Hello,
Thanks to snopro for his efforts on this topic...I received the results a day earlier ;-)
By my oppinion a variac is not needed. As can be seen all the measured tubes are having a little bit different operating conditions. All they are 300B fitting the WE300B datasheet (more or less) wthin the tolerances...The Takasuki's running a little "hotter" and the Psvanes a little "cooler". This is the effect of the deviations of real tube data...(against the design center values/plate curves in datasheet)
So the task is very simple. We have to select the "right" pairs of ER300B fitting to the operating conditions of the Franks (or any other amp whose conditions are known) in all cases(+10% or -10% main voltage) with a small safty margin.
A smart dealer like Gorge should be able to affairs which.
No variac is needed nor any changes in the amp...We only need to know the type of amplifier, so we can deliver the fitting tubes. (This way will improve the sound quality too.)
Regards, Matthias
Thanks to snopro for his efforts on this topic...I received the results a day earlier ;-)
By my oppinion a variac is not needed. As can be seen all the measured tubes are having a little bit different operating conditions. All they are 300B fitting the WE300B datasheet (more or less) wthin the tolerances...The Takasuki's running a little "hotter" and the Psvanes a little "cooler". This is the effect of the deviations of real tube data...(against the design center values/plate curves in datasheet)
So the task is very simple. We have to select the "right" pairs of ER300B fitting to the operating conditions of the Franks (or any other amp whose conditions are known) in all cases(+10% or -10% main voltage) with a small safty margin.
A smart dealer like Gorge should be able to affairs which.
No variac is needed nor any changes in the amp...We only need to know the type of amplifier, so we can deliver the fitting tubes. (This way will improve the sound quality too.)
Regards, Matthias