My second express, a little help please

[John_P_WI]

To me it sounds like grid block distortion. I'd look at the PI and surrounding wiring / components all the way to the power tubes. Check the grid leak resistors / grid stoppers on the power tubes etc (pre amp too). When tubes get driven positive and hang up they get woofy / farty / flat sounding. How is the tone stack ground too? Does the tone stack work as it should?

Just a few thoughts this morning....

[Mont]

I removed the C1 22uf cap from the cathode and that seems to have have done the trick except for some high pitched hum. I think I will try putting back the cap and raising the 1.5k ressitor and see what happens. I welcome all comments on this.

[Mont]

the tone stack does'nt work quite as well as the tone tone stack on my first build. I will check every thing again

[Mont]

Should I raise the value of the grid stoppers on the power tubes. also I am going stight from the jack to the grid on the preamp tube first tube( there is a 1 meg on the input jack) should I add a stopper there?

[passfan]

the tone stack does'nt work quite as well as the tone tone stack on my first build. I will check every thing again

I had a tone stack that didn't respond very well once and found a lifted ground off the end of the stack. Check soldered it and it started working again.

[Mont]

To anyone who has had problems with grid block distortion. the express schematic does not show a grid stopper. I added a 2.2k ressitor right at the grid of v1 and the problem was solved.