Synergy Hifi 12AX7 and 12AU7 tubes

New era

There is a new era of high quality tubes coming from different parts of the world and China is becoming (if not so already) one of the largest manufacturers of valves. While we might often connect products from East with massive production in  past few years we can see quite some rising stars from east in high-end audio, that offer not just good, but excellent products.

Vast universe

When you're into tube (valve) amplification the vast universe of opportunity opens up. It called "tube rolling" in the audiophile jargon. With the right topology many of the tubes from valve preamplifiers and amplifiers can be swapped and exchanged with new equivalents. We might use the analogy of guitar strings. For experienced master guitar performer different sets of strings produce different tones. They can instantly recognize them with the simple touch of the fingers and on the first note. In the same way, experienced tube amplifier owner can "adjust" or set the "tone" and voicing of the amp.

Carving the tone

Tubes can sound so different. For some this open up a tweaking heaven. With the knowledge and experience you might carve the tone and different sound priorities that you have with the way you perceive the music. Some tubes are better with vocals, some of them offer better dynamics and other can shape the tone and behavior of lower frequencies.

While there are certain factors that can predict the outcome of the  sound you might expect from using specific tube, it often depend on the topology and approach that designer of tube component has taken. So how to know where to go and what to do?

Tube camps?

There are quite some camps regarding tubes.To reveal two at least of them let me write a few words about them; enthusiasts of the tubes from vast past manufacturing heritage and contemporary designed tube lovers. With still quite large stocks of NOS (new old stock) tubes you can spend hours and days chasing some of the legendary tubes. If you're lucky you'll get the real originals and with even more luck they'll perform as expected. I heard many high-end gear using different both NOS and presently manufactured tubes and my conclusion is that there is  a place for both of them. Some of the NOS are specific in acquiring special tone and character that can convey music in very natural and instant recognizable way (Shindo etc.). On the other hand Leben audio approaches their sound with almost non tube character with their products and yet they build amplifiers with traditional approach. Not even to go further with hundreds if not thousands of valve based electronics from all over the world.

Dr. Ningsheng Liu

Dr. Ningsheng Liu of Synergy hifi kindly contacted me some time ago and in our correspondence, we exchanged quite few thoughts and views about audio and tubes. We set things up for a review 12ax7 tubes arrived quickly after.

Setups and history to run after

I tried them in few different setups, but ended using them in Hajdinjak Labs reference phono preamplifier. It was simply a great match. Tube preamplifiers can  be very sensible and tube specific/dependable, to achieve the best result. Phono preamplifier complicate things further. With amplification of very low gain, anything can affect sound in both positive and negative way. Low noise tubes and matched ones are simply a must. Both those two things could mean nothing if sound is recessed in any way. I heard many phono preamps with lower noise floor, that simply lacks the life. It's quite an art to implement all the right things into designing the tubes even with today's high quality industry knowledge and tools. With all the right specification you can go into right directions, but at the end audiophiles and music lovers ears will be the judges. Isn't it funny that this is actually a competition with the technology, solutions and non the less sound of the tubes that were produced for how long now? Yes, that long...

Spending the quality time

Reviewed tubes were left few weeks in the preamplifier before any serious listening. After that period I spend quite some time listening to my favorite vinyl records from 30's and up to 90's. Comparing Synergy tubes with some old NOS champs and modern tubes from other companies revealed that they're very fine products and not only up to date with the quality, but also with enough DNA and respect to the past.

Trends not to follow

Some of the modernly produced tubes can follow the trend of the past few years that advocate non natural dynamics, huge transparency, unnatural brightness and pin pointed details. While there is a need for all of this attributes,just push any of them over the edge and you'll kill the music. It's like walking on the razor edge. Every little thing can cause a disaster. Synergy hi-fi seems to manage to designed this tubes very carefully. I wouldn't call the sound of them classical or NOS, but more modern without being harsh or over warmish. They done they homework more then good.

NOS to the grave?

With crazy prices of some NOS tubes, Synergy hi-fi is offering reasonable priced power and preamp tubes that can be excellent match for your beloved valve electronics.

We are already working on upcoming review and I'm look forward to see how their 300b's and El84 perform sound-wise.

I would not hesitate recommending them to any serious tube lover.

Tube evaluation chart:

Bass: ****
Treble: ****
Highs: ****
Timbre: ****
Musicality: ****
Price: ****
Value: ****


Filament Heating(Serial/Paralleling)
UH 6.3/12.6V
IH 300/150mA
Maximum Rating (each triode, Class A amplification)
Plate voltage 330V
Grid negative voltage -50V
Grid positive voltage 0V
Plate power dissipation 1.2W
DC parameters
Ua 100/250V
Ug -1/-2V
Ia 0.5/1.2mA
Gm 1.25/1.6mA/V
Rk 270/200Ω
µ 100/100
Ri 80/62.5KΩ

Matej Isak: photos and text
Mono & Stereo high-end audio magazine
September 2010, All rights reserved