NOTICE: Be sure to enter the Make & Model of component you are purchasing tubes for. Failure to do so will delay processing of your order. We do not ship tubes without this information.
Amperex Medical 12AU7 - These were made for a company called Electronics For Medicine in New York back in the 1960’s. They needed to be the best, so they used Amperex Holland 12AU7’s that were made for the most critical applications. They are really special. The internal balance is so tight, the transconductance so healthy, the noise so low. You guys know I have been doing this FOREVER. I have only ever seen these one here and one there over the years. So when an opportunity came up to get a nice stash and offer them to you, I was all over it.
As good as they are, what is listed here is Platinum and Gold grade. So this is the cream of the crop. These were in a master box that was sitting for fifty years. The box had gotten damp at one point and some of them lost some of their logos. We will default by sending out the best testing first. If you need complete logos for display purposes, please let us know in the notes section and we'll do our best.
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. Logos may vary in quality from picture above. Price includes matching in any quantity you need at no extra charge.
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 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.