Great sounding tube the 6c33c with super low impedance. My experience was that they had a tendency to ‘run away’, glowing cherry red and extremely hot but are cheap enough to just replace periodically on a precautionary basis.
Its Cold War cousin, the 6336A, was the same way in my experience. Great sounding when it was stable, but a very fine line before those graphite plates were glowing and going into full meltdown.Great sounding tube the 6c33c with super low impedance. My experience was that they had a tendency to ‘run away’, glowing cherry red and extremely hot but are cheap enough to just replace periodically on a precautionary basis.
Don't try to match with a tube meter, just use the circuit amp. If it runs too fast or beyond the set point, turn off the amp. Place the tube in the oven at 150 degrees for at least 4 hours and let it cool. try again to see if it runs more stable. Attention I consider this tube unsuitable for cathode bias (resistor) a sensible adjustable negative grid bias works extremely well and stable. *A very working point is 165v anode /190mA current .runs after 2000 hours perfect. Of course, with this tube there is a lot of scrap that doesn't work 100%. Don't worry, make a chess figure out, it looks good as a tower.Great sounding tube the 6c33c with super low impedance. My experience was that they had a tendency to ‘run away’, glowing cherry red and extremely hot but are cheap enough to just replace periodically on a precautionary basis.
Love it! The CV378 (53KU) is my recti of choice and has been for some time in my Horizon. I've been through many of the 4V rectis with various adapters and always come back to the Cossor CV378 staggered plate. It's frequency response performance from outstanding deep bass, through a gorgeous midrange, to highs that capture the hall ambience has superb musicality that has caused me stop recti rollling. (It also doesn't hurt to appreciate that the best tube adapter is no adapter at all!) Two questions: