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Mullard M8136/12AU7 – Holy Mackeral! You know guys and gals, sometimes I get surprised. I guess you know that we have something to do with PrimaLuna products. And I asked specifically that they use 12AU7 tubes because there are more of them made today in great factories, and more vintage NOS (New Old Stock) from the great companies like Cifte, Mullard, Philips, Mazda, Siemens, Telefunken, La Radiotechnique, and Brimar than any other tube. None of this jive-ass 6H30 crap.
And with that I’m a man on a mission. I fight at every turn to get you the stuff you thought was gone forever. This is the early wrinkle-glass large getter ring, box anode M8136. It’s the same tube as the CV4003 you see elsewhere on this website. Made in the 60’s, the boxes didn’t make it, so they are in white box. The sound? Like the CV4003, they are typical Mullard beauty. Mids to die for. That’s what they do. The top end is just slightly relaxed. I have some in my personal preamp (PrimaLuna DiaLogue Premium) and love them. Though I’m gonna say the jury is out on what I like best because I love the air of the Brimar. Hey man, who cares. Uncle Kevy’s got ‘em. And that’s a thrill.
Each tube is graded carefully on both an Amplitrex AT-1000 and a Triplett 3444a. After that we grade for noise and microphony by ear with headphones in a single-tube moving coil phono stage circuit where the tube is really under a microscope and listed to with headphones. And we mean that. Every tube is listened to with headphones. Nobody spends as much time and grading tubes as Upscale Audio. And while other people are selling you used “New Old Stock” we have the real deal.
Price is for a single tube. These tubes come in generic white boxes. Price includes matching in any quantity you need at no extra charge. Logo quality may vary from picture above.
Platinum grade - The best of the best. Lowest noise and microphony with the tightest triode balance we have available. This is typically 10% or tighter, but may be higher depending on available stock.
Gold grade - Low noise and microphonics with a triode balance typically between 15% and 20%, but may be higher depending on available stock.
Driver/Buffer grade - Lowest noise but not the lowest in microphony. Triode balance will be similar to Gold grade.
This grade is only suitable for use in the driver stage of an amplifier, or the output/buffer stage of a DAC or CD Player.
If you have a preamp or phonostage, you need at least Gold grade.