Posts Tagged ‘how to’


The Advantage Of TubeSync Over Fixed Or Auto Bias

Tuesday, August 11th, 2009

TubeSync has many advantages over other bias methods. An amplifier with fixed bias needs to be set manually and adjusted frequently to maintain the correct bias. Also unless each tube has its own bias setting, at best the results can only be a compromise due characteristic spreads in the valves, which in push pull amplifiers can lead to saturation of the output transformer on high signals due to DC magnetization of the core due to unbalanced anode currents. TubeSync continuously monitors the bias current and ensures perfect DC balance. Auto bias can compensate for valve characteristic spreads providing the characteristics of the valves are closely matched. However auto bias introduces loses by subtracting the bias voltage from the power supply voltage and with some types of valve the losses can be considerable and this means that the anode of the valve has to be operated at a much higher voltage to compensate for the auto bias losses.

TubeSync Amp Biasing

Using TubeSync these losses are eliminated and the HT power supply voltage can be reduced or the amplifier can deliver more output power due to having all of the power supply voltage available to supply the load. TubeSync can compensate for much large spreads in valve characteristics without the need to use specially selected or matched pairs of valves and still maintain the linearity of the output stage.