• 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.

Traynor YBA 1 need a fan?

Sure, why not. More heat, less reliability. Try to get ventilation on the circuit boards
and electrolytic capacitors also. The tubes are designed to run hot, but the rest
of the parts are better off cooler.