• 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.

Meng 6PI Biasing Question

Often the Meng 6P1 has 4 trimpots, 2 for hum balance and 2 for phase splitter balance. The output valves are 6P1 (9 pin) and not 6AQ5 (7 pin) but they are generally considered equivalents. The output valves are self-biased so just fit the new ones, no adjustments should be needed. The Mengs I have seen have the 4 trimpots near the front two input stage valves, not the output valves, so if you have trimpots under the bases of the output valves then disregard this info.