Tube DIY Asylum

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RE:You mean run the amp w/out the driver tube?

Posted by DAK on January 14, 2017 at 08:47:42:
Since the amp seems to be "unstable" only at home seems meaningful. At home i have wifi, several computers hooked up to it and also a cellphone signal booster all in the same room.
The amp is a simple 2 stage SEUL, 6SN7 to KT90/120. in the design there is no grid stopper on the input/driver tube and the grid stopper for the kt90 is 240R. I have made 4 of these amps with no problems with instability. In this version the 6sn7 is biased with 2 LEDs instead of a 380 ohm resistor. This increased the gain of the tube because it made the amp louder compared to the carbon comp resistor.