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2 thoughts on “Genalex B739/12at7 Gold Lion – Great Britain”
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Tube Maze
Guides and reviews of vacuum tubes and tube equipment
I’ve been lagging behind on my review queue lately, but when I encountered this specific tube, I had to set everything else aside and just listen. There is a massive amount of hype surrounding Genalex—many audiophiles consider their glass to be the best in the world, often citing them as the only true rivals to the renowned Western Electric. In this case, I was not disappointed at all.
To be honest, I wasn’t expecting much from a 12AT7. While many of them sound perfectly fine as a driver, they usually offer nothing special as a preamp tube—with a few rare exceptions. This tube, however, brought exactly what other 12AT7 tubes are missing: it has balls. Where many 12AT7s sound thin and clinical, this one has the body of a bodybuilder and the voice of an angel. The bass is incredibly tight, controlled, and powerful, paired with a midrange that rivals the legendary Telefunken ECC803S. It is exceptionally dynamic and transparent, finished with just a touch of musical warmth.
The History of Genalex and Rebranding
Genalex was the premium brand name of the Marconi-Osram Valve Company (M-O V), a British manufacturer. During the mid-20th century, the vacuum tube industry was highly collaborative. M-O V often sourced tubes from other world-class factories, such as Mullard (under the Philips umbrella).
Genalex rebranded these tubes for their own use to signify a “super-grade” product. They didn’t simply slap a new label on standard stock; they implemented a rigorous secondary screening process. They selected only the tubes with the lowest noise floor, highest gain, and most robust construction from the factory’s production runs. By rebranding these elite specimens as Genalex, they created a luxury tier of components specifically for high-fidelity audio and critical industrial applications where standard consumer tubes might fail.
Why the “Gold Lion” Image?
The Gold Lion branding was chosen to evoke a sense of British prestige and undisputed “regal” quality. The lion is a symbol of British heritage and strength, and by rendering it in gold, Genalex signaled that these tubes were the “Gold Standard” of the industry. It was a marketing masterstroke designed to differentiate their hand-selected, premium-tested valves from the “standard” Marconi or Osram labeled versions. The Gold Lion became a badge of honor, assuring the customer they were buying the absolute peak of vacuum tube technology.
Final Verdict: The Genalex B739 Gold Lion is a transformative upgrade for any preamp stage. It provides a rare combination of muscular authority and delicate transparency. STRICTLY RECOMMENDED.
The Genalex B739 shown above was, of course, made by Mullard for the Genalex Gold Lion/M-O Valve company. It is 100% Mullard all the way. It is said that “extra stringent quality control and selection standards” were applied to incoming raw stock of Mullard ECC81/12AT7 tubes.. and that this extra selection process produced a consistently excellent supply of Genalex B739 labeled Mullard 12At7s. The Genalex B739s I have heard pretty much sound 100% like regular Mullards.. only they are 100% free of microphonics and noise. Just like Mullards they have a highly detailed midrange with great soundstaging and smooth, almost “liquid” treble– great tubes. Are they worth paying 10 to 15 times what a regular Mullard 12AT7 costs? Of course not. But the B739s are cool, collectible, and have that gorgeous eye-candy “Genalex” sticker on them. Better, though, to seek out the Mullard CV 4024, the much different (and far superior) British Military version of ECC81/12AT7 made by Mullard. These are still readily available, but with all the new Chinese gear that uses all 12AT7s, prices are climbing.