Thanks Marcel,
In the audioXpress article JT describes finding difference in the bass by changing the tubes in the first section and that changing in the second seemed not to make any.
I have to make up another board anyway so there'll be time to read more on filters. My math abilities are basic arithmetic so it takes a while to form descriptions that I can put into effect.
On top of that , I 'm not sure what the cause is for that ragged behaviour at 50-500Hz .
(If it turns out to be layout related it would surely be nice to have that figured out before I build another. My trouble is impatience. I'll likely not be able to stop myself building the second channel as soon as I find the time, whether I know or not.) : )
In the audioXpress article JT describes finding difference in the bass by changing the tubes in the first section and that changing in the second seemed not to make any.
So perhaps to make use of my larger value capacitors a place to start is simply to calculate the R values for the zero and second pole as you detailed above and then experiment with the second stage to get the first pole right.
I have to make up another board anyway so there'll be time to read more on filters. My math abilities are basic arithmetic so it takes a while to form descriptions that I can put into effect.
On top of that , I 'm not sure what the cause is for that ragged behaviour at 50-500Hz .
(If it turns out to be layout related it would surely be nice to have that figured out before I build another. My trouble is impatience. I'll likely not be able to stop myself building the second channel as soon as I find the time, whether I know or not.) : )
