I start at 1/3 and then adjust to taste but mainly depending on V1 gain, I go just a little higher if I put a low-mu AX7 such a Mullard kind in V1 and a little lower with "high gains" such as EH.
BTW what are your "input network" values? Mine are 100k resistor and 100k trimmer, talking about the low-gain e.pro style values would be a completely different matter.
As per Dogears, I set mine to 235K total from the coupling cap to the grid. I've screwed around with it some after that but find this to be the best setting.
....but with 180K series resistor I cant get any lower reading than 248K from cap to grid with trim pot all the way down. I have 180K + 100K trim +68K grid stopper.... So 248K with no trim resistance.
Was 235K with your 169K series resistor ( before Scott suggested a 180K ? )
is it because the trim pot leg is grounded - do I need to disconnect from ground - get a reading , then reconnect ?
Because you can't! You may want to try a smaller resistor over the 100k trim. I currently opted for 158k..... Don't be bashful. Try even lower. You may need to raise the snubbers to tune the highs... The feel is very nice and the amp really sings.
pedro wrote:....but with 180K series resistor I cant get any lower reading than 248K from cap to grid with trim pot all the way down. I have 180K + 100K trim +68K grid stopper.... So 248K with no trim resistance.
Was 235K with your 169K series resistor ( before Scott suggested a 180K ? )
is it because the trim pot leg is grounded - do I need to disconnect from ground - get a reading , then reconnect ?
Also - Pedro, do not consider the grid stopper resistance the same as the rest - because the rest is the resistance to ground, unlike the 68K. The 68K grid stopper interacts with the tube's miller capacitance but the other is the voltage divider that sets your signal strength.
Has anyone any experience with using a resistor, with one resistor at each end, that are both grounded through a trim pot `? I see this on some boards..
