GemTune BL-02 Tube Amplifier Reviewed!

2 thoughts on “GemTune BL-02 Tube Amplifier Reviewed!”

  1. The schematic for this amp is a popular chinese design for many manufacturers amps. I own an amp by another manufacturer with an almost identical schematic for voltages and component values but, probably better OTs.

    The cathode resistor is about twice what it should be and probably biases the amp very cold at 40-50ma.

    It does not have a screen grid resistor, the screen grid supply is from the same tap as the plate supply and it is most likely higher than the actual plate voltage.

    It is a pentode SE but there is no local or global feedback.

    I corrected all of these items in my BEZ. Before correction it was very distorted at 2 watts and clipped at 3+. Afterwards it had excellent performance up to clipping which occurred at about 7 watts.

    Steve

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