Product: Treasure 6SN7-SE Globe bottle double triode
Distributor: Grant Fidelity
Price: $315.00 tested matched pair; premium selected quality (as tested) $375.00USD per matched pair tested for section balance & "super low noise". YMMV due to currency volatility
Valve base type: Octal
Reviewer: Mark Wheeler - TNT UK
Reviewed: February, 2016
Some readers might ROFL (Roll On Floor Laughing) at the thought of paying over 300 bucks for a brand new pair of valves, even if some elderly tubes go for even more dosh. It is a bit like the classic car market, that has gone berserk recently as interest rates and equities offer poor returns, people are now seeing them as investments. A typical old air-cooled 911 now costs more than a reliable new Porsche 911 and there is a danger that will happen to NOS valves. There are now collectors of old valves (tubes) and NOS valves have already become stupidly expensive and simple economic theory (demand and supply) implies this will get worse. This may be reminiscent of the Tulipomania tulip bulb bubble of the seventeenth century. You'd be stupid to pay the figures asked by collectors of tulip bulbs or glass bulbs, inflated by scarcity and demand, when what you really want is better sound. This makes it worthwhile for manufacturers to consider new designs aimed at audio excellence, confident the low volume production prices look reasonable next to the collector's NOS prices. ROTR (Roll On Tube Rolling) though, must be replaced today with ROVR (Roll On Valve Rolling), because we are not rotters (ROTR's), but rovers (ROVR's). ROVR's not to be confused with classic cars or pedigree dogs, but Roll On Valve Rolling, because the The Shuguang 6SN7-SE are not tubes but globes. Equally, they are not 6SN7GT, a suffix denoting Glass Tube not Grand Tourer, they are 6SN7-SE.
"What is this rambling drivel?" challenge plebs chorus, stage left, "This is the fifth TNT-audio review of Shuguang valves. Are TNT-audio.com now accepting payola like the advertising driven audio comics?"
Shuguang have been busy developing new high-end audio valves recently and are not afraid to submit them to TNT-audio.com's unbiased criticism. Their North American distributor manages to get them promptly to TNT-audio reviewers without customs & excise hassles so we reviewers are happy to cast an ear in their direction. Recent releases have been aimed at applying modern design and production techniques to raising the bar above the preferred NOS (New Old Stock) types, like the Treasure 6SL7-Z. The Shuguang Treasure Globe 6SN7-SE is exclusive to Grant Fidelity as it was commissioned by them and developed as a joint enterprise between them. It is available in two grades, the extra 60 dollars buys the samples with the lowest noise. The $315 per matched pair grade are also said to be tested for low noise so the difference might well be in the diminishing returns zone. This implies that for most positions in most circuits $315 will be enough to spend, but for the input valve on a single-ended zero feedback circuit the extra money might be well spent as any residual noise would be amplified downstream.
The 6SN7 is an octal base (8 pins at a radius of 17.45mm, K8A standard) double triode. It is electrically similar to the miniature 6CG7 and 6FQ7 (B9a or Noval base) used in the middle position by Doug Dunlop in the Concordant Excelsior and Explicit power-supply. The 6SN7GT was nominally two 6J5 triodes in one glass envelope. There was once a metal base 6SN7 type known as the B65, but the similarity to the metal base Shuguang 6SN7-SE ends there. There was a time when it would be possible to say that the octal base valves tended to be seen more commonly in esoteric North American amplification while the ECC series tended to be dominant in Europe. This is not true anymore as the internet has created a global market and offered access to libraries of data sheets of almost every valve type imaginable. The 6SN7 was designed for audio applications and is still used for valve hi-fi amplifier designs. The glass tube envelope of the 6SN7GT (Glass Tube, not Grand Tourismo) is 27 mm diameter and 64mm tall, excluding the pins. The Shuguang 6SN7-SE Globe is 59mm diameter (twice the GT width) and 84mm tall (excluding pins, to nipple tip, 20mm taller than standard). Its base is a beautiful polished and lacquered brass 31mm diameter cylinder, like the 31mm diameter of the 'correct' 6SN7GT base. The alternative Shuguang CV181 has a ceramic base 35mm diameter and it is 95mm tall and 45mm shouldered. These new valves are more likely to be used in open chassis amplifiers where there will be enough space to house them and allow enough room for cooling air to circulate.
The sound of particular valves (and their ensuing reputation as soon as this sound is posted on a discussion board) is often no more than a variation in one electrical parameter;
e.g. the ECC32 has a reputation as a super 6SN7 but has slightly more gain, which is either louder or driving the next stage harder in a guitar amp, resulting in 'tone'.
There are features that can affect performance, such that a difference might be heard but not measured. The carbon coating in some Brimar samples (and many other brands) was designed to prevent stray electrons from massing on the glass. Because the electrons will tend to stray from the same areas of the plate, grid and cathode assembly their negative charges will be concentrated and will exert forces in the envelope that may affect performance of the valve.
Extended operation would result in the cumulative effects. Hence, the recently reviewed Shuguang CV181 boasts a newly developed high-performance coating (obviously named HPCC).
Post-war cost-cutting was blamed for the disappearance of the carbon coating, but that cannot explain its absence on the Shuguang Globe 6SN7-SE. Electrons striking glass can also release oxygen which is a bad thing in a valve (vacuum tube) causing the hot cathode to be poisoned.
The large globe shape of the glass envelope may mitigate the stray electron massing problem and the choice of uncoated clear glass is probably aesthetic.
These babies are designed to be on show on your couture steampunk copper chassis single-ended monster.
The getter has been flashed to a small area at the bottom of the envelope on one side close to the circular getter structure.
The getter is an important element of valve design in contributing to extended life by mopping up gas contaminants in the glass envelope, which might contribute to problems like cathode poison, and is usually made from a small quantity of barium.
The anodes (plates) are grey box plates (T-profiles) extending about 25mm tall and spaced further apart than in typical GT types. The bigger bottle of octal valves than B9a types has often meant much lower crosstalk between the two triode sections (measured at worse than 60dB on the b9a miniature ECC88/6922). Bigger valve internal structures can be more microphonic, hence the octal type's reputation for microphonic bloom colouration. These factors might all affect how valves sound different despite electrical similarities and you pays yer money and you takes yer choice.
Hand assembly and tight quality control are boasted by Shuguang for all their Treasure series, and no extra claims are made for the 6SN7-SE. Grant Fidelity, the the instigators and Western importers of these devices, add a further degree of selection and matching. The valves are packed in pairs, with their inspection docket, in cardboard boxes with accurately cut foam protection inside.
The only amplifier I have where there is space for the Shuguang 6SN7-SE is the hot-rodded Assemblage (nee Sonic Frontiers) SET300B SE Signature.
This is the input valve position and the valve is common between the two channels.
Therefore, each of the two triode sections provide the initial gain in this amplifier and the absence of feedback means hearing the valve, the whole valve and nothing but the valve (all else being unchanged).
It is worth repeating that Octal base double triodes often have lower crosstalk between sections than miniature b9a valves, probably because there is more room to space the individual components.
Equally worth the repetition is that the clear globe of the review valve forsakes the opportunity of Shuguang's proprietary HPCC inner coating to suppress secondary electron emission from the glass. Presumably this is on aesthetic grounds and the large globe shape may negate its necessity.
Single-ended circuits expose an amplifying device ruthlessly. There is no noise or distortion cancellation like there is in a difference, balanced or push-pull amplifier.
There is no feedback to reduce distortion and improve stability. In a single-ended power amplifier circuit the input valve works hardest to provide gain and therefore noise is a premium.
Any noise in this valve is amplified by every subsequent valve. Even if relatively inaudible, the noise will mask the subtle details and nuances of performance.
If the 6SN7 is in a driver position in the circuit, where it will be juiced up hard and providing minimal gain, the regular $315 valve is likely to be indistinguishable from the dearer samples.
After the 6SL7-Z review had gone to press, the 6SL7-Z continued to improve. This makes it more challenging to identify differences as the new Globe 6SN7-SE is inserted into the system. Comparisons were therefore undertaken using the stock Canor TTM selected valves in the phono section. Later the Treasure 6SL7-Z was inserted into the Canor TP306 VR+ to establish the cumulative effect. This importance of cumulative effect was demonstrated to Your Old Scribe, by Doug Dunlop, of Concordant. It was Doug who introduced your Old Scribe to the arcane rituals of tube-rolling, and Doug often insisted that two much of one brand of valves in one system could create an overwhelming character.
Considerable experimentation has indicated that the Canor TP306 VR+ gives of its best supported by 3 Yamamoto PB9 & PB10 setting bases and point receivers on the ERaudio SpaceHarmoniser platform. This stands on ERaudio Steel Cones, mounted on a something solid shelf, on the Something Solid XR4 rack standing on Something Solid Missing Link feet. The importance of tuning and vibration control cannot be overstated for valve equipment. Between the the Canor TP306 VR+ phono-stage and the Assemblage SET300B SE Signature there is nothing more than a variable transformer, supported by 3 BrightStar Isonodes. In this context, the Grant Fidelity Globe 6SN7-SE could show its mettle.
For the last few albums, the black bottle Grant Fidelity 6SL7-Z were re-inserted into the Canor TP306 VR+ phono pre-amplifier input valve position, the cumulative benefits emerged. The 6SL7-Z were originally reviewed in the Canor TP306 VR+ through the Canor TP106 VR+ ultralinear push-pull integrated amplifier. Now the phono pre-amp is being heard through the zero negative feedback all triode single ended power amplifier. Volume control is via an IAG variable transformer using Sowter windings (IAG being the name of a specialist American audiophile DIY component supplier as well as the name of a massive trans-global holding company who own classic brands like Quad and Wharfedale.
Percussion might seem an odd choice to demonstrate the strengths of zero NFB triodes, but Billy Cobham's much sampled classic album, Spectrum spins first. The unusual timbre of Cobham's unique North drums (single skin with a bell-mouth) is accurately rendered. Cobham"s Simplicity of Expression: Depth of Thought has to be on next. Through the Assemblage SET300B (Assemblage being the DIY branch of Sonic Frontiers), immediately, a different set (plebs groan at pun) of strengths become apparent from the whole system.
Sublime midrange invites female vocalists to the platter, from the blues of Billie Holiday to the power of Grace Slick. The softer single-ended triode bass seems better articulated than I remember from this amplifier. The glass is only there to drive the iron, and the big custom wound output transformers offer much better bass than most directly-heated triode output stages, regardless of 300B brand chosen. Even with the Valve Art 300B in place while burning-in the Grant Fidelity Globe 6SN7-SE, the differences are obvious. The Valve Art valves are the least favoured in this amp, even though they were the standard specified original equipment.
Moving uptempo to the soulful electronica of cousin Caron Wheeler a spot of tube rolling is in order. The JJ Meshplate 300B is first to the plate. There are mixed views about this valve, but it did some things really well, especially vocals. Sadly the rigorous life in a reviewer's system has taken a toll, and one of the pair is no longer heating after one too many cycle of unplugging and replugging in its socket. Onto the main course then and in go the Western Electric 300B pair. Immediately, from cold, the bass is firmer, the vocals are clearer and the soundstage more defined.
In any system there are two directions of performance. Musical information starts with the recording, moves on through the storage medium, the retrieval system, the pre-amplifier stages (and active crossover), the power amplifier stages, the passive crossover and the drivers and cabinet system. Musical presentation is affected the other way around. The speaker-room interface is most immediately obvious, then the amplifier-crossover interface, then power amplifier, pre-amplifier and source. Occasionally a particularly characterful turntable or ruthlessly revealing studio monitors (active) will upset these hierarchies, but the established wisdom usually holds.
Within a Single Ended Directly Heated Triode (SEDHT) valve power amplifier, this hierarchy holds INTERNALLY too. The performance of the output transformer (OTX) is noticeable in its presentation of dynamics, transparency and bass performance. Any sense of strain is often down to under-specified iron. The output valves (in this case 300B) can only drive the iron as well as they are driven themselves. It is the input valve's task to translate every electron at the grid into music for the driver stage. To ease the task, this example of the Assemblage SET300B has every resistor, capacitor and mm of hook-up wire replaced with the best component for the job in that location; even some circuit board tracks have been replaced by point-to-point wiring. The valves are operating in optimum conditions, so if differences are observed, they will be typical.
How does the Shuguang Globe 6SN7-SE differ from the Shuguang CV181? inquire plebs, stage left.
The Shuguang so-called CV181 is REALLY a 6SN7. What's in a name? That they call a CV181 by any other name would sound as sweet. So CV181 would, were it not CV181 call'd, retain that dear perfection which it owes, without that title. The differences between these two valves are understandably subtle. Both valves were designed by the same team. It is impossible to observe the internal construction of the black bottle Shuguang, nor the previously favoured black bottle NOS Brimar. Hence only subjective impressions serve to indicate whether there are real differences between these valves or whether the differences are down to hours in use and sample variation.
The differences are subtle. The Globe valve has slightly less gain than the CV181 (a little over 1dB at a guess). Fundamentally the sound differences between these two iterations of the 6SN7 specification fall into two groups of differences.
The first group of differences were in the domain of articulation. The differences in bass articulation are of less magnitude than between the Valve Art 300B and the Western Electric 300B. The Globe 6SL7-SE is consistently slightly better than the CV181, which in turn was better than all NOS tried.
The second group of differences concern what the late Australian valve amplifier designer Allen Wright calls "Downward dynamic range". This includes the Flat Earther's concept of "information retrieval" but picks up that idea and carries it further into the zone of quality of information as well as quantity of information. The new Shuguang Globe 6SN7-SE consistently widens the dynamic envelope further downward compared with the so-called CV 181. In practice this sounds like the upper limits of dynamic range are no different; peaks sound similar and big transients have similar impact. However, subtle nuance, usually concealed during dense passages of orchestration, or production, become explicit. Individual bowing of original instruments in the Hogwood Beethoven becomes newly noticeable if listened for, but not distractingly foregrounded.
After hearing new details in the reissue familiar Hendrix Axis Bold As Love, your Old Scribe had to play his 40 year old original to check the newly heard details are not merely newly audible on the new pressing. Although A-B comparisons are ill-advised, because they tend to exaggerate subtle differences, it was through back to back listening that the differences became explicit. This is time consuming and requires care not to damage the valves or the valve bases and it requires ensuring equality of cool-down and warm-up times for each valve. A similar experience (Plebs Chorus emit another deep groan at another appalling pun) was had with the reissue of Hendrix's Electric Ladyland.
Curiously, the nearest familiar comparison that comes to mind between the characters of these two valves is between two brands of solid state amplifier. Imagine two similarly priced classic Naim and Musical Fidelity amplifiers. The Naim will offer more information, articulation and bass definition and deliver it with more forward presentation. The Musical Fidelity will offer smooth sweetness and a soundstage further back behind the speaker plane. Now imagine moving up one model pre-amp power supply (say SNAPS to HiCap) up in the Naim hierarchy; that is the kind of difference between these two valves.
By switching to the modified Shanling CDT100c CD player DI'd into the modified Assemblage (née Sonic Frontiers) SET300B Signature the Shuguang Globe 6SN7-SE faces more challenging operating conditions than those of the variable transformer passive volume control. The Chesky set up disc was used to optimise the system and the listening began. Soon the downward dynamic range advantage of these valves led to listening to some of the Mapleshade recordings. Midnite's Ras Mek Peace demonstrates how well this valve handles vocals while bass is going on. Yucca Flats' Garden of Weeds recording contains a wealth of low-level detail that the Shuguang Globe 6SN7-SE revealed coherently. The globe 6SN7=SE grid is as happy being driven by the Shanling's cathode follower output as by the IAG matching transformer.
If you already own great NOS 6SN7 valves, and there are other areas where your system needs improvement, the money would be better spent there. If you already have the Shuguang CV181 version of the 6SN7, it would be worth waiting until they drift off spec, before replacing them. If you do not have space for the extra width of the globe bottle, the CV181 would be fine and more predictable than NOS.
Most customers for the Shuguang Globe 6SN7-SE will be attracted to the looks. That big glass globe and the polished brass base make a real statement. The sound backs up those looks. The inconsistency of NOS samples makes them an expensive gamble now (your old scribe's collection was amassed before the existence of flea-bay). Both the Shuguang CV181 and the Shuguang Globe 6SN7-SE are limited in application by the size of their non-standard glass envelopes. The extra space may have enabled the performance gains, but in an enclosed chassis amplifier they may not be feasible.
The better articulation (especially bass) and downward dynamic range make the Shuguang Globe 6SL7-SE a worthwhile choice in a high resolution single-ended triode system, especially where they will be on view. It is deeply ironic that in 2015, the pre-1950's technologies of valve and vinyl are still making strides ahead.
The question of value is difficult to evaluate. A pair of these valves cost considerably less than a metre pair of fancy interconnect wire and will almost certainly make more difference. The active devices in audio systems (usually valves or transistors, however miniaturised) make considerably more difference (for obvious reasons) than the reactive devices (capacitors and inductors) or passive devices (diodes, resistors and wires). The fact that all these devices have a tendency to be reactive is merely part of the pallette of inaccuracies that plague audio. Balancing these inaccuracies is as much a creative art form as it is engineering. Using these valves in place of cheap modern equivalents is worth far more than the difference between giveaway interconnect and 300 dollar interconnect.
The difference between these valves and $100 NOS 6SN7GT tubes is impossible to quantify as such merchandise is so variable, having endured years either being shunted around various dusty warehouses or spent years stored in climate controlled military storage. With valve based audio amplification the hierarchy of difference begins with valves, then with vibration control, then reactive devices and finally reaches passive components. This apple-cart is only upset when passive devices behave reactively (inductive resistors for example). In a cheap modern amplifier the extra cost is not justified, because upgrading all the valves would be a better way to spend $300 initially.
If your 6SN7's are on show and there is space for them, there is every reason, sonic and aesthetic, to install the Shuguang Globe 6SN7-SE. In a high resolution system, especially of the low-to-no negative-feedback persuasion, these Shuguang globe 6SN7-SE bottles are the state of the new-wave-of-valve-production (NWOVP). So far Shuguang have not put a foot wrong and we can hope they continue to innovate new versions of those classic valves we all love.
|Music enjoyed during this review||Reference system|
Equipment used in this review:
Copyright © 2016 Mark Wheeler - firstname.lastname@example.org - www.tnt-audio.com