Opera Audio Reference 1.1 Vacuum Tube Preamplifier

Pan Zhi-Qiang

Before the audition of the Reference 1.1 preamplifier from Opera Audio, I noticed several things. Firstly, this is the first reference series preamplifier from Opera Audio since their establishment. The selling price is RMB 10,000. - Secondly very seldom Chinese made preamplifiers are being sold at this price level. It is because the imported brands such as Audio Research LS8, Sonic Frontiers SFL1 and Matisse Atom already enjoyed a very good reputation in the market. The most appealing factor to me is, this preamplifier has been selling very well since launch although the factory only puts up the information in their web page (www.operaudio.com.cn). Orders just keep coming in and this is very rare when the current Hi Fi market is very weak.

After receiving the R1.1, I realize its appearance is really special, unlike any other preamplifiers made by Opera Audio. Like other products from Opera Audio, the R1.1 uses wood as part of the chassis but skillfully utilize the cherry wood to form the chassis cover. Not only does it look nice; it is part of the damping system. The front plate is made of well machined aluminum with a curved upper edge in sync with the cherry wood cover. Its outlook scores well in terms of elegance and dynamics. The four silver knobs in the front panel are for power on/ff, input selector, and volume control and mute control. The mute control has only two positions, normal and mute. When in mute position (-10dB) there is still sound output and the reason for this design is to reduce the use of the expensive volume control (like when you need to reduce the volume when the phone rings). R1.1 uses plated brass as equipment feet as well. The attention to detail is good in such an area too. You could select up to three inputs and there is one set of output. All the connectors are RCA since R1.1 is not a full balanced design.

When the cover is removed, the content of R1.1 is quite surprising. This is a preamplifier that uses very Hi End construction and components. A lot of preamplifiers use hard wired construction. What about R1.1? There is a large PCB. However the factory said it is only acting as a mounting frame for components like tube sockets. Underneath it is hard wired. In this way, not only it uses hard wired construction; the layout of the components is very neat too. On the left hand side of the chassis lies the EI type power transformer and the filtering choke, shielded by a metal cover. They are made of high grade silicon steel in order to obtain better high frequency response. Power supply rectifying does not use vacuum tube rectifier and this is after special consideration. Filtering capacitor is using Solen non-polar MKP, with one at 47uF/400V and the other at 100uF/400V. One more Philips electrolytic capacitor 47uF/400V is added for the consideration of sound performance. R1.1 is using very Hi End components. The common Rel-Cap and Multicap coupling capacitors used by ARC and Sonic Frontiers are used in R1.1 and this is rare in Chinese made amplifiers. The circuit used by R1.1 is very simple. It uses two 12AU7 in classic SRPP configuration. Although the circuit is very simple but implementation is very thoughtful. Apart from using a heavy duty power supply, the choice of components is also very strict. R1.1 uses very good coupling capacitors and resistors. The internal hookup wire is from VDH. The volume control is very special. It uses 24 steps ELMA and best resistors available. Stepped volume control has good separation and life span but its adjustment is not continuous. Opera Audio understands this and in the most frequently used ranges there is no problem of too big a step.

The vacuum tubes used are NOS RT 12AUT made in France. Two tube coolers are supplied to help reduce any microphone effect. In order to test R1.1, I tried to borrow other famous tubes like Mullard and Telefunken but in vain. I only get hold of the 1960s RFT tube made in Germany. Originally I tried to borrow an ARC LS8 MKII for comparison purpose but also not available.

The audition uses Aragon 8008B power amplifier, Meridian 506, Original A9 CD player and Audioquest cables. I also have Krell KAV500i and Meridian 551 integrated amplifier that has preamplifier output for comparison purpose.

R1.1 belongs to the high price Chinese made preamplifier. What about its quality? Before listening to R1.1 I have been using Krell KAV500i and Meridian 506 to drive Dynaudio's Contour 1.3SE bookshelf speaker. This combination gives high density and great dynamic sound. With so much clarity it is perfect for listening to guitar and piano. With symphonies it is very good in imaging and soundstage presentation. After changing to R1.1 and 8008B I can feel the increase of smoothness with more meat and glamour in middle frequencies, The soundstage is smaller but with good transparency. The imaging is not as sharp as the 500i. While listening to violin solo R1.1 brings out more air, harmonics at ease with softer sound than 500i and is more human. With vocals and strings it is even more touching. Although it is not very "tube" sounding but I can easily tell the fundamental difference between solid state and tube sound. After more than a months auditioning I have the following major observations:

Firstly R1.1 is very balanced, neutral and natural sounding. It has the capability of a reference level preamplifier performance. Its sound is open; transparent while it tonal character is neutral and smooth. There is no obvious deviation or coloration. This is what a "reference" preamplifier should be. R1.1 has very simple circuitry, best choice of components and as a result exhibit very low coloration, high resolution and soundstage clarity. The frequency extension of R1.1 is very good. While listening to violin solo, the vacuum tube preamplifier presents more realism of the instrument sound at ease with rich harmonics and air. This is very difficult for a similar priced solid state preamplifier to achieve. Comparing with R1.1, Meridian 551's preamp output is also very full and smooth with good vocal. However the special richness and delicate, airy high frequency sound unique to vacuum tube cannot be reproduced with the Meridian 551. R1.1 does not have the characteristic "sweetness" or "thickness" of certain vacuum tube preamplifier. It's frequency response is very flat from high to low. From the neutral, balanced and relaxed foundation it brings in a bit more of the vacuum tube flavor. You can listen to it for a long time.

Secondly R1.1 has good resolution. Not only does it sound real and natural; it also reveals clearly the minor details in music. Its dynamic response is very good. From chamber music involving only several instruments to symphonies with lots of players, R1.1 reproduces them at ease even during high level playback. R1.1 is fast and clean sounding, balanced in any frequency range. Its frequency extension and resolution is comparable with some other more expensive import preamplifiers. The usual "misty" behavior in lower priced preamplifier cannot be found on the R1.1. Although the R1.1 presents a smaller soundstage comparing with Krell and its imaging is not as sharp, the resolution power is very good. Tonal character of R1.1 is also better than Krell's preamplifier section.

In addition, R1.1 is a very sensitive preamplifier. If you change a tube or add a tube cooler, the sound changes. When the R1.1 is first turn on, its sound is a bit bright and tight. This improves after 1 to 2 days of breaking in. I tried removing the tube cooler and the sound becomes more relaxed but not as focus as before. However the tube cooler is designed to reduce microphone effect and I suggest to leave it untouched. Later I change the tube into RFT 12AU7. The sound then becomes richer in middle frequency and feels more relaxed. However resolution is worse than before with less glamour in the high frequencies. Since R1.1 is a reference preamplifier and is designed to be neutral with high resolution, you should leave the stock components alone.

R1.1 is neutral sounding with high resolution and beautiful tonal characteristic. Opera Audio's designer thinks a "reference" preamplifier should not be colored and has too much character of its own. It has to focus on the overall performance such as "simple, natural and neutral". According to this R1.1 is heading the right path.

What should be the right amplifier to match R1.1? I think either solid state or vacuum tube is suitable since it is a very high quality preamplifier.

Before finishing this review, I have opportunity to hear the R1.1 and R9.9 combination playing in two different occasions. R9.9 is a 845 single end 30W class A power amplifier. It matches very well with R1.1. The R1.1 and R9.9 combination features a rich, relaxed and transparent sound way ahead of the R1.1 and 8008B combination I have in my review. The density of sound, the ease of playing is truly musical. Although the speed and power is weaker than 8008B but all else are better. Hearing the R1.1 and R9.9 driving a floor standing speaker consisting of Scan-Speak drivers the 30W output is not weak at all. Smoothness of sound, lively reproduction , density and frequency extension are all very good.
While using R1.1 and 800B I thought R1.1 is a very good top of the range preamplifier. But after hearing R1.1 and R9.9 I am deeply attracted by this reference series amplifier. I remember in 1999 Spark's 9084D 845 amplifier once gave me a shock and I was attracted by it. Now in 2000 Opera Audio's R1.1 and R9.9 gives me the same feeling. A customer already buys the R1.1 and R9.9 I listen to. Next time I would really like to audition them again in my listening room.

High Fidelity 2000 issue 11, China

Copyright©2004 The Opera audio Co.,Ltd
  powerby hifi-china.com