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Mullard CV4003 / 12AU7 Vintage New Old Stock
These Mullards are the real deal made in the U.K., not a reissue made in Russia. They come in the original boxes – the very same ones that shipped to the Royal Air Force base in Carlisle, Cumbria, England. It has the classic box-shaped plate and is one of the few 12AU7 tubes that will stand up to difficult applications like CJ and CAT pre-amps. Not to mention that wonderful Mullard midrange.
BUT be aware the Mullard CV4003, as well as the M8136, will relax the top end just a smidge at the tippy top!! If you want the midrange glory of a Mullard but want to maintain that air on top, go to Uncle Kevvy’s personal favorite the British made Brimar CV4003. Also, the Brimar will hold up in CJ, CAT, and other preamps!
Attention Rogue, Conrad Johnson and other "picky" preamp owners!! I had about enough of the PV-10, 11, and 12 being tough on 12AU7's, and was suggesting folks stay with Chinese or RFT, even though they don't sound as good as a Mullard. We now have a test where we can supply you with premium tubes that are quiet and don't go microphonic, and the CV4003 is the only one that will hold up under this test.
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.
Special CJ Test - For guys with Conrad Johnson or Rogue preamps, you want this grade. The absolute tightest triode balance, with the lowest noise and microphony. Then we put these tubes through another special test to ensure they stay low in microphony.