• 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.

Art Audio Quintet MK1 EL34 PP resistor value

Hello, I have been enjoying an Art Audio Quintet MK1 EL34 PP ( the one with switch Triode & Ultra Linear) for several years now since I bought it second hand several years in London.

This liittle amp used 2x EL34 per channel and run 15w with triode and 25w with Ultra linear.

Now one of the resistor for EL34 is burnt. The resistors used stated 560 ohm. However I am not sure if it is the original one as the amp is some 20 years old and some parts may have changed since. The circuit diagram I can find online how 470 ohm. Which one should be the right one? Thanks

The standard Mullard 5-20 cathode resistor for UL EL34 is 470R (5W?), but this runs the valves quite hot. Provided you don't intend doing continuous sine wave testing then 560R will be cooler and, perhaps, slightly better on normal music.

The screen grid resistor could be 470-1k - value not too critical, maybe 2W dissipation.