could muster.
I had some high hopes for Operas Reference 1.1 preamplifier, coming as it did on the heels of Operas wonderful power amplifiers. I anticipated greatness in excess of its price class. Unfortunately, though not without real merit in some areas, the Reference 1.1 didnt fare well in my system. I was disappointed with the soundstaging and bass detail, and while other aspects of the Reference 1.1's sound were acceptable and even good, cost starts to come into play. Therefore, at best I have to recommend a very careful audition of the Reference 1.1 preamplifier against other preamps in its price range.
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