Inspired by the Bugle Boy rectifier, I replaced the LM-518's Russian 6P3P driver tubes with some NOS, new-in-box (NIB), 1959-issued metal-bodied RCA 6L6GCs. The change in sonics was noticeable but less dramatic than when I changed out the rectifier. Best of all, those black-metal tubes look super-cool and are built to outlast diamonds. I kept them in. Later I experimented with some hip, vintage 12AX7s. They made the sound a bit more vivid and intricate, but none were as quiet as the stock tubes. I stuck with stock and they are still working quietly six years later.
I tube roll partly because I enjoy researching how vacuum tubes are constructed. When, where, and by whom they were created? What practical purposes did they originally serve? It's an endlessly fascinating subject.
When I began buying tubes, they were almost free. I found wood barrels full of loose tubes at army surplus stores ($1 each), NIB TV and radio tubes at garage sales ($2 if you take the whole lot), and NOS transmitter tubes at ham fests. One upstate military surplus depot sold used tubes, mil-spec wire-wound resistors, and the highest quality potted transformers—by the pound!
My most enduring love affair has been with 1940s-vintage 2A3s. In the '80s, I would buy them only if they were in undamaged, original boxes. Used, unboxed 2A3 "pulls"—tubes pulled from junk radios or test equipment—never cost more than $5, but the price rose quickly to at least $10 for NIB. Unlike military-spec, "Joint Army Navy" (JAN) tubes, which came in plain boxes with essential tube data printed boldly on the side, consumer-packaged radio and television tubes, like those sold at every American drugstore during my childhood, came in eye-catching, distinctly branded boxes printed with pigment-rich, pre-OSHA inks. I've bought many tubes just because I liked the boxes.
The danger
Tube rolling can be a fun, colorful adventure, but it is also dangerous—to amplifiers, not people. Tube rolling is one of the main reasons amplifiers end up in repair shops. When scouting for tube amplifiers to review, my first consideration is always Is it a simple design and built to last? Generally speaking, if an amp is hard-wired (ie, point-to-point with wires as opposed to circuit boards), it can be handed down to your grandchildren like a fine watch or a Rembrandt etching. If a simply designed tube amp stops working, it is most likely a user-replaceable tube. (That's why tubes were sold in every drugstore.) If the problem is not a tube, the fault will likely be an easily replaceable diode, resistor, or capacitor. My mother fixed tube radios on her kitchen table.
That being said, if you are a complete novice, tube rolling is best navigated with the approval and guidance of your amplifier's dealer, distributor, or manufacturer.
Sound tastings
If the 300B is tube audio's Venus of Willendorf, miniature, nine-pin twin-triodes like the ubiquitous 6DJ8/12AX7/12AU7 are tube audio's tasty bonbons. Because these bonbons amplify low-level voltages, they are the tubes most likely to change the flavor of the sound when exchanging one brand or provenance for another.
While I was writing my Decware 25th Anniversary Zen Triode report, I stumbled on a most tasty radiance-filled bonbon in the form of a made-in-Japan, Electric Industry Co. Ltd. 7DJ8/PCC88 voltage amplifier/driver tube.
You see, Decware's Steve Deckert so loves tube rollers that he offers Zen Triode owners an optional Pelican-cased tube-roller kit that includes alternative/replacement tubes at each circuit position. The Japanese 7DJ8 was the first driver tube I selected from the easy-to-store case.
Driving the Zu Audio Soul Supreme loudspeakers, the Zen Triode amp made recordings sound as pure, nuanced, and radiant as I've ever heard recordings sound. At the start of my auditions, I thought the purity and brilliance I was experiencing were caused by the Zen amp's unique OA3-tube voltage regulators. I was wrong.
When I replaced the Japanese tube with a Russian-made 6H5n, the bass became more powerful and succinct. Drumbeats felt more punctual. Horns sounded brassier. But luminance was dramatically reduced. Both tubes were a pleasure to use, but the Russian tube punched harder and was more plain-truth than the Japanese tube, which generated a more dazzling presence.
12AX7
The 12AX7 was developed by RCA in 1946 as a high-gain, low-noise, audio-frequency amplifier. Current versions are made in China (Shuguang and Psvane), Russia (New Sensor), and Slovakia (JJ Electronic). The ubiquitous 12AX7 is the prince of tubes and, as such, has delivered more music pleasure to more people than any other tube, ever. Just as the Decware Zen was the perfect amp to test 6DJ8s, the Elekit TU-8600S amp is perfect for swapping 12AX7s. For each channel, the TU-8600S employs one section of a 12AX7 twin-triode to drive the paralleled sections of a 12AU7, which, in turn, drives a single, fixed-bias 300B output tube.
During my time with these amplifiers, I have tried as many different 12AX7s as I could rustle up. While I was writing this report, I switched from a hauntingly quiet Gold Aero Platinum Series tube (remember Gold Aero from the 1980s?) to a smooth-plate Telefunken "pull" that was a gift from my buddy Blackie Pagano: musician, cofounder of New York Noise, and legendary tube-amp repair wizard.
One not-insignificant benefit of tube rolling is the possibility of finding extra-extra-quiet tubes. When I get extra silence without losing excitement, I get extra happy. The smooth-plate Telefunken was almost as quiet as the Gold Aero Platinum but much more vivacious, detailed, and creamy sounding. Similarly, the smooth-plate was less quiet than a new Psvane, but the Psvane could not match the Telefunken's exciting textural presence on voices and stringed instruments.
Who makes the best bonbon?
I could bore you with endless miniature-tube comparisons, but their relevance would be limited by the fact that my audio system is different than yours. More importantly, tubes are not made by recipe—they are made in huge batches, using whatever materials were available at the time, aimed at measurable but constantly shifting design parameters. Plus, every tube's cathode emission changes over time. In other words, my Psvane is not likely to sound like your Psvane.
And again, if you never loved your amp's sound, tube rolling isn't going to make you love it. However, if you once loved your amp and now it sounds dull or boring, it will probably perk up with fresh tubes. Here are a few "Herb rules" to guide you in your replacement strategy:
If your amp is a classic '50s or '60s design, save your money and buy good-testing or NOS tubes of the same type it rolled out of the factory with.?
If your amp is of recent manufacture, start by consulting the dealer or distributor who sold it. If it is simple and sturdy like the amps I've discussed, consider using vintage tubes, as they will likely sound stronger, richer, and more exciting while offering greatly extended tube life. The higher cost of NOS tubes will be amortized over their longer useful life.
If you choose to use currently manufactured tubes, I advise you to proceed with caution, spend as little as possible, and assume the tube will last only as long as its warranty. This caution includes new-production 300B tubes.
That being said, the most exciting sector of new-tube manufacturing is the 300B sector. An incredible range of these tubes are currently offered for sale.
300Bs
I have no original Western Electric 300Bs to use for comparison; if I did, they'd be worth at least $3000 each. What I experience every day with my current-production, $120 ElectroHarmonix EH Gold 300Bs seems no less lucid, dimensional, or beautiful of tone than those WE tubes. The Russian-manufactured EH Golds do sound a bit rougher, warmer, thicker, and less starkly clear than old Western Electrics, but I don't care. They have proven their durability and deliver an authentic, satisfying 300B experience. That is why I stick with them.
Unfortunately, I no longer have the made-in-Japan Takatsuki Electric Industry TA-300Bs I used in my review of the Woo Audio WA5 300B amplifier. Back then, I thought the $2500/ pair Japanese 300Bs sounded more like a Western Electric 300B than an actual Western Electric 300B sounds like a Western Electric 300B.
Lately, at Victor Kung's suggestion, I've been using the $495/pair "Cossor"-branded WE300Bs made by Linlai, a company formed by former engineers of Psvane in China (footnote 3). They look and sound an awful lot like those Western Electric tubes we brought back from North Carolina.
Many of today's most reasonably priced, highest-value tube amplifiers are sold without tubes. This makes choosing tubes and tube rolling a necessary part of the purchase-and-ownership process. I approve of this trend; obviously, so do many tube aficionados. In 1989, when those shirtless boys were popping WE300Bs with their pistols, no factories were making them. Today, more than a dozen factories, located in China, Europe, Russia, and Japan, are all manufacturing new versions of Western Electric's most famous tube. Competition is fierce to sell the highest-quality tube at the lowest-possible price. Now is a perfect time to start digging those Venus tubes.
Footnote 3: "Cossor" refers to a British company that ceased operations under that name in the middle of the last century. The trademark is owned by tube-reseller Wi Wi, which commissions tubes under the "Cossor" name.—Jim Austin
Tube rolling can be a fun, colorful adventure, but it is also dangerous—to amplifiers, not people. Tube rolling is one of the main reasons amplifiers end up in repair shops. When scouting for tube amplifiers to review, my first consideration is always Is it a simple design and built to last? Generally speaking, if an amp is hard-wired (ie, point-to-point with wires as opposed to circuit boards), it can be handed down to your grandchildren like a fine watch or a Rembrandt etching. If a simply designed tube amp stops working, it is most likely a user-replaceable tube. (That's why tubes were sold in every drugstore.) If the problem is not a tube, the fault will likely be an easily replaceable diode, resistor, or capacitor. My mother fixed tube radios on her kitchen table.
If the 300B is tube audio's Venus of Willendorf, miniature, nine-pin twin-triodes like the ubiquitous 6DJ8/12AX7/12AU7 are tube audio's tasty bonbons. Because these bonbons amplify low-level voltages, they are the tubes most likely to change the flavor of the sound when exchanging one brand or provenance for another.
The 12AX7 was developed by RCA in 1946 as a high-gain, low-noise, audio-frequency amplifier. Current versions are made in China (Shuguang and Psvane), Russia (New Sensor), and Slovakia (JJ Electronic). The ubiquitous 12AX7 is the prince of tubes and, as such, has delivered more music pleasure to more people than any other tube, ever. Just as the Decware Zen was the perfect amp to test 6DJ8s, the Elekit TU-8600S amp is perfect for swapping 12AX7s. For each channel, the TU-8600S employs one section of a 12AX7 twin-triode to drive the paralleled sections of a 12AU7, which, in turn, drives a single, fixed-bias 300B output tube.
I could bore you with endless miniature-tube comparisons, but their relevance would be limited by the fact that my audio system is different than yours. More importantly, tubes are not made by recipe—they are made in huge batches, using whatever materials were available at the time, aimed at measurable but constantly shifting design parameters. Plus, every tube's cathode emission changes over time. In other words, my Psvane is not likely to sound like your Psvane.
I have no original Western Electric 300Bs to use for comparison; if I did, they'd be worth at least $3000 each. What I experience every day with my current-production, $120 ElectroHarmonix EH Gold 300Bs seems no less lucid, dimensional, or beautiful of tone than those WE tubes. The Russian-manufactured EH Golds do sound a bit rougher, warmer, thicker, and less starkly clear than old Western Electrics, but I don't care. They have proven their durability and deliver an authentic, satisfying 300B experience. That is why I stick with them.
The TA-300B, Takatsuki Electric's version of the Western Electric 300B.
The Takatsuki Electric TA-300B is Japan's first domestically produced vacuum tube in more than 35 years. Takatsuki's stated engineering goal was to improve on the manufacturing precision of the original Western Electric tube. The scope of this ambition is mind-boggling and shows just how much love and reverence the Venus tube continues to inspire. My perception was that the engineers behind this Japanese tube aimed for a pure, authentic WE sound, but, with great respect but also some pride, to add something special of their own, something I would describe as increased corporality or there-ness. Which is why, today, the Takatsuki would be my first choice of new-manufacture 300B tube.
The Linlai 300BLately, at Victor Kung's suggestion, I've been using the $495/pair "Cossor"-branded WE300Bs made by Linlai, a company formed by former engineers of Psvane in China (footnote 3). They look and sound an awful lot like those Western Electric tubes we brought back from North Carolina.
"Cossor" Western Electric replica 300B from Chinese company Linlai, a relatively new player on the tube scene.
Linlai developed these tubes to be "100% 1:1 replicas" of Western Electric's original design. I think they've hit on something: The Linlai replicas deliver all of that unique, audio-on-acid WE transparency, which previously only the Takatsuki replica has achieved. It is too soon to speculate on the tube's real value or verify its durability, but the Cossor WE-replica 300Bs present an exciting, authentic-sounding option at a crazy good price.
You've probably noticedMany of today's most reasonably priced, highest-value tube amplifiers are sold without tubes. This makes choosing tubes and tube rolling a necessary part of the purchase-and-ownership process. I approve of this trend; obviously, so do many tube aficionados. In 1989, when those shirtless boys were popping WE300Bs with their pistols, no factories were making them. Today, more than a dozen factories, located in China, Europe, Russia, and Japan, are all manufacturing new versions of Western Electric's most famous tube. Competition is fierce to sell the highest-quality tube at the lowest-possible price. Now is a perfect time to start digging those Venus tubes.
Footnote 3: "Cossor" refers to a British company that ceased operations under that name in the middle of the last century. The trademark is owned by tube-reseller Wi Wi, which commissions tubes under the "Cossor" name.—Jim Austin
