Mullard CV4004 / 12AX7 - Price of NOS 12AX7s got you down? This new re-issue of the famous Mullard CV4004 made in Russia is the answer to your woes! This is a short plate version of New Sensor's excellent Mullard 12AX7. Very low noise and microphony make this tube an excellent candidate for many touchy preamps and phonostage applications. By all reports, these are even quieter than the long plates, so if you have a difficult circuit, this tube may be your solution.
Like it's long plate brother, the CV4004 has a smooth midrange. Some folks have reported them to be a smidge relaxed on top. If you want something with a little more lively presentation, try the new production Tung-Sol 12AX7.
A quick note on this tube: The filaments on these tubes are almost completely encased in the plate structure. So if you don't see them glowing as bright as some of your other 12AX7s... don't sweat it. It's normal for this tube.
This tube tested extremely low in noise and microphonics across the board, so we do not have any Driver Grade.
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.