Phono and Line Stage Tubes for the WV Preamps.

"I am surprised when people with high dollar audio gear complain about the cost of good tubes. It is like a Ferrari owner griping about $300 tires. Do you want good sound or not?"

I have received many inquiries about which audio tubes are best for the WV series of preamplifiers. I don't want to tell people which tube to use, but I am happy to provide some general recommendations.

The most common audio tube that will be used in the WV Series will be the 6DJ8 (ECC88) family, which also includes the 6922 (E88CC) and the 7308 (E188CC), athough many other tubes types can be used in the line section of the WV5/WV11. This article will will focus on this tube type, and will include only US and western European "new-old stock," (NOS, i.e., old but unused) 6DJ8 types, and none of the current production tubes, e.g., Russian, eastern European, or eastern Asian tubes will be covered.

Originating from Philips' frame grid 6DJ8, this tube was first produced in 1958-1959, and a good rule of thumb for any of these tubes (as with most audio tubes), is that the earlier versions tend to be the most desirable and their prices will reflect it.

First-time tube buyers should know a couple things:

1.  There is always some risk of paying for a genuine tube but getting an inferior one. Buy your tubes from a reputable source that will guarantee their tubes and have some kind return period. The internal construction of the tube will always reveal whether it is the genuine article or a fake, while the labeling on the bottle is less trustworthy because there are "counterfeit" tubes on the market, inferior tubes that have been rebranded with the markings of a more desirable tube, and even some legal rebrandings. For example, Richardson Electronics in Chicago bought the rights to the Amperex name and use the Bugle Boy logo a few years ago and began rebranding 70' and 80's Sylvania production as Amperex Bugle Boys. They are poor imitations of the originals sonically and can be easily distinguished from the originals by being shorter, fatter and without the hallmark ridges on the top of the tube which both Siemens and Amperex have. Without getting too geeky, the getter flashing ("chrome" inside the bottle) seen on the top of Siemens, Amperex and Telefunkens does not go down the side of the tube to nearly the extent that the Sylvania tubes do. The internal construction is also quite different. The Sylvania is not a "bad" tube, but not one I would use in the WV when any of the others were available. Another company, New Sensor, has bought the rights to the Tung-Sol, Mullard, and Gold Lion and is marketing new production tubes under those names and seems to be trying to build a quality tube.

2. There is no "perfect" tube. Each will have a sonic personality. "Tube rolling," i.e., trying different tubes in your audio gear, is part of the pleasure of owning tube equipment and the WV will let the tube sound shine through so you can become familiar with the different tubes sound like, and tune your system to your sonic preferences.

That said, there were three dominate Western manufacturers of 6DJ8 variants: Siemens, Amperex, and Telefunken. Each of these three manufacturers has a "house" sound and each will have its own appeal. Another major brand, Mullard, reputedly used Amperex designed equipment to build their 6DJ8's, and while they are also excellent tubes, they don't enjoy the reputation that Amperex does. Since we are talking about providing tubes for a truly great preamplifier, only the tubes that in my opinion represent the best of the best will be addressed.

The Siemens tubes tend to be the most "neutral," being very linear, quiet and detailed with excellent extension at both ends of the frequency spectrum. They have a very clean, transparent sound by comparison with the other two. That does not mean they sound lean, but they do not have as much of the warm "tube" sound as some might like. This sound is pretty consistent over age and over the product line. They also tended to have very good quality control with close triode-to-triode matching, which is seen even their commercial-grade 6DJ8's. The most desired of the Siemens is the early CCa, which is a 6922 spec'd for the German telephone service. Siemens 7308's are also a great choice and RCA re-branded these tubes under their name as well, so watch for those.

The Amperex Company (a US division of Philips of Holland) is the originator of the frame grid 6DJ8, and Rogers Electronics in Canada sponsored the registration of this tube with the US's EIA/RETMA. in 1958 The Amperex products tend to be middle-of-the-road-sounding tubes, with very lively sound. Amperex produced the broadest range of 6DJ8 variants from the late 50's until the late 70's, although their 6DJ8s lacked some of the quality control seen in their 6922s and 7308s. There are several very desirable Amperex versions: The rarest and most pricey is the "Pinch Waist" 6922. As its name implies, this tube has a slight narrowing of the glass bottle at the middle which makes it unique. It was produced in the late 50's and few who have heard it have failed to fall under its spell. But don't overlook the early 60's Bugle Boys (not to be confused with the rebranded Sylvania tubes mentioned above) and Orange label "Globe" 6DJ8s, rebranded by many companies, but most notably Hewlett-Packard (HP) for use in their oscilloscopes. While not the quietest, nor the most extended, they are among the most musically enjoyable and engaging tubes ever made. They have great sense of pace, rhythm and tempo, and excellent bass/mid bass punch. They may not the best choice for Classical tastes (Siemens fit the bill there) but are excellent for Pop: they will keep your toes tapping and a smile on your face. My overall favorites of the Amperex are the early and mid-60's 7308's, either the USN-CEP or the PQ types. They have exceptional quality control, are quiet, and possess excellent extension at the extremes; neither of these two will disappoint you. This is a tube that is easy to return to and live with, presenting a balance between the neutrality of the Siemens and the romanticism of the Telefunkens. Philips also manufactured these in Holland under the Philips brand as well as marketed them under the Belgian Adzam (Mazda backwards) label. The Dutch tubes don't have quite the name recognition of the US manufactured products, but they do share the Amperex house sound which makes them very desirable as well.

Then there is Telefunken , which is renowned for its 12AX7 tubes, but only in the last few years have their 6DJ8s attained an equal level of prominence. Telefunkens, of the three discussed here, are the most easily identified with a diamond shape ("<>") cast in the bottom between the pins, which makes them the hardest to fake. They have the most uniform sound and quality control over the entire production period of the three manufacturers discussed here, i.e., they all sound very much the same regardless of production date. Telefunken produced all the 6DJ8 variants as well, but are best known for their 6922/E88CC and their CCa. They also made a 7308/E188CC, but it is less common. Telefunkens have a classic "tube" sound. They are very lush sounding with gorgeous harmonics, but because of that some consider them to sound "dark" by comparison to either the Amperex or especially the lighter-toned Siemens. I find these very satisfying especially with female vocals.

So, to summarize I would list the following as the best of the best of these tubes in no particular order:

Amperex:

• 6DJ8 Bugle Boys and Orange label "World Globes" for fun sound.
• Early 6922's (middle 60's and earlier)
• 7308's; USN-CEP, PQ's and even those into the late 60's and early 70's.

Siemens:

• Early 6DJ8s
• 6922 and CCa's, 60s' are the most desirable
• 7308's until early 70's

Telefunkens:

• All.

Note that in the WV5, there is no need to use the same tubes in the phono stage that are used in the line stage (in fact the WV's line stage's versatility invites trying many tube types there). A very good result can be had by mixing the voices of two tube types. For example, I have gotten very good results using a pair of Siemens ECC88s in the phono stage and a pair of Telefunken 6922s in the line stage. And for lower gain operation, the 12AU7-derived Telefunken ECC802S also sound quite nice in the line stage.

Resources

• Joe's Lore on Tube Asylum provides a pretty comprehensive listing of 6DJ8 variants and their sound though not everyone agrees with all of his comments.
• Audiotubes.com has a lot of information, too.
• Tubemonger.com has a great photo gallery of NOS tubes.
  
• Vendors of good tubes include The Tube Depot, Upscale Audio, Vintage Tube Services, Vacuum Tube Valley, thetubestore.com, and Antique Electronic Supply.