FAQ Page 2

What is the advantage of TubeSync over fixed or auto bias? 

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 magnetisation 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. 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.

Does TubeSync reduce distortion?

No : TubeSync will always ensure that the output tubes are correctly biased and will always ensure that output tubes are operated in push pull are balanced

Will TubeSync make the tubes last longer ?

Yes : TubeSync will make tubes last longer, by continuously monitoring and maintaining the correct bias for the tubes and making use of the auto standby option, excessive dissipation in the tubes can be reduced along with the bulb temperature which will allow the getter in the tube to absorb and residual gas and metallic vapours evaporated from the electrode structure. This can reduce the possibility of metallic vapours condensing on the insulating mica supports of the tube electrode structure which eventually can lead to electrode leakage.

Can TubeSync detect leaky tubes ?     

Yes : However it must be noted that all tubes have some leakage, in the case of a new tube this is usually due to residual gas. This is not usually a problem if the valve is used within its normal limits, as the purpose of the getter is to absorb this residual gas. However the operation of the getter is temperature dependant and relies on the glass bulb being at a slightly lower temperature than the electrode structure in order to operate correctly. TubeSync maintains the correct operating conditions of the valves and the dissipation and ensures that the getter can do its job. If a tube has leakage on its electrodes it can result in an increase in cathode current and this, will be detected by TubeSync which will adjust the bias voltage applied the tube to maintain the correct cathode current. Should the current continue to increase beyond the pre programmed limits TubeSync can switch off the HT power supply and indicate the faulty tube by means of an LED.

 Will TubeSync change the audio output of the amplifier ?

TubeSync will not change the quality or tonal range of the audio amplifier. TubeSync only adjusts the bias when the amplifier has no signal input, but it will maintain the correct bias and maintain linearity of the output stage over the working life of the valves thus ensuring perfect balance of the output stage at all times.