Radiotechnique 12AU7 - Made in France. This is the earliest version of this tube, period. There was a middle version that we had available, but did not dig as much. In fact there are four versions that I have in stock. Only this version, and the 1965 version are cool in my book. This one is made from 1956 to 1960, early getter, small plate. Sound wonderful, and seem to last.
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. For more info on the Philips factories, click here. This tube blooms more and has a decided 3d effect. The top end is extended but not bright. Bass is fabulous.
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 - Not available at this time. Don't be a cheapskate. Get the best stuff.