April 2005Opera Audio Consonance Cyber-10 Signature Integrated Amplifier
by Vade Forrester
Opera Audio is a Chinese firm that produces several lines of hi-fi equipment: a budget line called the M-Value series, a mid-level line called the Cyber Signature series, and a high-end line called the Reference Series. There is also a super-high-end Droplet series consisting of a turntable and a CD player, whose striking designs could easily incite severe cases of audiophile lust.
Opera explores interesting circuit designs and feature combinations that other companies overlook. The $2000 Cyber-10 Signature is an example of the company's audio audacity. It's a push-pull, remote-controlled integrated amplifier built around the 2A3 triode tube. Despite its relatively low power output (typically only 3 1/2 watts), the 2A3 power triode is extremely popular for use in single-ended-triode amplifiers. Wright Sound Company is the only other company I know of that currently manufactures a push-pull 2A3 amplifier, and thats a monoblock power amp, not an integrated. The four 2A3 tubes in the Cyber-10 Signature produce a claimed output of 11Wpc. The integrated operates in class A, with only 3dBs of negative feedback.
Although the high-end audiophile paradigm favors separate preamps and power amps, there is no real reason an integrated amp cant sound just as good, if not better, than separates. Todays preamps are so minimalist, with few controls other than a source selector and volume control, that its hard to justify putting those functions in a separate box. Eliminating interconnect cables between an amp and preamp should improve the sound and remove a possible source of hum-producing ground loops. Fewer links in the audio chain also means less money spent.
The Cyber-10 Signature has only a volume control and selector switch on its front panel, and both are duplicated on the remote control. There is a mute feature, but it is operable only from the remote. Five blue LEDs on the front panel show which source is selected, although they arent labeled to indicate which source each LED represents. The Cyber-10 Signature lacks a tape loop and a ground terminal, but you may not need them. It also doesnt have preamp outputs, which would have been useful for connecting a subwoofer or a second amp for biamping.
The Cyber-10 Signature measures 16 7/8"W x 7 3/4"H x 15 1/2"D, and weighs a hefty 55 pounds. Heavy chromed knobs for the selector switch and volume control are mounted on a slightly arched silver-gold aluminum faceplate. Several strips of cherry wood adorn the top of the transformer cover. Opera Audio uses wood strips for resonance control; they also make the products look less austere.
On the rear of the amp are five pairs of very sturdy-looking RCA jacks for inputs, and two sets of WBT-style speaker binding posts. Separate connections for four-ohm and eight-ohm output are provided. Unfortunately, the binding posts are not marked to indicate which speaker should be connected to each set. Since the inputs are marked with channel orientation (via red and white colored rings), its hard to understand why the outputs arent. When youre fumbling around in the back of the unit connecting the speakers, it would be a great help to know which connectors are for each channel.
Tubes in the review unit consisted of a quad of Electro-Harmonix 2A3s with ceramic bases. Electro-Harmonix 12AX7EH tubes served as the input stage for the Cyber-10 Signature, while a pair of metal-base Chinese 6SL7 tubes (labeled only with a "J") served as drivers. (The manual says the drivers are 6SN7s, but the website says 6SL7s, and the distributor confirmed this to be correct.) All of these tubes are in current production, and NOS versions of 6SL7 and 12AX7 tubes are available. A quick scan of tube suppliers shows Electro-Harmonix 2A3s available at $90 for a matched pair.
Four adjustable hum pots (directly heated triode output tubes frequently have hum pots) are located on top of the amplifier near the 2A3 tubes. The instructions for using these pots were rather vague, but fortunately, the amp was very quiet, so I didnt need to make adjustments. The Cyber-10 Signature automatically sets the bias voltage for the 2A3 tubes, so the user just has to plug in a new tube when one wears out (or if the user wants to experiment with different tubes).
The remote control is a slim, very solid metal unit with a minimum of buttons. The remote was obviously designed to control both the Cyber-10 Signature and a CD player. Much to my surprise, the CD controls operated my Meridian 508.24 CD player. The remote lacked a numeric keypad, so I couldnt access tracks directly, but all the basic controls worked fine.
The Cyber-10 Signature rests on four rubber feet -- nothing fancy. An IEC connector in the back lets you use the power cord of your choice.
The simplicity of the Cyber-10 Signature makes setup a breeze. The amp ships with the tubes installed and protected by a heavy black tube cage. You must remove the tube cage and packing material and make sure the tubes are correctly seated before turning the Cyber-10 Signature on. Opera Audio thoughtfully includes an Allen wrench to unfasten the tube cage, along with some white cotton gloves to keep from getting oil from your fingers on the tubes. A tube cage is often an extra-cost item, but its very useful if you have inquisitive little ones or curious pets in your home. Otherwise, you will enjoy watching the warm glow of the tubes, so you can leave the tube cage off, as I did.
By current standards, the Cyber-10 Signatures claimed 11Wpc output is rather low, but for my 104dB-sensitive Second ReTHM speakers, it's huge. I seldom turned the volume control past the nine-oclock position, and there was always a lot of headroom. However, the Cyber-10 Signature needs to be paired carefully with suitable speakers. Theres no cut-and-dried sensitivity rating for which this amp will be suitable; however, it should comfortably drive speakers of 94dB sensitivity and above, and it may work with speakers of even lower sensitivity. Because manufacturers tend to calculate speaker sensitivity differently, and some even pad their figures, I strongly recommend trying the Cyber-10 Signature amp with your speakers in your listening space before making a purchase decision.
Initially, the Cyber-10 Signatures sound was slightly skewed toward the high frequencies, and its entire presentation was slightly mechanical. In other words, bass did not go very deep, and, as a result, the high frequencies seemed to be overly prominent. A Silver Circle Audio power cord improved the sonic picture a bit, increasing bass extension and weight, thus bringing the high and low frequencies into better balance. It also added a bit of midrange dimensionality and purity.
Still, while the Cyber-10 Signature produced bass with considerable punch and slam, it never really went as low as Ive heard from some other amps, including several SET units. When I replaced the stock 12AX7EH tubes with some prized smooth-plate Telefunken ECC83s, the highs became smoother, although the bass was not quite as punchy. Overall tonal accuracy improved, too. But Telefunkens are getting hard to locate, and if you do find some, they will be very expensive. All my listening observations were made with the stock tubes in place, but keep in mind that you can tune this integrated amp to produce sound more to your liking.
The Cyber-10 Signature powers up very quickly for a tube integrated amplifier. Music is playing within ten seconds after turn-on. Warm-up time is also fast: 15 minutes should suffice except for the most critical listening.
A sonic quality of the Cyber-10 Signature that immediately stood out was its startling dynamics, and this was enhanced by the unit's very quiet nature, a plus given the very sensitive speakers with which it should be paired. While listening to Martin Haselböck and the Wiener Akademies Tänze und Menuette [Novalis 150059-2], "Mozart: Deutsche Tanz C-dur," I was startled at the impact the chamber orchestra made when the playing started, even though the musicians were playing period instruments not known for large dynamic blasts. Similarly, with the CD layer of RCAs newly remastered hybrid SACD of Fritz Reiner and the Chicago Symphony Orchestras Dvorak Symphony Number 9 and Other Orchestral Masterpieces [RCA 82876-66376-2], I was again impressed with the Cyber-10 Signatures effortless macrodynamic swings. I was also impressed with how good the newly DSD-remastered version of this recording sounds.
Soundstaging was quite good, if not quite as three-dimensional as a SET amp might deliver. Instruments and singers were arrayed in front of me in a continuous arc, not scrunched into the center or stuck to the speakers. Detail was quite well delineated without being etched or hard. With my all-time-favorite test cut, "Folia: Rodrigo Martinez," from Jordi Savall and associates La Folia 1490-1701 [AliaVox AV 9805], the opening cascabels were clear; however, the guitar and harp parts were a little difficult to follow. On the other hand, Savalls viola da gamba, playing the main melody, was easy to follow and displayed accurate tonality. The drum thwacks had terrific impact, but they didnt go quite as low as Ive heard with some other electronics. Microdynamic swings were also handled well, but they lacked some of the subtlety Ive heard in the past.
"The Panther" from Jennifer Warnes's The Well [Cisco SCD 2034] is one of my favorite tracks for evaluating treble quality. A series of chimes and percussion effects is very revealing of high-frequency performance; the Cyber-10 Signature delivered truly excellent detail and extension without any peakiness. Warnes's voice was nuanced and expressive, and the recording portrayed a believable performance space.
This sounds almost metaphysical, but while listening to The Well it struck me that the Cyber-10 Signature just made sense out of the songs. It put an architectural structure into perspective, making the songs much more than a series of well-crafted notes and words. Vocal intelligibility through the Cyber-10 Signature was outstanding, making it easier to understand the words of the songs, even though I have heard them hundreds of times.
I compared the Cyber-10 Signature to my $1430 Wright Sound Company WPA3.5 monoblock amplifiers, which also use 2A3 tubes, and the exceptional $4000 deHavilland Mercury preamp. To make the playing field as level as possible, I used Electro-Harmonix 2A3 tubes and 6SN7 drivers, although my tubes had been cryogenically treated. Like most 2A3 SET amps, the WPA3.5s are rated at only 3 1/2 watts, so they were at a power disadvantage. However, this combination of preamp and mono amplifiers was nearly three times as expensive as the Cyber-10 Signature. Was it three times better? I wish.
The WPA3.5 amps produced true SET sound, which differed from the Cyber-10 Signature in its presentation. The WPA3.5s sound was more palpable; instruments and vocalists were better defined in space and had a more "you are there" feel. Surprisingly, the WPA3.5s bass went deeper, albeit with less impact and slam. OK, not a lot deeper, but perceptibly so; neither integrated amp nor amps and preamp would ever be mistaken for Krell equipment. With the separates, highs were smoother and, thanks in part to the deeper bass extension, better balanced. Instrumental and vocal timbres were more realistic. These observations sound like a list of differences between SET and push-pull amps, and I suspect thats the main difference here.
The WPA3.5s ran out of power much sooner than the Cyber-10 Signature. Even with high-sensitivity speakers like the Second ReTHMs, that can make a difference. Because the WPA3.5s are strictly power amplifiers, they need a separate preamp to provide control and switching functions, and the WPA3.5s are (charitably) plain-looking, while the Cyber-10 Signature is quite attractive. The rather insensitive WPA3.5s require a lot of gain from a preamp to produce their rated output.
Listening to "Rodrigo Martinez" through the WPA3.5s, I was struck by how much easier it was to follow the guitar and harp parts, and how those instruments seemed more "whole." The drum went lower in frequency, although it wasnt as powerful. Microdynamics were better defined; it was easy to tell when Savall leaned into his instrument to phrase parts of the music. His vocals were more prominent as well.
With suitable speakers, the Cyber-10 Signature is a gutsy integrated amplifier with huge dynamics. It sounds muscular, detailed, and smooth. The Cyber-10 Signature handled vocals with noteworthy clarity and intelligibility. It came close to matching the sound of my much more expensive reference electronics, at just over one-third their cost. I could (and did) listen blissfully to the Cyber-10 Signature for many day-long sessions.
The Cyber-10 Signature is a pleasure to use, and its classy appearance would grace any audio system. While Im not ready to give up my SET amplifiers in favor of the Cyber-10 Signature, if I did, I would not be missing much. It preserves the purity of 2A3 triode sound, while putting out much greater power that can drive a wider range of speakers than 2A3 SET amps.
If you need even more power, Opera Audio offers the Cyber-100S Signature integrated amp, which uses 300B triodes to produce 22Wpc. For fans of low-power tubes, Opera Audio's various product lines may prove interesting and enticing.
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