WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
i wanna build Tube pre-amp. im using 5687 tube.
i have found The Pre-amp circuit but that circuit biased by LED...
what is the profit if i using LED for biasing..??
thanx..