The Shuguang factory in China is currently responsible for approximately 40% of the world’s production of vacuum tubes. While much of their production is mass produced and not subject t to rigid quality controls and priced accordingly, they have recently begun to produce much higher quality tubes in limited quantities which they refer to as their Treasure Series. The Treasure Series of 300B tubes was first introduced in 2008 and incorporates approximately sixty parts changes from the generic version. Final assembly is accomplished manually with a small cadre of senior workers. These are often referred to as the “black bottle” Shuguangs since the inside of the glass envelope is coated with a black high polymer compound carbon coating which is said to allow for greater electron concentration than is available in a tube with no coating while suppressing secondary electron emission, thereby reducing internal noise. These tubes also employ a “Super Alloy” technology which is claimed to improve electron emission and electron current stability. Not being an engineer, I cannot say whether these claims are true; however, based on an extensive comparison of the Treasure Series 300B’s with the generics, I can say that the Treasures are superior in every way and justify their more expensive price.
The sound of an output tube is a function of the circuit in which it is employed, the tube which drives it, whether rectification is solid state or tube (and if tube, the tube used) and the design of the output transformer. There is widespread agreement that, all else being equal, the less complex the circuit, the more the sound will be affected by the choice of parts and their quality. This is particularly true with respect to single ended tube amps with little or no overall loop feedback. Here the sonic performance of each tube is laid bare. There are fewer circuit mechanisms to hide or compensate for tube performance. In particular there is no negative feedback to increase the bandwidth of the tube or balanced operation to cancel out even order distortion products.
For this review I compared the Shuguang Treasure 300B’s with those from other manufacturers, using Audio Note U.K. Balanced Kegon amplifiers. The Kegon amps employ only nine parts in the audio circuit path: three transformers (input, interstage coupling and output), two tubes (a driver and a 300B), and four passive components. Notably, there are no capacitors in the signal path.
Prior to the comparison of 300B’s, I spent about five hours listening to n.o.s. tubes other than 300B’s, primarily VT25/10 and 10Y and rectifiers, plus 5U4G and GB. Also, I have learned the box and stenciling on the glass are not a guarantee of the actual provenance of a tube. Even with respect to authentic n.o.s. tubes, RCA might have purchased a particular tube from Sylvania and vice versa. Most manufacturers did not make in-house every tube that they sold under their brand, sometimes farming out the manufacture of a particular tube to another manufacturer. Even today Shuguang manufactures tubes which are rebranded and sold by other suppliers. Having said this, I have had good luck with Josh at Tejas Tubes in Houston. After he and I listened all day one Saturday, I was able to determine that my balanced Kegons clearly and consistently preferred 10Y to 10 variants of the VT25 and the 5U4G to the GB variant. With respect to the VT25, 1940’s Sylvanias seemed well suited to my amps. The Sylvanias were cleaner, more extended at the frequency extremes, more dynamic and richer sounding in the upper bass through the lower midrange. With respect to the rectifiers, Nationals from the 1950’S worked well as did brown base RCA’s. This set the stage for the comparisons which follow.
I should perhaps also point out that the Shuguang Treasure tubes require a rather significant break in period. In my system, they continued to improve until they reached 300 hours after which I noticed no further changes. The tubes even straight from the box were never unpleasant, but the midrange was initially a bit recessed and required significant break in before it seemed correctly in balance with the bass and treble. The same can be said for the crystalline clarity and dimensionality, both of which took time to properly develop. Given that the Western Electric 300B had trounced the generic Shuguangs in earlier listening sessions, I saw no point in including the generics in the final listening.
After I was confident that the Chinese tubes had broken in, it was time to subject them to the acid test: How would they sound against the Western Electric tubes?
I invited one of my audiophile friends over to assist in this comparison. The system was fully warmed up, with the Chinese tubes in place, and we decided to concentrate our efforts on vinyl playback since, in my system, that is where I can get the best resolution.
We began with a promo copy of the US pressing of Donald Fagan’s 1982 solo effort, Nightfly. Fagan, as always, clearly put a great deal of effort into obtaining excellent timbral definition of the instruments, appropriate balance among them, with considerable attention to the smaller details. The slight growl of the Fender-style bass was evident, and satisfying, in several of the tunes. The album serves as almost a lesson in spacious and detailed recording of background voices and winds. And, even being an early digital recording, the overall effect was quite musical most of the time. However, in the last cut on the first side, “Maxine,” we noticed a slightly odd effect — although Fagan’s was the only voice, albeit extensively overdubbed, in the thick, jazzy harmonies, there was just such lack of clarity as revealed by the system that it was not clearly all Fagan and no one else.
Next up was Steve Reich’s Variations for Winds, Strings and Keyboards, played by the San Francisco Symphony conducted by Edo de Waart, an early Phillips digital recording. This piece is in some ways very dense, combining a complex chiaroscuro of woodwind and percussion patterns against slowly moving chordal commentary of predominantly brass choir and bass. The brass/bass parts provided strong and powerful underpinning and highlighting as the piece progressed, which was satisfying, but tended to have a bit of a monolithic sound. The voices of the restless wind/keyboard/percussion patterns were sometimes vague, again as revealed by the system. I must confess that I found myself becoming bored by the repetitiveness, eventually, which can happen with Reich — but was this problem all Reich’s?
Finally, we tried a pure analog recording — again, Phillips — this time of Michael Tippet’s Suite for the Birthday of Prince Charles, written at the time of the Prince’s birth, conducted by Colin Davis with the London Symphony. Phillips recordings, in my view, tend to be inappropriately underrated. However, when we set the stylus onto this LP, I could not help but think that this one was another unfortunate issue. The strings were quite strident — practically leaping out of the left speakers — although the brass, winds and lower strings were fine. Not far into this record, my friend, who knew the recording well, suggested that we see if the irritation was caused by the recording, or if the Western Electrics would bring some relief. So we took a break, let the Chinese tubes cool, installed the Western Electrics, and gave them a brief period to warm up.
The difference in the sound of the tubes was apparent immediately, even without a lengthy warm up period. The strings in the Tippet fell back into the soundstage and, though still with an edge, sounded substantially less “etched” and more like a section of violins. The soundstage was larger and the overall timbre of the instruments was richer — for example, a brief clarinet solo emerged from the string passages with a woodiness that we hadn’t heard before, and the prominent lower brass was more burnished and full.
We moved back to the Reich next. Somewhat to both of our surprise, we listened to the entire piece again, never fatigued for a moment. The busy wind choirs with percussion became more distinct timbrally, such that the lines, rhythms and counter-rhythms became more distinct, requiring less effort to follow. And, as in the Tippet, the brass commentary gained in richness and roundness. The bass may not have been quite as prominent as with the Chinese tubes, but the difference was lost in the overall effect of a more distinctive group of diverse instruments, as opposed to a low-end monolithic line. When it was over, my friend summed it up very simply: “I don’t fully understand why, but this time the Reich was simply more absorbing to hear; I just didn’t want to stop — and it seemed shorter.”
Last, we revisited Donald Fagen and Nightfly. In some ways, I would say the Chinese tubes provided nearly as satisfying a listening experience with this masterful pop/jazz recording. However, we both noticed a new fullness to the vocals and the brass. This came out most noticeably in Maxine — there they were, five or six Donald Fagens, in their dense harmony — no mistaking the voice. And at the end of “Ruby, Ruby”, which devolves into a crowd scene of clapping, shouting, talking, etc, the air and spaciousness was vivid and outstanding.
There is much to like about the Shuguang Treasure 300B tubes. They are clearly superior to generic Shuguang 300B’s and to many of the currently available 300B’s. They excel in many areas, particularly extension at the frequency extremes, dimensionality and low noise; however, in comparison to new old stock Western Electric 300B’s which are no longer in production and only available at significantly higher prices than the Shuguang Treasures, they are clearly leaner and less resolving in the midrange. How you react to this will probably be a function of the type of music that you listen to and your priorities. For rock and pop, they are highly recommended, but for classical music, I would recommend searching out Western Electrics if your budget permits. Again, let me stress that my conclusions are based on listening to these tubes in my amplifiers, and that in a different circuit, the results might have been different.
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