Consonance Reference 9.9 Power Amplifier

Ma Rong-Hui
Pan Zhi-Qiang

There is a saying about beautiful women. The most ideal being beautiful both inside and out. If she is beautiful on the inside but without the looks, then it is still regret. This is the case with the tube amplifiers made by Opera Audio. They are known for producing beautiful music but not the looks. However the new Reference 9.9 power amplifier with the matching Reference 1.1 preamplifier is a breakthrough for Opera Audio. Not only it has refreshing new outlook; the sound also has a unique character of its own. I can say this reference series has revolutionary changes both inside and out.

Once the "reference" word is mentioned, audiophiles alike are paying special attention. It is because audiophiles seek after most amplifiers bearing this word. Matisse, Audio Research and Sonic Frontiers all has reference series products that are very famous. The fact is reference level equipment are highly rated and respected by the Hi-End market. Now Opera Audio also produces reference 845 mono-block power amplifier to compete with the US and European makes. Is this a real challenge or hoax? Let us check it out.

Outlook

This R9.9 review is not following the usual pattern of talking about outlook, design and then sound. I really have to talk about the R9.9 outlook. Comparing with the other products of Opera Audio that follows the traditional path, the R9.9 is a complete breakthrough with the outlook that gives a tremendous feel of quality. Consonance's line of tube amplifiers is famous for delivering good sound and is well respected in China market solely due to the quality of the sound. The outlook according to the "simple, human" philosophy is a bit disappointing (at least to me). However R9.9 is a milestone for Opera Audio. Since then Opera Audio's tube amplifiers will not be judged only by their sound.

Tube amplifier design can be the box or open type. Box type looks tidier but the open type has more audiophile feeling. For audiophiles who like tube rolling they prefer the open type that looks more elegant and warm. However they are also very difficult to look tidy as well, especially you have to take into consideration the relatively big transformers and power supply filtering components. However the R9.9 design is quite innovative due to its "half" box type design. The front half facing the front panel is box type housing the transformers, choke and electrolytic capacitors. These are covered with the top cover using cherry wood as decoration. It has a quality feel. The bottom half is open type with an 845 power tube, an E88CC and 5687 small vacuum tube. The height of the 845 tube is higher than the chassis cover surrounded by plated metal rods. The front panel is made of aluminum with a curved top edge and the power on/off push button is at the lower middle position. Above the power switch there is a small black metal opening housing the "cats' eye". This is another new design. Inside the "cats' eye" is a 6E2 vacuum tube. It is used in the vintage type radio receiver. The amount of closing of its green display indicates the current output power. This is a nostalgic, human and warm design better than using a conventional VU meter.

The size of R9.9 is not small but also not too bulky. It looks classic and elegant with a bit of modern glamour. This is a result of numerous fine-tuning the proposal from The Beijing Institute of Arts. In my opinion, this design should be patented.

Design

Although the manufacturer does not want to publish the circuit diagram, I would still like to talk about it. R9.9 uses one 845 in each channel for single end amplification. The front end is using an E88CC in common cathode voltage amplification. Another 5687 is used as driver. The driving stage is key in R9.9. The use of 845 in class A single end amplification is to make use of its warm and "thick" character of a directly heated triode as well as large output power. The 845's plate voltage is more than 1000V and the grid voltage is more than -100V. Due to this, the voltage swing during operation is quite large in order to obtain enough margin for linear operation. This presents a difficult task for the driver, as it needs to have enough capability to satisfy and adapt to the operation characteristic of 845. Due to this, the 845 amplifiers made in China are using different means in implementing their driver stage. The most common method is the use of inter-stage transformer to increase the voltage swing. There are also others using EL34, 6P3P and 300B as driver but they face other problems. The use of EL34 or 6P3P as driver will bring their pentode and tetrode tube sound into the 845 and polluting the tumbrel balance of the directly heated triode. The use of the expensive 300B to drive 845 will increase the cost of the amplifier. On the other hand, the 300B driver circuit is complex and will color the sound of the 845. When implemented poorly it will degrade and dominate the output sound. You lose more than you gain. As a result, when designing 845 amplifier the driver stage is very important.

R9.9's driver stage does not have inter-stage transformer and power tube but uses a single high mu 5687 dual triode. Although 5687's mu is higher than other dual triodes, its plate voltage and filament voltage is far from meeting the 845 requirement. How can it survive the macro-dynamics? R9.9 is using relatively mild plate voltage of 1000V, not higher to achieve the necessary gain. Hence with this configuration how can the R9.9 achieve the output power of 28W? The mystery lies with the use of 5687 in.... The mystery lies with its circuit design.

In addition, R9.9 uses three transformers, a filtering choke and 6 220uF Rubycon electrolytic capacitors in each channel. Among the three transformers, one is for high tension and front stage, one is the output transformer and the smaller one is for the 845 filament supply. 845 is directly heated and its filament is the cathode. Using a separate filament supply will reduce the inter-modulation distortion due to stability of the filament voltage under all circumstances. Furthermore, the front stage vacuum tubes are carefully selected. E88CC is the gold pins Siemens made in Germany. 5687 is the US GE NOS. Internal circuit is very simple with few components. However premium components like Rel-Cap coupling capacitors can still be seen.

Sound

The initial impression after hearing the R9.9 can be described as follows; if you do not know what it means by "tube" sound, please hear the R9.9. This is the richest "tube" sounding amplifier that I have ever listened to. Warm, full of body, sweet, transparent, airy, detail and rich in harmonics; any description you have for "tube" sound are here. No matter what kind of music you play, from violin solo, symphonies to piano, it elevates you to a higher state. In the past whenever I listen to a tube amplifier, I always have the thought that a good quality solid state amplifier can achieve the same sound. But here the sound is warm, full of body, lively, delicate and dynamic makes you forget about solid state amplifier forever due to its harshness in comparison.

Does it mean coloration then? It should be yes but you cannot conclude this coloration as a result of distortion. The coloration of R9.9 is the kind founded on the faithful reproduction of the original. It is like the Amsterdam Philharmonic Orchestra has their unique Amsterdam timbre to it. If you go attend their live performance, you will notice that they have their own characteristic sound that is warm and sweet. Can you then say their performance is colored?

Since the new products have received more than expected orders, Opera Audio does not have any spare R9.9 on loan for review. Hence this review took place in their auditioning room. The review combination uses their R1.1 preamplifier, Harbeth HL Compact 7 speaker. Source is Philips 951 as transport with Parasound as D/A. I have been using the same speaker for 5 years and am very familiar with it. I drove it with numerous amplifiers but none of them gave the sound like R9.9. The rich middle frequency of HL7 has authority and the low frequency goes very deep. This is not the same HL7 that I am familiar with. While giving R9.9 an evaluation, the HL7 should also be given a new evaluation.

The sound of R9.9 is laid back but not soft, full of body but not over done, delicate but does not lack authority. Once you hear it you have the immediate feeling that this comes from a high end amplifier. R9.9 has both the warm, full body and transparent character of a directly heated triode, and the strength and authority of a high power pentode. The violin sound reproduced is no less beautiful than a good 300B single end amplifier. With symphonies it displays its special style, such as rich hall sound, wide soundstage and clear imaging. It is like the band is playing right there at ease. It handles peak dynamics well. Not in an aggressive way but extends to the extremes. The bass is tuneful with weight and goes deep. R9.9 has very good vocal imaging. While playing Cai Qin's old songs CD her vocal imaging is clear with each and every minor details revealed. What is touching is the revealing of the inner content and feelings of music. This is exactly what distinguishes between an art and a machine, an artist and a craftsman. The rich musical performance and artistic influence is clearly the model for great high fidelity equipment.

The resolution of R9.9 belongs to above average but not the best comparing with high quality solid state amplifier. However for tube amplifier it is like that. Resolution is like cameras. If high quality solid state amplifier is comparable to Nikon, then R9.9 is equal to Canon.

The sound of R9.9 is on the warm side. The overall feeling is intimate, rich, solid and dynamic. You can never play R9.9 to thundering sound pressure level but you should not look down upon it. Its middle and low frequency has authority, density and weight. R9.9 takes a firm position in revealing the inner dynamics of music. There is no doubt R9.9 can live up to be the reference level power amplifier of Opera Audio and among Chinese tube amplifiers.

Personally I prefer large pieces of hi-fi equipment since they can reproduce delicate music as well. The reason of me using Krell amplifier is due to its power and versatility. After hearing the R9.9 I am a bit moved. If R9.9 can drive ATC speaker then it will be amazing. How much driving power R9.9 has is not known and I do not have the opportunity of testing the R9.9 driving Spendor SP100 or ATC. Theoretically it is possible but using one pair of 845 is kind of tough. If only I can try using two pairs in bi-amp configuration it will be interesting. The imported high power tube amplifiers are very expensive and I cannot afford them. Jadis JA500 is very good but replacing the power tubes for both channels involves 24 pieces of 6550. This alone is scary. R9.9 is more than 10 thousand RMB per pair. For two pairs it is about the same price as Krell 300i. For users of either bookshelf or larger speakers they should give the Reference 9.9 an audition.

High Fidelity 2001 issue 1, China