It is a stock Dynaco, nothing new except a "new board" with new parts and the Auricaps I spoke of and got your advice on polarity orientation.
I will put back the original Dynaco 7199 tubes and check my bias [15.6?] volts right? Not sure where to check the cathode resistors but I will consult the manual to see what I can dig up.
thanks very much
TomMcNally wrote:Is this a newly built ST-70 ?
Did you set the Bias correctly ? If the tubes are
running too cold, you may experience that kind of
action ... nothing happens until you drive them hard.
Check the bias and make sure you understand what
you should be getting.
I don't know what variety of ST-70 or driver board
you are using, so I can't add much more.
Also, if it's a new build, double check your cathode
resistors and make sure they are 10 ohms, not 100 or 1000 !
... tom