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Radiotechnique 12AU7/6189 - 1965 vintage made in France. This is the French arm of Philips Holland who also owned Amperex and Mullard. So it makes sense these have a plate structure similar to Amperex Bugle Boys. But better IMHO because so many Bugle Boy 12AU7's I see being offered are leftovers. These were released by the French Army where they sat since 1965.
The are in military box, and are sealed in a small vinyl bag, until we cut the bag open and test them for Gm/noise/microphony one at a time, and give you the measurements. God sent for VAC, CAT's, and other products as customers report.
Radiotechnique was the French arm of Philips Holland, and this tube shares many sonic characteristics with its Dutch cousins, most notably it's holographic soundstaging and open, airy top end. May be one of the more dynamic 12AU7's. For more info on the Philips factories, click here.
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.